Class 10 Life Science

Chapter 2 Mitotic And Meiotic Cell Division Summary

WBBSE Class 10 Mitosis Overview

• Mitotic cell division is mainly divided into two parts karyokinesis and cytokinesis. In karyokinesis, the division of the nucleus occurs in four stages-prophase, metaphase, anaphase and telophase and after completing karyokinesis, cytokinesis or cytoplasmic division takes place.
• As said earlier, karyokinesis occurs in four phases-prophase, metaphase, anaphase and telophase. In prophase, chromatins are getting packed densely to form chromosomes along with spindle fibre.
• In metaphase, chromosomes become arranged in an equatorial line. Chromatids move to opposite poles, during anaphase. And lastly, during telophase two daughter nuclei are formed at two poles of the cell.

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• The cytokinesis process is quite different in animal and plant cells. In the case of animals, the cleavage method takes place to complete this process but in case of plant cells, cell plate formation is mandatory for cytokinesis.
• Along with mitosis, meiosis cell division also takes place. It is important for the formation of the gamete. Meiosis is of two types-Meiosis I also known as reductional division and meiosis II, which is also known as equational division.
• Like mitosis, meiosis is also divided into karyokinesis through prophase, metaphase, anaphase and telophase and cytokinesis. Though in the mitotic division, the number of chromosomes stays constant, in the meiotic division the chromosome number reduces to half.
• During gametogenesis by meiosis, crossing occurs between two non-sister chromatids of two homologous chromosomes, helping to produce a variation.

Chapter 2 Mitotic And Meiotic Cell Division Long Answer Type Questions

Question 1. Mention the different phases of mitosis and point out the main events of each phase.

Answer:

Different phases of mitosis and the main events of each phase:

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Mitosis occurs in two main phases, karyokinesis or nuclear division and cytokinesis or cytoplasmic division. Karyokinesis is subdivided into four phases-prophase, metaphase, anaphase and telophase. The main events of these phases are mentioned below.

Question 2. Describe the prophase of mitosis in plant and animal cells.

Answer:

Prophase of mitosis in plant and animal cells:

The first phase of karyokinesis is called prophase. The events which take place during this phase, in both plant and animal cells, are discussed here.

Prophase in plant cells:

The events occurring during prophase in plant cells are as follows-

1. During this phase, the nucleus swells.
2. The chromatin reticular start coiling, get dehydrated and form chromosomes.
3. Each chromosome appears with two chromatids, which remain attached to each other by the centromere.
4. Chromatids undergo coiling or serialisation to make the chromosome thick.
5. Nucleolus gradually diminishes in size. At the end of this phase, both the nucleolus and nuclear membrane disappear.
6. Within the cytoplasm, microtubules grow, which form the ancestral spindle during the later phases.

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2. Prophase in animal cells:

The above-mentioned events also occur in animal cells except for the development of microtubules for spindle formation. Other than these, certain typical events occur in animal cells during prophase.

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These are as follows-

1. The two centrosomes with paired centrioles, formed during interphase, start moving to two opposite poles of the cell during early prophase.
2. Astral rays radiate from the two centrosomes. Gradually, the rays grow in length, which in the later phase, prepare the astral spindle.

Stages of Mitosis Explained

Question 3. Describe the metaphase of mitosis in plant and animal cells.

Answer:

Metaphase of mitosis in plant and animal cells:

The second phase of karyokinesis is called metaphase. The events occurring during this phase in both plant and animal cells are discussed below.

1. Metaphase in plant cells:

The events occurring during metaphase in plant cells are as follows-

1. The nuclear membrane and nucleolus disappear completely.
2. Cytoplasmic microtubules arrange to form a spindle. This spindle is formed without the involvement of the centrosome, therefore, it is called an astral spindle.This spindle comprises two types of fibres, which are-
3. Chromosomal spindle fibres, which bind one pole of the spindle to the centromere of chromosomes and
4. Continuous spindle fibres, which connect the two poles of the spindle.
5. All the chromosomes arrange along the equatorial plane of the dividing cell and the chromatids of each chromosome stay parallel to that plane. This typical distribution of the chromosomes forms the metaphase plate or equatorial plate across the cell.
6. Chromosomes become the densest and thickest.
7. At the end of this phase, the centromere of each chromosome starts to split longitudinally.

2. Metaphase in animal cells:

All the above-mentioned events occur in animal cells also, except the spindle formation. Here, the spindle is formed by the extension of astral rays from the centrioles, positioned at the two opposite poles of the dividing cell.

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Question 4. Describe the anaphase of mitosis in plant and animal cells. Or, Mention three changes that occur in the anaphase stage of mitosis in animal cells.
Or,
Draw a neat diagram of the anaphase of mitosis of an animal cell and label the following parts:

1. Polar region,
2. Spindle fibre,
3. Chromatid,
4. Centromere.

Answer:

Anaphase of mitosis in plant and animal cells:

The third phase of karyokinesis, in which the daughter chromosomes move from the equatorial plate towards the two opposite poles of the dividing cell, is called anaphase. The events which occur during this phase, in both plant and animal cells, are discussed below.

1. Anaphase in plant cells:

The events occurring during anaphase, in plant cells, are as follows-

1. The Centromere of each chromosome splits longitudinally, as a result, two sister chromatids separate from each other with their own share of centromere and emerge as two daughter chromosomes.
2. The Centromere of each daughter chromosome remains attached to the chromosomal spindle fibre.
3. Inter-polar or Chromosomal continuous spindle fibres connect the two poles of the -spindle fibre spindle.
4. Gradually, the chromosomal fibres contract. -Chromatid to pull half of the daughter chromosomes towards one separation Inter-zonal pole and the remaining half to the opposite pole. This is a spindle fibre called anaphasic movement.
5. During anaphasic, movement, metacentric, sub-metacentric, acrocentric and telocentric chromosomes appear like the English letters ‘V’ ‘L’, ‘J’ and ‘I’ respectively, based on the position of centromere on the chromosome.

2. Anaphase in animal cells:

The above-mentioned events also occur during anaphase in animal cells. Here, inter-zonal spindle fibres cluster in between separating chromosomes to form columnar stem bodies, which help in anaphasic movement.

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Question 5. Describe the telophase of mitosis in plant and animal cells.

Answer:

Telophase of mitosis in plant and animal cells:

The fourth phase of karyokinesis, in which two daughter nuclei are formed within a dividing cell, is called telophase. The events which take place during this phase, in both plant and animal cells, are discussed below.

Telophase in plant cells:

The events occurring during telophase, in plant cells, are as follows-

1. At the start of telophase, an equal number of chromosomes reach the two opposite poles of the spindle.
2. The chromosomes uncoil and rehydrate to become thin and long to form chromatin.
3. The nuclear membrane reappears around chromatin.
4. Nucleolus reappears within the nucleus.
5. Finally, two equal numbers of chromosome-bearing and morphologically identical nuclei form within the dividing cell.
6. After the formation of two daughter nuclei, during the end of telophase, cell plate formation starts by deposition of phragmoplast granules in the equatorial plane of the cell.

2. Telophase in animal cells:

The events of telophase in animal cells are the same as that of plant cells except, in the case of animal cells a cleavage or furrow appears in between the cytoplasm during the late telophase stage, instead of phragmoplast.

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Meiosis vs Mitosis Comparison

Question 6. Describe the events occurring during cytokinesis in plant and animal cells.

Answer:

Cytokinesis in plant and animal cells:

The cytokinesis phase actually starts from the late telophase stage and continues until the cytoplasm of the cell divides into two halves, thus creating two daughter cells.

1. Cytokinesis in plant cells:

The events which occur during cytokinesis in plant cells are as follows-

1. At the end of telophase, microtubules, microfilaments and endoplasmic reticular elements arrange along the equatorial plane to form phragmoplast.
2. Golgi vesicles align along the two sides of the phragmoplast and form the cell membrane of the two daughter cells.
3. In the course of time, the phragmoplast forms a thin cell plate, which transforms into middle lamella, composed of calcium and magnesium pectate.
4. Cellulose, hemicellulose, callose etc. accumulate at two sides of the middle lamella to form the primary cell wall. With the formation of the primary cell wall, the cytoplasm of the mother cell separates completely to give rise to two daughter cells.

2. Cytokinesis in animal cells:

The events which occur during cytokinesis in animal cells are as follows-

1. At the start of telophase, the cell membrane moves inward along the equatorial line to form a constriction or furrow. Microfilaments accumulate below the cell membrane and their interaction pulls it to develop the furrow.
2. With time, as the cell enters cytokinesis, the furrow grows deeper and finally separates the cytoplasm to form two identical daughter cells.

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Cytokinesis in animal cells is therefore known as furrowing or cleavage.

Question 7. Distinguish between mitosis in plant and animal cells based on spindle formation and cytokinesis. What is mitotic meiosis?

Answer:

Differences between mitosis in plant cells and animal cells:

Mitotic meiosis

The haploid daughter cells produced during meiosis-I, undergo equational division in meiosis-II. Therefore, meiosis II is known as mitotic meiosis.

Question 8. Briefly describe the main features of meiosis-I and meiosis-II.

Answer:

Main features of meiosis-l:

The main features of meiosis-I are given below.

1. Chromosomal separation:

1. During prophase-I of meiosis-I, an exchange of chromosomal materials occurs between homologous chromosomes.
2. In metaphase-I, the homologous chromosome pairs arrange along the equatorial plane.
3. In anaphase-I, homologous chromosome pairs separate and two separated sets of chromosomes move towards two opposite poles of the cell.

2. Reduction in chromosome number:

In meiosis-I, each daughter nucleus gets half the pairs of homologous chromosomes. Therefore, the chromosome number of the daughter cell reduces to half of the somatic cell.

3. Crossing over:

The exchange of portions between non-sister chromatids of homologous chromosomes occurs in meiosis-1. This is called crossing over. In this process, the chromosomes get new genetic combinations.

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Main features of meiosis-II:

The main features of meiosis-II are given below.

1. Separation of chromosomes:

In anaphase of meiosis-II, the centromere of each chromosome splits, and sister chromatids get their share of centromeres and are transformed into daughter chromosomes.

Two sets of daughter chromosomes move to two opposite poles of the cell and get into two daughter nuclei.

2. Equational division:

Unlike mitosis, meiosis-II involves a haploid set of chromosomes. However, equal division of chromosomes takes place in meiosis II. As a result, the chromosome number of the daughter cells of meiosis-I and daughter cells of meiosis-II remains identical.

Question 9. Why is meiosis called reduction division? Distinguish between mitosis and meiosis based on site of occurrence, nature of chromosomal division and number of cells produced.
Or,
Meiosis is characteristically different from mitosis-how would you justify the statement?

Answer:

Meiosis is called as reduction division:

In meiosis, the chromosome number of a diploid mother cell reduces to its half to give rise to a haploid number of chromosome-bearing daughter cells. Thus, meiosis is called reduction division.

Differences between mitosis and meiosis:

Phases of Meiosis

Question 10. Explain the process of crossing over and reduction in chromosome number. Mention the significance of crossing over and reduction in chromosome number in meiosis.

Answer:

Process of crossing over and reduction in chromosome number:

The reduction of chromosome number through the process of crossing over are given here.

1. Crossing over:

During prophase, homologous chromosomes arrange in parallel pairs, this event is called synapsis. The paired homologous chromosomes are known as bivalent. Later, each chromosome splits longitudinally into two sister chromatids.

In this state, the bivalent appears with four chromatids, which is called a tetrad. While coiling, the non-sister chromatids of a tetrad cross over each other at some points, which appear as chi. These points are called chiasmata.

During crossing over, non-sister chromatids reciprocally exchange their segments, which results into new allelic combinations in the homologous chromosomes.

2. Reduction in chromosome number:

In anaphase-1, homologous chromosome pairs separate and the two separated sets of chromosomes move towards two opposite poles of the cell. Finally, during telophase-1, each set of chromosomes gets into each of the daughter nuclei.

By this process, a diploid number of chromosomes of the mother cell becomes haploid in daughter cells.

Significance of crossing over and reduction in chromosome number in meiosis:

The significance of crossing over and reduction in chromosome number in meiosis are given below.

1. Significance of crossing over:

By means of crossing over, genetic recombination takes place, which creates variation. Crossing over confirms the linear arrangement of genes on a chromosome.

2. Significance of reduction in chromosome number:

In meiosis, chromosome number reduces to give rise to haploid gametes. After fertilisation of two haploid gametes, diploid zygotes are formed. By this process, the chromosome number of a species remains constant.

Question 11. Write down the significance of mitotic cell division.

Answer:

Significance of mitotic cell division:

The significance of miotic cell division in plant and animal cells is mentioned below.

1. Growth in size:

The number of somatic cells in any organism increases by continuous mitotic division. Through this process, the overall size of the organism increases. The unicellular zygote undergoes mitosis to develop into a multicellular organism.

2. Cell replacement and healing of wounds:

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The damaged and aged cells of the body are replaced by new cells through mitotic division of the healthy neighbouring cells. This process heals any wound of our body.

For example, the epidermal cells of our body are depleted continuously by friction. These are replenished very quickly by the process of mitosis.

3. Regeneration:

Certain animals have the ability to regenerate their lost body parts. Arms of starfish, appendages of prawns and crabs, tail of house-lizard etc. can be regenerated. Mitotic cell division makes it possible.

4. Reproduction:

Several unicellular organisms undergo mitosis to perform asexual reproduction. Amoeba, Paramoecium, yeast etc. perform asexual reproduction by mitosis. The vegetative reproduction in plants like water hyacinth, sweet potato, Bryophyllum etc. occurs by mitosis.

5. Equational division:

The daughter cells produced by mitosis are genetically and morphologically identical to their mother cell. This process is essential to maintain the integrity of the cellular character of a tissue.

Question 12. What is meiosis? Explain the significance of meiosis.

Answer:

Meiosis:

The cell division in which, a germ mother cell of a diploid organism or zygote of a haploid organism undergoes two successive divisions to give rise to four daughter cells, each carrying half the number of chromosomes of its mother cell, is called meiosis.

Significance of meiosis:

The significance of meiosis are given below.

1. Keeping the chromosome number of a species constant:

During meiosis, chromosome number in daughter cells reduces to half of that of their mother cell. The haploid gametes, produced by this process, undergo fertilisation to produce a diploid zygote, which finally develops into a full-grown organism.

By this process, the chromosome number of parents remains identical to that of their offspring. If there had been no meiosis, the number of chromosomes in sexually reproducing organisms would have increased geometrically with generations.

2. Origin of genetic variation:

During crossing over, the exchange of segments of chromatids takes place between homologous chromosomes. By this process, the recombination of genes occurs, which results in the origin of new genetic variations.

3. Gamete formation:

By meiosis, haploid gametes (sperms and eggs) are formed from diploid germ mother cells.

4. Maintenance of alternation of generation:

By this cell division, a cyclic alternation occurs between diploid sporophytic generation and haploid gametophytic generation in several organisms. Thus, alternation of generation is maintained.

Question 13. Distinguish between-

1. Mitosis and amitosis,
2. Karyokinesis and cytokinesis.

Answer:

Differences between mitosis and amitosis

Differences between karyokinesis and cytokinesis

Question 14. Distinguish between

1. Meiosis-I And meiosis-II,
2. Cytokinesis in plant cells And animal cells.

Answer:

Differences between meiosis-I and meiosis-II

Differences between cytokinesis in plant cells and animal cells

Question 15. Draw a neat diagram of the metaphase of mitosis of a plant c cell or an animal cell division and label the following parts:

1. Chromosome,
2. Spindle fibre,
3. Polar region,
4. Centromere

Similar Question, Draw a neat diagram of the metaphase of mitotic cell division in an animal  cell and label the following parts:

1. Chromatid,
2. Centromere,
3. Polar region,
4. Spindle fibre.

Answer:

Chapter 2 Mitotic And Meiotic Cell Division Short Answer Type Questions

Question 1. In which phase of mitosis the chromosomes appear with two chromatids (become double-stranded) and in which phase they appear again as single-stranded chromosomes?

Answer:

In late prophase, the chromosomes appear double-stranded with two chromatids. In anaphase, the chromatids reappear as single-stranded chromosomes.

Question 2. What are stem bodies?

Answer:

Stem bodies:

During anaphase in animal cells, several inter-zonal fibres appear as column-like structures in between the spindles. These structures are called stem bodies.

Question 3. What will happen to a cell if karyokinesis continues in it, but cytokinesis does not?

Answer:

If karyokinesis continues in a cell without cytokinesis, the cell will become multi-nucleated but the number of cells will not increase. Such cells with multiple nuclei in plants are known as coenocytes and in animals, it is known as syncytium.

Question 4. What are spindle fibres? Mention their types.

Answer:

Spindle fibres:

Spindle fibres are fine microtubular filaments, which are arranged like a spindle within a dividing cell. Spindle fibres hold the chromosomes at the equatorial plane and then shrink to help in the anaphasic movement of the chromosomes.

Types of spindle fibres:

Spindle fibres are of three types-chromosomal fibres, interpolar fibres or continuous fibres and inter-zonal fibres.

Question 5. At which position of a cell do the chromo- somes are arranged during metaphase? How many types of chromatin are seen in a nucleus?

Answer:

Arrangement of chromosomes during metaphase:

During metaphase, the chromosomes are arranged along the equatorial plane of the dividing cell.

Types of chromatin in a nucleus:

There are two types of chromatin found in a nucleus. These are euchromatin and heterochromatin.

Question 6. What is meant by bivalent and tetrad?

Answer:

Bivalent:

During the zygotene sub-phase of pro-phase-I in meiosis-1, homologous chromosomes come side by side to form pairs. These pairs of homologous chromosomes are called bivalent.

Tetrad:

During the pachytene sub-phase of prophase- I in meiosis-I, each chromosome of a bivalent splits along the length into two chromatids. At this state, each bivalent appears four-stranded, which is called a tetrad.

Question 7. How can you distinguish between the mitosis of plant cells and that of animal cells on the basis of the formation of spindle fibre and the process of cytokinesis?

Answer:

Distinguish between the mitosis of plant cells and that of animal cells are-

Question 8. What are chiasmata?

Answer:

Chiasmata:

During the late pachytene sub-phase of prophase I in meiosis-I, the non-sister chromatids of a tetrad cross over each other at certain points. These crossing points appear as the Greek letter chi (x).

These points of crossing over are called chiasmata (singular-chiasma).

Importance of Cell Division in Growth

Question 9. What is interkinesis?

Answer:

Interkinesis:

The brief phase in between meiosis-I and meiosis II is known as interkinesis. During this phase, DNA synthesis does not occur like interphase.

Question 10. What are meant by a sister and non-sister chromatids?

Answer:

A sister and non-sister chromatids:

In the zygotene sub-phase of meiotic prophase-I, the homologous chromosomes undergo pairing to form bivalent. During pachytene, each of the homologous chromosomes splits into two chromatids to form a four-stranded tetrad.

Out of these, the two chromatids of the same chromosome are called sister chromatids, whereas the two chromatids of two different chromosomes of a homologous pair are called non-sister chromatids.

Question 11. Mention the main features of meiosis-l.

Answer:

The main features of meiosis-I are as follows-

1. In meiosis-I, crossing over and recombination of genes occur between homologous chromo- somes.
2. The homologous pairs separate and each chromosome of the pairs move towards the two opposite poles of the cell.
3. Finally, two hap-loid daughter nuclei are formed from a diploid (2n) nucleus.

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Question 12. Mention the main features of meiosis-II.

Answer:

The main features of meiosis-II

Events of meiosis-II are identical to a mitotic division. In anaphase of meiosis-II, chromatids of a chromosome split to form two separate chromosomes. Two haploid cells, produced after meiosis-I, divide in this phase to give rise to four haploid daughter cells.

Question 13. Mention two points of significance of meiotic cell division.

Answer:

Two points of significance of meiotic cell division are as follows-

1. By meiotic cell division, chromosome number of sexually reproducing organisms reduces to half, so that it remains constant after fertilisation.
2. In meiosis, the recombination of genes takes place, which produces new genetic variations and helps the organisms in adaptation and evolution.

Question 14. A somatic cell of a plant has 18 chromosomes. What will be the number of chromosomes in its

1. Root cells,
2. Endosperm nucleus and
3. Definitive nucleus?

Answer:

A somatic cell is diploid, hence, 2n=18. Therefore

1. The chromosome number of the root cells will be 2n=18,
2. The chromosome number of the endosperm nucleus will be 3n=27,
3. The chromosome number of the definitive nucleus will be 2n=18.

Question 15. What do you know about synapsis and syndesis? What is the significance of synapsis?

Answer:

Syndesis:

The pairing of two homologous chromosomes, at prophase I of meiosis I is called synapsis or syndesis. The synaptonemal complex helps in a pairing of this chromosome.

Significance:

By the process of synapsis, chiasma formation and crossing over take place. This leads to variation in new progeny.

Question 16. What do you know about dyad and monads?

Answer:

Dyad:

After completing the replication of the DNA of a chromosome, a conjugated pair of homologous chromosomes or sister chromatids are formed, called a dyad. This type of structure is mainly seen in prophase and metaphase.

Monad:

The single chromatid of chromosomes is called a monad. This type of structure is mainly seen in anaphase.

Question 17. What do you know about disjunction? When it is seen?

Answer:

Disjunction:

During anaphase of cell division, two chromatids of each chromosome moves to the opposite direction due to the constriction of the spindle fibre. This ‘process is called a disjunction. It is seen at the begin- ing of the anaphase stage of mitosis and meiosis.

Question 18. What is meant by crossing over?

Answer:

Crossing over:

In the pachytene sub-phase of meiotic prophase-I, the non-sister chromatids of homologous chromosome pairs cross each other at a number of points.

At these points of crossing, the chromatids cut and exchange the segments with each other. As a result, the chromosomes get new genetic combinations and this event is known as crossing over.

Question 19. What is the significance of crossing over?

Answer:

The significance of crossing over:

Body part exchange between two homologous chromosomes takes place during crossing over. This generates variation in the gamete. This variation brings new characters which helps in adaptation.

Question 20. What is the spindle apparatus?

Answer:

The spindle apparatus:

The specialized structure composed of centriole and spindle fibre to which chromosomes are attached during cell division is called the spindle apparatus.

Question 21. What is phagosome? What is its significance?

Answer:

1. Pharagmosome: The thin cytoplasmic plate that form at the middle of the cell during miotic division in a plant cell is called phagosome.
2. Significance: It helps in phragmoplast formation.

Question 22. What Is a metaphase plate?

Answer:

Metaphase plate:

All the chromosomes are arranged in the equatorial line of the cell during mitosis and meiotic cell division. This looks like a plate-like structure called metaphase plate.

Question 23. What is the synaptonemal complex?

Answer:

The synaptonemal complex:

The synaptonemal complex is a proteinaceous between two fibrous structures formed by homologous chromosomes during prophase I. It helps two forms divalent.

Question 24. What will happen if cytokinesis does not take place?

Answer:

If cytokinesis does not take place then the two cells will not separate. As a result a binucleate cell. will be formed. For example, an osteoclast cell of bone is such a cell with many nuclei.

Question 25. “In case of prophase and telophase changes of opposite nature happens”-Write two such changes.

Answer:

“In case of prophase and telophase changes of opposite nature happens”

In prophase, the nucleus and nucleolus get disappeared, but it reappeared in telophase.

In prophase, chromatin fibre gets condensed to form a distinct chromosome. Whereas in the case of telophase, the chromosome begins to uncoil and hydrated to form fine chromatin reticular.

Question 26. During the meiosis cell division, a reduction in the number of chromosomes and exchange of segments between chromatids take place- Analyze what are the significances of these two phenomena.

Answer:

During meiotic division, the number of chromosomes get reduced from 2n to n for gamete formation. Because during fertilization two cells get fused with each other and form Zygote (2n).

So if these cells have contain 2n chromosomes then the zygote will possess 4n number of chromosome, that is not impossible for the existence of an organism. For that reason, the gamete should contain only half the number of chromosomes (n).

This reduction in chromosome number is only possible because of meiotic division. Another important phenomenon is an exchange of segments between two chromatids.

This exchange can play an important role in genetic recombination, that will give rise to variation in the new progeny. This variation is most important for the newly formed progeny because it helps them tp with the changed environment and to survive. this has an ultimate effect on evolution.

Question 27. Differentiate between synapse and synapsis.

Answer:

Differences between synapse and synapsis are-

Question 28. Differentiate between Meiosis I and Meiosis II.

Answer:

Differences between meiosis I and meiosis II are-

Question 29. Identify the stages of karyokinesis of mitotic cell division depending on the following features:

1. Alignment of chromosomes along the equator of the cell and their arrangement in a definite pattern.
2. The disintegration of spindle fibre.
3. The disappearance of nuclear membrane and nucleolus.
4. Movement of daughter chromosomes to the opposite poles of the cell.

Answer:

1. Alignment of chromosomes along the equator of the cell and their arrangement in a definite pattern-Metaphase
2. The disintegration of spindle fibre-Telophase
3. The disappearance of nuclear membrane and nucleolus-Prophase
4. Movement of daughter chromosomes to the opposite poles of cell-Anaphase

Chapter 2 Mitotic And Meiotic Cell Division Very Short Answer Type Questions Multiple Choice Questions And Answers [Mcq]

Question 1. Mitotic cell division occurs in—

1. Germ mother cell
2. Egg cell
3. Somatic cell
4. Male gamete

Answer: 3. Somatic cell

Question 2. The phrase, of mitosis in which nucleolus reappears, is—

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Answer: 4. Telophase

Question 3. The Nucleolus of a dividing cell disappears in—

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Answer: 1. Prophase

Question 4. The stage of cell division in which sister chromatids separate and move towards two opposite poles is—

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Answer: 3. Anaphase

Question 5. The term ‘karyokinesis’ was coined by—

1. Lamarck
2. Schleicher
3. Darwin
4. Johannsen

Answer: 2. Schleicher

Question 6. Who first stated that ‘two sets of ceil division occur during the formation of germ cells’?

1. Oparin
2. Haldane
3. Flemming
4. Weismann

Answer: 4. Weismann

Question 7. The formation of cell plate occurs with the help of—

1. Golgi bodies
2. Ribosomes
3. Mitochondria
4. Lysosomes

Answer: 1. Golgi bodies

Question 8. Which of the following help(s) in chromosomal movement during cell division?

1. Spindle fibres
2. Cytoplasm
3. Ribosomes
4. Mitochondria

Answer: 1. Spindle fibres

Question 9. Which of the following phases of cell division is a complex process?

1. Amitosis
2. Meiosis-I
3. Meiosis-II
4. Mitosis

Answer: 2. Meiosis-I

Question 10. Determine from the answers given below in which phases of karyokinesis during mitotic cell division following two incidents happen—

1. Daughter chromosomes tend to move apart from each other towards their own poles

2. Nuclear membrane and nucleolus disappear

1. 1 Prophase 2 Anaphase
2. 1 Anaphase 2 Prophase
3. 1 Telophase 2 Metaphase
4. 1 Metaphase 2 Telophase

Answer: 2. 1 Anaphase 2 Prophase

Question 11. The shortest phase of cell division is—

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Answer: 3. Anaphase

Question 12. The longest phase of mitosis is—

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Answer: 1. Prophase

Question 13. In which of the following organisms is an astral mitosis seen?

1. All living beings
2. Higher plants
3. Higher animals
4. Lower animals

Answer: 2. Higher plants

Question 14. Neither chromosomal movement nor disappearance of the nuclear membrane occurs in—

1. Mitosis
2. Meiosis
3. Amitosis
4. Both 1 and 2

Answer: 3. Amitosis

Question 15. During anaphasic movement, metacentric chromosomes appear like—

1. I
2. J
3. V
4. L

Answer: 3. V

Question 16. Sperms and Ova are produced by—

1. Mitosis
2. Meiosis
3. Amitosis
4. Budding

Answer: 2. Meiosis

Wbbse Class X Life Science

Question 17. The mitotic cell division, in which spindle fibres do not grow from the centriole, is called—

1. Equal division
2. Unequal division
3. Astral mitosis
4. Anastral mitosis

Answer: 4. Anastral mitosis

Question 18. The stage, in which you can get the best view of chromosomes within a cell, is—

1. Prophase
2. Anaphase
3. Telophase
4. Metaphase

Answer: 4. Metaphase

Question 19. Which of the following is the unit of crossing over?

1. Chloroplast
2. Ribosome
3. Chromatid
4. Lysosome

Answer: 3. Chromatid

Question 20. If chromosome number of a somatic cell is 46, by which type of cell division will it come down to 23?

1. Mitosis
2. Meiosis
3. Amitosis
4. Budding

Answer: 2. Meiosis

Question 21. The fourth phase of mitosis is called—

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Answer: 4. Telophase

Question 22. Crossing over occurs during—

1. Amitosis
2. Mitosis
3. Meiosis-I
4. Meiosis-II

Answer: 3. Meiosis-I

Wbbse Class X Life Science

Question 23. The stage of cell division, in which astral and ancestral spindles develop respectively in animal and plant cells, is—

1. Early prophase
2. Late prophase
3. Metaphase
4. Anaphase

Answer: 2. Late prophase

Question 24. The main component of the cell wall of a plant cell is called—

1. Chitin
2. Protein
3. Lipid
4. Cellulose

Answer: 4. Cellulose

Question 25. The cell division, in which genetic variation takes place, is—

1. Amitosis
2. Mitosis
3. Meiosis
4. Both 2 and 3

Answer: 3. Meiosis

Question 26. The cell division, in which recombination of genes occurs, is—

1. Meiosis
2. Mitosis
3. Amitosis
4. Both 1 and 2

Answer: 1. Meiosis

Question 27. The chromosome number of germ cells is—

1. Diploid
2. Triploid
3. Polyploid
4. Haploid

Answer: 4. Haploid

Question 28. Spindle fibres are composed of—

1. Humulin
2. Intermediate filament
3. Flagellin
4. Tubulin

Answer: 4. Tubulin

Wbbse Class 10 Life Science Solutions

Question 29. The term ‘cytokinesis’ was coined by—

1. Boveri
2. Remak
3. Whitman
4. Lamarck

Answer: 3. Whitman

Question 30. The process of cell division that occurs in germ mother cells to give rise to germ cells is known as—

1. Mitosis
2. Meiosis
3. Amitosis
4. Endomitosis

Answer: 2. Meiosis

Question 31. Cytokinesis in animal cell occurs by—

1. Cell membrane formation
2. Cell plate formation
3. Cleavage or furrowing
4. Anaphasic movement

Answer: 3. Cleavage or furrowing

Question 32. The cell division, in which spindle fibres are not formed, is called—

1. Amitosis
2. Mitosis
3. Meiosis-I
4. Meiosis-II

Answer: 1. Amitosis

Question 33. The cell division that keeps a constant chromosome number of a species, is called

1. Amitosis
2. Mitosis
3. Meiosis
4. Both 1 and 3

Answer: 3. Meiosis

Wbbse Class 10 Life Science Solutions

Question 34. The phase of cell division, in which chromosomes take various shapes based on the location of centromere—

1. Prophase
2. Metaphase
3. Telophase
4. Anaphase

Answer: 4. Anaphase

Question 35. You have to observed the separation of two sister chromatids at one stage of mitotic cell division. The stage is—

1. Prophase
2. Telophase
3. Anaphase
4. Metaphase

Answer: 3. Anaphase

Question 36. In which stage of mitosis cell division, the nuclear membrane and nucleolus are seen to disappear?

1. Anaphase
2. Prophase
3. Metaphase
4. Telophase

Answer: 2. Prophase

Question 37. Determine which of the following statement is correct regarding the significance of meiosis—It results in overall growth and development of the body.

1. It results in the growth of reproductive organs and embryo of the organism
2. It produces haploid gamete containing hereditary variations
3. It regenerates the organ in the body of some animals, if it is lost

Answer: 3. It produces haploid gamete containing hereditary variations

 

Chapter 2 Mitotic And Meiotic Cell Division Answer In A Single Word Or Sentence

Question 1. By which type of cell division does a cell develop its own replica?
Answer: By mitotic cell division a cell develops it own replica.

Question 2. Where does mitotic cell division occur?
Answer: Somatic cells of a living organism

Question 3. Which type of cell division increases the number of somatic cells in a living body?
Answer: Mitotic cell division

Question 4. Where does equational cell division occur?
Answer: Somatic cells

Wbbse Class 10 Life Science Solutions

Question 5. Which cellular component is formed to help cytokinesis in a plant cell?
Answer: Formation of cell plate

Wbbse Class X Life Science

Question 6. Where do the chromosomes lie within a cell during metaphase stage of cell division?
Answer: Equatorial plane of a dividing cell

Question 7. How many daughter cells are produced from a single cell after a mitotic division?
Answer: Two daughter cells are produced

Question 8. What is the role of the centrosome in animal cell division?
Answer: Centrosome helps in the formation of spindle fibres.

Question 9. Which parts of a plant cell help in spindle fibre formation during cell division?
Answer: Microtubules of the cytoplasm of a plant cell help in spindle fibre formation during cell division.

Question 10. How will the absence of a centrosome in an animal cell affect cell division?
Answer: The absence of a centrosome in an animal cell will not allow spindle fibre formation and thereby, the cell division process will stop.

Question 11. How many daughter cells will be produced after a single meiosis of a mother cell?
Answer: Four daughter cells will be produced after a single meiosis of a mother cell.

Question 12. Where does meiotic cell division occur?
Answer: Meiotic cell division occurs in the germ mother cell (inside the testis and ovary in animals and anther and ovary of flowers).

Question 13. Where does meiosis occur in lower plants?
Answer: In lower plants, meiosis occurs in zygotes and spore mother cells.

Cell Cycle Phases for Class 10

Question 14. To which portion of a eukaryotic chromosome does spindle fibre attach during metaphase?
Answer: During metaphase, spindle fibres attach to the centromere or kinetochore of an eukaryotic chromosome.

Question 15. What is a dyad?
Answer:

Dyad

A chromosome, with two distinctly visible. chromatids, is called dyads.

Question 16. Which cell organelle takes part in the formation of the two poles of mitotic spindle in an animal cell?
Answer: Centrosome

Wbbse Class X Life Science

Question 17. In which type of cell division does crossing over take place?
Answer: Crossing over takes place in meiotic cell division.

Question 18. Which special cellular components help in cytokinesis in plant cells?
Answer: Phragmoplasts

Question 19. Which type of cell division helps in the healing of wounds in living organisms?
Answer: Mitotic cell division

Question 20. What is Karyokinesis?
Answer:

Karyokinesis

Karyokinesis is the division of the nucleus

Question 21. In which phase of cell division spindle fibre is formed?
Answer: Prophase

Question 22. In which phase of cell division non-disjunction of chromosome takes place?
Answer: Anaphase

Question 23. What is the alternative name of synapsis?
Answer:

Alternative name of synapsis is

Syndesis

Question 24. In which phase of cell division chiasma is formed?
Answer: Prophase I of meiosis

Wbbse Class 10 Life Science Solutions

Question 25. Which protein form the spindle fibre?
Answer: Tubulin

Question 26. Name the five subphases of meiotic prophase I.
Answer:

The five subphases of meiotic prophase I

Leptone, zygotene, pachytene, diplotene and diakinesis.

Common Mistakes in Understanding Cell Division

Question 27. Mention the significance of crossing over.
Answer:

Significance of crossing over

Genetic recombination.

Question 28. Name the phase, where disintegration of spindle fibre occurs.
Answer: Telophase.

Question 29. Name the process by which cytokinesis of the plant cell happen.
Answer: Cell plate formation.

 

Chapter 2 Mitotic And Meiotic Cell Division Fill In The Blanks

Question 1. _________ takes part in spindle formation during animal cell division.
Answer: Centrosome

Question 2. _________ haploid daughter cells are produced by the meiotic division of a single mother cell.
Answer: Four

Question 3. Chromosomal movement is seen during _________ stage.
Answer: Anaphase

Question 4. By the formation of _________, cytokinesis occurs in plant cells.
Answer: Cell plate

Question 5. The intermediate stage in between meiosis-I and meiosis II is_________.
Answer: Interkinesis

Question 6. Each of the homologous pair of chromosomes, which occur during prophase-I is called _________.
Answer: Bivalent

Wbbse Class 10 Life Science Solutions

Question 7. The process of pairing of homologous chromosome pairs is called _________.
Answer: Synapsis

Question 8. A bivalent of two homologous chromosomes has four chromatids. This is called a _________.
Answer: Tetrad

Question 9. The X-shaped structure formed due to the crossing between two non-sister chromatids of a homologous chromosome pair is called _________.
Answer: Chiasma

Question 10. The third phase of karyokinesis is called _________.
Answer: Anaphase

Question 11. Chromosomes are arranged in an equatorial line in _________ phase.
Answer: Metaphase

Question 12. Gamete formation takes place by _________ cell division.
Answer: Meiosis

Question 13. The number of chromosomes is reduced in _________ phase of meiosis I.
Answer: Anaphase I

Question 14. The alternative name of crossing over is _________.
Answer: Recombination

Wbbse Class 10 Life Science Solutions

Question 15. _________ and _________ combinely formed phragmoplast.
Answer: Microfilament, Microtubule

Question 16. Interzonal fibre is formed during _________.
Answer: Anaphase

Question 17. The third phase of karyokinesis is called _________.
Answer: Anaphase

Question 18. Cytokinesis of animal cells occurs by _________.
Answer: Furrowing/ Cleavage

Chapter 2 Mitotic And Meiotic Cell Division State True Or False

Question 1. Mitochondria and chloroplasts can take part in spindle formation.
Answer: True

Question 2. Crossing over occurs by the exchange of segments between non-sister chromatids.
Answer: True

Question 3. Cytokinesis occurs in plant cells by cleavage.
Answer: False

Question 4. The parallel positioning of two homologous chromosomes is called a synapse.
Answer: False

Question 5. Astral ray is formed in mitosis.
Answer: True

Question 6. Spindle fibre disintegrates in metaphase.
Answer: False

Wbbse Class X Life Science

Question 7. Crossing over takes place more heterochromatin.
Answer: False

Question 8. DNA is doubled in G₂ phase.
Answer: False

Question 9. Crossing over produces variation in organisms.
Answer: True

Question 10. Only one crossing-over can takes place between two homologous chromosomes.
Answer: False

Wbbse Class 10 Life Science Solutions

Question 11. The shortest phase of cell division is prophase.
Answer: False

Question 12. Ovum is only produced as a result of mitosis.
Answer: False

 

Chapter 2 Mitotic And Meiotic Cell Division Match The Columns

Question 1.

Answer: 1. B, 2. C, 3. D, 4. A, 5. F, 6. G

Question 2.

Answer: 1. D, 2. A, 3. B, 4. C, 5. F, 6. G

Wbbse Class 10 Life Science Solutions

Chapter 2 Mitotic And Meiotic Cell Division Find The Odd One Out

Question 1. Condensation of chromosomes, Moving of chromosomes to the equatorial plane, Anaphasic movement of chromosomes, Formation of cell plate
Answer: Formation of cell plate

Question 2. Formation of the chiasma, Formation of the tetrad, Synapsis, and Anaphasic movement.
Answer: Anaphasic movement

Question 3. Spiralization of the chromosome, Disintegration of the nucleus, Reappearance of the nucleolus, and Spindle fibre formation.
Answer: Reappearance of the nucleolus

Question 4. Prophase, Metaphase, Telophase, Cytokinesis.
Answer: Cytokinesis

Wbbse Class 10 Life Science Solutions

Chapter 2 Mitotic And Meiotic Cell Division Fill In The Blanks By Looking At The First Pair

Question 1. The single nucleus in a cell: Prophase:: Two nuclei in a cell: _________
Answer: Telophase

Question 2. Animal cell: Cleavage:: Plant cell: _________
Answer: Cell plate

Question 3. Growth: Mitosis:: Variation: _________
Answer: Meiosis

Question 4. Chromosomal disjunction: Anaphase 1:: Crossing over: _________
Answer: Prophase I

Question 5. Prophase: Disappearance of nuclear membrane and nucleolus:: _________: Reappearance of nuclear membrane and nucleolus.
Answer: Telophase

Question 6. Synopsis: Dyad::Crossing over: _________
Answer: Tetrad

Wbbse Class 10 Life Science Solutions

Chapter 2 Mitotic And Meiotic Cell Division Among The Four Concepts Given Three Of Them Belong To One Find That

Question 1. Regeneration, Cell replacement, Mitosis, Growth.
Answer: Mitosis

Question 2. Tetrad, Crossing over, Pachytene, Chiasma.
Answer: Pachytene

Question 3. Synopsis, Prophase I, Chiasma formation, Terminalisation.
Answer: Prophase I

Question 4. Alternation of generation, Meiosis, Recombination, and Gametogenesis.
Answer: Meiosis.

Chapter 2 Cell Division Associating Organelles Significance Type And Cell Cycle Summary

• Cell organelle plays a major role in cell division. Most importantly nucleus is the container of chromosomes, while centrioles help to organize chromosomes before cell division, besides these functions, centrosomes and microtubules produce spindle fibre.
• Ribosomes synthesize protein and mitochondria provide ATP for the whole process of cell division. Cell division is essential for the growth, reproduction and healing process of the body.
• In living organisms, three types of cell divisions are mostly seen, These are-Amitosis, mitosis and meiosis. Amitosis are seen in the lower group of organism.

Read and Learn More WBBSE Solutions for Class 10 Life Science And Environment

• Mitosis is responsible for growth and healing because it mainly occurs in somatic cells. Whereas meiosis takes place in gametes formation. Most importantly mitosis and meiosis are mostly found in higher order organisms.
• A series of events that takes place in the cell cyclically during its growth and division is called the cell cycle. The cell cycle is mainly divided into two phases, these are-Interphase or undivided phases and the mitotic or dividing phase.
• This interphase or undivided phase also divided into three phases-G₁. S and G₂. Cells which are going through G₁, S and G₂ phases, are prepared for cell division.
• The mitotic phase is composed of karyokinesis (a division of the nucleus) and cytokinesis (a division of the cytoplasm). Karyokinesis also occurs through certain subphases, like prophase, metaphase, anaphase and telophase.
• In the process of the cell cycle, there is a phase called G°, is a resting phase, where the cell exists in a quiescent state. By checking the physical status of the cell and the suitability of the environment for its division, the G decides whether the cell will be going to divide or stays quiescence.

Chapter 2 Cell Division And Cell Cycle Long Answer Type Questions

Question 1. Describe different phases of the cell cycle.
Or,
What types of chemical components are synthesized in different stages of interphase in a cell cycle? What might happen if normal control at different points of a cell cycle is lost?

Answer:

Different phases of cell cycle:

The systematic and cycle of events, which continuously occurs from the end of a cell division to the end of the next cell division, is called the cell cycle. A cell cycle has two main phases-

1. Interphase:

The longer phase of a cell cycle in which a new daughter cell grows by synthesis of DNA, proteins, RNA etc. and gets all necessary cellular components to become a fully matured cell, ready for division, is called interphase.

This phase is divided into three sub-phases-G₁ or growth-1 phase, S or synthesis phase and G₂ or growth-2 phase.

1. G₁, or growth-1 phase: It is the primary phase of interphase, where rRNA, mRNA, tRNA, ribosomes and the materials necessary for DNA synthesis are produced. Doubling of various cell organelles occurs in this phase.
2. S or synthesis phase: This is the intermediate phase between G₁, and G₂ phases. During this phase, the synthesis or replication of DNA and the synthesis of histone proteins occur. Here, the DNA content of a chromosome becomes double.
3. G₂ or growth-2 phase: It is the last phase of the interphase. In this phase, the proteins, necessary for upcoming cell division, are synthesised.

Life Science Class 10 Wbbse

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WBBSE Class 10 History Multiple Choice Questions

 

2. Mitotic phase:

It is the shortest phase of a cell cycle. This phase is divided into two sub-phases-

1. Karyokinesis, where the nucleus of a cell divides through prophase, metaphase, anaphase and telophase.
2. Cytokinesis, in which cytoplasm divides to give rise to two daughter cells.

A human needs 20-24 hours to complete a cell cycle, of which 19-23 hours go for interphase only and 1 hour for the mitotic phase.

Result of the uncontrolled cell cycle:

If for certain reasons, the checkpoints of cell cycle lost its function, then any diseased or torn-out cells can easily proceed towards cell division in an uncontrolled way and thereby give rise to cancer.

Question 2. Mention the significance of cell cycle. Write down the importance of cell division. Part Question, Analyze the role of cell divisions in controlling growth, reproduction and repair in an organism.

Answer:

Significance of cell cycle:

The significance of cell cycle is mentioned below-

1. Controlling cell division:

Certain points of the cell cycle control cell division. These are known as checkpoints. In case of any functional disruption at any of those points, the cell division process becomes uncontrolled, which may lead to tumour formation.

Tumours are of two types-benign tumour and malignant tumour. Benign tumours are harmless but malignant tumour cells invade other tissues through blood or lymph and form tumours there.

This phenomenon is called metastasis, which is a characteristic feature of cancer cells.

WBBSE Class 10 Cell Division Overview

2. Normal growth and wound healing:

Cell division helps an organism to grow in size. It also assists in wound healing.

Importance of cell division:

The importance of cell cycle are given below.

1. Growth:

Number of cells of an organism increases due to cell division. The daughter cells produced by this process also grow in size. Therefore, the growth of any organism depends directly upon cell division.

2. Reproduction:

Amitosis, mitosis and meiosis help in different types of reproduction processes. Simple unicellular organisms like Amoeba, reproduce by the amitosis process. Mitosis helps in asexual and vegetative reproduction in animals and plants.

By meiotic division, gametes and spores are formed. Therefore, meiosis helps in sexual and asexual reproduction.

Life Science Class 10 Wbbse

3. Wound healing:

Mitosis helps in the repair of wounds and the regeneration of organs in plants and animals.

4. Transfer of genetic characters:

By cell division, the characters of the mother cell are transferred to the daughter cells. In a broader perspective, the newer characters in daughter cells help in adaptation and evolution.

Question 3. Name the cell organelles involved in cell division. Mention the role of those organelles in the cell division process.

Answer:

Cell organelles involved in cell division:

The cell organelles which are involved in the cell division process are-nucleus, centrosome, microtubules, ribosomes and mitochondria.

Role of cell organelles in cell division:

The roles of the cell organelles in cell division are discussed below.

1. Nucleus:

It carries chromosomes, which are transferred from mother cells to daughter cells along with the genetic materials during cell division.

2. Centrosome and microtubules:

In animal cells, centrosomes and in plant cells, cytoplasmic microtubules form spindle fibres during metaphase. These help in chromosomal movement during anaphase.

3. Ribosomes:

Ribosomes take part in protein synthesis. During cell division, they help in the formation of chromosomes and other cellular components, such as cell organelles, cytoplasm etc.

4 Mitochondria:

They supply the necessary energy for different activities in a dividing cell. They also regulate the cell cycle.

Chapter 2 Cell Division And Cell Cycle Short Answer Type Questions

Question 1. What is meant by cell division?

Answer:

Meaning Of Cell division:

The process, by which a fully matured cell or a mother cell divides to give rise to two or more daughter cells, is known as cell division. By means of cell division, unicellular organisms reproduce and multicellular organisms grow in size.

Question 2. How many types of cell division occur in the living world?

Answer:

Types of cell division occur in the living world:

In the living world, two main types of cell division occur. These are direct cell division and indirect cell division. Direct cell division includes amitosis.

Indirect cell division is of two types-

1. Mitosis And
2. Meiosis.

Question 3. Write down the significance of cell division.

Answer:

The significances of cell division are as follows-

1. Increasing the number of cells for the growth of an organism.
2. Production of germ cells for reproduction.
3. Healing of wounds.

Types of Cell Division Explained

Question 4. Mention the role of mitosis in the growth of an organism.

Answer:

The role of mitosis in the growth of an organism:

As a somatic cell of an organism attains maturity, it undergoes mitosis. By this process, the number of body cells increases. As a result, the whole body of the organism grows. So, it can be said, mitosis is the cause and growth is its result.

Question 5. Mention the names of different phases of a cell cycle.

Answer:

The names of different phases of a cell cycle:

The two main phases of a cell cycle are- Interphase and mitotic phase. Interphase is sub-divided into three sub-phases, these are G₁, S and G₂, phase and the mitotic phase has two sub-phases – karyokinesis and cytokinesis.

Karyokinesis is further divided into four phases-prophase, metaphase, anaphase and telophase.

Question 6. What is meant by Go phase? State its by significance.

Answer:

Go phase:

In cell cycle, there is a certain point, where any change related to cell division stops completely.

G₀ is an inactive state of the cell cycle, where cells remain in a quiescent state, or else it waiting for the favourable environment or particular signal for going to the divisional phase. This phase is also known as gap phase.

Significance:

It helps to keep the cell in a quiescent State and by that way if prevents the cell from undergoing uncontrolled division. Most cells bypass this phase, but a few, like nerve cells and cardiac muscle cells, enter this phase and do not undergo any cellular division.

Question 7. What is interphase?

Answer:

Interphase:

The phase of cell cycle between the end of a cell division to the start of the next cell division, in which the growth of a daughter cell and the preparatory events for the next cell division occur, is known as interphase. Interphase is also known as the resting phase of cell cycle.

Question 8. Why is interphase necessary before cell division?

Answer:

During interphase, certain preparatory events occur within the cell to make it ready for division and to provide the daughter cell with their necessary cellular components. The events which occur during interphase are as follows-

1. Synthesis of DNA and certain proteins, duplication of certain cell organelles and
2. Synthesis of ATP to supply essential energy during cell division activities. Therefore, interphase is necessary before cell division.

Question 9. What is meant by mitotic cell division?

Answer:

Mitotic cell division:

Mitosis is a type of cell division, in which the mother cell divides to produce two identical daughter cells. The daughter cell contains the same number of chromosomes, like the mother cell.

Life Science Class 10 Wbbse

Question 10. Where does mitotic cell division occur?

Answer:

Mitotic cell division occurs in the following regions-

1. It occurs in the meristematic tissues of plants and the body cells of animals.
2. Mitosis occurs in the embryos of plants and animals during their development.
3. In unicellular organisms, mitosis occurs during vegetative and asexual reproduction.

Question 11. What is karyokinesis?

Answer:

Karyokinesis:

The word ‘karyon’ means nucleus and the word ‘kinesis’ means to move. So karyokinesis is the first and prolonged phase of mitotic division, in which the nucleus of the mother cell divides to give rise to two daughter nuclei.

Question 12. What is cytokinesis?

Answer:

Cytokinesis:

The phase of cell division, in which the cytoplasm of the mother cell divides into two halves to give rise to two daughter cells, is called cytokinesis. Cytokinesis occurs after karyokinesis.

Question 13. What do you mean by checkpoints?

Answer:

Checkpoints:

To avoid unnecessary division, three stages are there in the cell cycle at which cells are go through internal and external cues to decide, whether it will be move forward for cellular division or stay quiescent.

Generally, three checkpoints are there-G₁/S, G₂/M and the mitotic checkpoint. All these checkpoints proceed only with healthy cells towards the division and pushed torn-out cells towards apoptosis. By this process, it maintains the cellular division in a healthy way.

Phases of the Cell Cycle for Class 10

Question 14. State the significance of cellular checkpoints. Or, Establish the relationship between the formation of malignant tumour in the human body with the loss of control in the cell cycle.

Answer:

The significance of cellular checkpoints:

Checkpoints prevent uncontrolled cellular growth and thereby cancer. It mainly checks the genetic as well as physical integrity, if they found any genetic defect, they immediately arrest the cell from going to cellular division.

All cells will be checked by three stages. But if the genes which are responsible for the synthesis of checkpoints are mutated then they lost their control over cell division and the cells are going to divide in an uncontrolled way.

This uncontrolled cellular division gives rise to a cellular lump, called a tumour.

Life Science Class 10 Wbbse

Question 15. Why is mitosis called equational division?

Answer:

Mitosis called equational division:

In mitotic cell division, the number of chromosomes acquired by two daughter cells is equal to that of their mother cell.

The size and shape of those daughter cells also become identical to the mother cell. That is why, mitosis is called equational division.

Question 16. In which phase of mitosis the chromosomes appear with two chromatids (become double-stranded) and in which phase they appear again as single-stranded chromosomes?

Answer:

In late prophase, the chromosomes appear double-stranded with two chromatids. In anaphase, the chromatids reappear as single-stranded chromosomes.

Question 17. Mention five different cell organelles taking part in the cell division process.

Answer:

Five different cell organelles taking part in the cell division process

The nucleus, centrosome, microtubules, Golgi bodies, ribosomes and mitochondria are five cell organelles taking part in cell division.

Question 18. Mention the roles of the nucleus and Golgi bodies in cell division.

Answer:

Role of the nucleus: During cell division, the chromosomes divide equally and thus distribute the genetic material within it evenly among the daughter cells.

Mitosis vs Meiosis Comparison

Question 19. Mention the roles of centrosomes and microtubules in cell division.

Answer:

Role of centrosome:

In animal cells, the centrosome divides into two during prophase. Each centrosome with a pair of centrioles then moves to two opposite ends of the dividing cell to act as the poles of the spindle.

Role of microtubules:

Microtubules form the spindle fibres. These fibres attach with the centromeres of chromosomes and help them to split into daughter chromosomes during anaphase.

Question 20. Mention the role of mitochondria in cell division.

Answer:

The role of mitochondria in cell division:

Mitochondria are the powerhouse of a cell. During cell division, extra energy is needed. Mitochondria supply that energy to the dividing cell. Thus mitochondria also play an important role in controlling the cell cycle.

Question 21. Mention the role of the ribosome in cell division.

Answer:

The role of the ribosome in cell division:

Ribosomes help in the synthesis of proteins which are essential for cell division. They take part in the synthesis of enzymes necessary for protein synthesis. They also help to synthesise histone and non-histone daughter chromosomes.

Question 22. How does the absence of a centrosome affect the cell division of an animal cell?

Answer:

In animal cells, the centrosome helps in forming spindle fibres which help in chromosomal movement and it’s separation.

If there is no centrosome in an animal cell, chromosomal separation and daughter nuclei formation will not occur. As a result, cell division will not take place.

Question 23. From where do spindle fibres develop during cell division in plant and animal cells?

Answer:

During cell division in plant cells, spindle fibres develop from cytoplasmic microtubules. In animal cells, spindle fibres grow from the two centrioles, positioned at two opposite poles of the dividing cell.

Life Science Class 10 Wbbse

Question 24. Which problems would a multicellular organism face if mitosis stops completely?

Answer:

If mitosis stops completely, then the following complications will occur in any multicellular organism-

1. The growth and wound healing process will stop.
2. Vegetative reproduction will stop.
3. The dead and aged cells of the body will not be replenished.

Question 25. What are oncogenes?

Answer:

Oncogenes:

The genes, which transform a normal cell into a malignant cell or more simply the genes which are responsible for developing cancer, are called oncogenes.

Oncogenes are formed by mutations or by carcinogens and affect the regulatory system of cell cycle. Finally, uncontrolled cell division leads to cancer.

Question 26. What do you mean by metastasis?

Answer:

Metastasis:

Metastasis is the main characteristic of malignant tumours or cancer cells. By this process these cells can spread all over the organ of the body, not only that, it can form tumorous growth (2° tumour) of different regions of the body.

The process of spreading of cancerous cells through blood and lymph to other parts of the body is called metastasis.

Functions of Cell Division in Growth

Question 27. What are tumour suppressor genes? Give example.

Answer:

Tumour suppressor genes:

The genes which hinder the activity of oncogenes and thus prevent tumour formation, are called tumour suppressor genes.

Example:

p53, and pRb are tumour suppressor genes. If these genes are inactivated by any means, regulation of cell cycle disrupts and tumour formation occurs.

Question 28. What is meant by a malignant tumour?

Answer:

Malignant tumour:

Due to any irregularity in the cell cycle, normal cell division is hampered. In that case, uncontrolled cell division occurs to form a lump of cells in the body which are known as tumours.

If the tumour cells are spread through body fluids to invade other tissues of the body and form new fatal tumours, those are then called malignant tumours.

Question 29. What is amitosis?

Answer:

Amitosis:

Amitosis is a primitive type of cell division, in which the nucleus and cytoplasm divide directly into two daughter cells by simple cleavage formation without forming, a spindle apparatus Amoeba and few other unicellular organisms reproduce by amitosis.

Question 30. Mention the characteristic features of amitosis.

Answer:

The characteristic features of amitosis are as follows-

1. During amitosis, the nuclear membrane remains intact and spindle formation does not occur.
2. During this division, the nucleus develops a constriction at its centre that gives the nucleus a shape like a dumbbell.
3. The cell cytoplasm also develops a constriction at the same position as the nucleus. Both the constrictions start increasing and finally, both cytoplasm and nucleus separate into two daughter cells at a time.

Question 31. A somatic cell of a plant has 18 chromosomes. What will be the number of chromosomes in its

1. Root cells,
2. Endosperm nucleus and
3. Definitive nucleus?

Answer:

A somatic cell is diploid, hence, 2n=18. Therefore

1. The chromosome number of the root cells will be 2n=18,
2. The chromosome number of the endosperm nucleus will be 3n=27,
3. The chromosome number of the definitive nucleus will be 2n=18.

Question 32. In a human somatic cell, diploid chromosome number is 46. What will be the chromosome number of a daughter somatic cell and a gamete?

Answer:

In a human somatic cell, the diploid chromosome number is 46 (2n). The chromosome number of the daughter somatic cell will be 46 (2n). The chromosome number of the gamete will be 23 (n).

Question 33. How many nuclear divisions occur in meiosis and mention the nature of those divisions.

Answer:

During meiosis, two nuclear divisions take place. The first of these two nuclear divisions is reduction division where the number of chromosomes is reduced to half and the second one is equational division as there is no replication of the existing chromatids.

Question 34. A diploid cell contains 24 chromosomes in its nucleus. How many chromosomes will be there in the daughter cells after-

1. Mitosis,
2. Meiosis-i and
3. Meiosis-II?
4. Answer:

The diploid cell contains 2n = 24 chromosomes in its nucleus. Therefore-

1. After mitosis, the chromosome number will remain as the mother cell, i.e., 2n = 24,
2. After meiosis-I chromosome number will reduce to half the number of chromosomes in its mother cell, i.e., n = 12,
3. After meiosis-II chromosome number will remain as the daughter cells of meiosis-I, i.e., n = 12.

Question 35. What are meiocytes and meiospores?

Answer:

Meiocytes:

The diploid cells, which undergo meiotic division, are known as meiocytes.

Examples: Spermatocytes, oocytes etc.

Meiospores:

The haploid spores, which are produced from meiotic cell division, are called meiospores.

Example: Spores of ferns.

Question 36. Compare between meiosis-II And mitosis.

Answer:

Comparison between meiosis-II and mitosis are-

Key Stages of Mitosis

Chapter 2 Cell Division And Cell Cycle Very Short Answer Type questions Multiple Choice Questions And Answers [MCQ]

Question 1. In 1840, the process of amitosis was first described by—

1. Walther Flemming
2. Strasburger
3. Moore
4. Robert Remak

Answer: 4. Robert Remak

Question 2. The term ‘mitosis’ was first coined by—

1. Boveri
2. Moore
3. Walther Flemming
4. Remak

Answer: 3. Walther Flemming

Question 3. The cycle of events occurring after the end of one cell division to the end of next cell division is called—

1. Ornithine cycle
2. Cori cycle
3. Cell cycle
4. Krebs cycle

Answer: 3. Cell cycle

Question 4. The cell cycle is broadly divided into—

1. Two phases
2. Three phases
3. Four phases
4. Six phases

Answer: 1. Two phases

Question 5. The phase in which DNA replication occurs is called—

1. G₁phase
2. S phase
3. G₂ phase
4. M phase

Answer: 2. Two phases

Question 6. The intermediate phase of DNA synthesis and the start of the prophase is—

1. G₀ phase
2. G₁ phase
3. M phase
4. G₂ phase

Answer: 4. G₂ phase

Question 7. Interphase is placed in between—

1. Prophase and metaphase
2. Metaphase and anaphase
3. Telophase and prophase
4. Anaphase and telophase

Answer: 3. Telophase and prophase

Question 8. Which is not a character of interphase?

1. The volume of a cell increases
2. Nuclear membrane disappears
3. Energy is stored for next division
4. DNA, RNA and proteins are synthesised

Answer: 2. Nuclear membrane disappears

Question 9. In which phase of cell cycle mitosis occurs?

1. After G₁ phase
2. After S phase
3. Before G₂ phase
4. After G₂ phase

Answer: 4. After G₂phase

Importance of the Cell Cycle in Organisms

Question 10. In which type of cell division two daughter cells are formed with chromosome numbers identical to the mother cell?

1. Amitosis
2. Mitosis
3. Meiosis
4. Both 1 and 3

Answer: 2. Mitosis

Question 11. The phase of cel! cycle, in which cell division-related activities are completely stopped, is called—

1. G₁ phase
2. G₂ phase
3. S phase
4. G₀ phase

Answer: 4. G₀ phase

Question 12. The phase of cell division in which counting the number of chromosomes becomes the easiest is—

1. Prophase
2. Metaphase
3. Anaphase
4. Telophase

Answer: 2. Metaphase

Question 13. Meiotic cell division is also called—

1. Equal division
2. Multiple division
3. Unequal division
4. Reduction division

Answer: 4. Reduction division

Question 14. Which of the following will you not draw in the diagram of a prokaryotic cell?

1. Mitochondria
2. Chromatophore
3. Mesosome
4. Nucleoid

Answer: 1. Mitochondria

Question 15. The phase in between two successive cell divisions is called—

1. Prophase
2. Interphase
3. Metaphase
4. Telophase

Answer: 2. Interphase

Question 16. Bacterial cell division is called—

1. Mitosis
2. Amitosis
3. Meiosis
4. Endomitosis

Answer: 2. Amitosis

Question l7. The chromosome number of an organism is 2n=24. What will be the chromosome number of its sperms or ova?

1. 6
2. 12
3. 18
4. 24

Answer: 2. 12

Question 18. The disease caused due to uncontrolled cell cycle is—

1. Cancer
2. Malaria
3. Cirrhosis
4. Tuberculosis

Answer: 1. Cancer

Question 19. Which of the following is called direct cell division?

1. Mitosis
2. Meiosis
3. Amitosis
4. Endomitosis

Answer: 3. Amitosis

Question 20. The mode of reproduction in unicellular organisms is—

1. Somatic cell formation
2. Cell cycle
3. Cell membrane formation
4. Cell division

Answer: 4. Cell division

Question 21. Which of the following helps in movement of chromosomes during cell division?

1. Spindle fibre
2. Cytoplasm
3. Ribosome
4. Mitochondria

Answer: 1. Spindle fibre

Question 22. Which of the following supplies energies during cell division?

1. Centrosome
2. Cytoplasm
3. Ribosome
4. Mitochondria

Answer: 4. Mitochondria

Question 23. Who coined the term amitosis?

1. Walther Flemming
2. Strasuburger
3. Robert Remauk
4. Robert Hook

Answer: 1. Walther Flemming

Question 24. Which of the following is a direct cell division?

1. Mitosis
2. Meiosis
3. Endomitosis
4. Amitosis

Answer: 4. Amitosis

Question 25. In which type of cell division metaphase does not take place?

1. Mitosis
2. Amitosis
3. Meiosis
4. None of the above

Answer: 2. Amitosis

Question 26. Meiosis is—

1. Equational division
2. Multiple fission
3. Reductional division
4. Unequal division

Answer: 3. Reductional division

Question 27. In which of the following phase cell can not divide?

1. G₁
2. G₂
3. S
4. G₀

Answer: 4. G₀

Question 28. Which of the following sequence is right?

1. G₁— s—M— G₂
2. G₁—S—G₂—M
3. G₁—G₂—S—M
4. M— G₁—S— G₂

Answer: 2. GJ—S—G₂—M

Question 29. Which of the following is not a character of Interphase?

1. Increase in volume of cell
2. The disintegration of nuclear membrane
3. Energy production
4. DNA production

Answer: 2. Disintegration of the nuclear membrane

Question 30. On which of the following organism amitosis takes place?

1. Human
2. Amoeba
3. Frog
4. Mango plant

Answer: 2. Amoeba

Question 31. Determine the number of DNA molecules that get coiled to form each chromosome in a newly formed daughter cell produced by mitotic cell division in the human body.

1. 46
2. 1
3. 23
4. Numerous

Answer: 2. 1

 

Chapter 2 Cell Division And Cell Cycle Answer In A Single Word Or Sentence

Question 1. By which process two or more daughter cells develop from a single cell?
Answer: Cell division

Question 2. How much increase in DNA content within the nucleus initiates cell division?
Answer: When the content of DNA within a nucleus becomes double, cell division is initiated.

Question 3. Which organic matter initiates cell division process in plant and animal bodies?
Answer: Specific protein factors or growth hormones in animal and plant bodies initiate cell division.

Question 4. Name two compounds which prevent cell division.
Answer: Azides and cyanides

Question 5. What is karyokinesis?
Answer: Nuclear division within a cell is called karyokinesis.

Question 6. What is cytokinesis?
Answer: Splitting up of the cytoplasm in a dividing cell is called cytokinesis.

Question 7. Where does amitotic cell division occur?
Answer: Amitotic cell division occurs in lower groups of organisms like bacteria, yeast, an alga named Chara etc.

Wbbse Class X Life Science

Question 8. Name two animal cells which remain in G₀ phase.
Answer: Nerve cells and cardiac muscle

Question 9. In which phase of cell cycle does DNA synthesis occur?
Answer: In the S phase

Question 10. The somatic cell of a plant carries 14 chromosomes. After mitotic division, how many chromosomes will be there in the daughter cell?
Answer: If the somatic cell of a plant carries 14 chromosomes, then after mitosis the daughter cell will also carry chromosomes.

Question 11. Why nerve cells do not undergo cell division?
Answer: Since nerve cells possess inactive centrosomes which are unable to produce spindle, so these cells do not undergo cell division.

Question 12. What type of cell division is the binary fission of Amoeba?
Answer: Binary fission of Amoeba is an amitotic cell division.

Question 13. Which cell organelle supplies energy for human cell division?
Answer: Mitochondrion

Question 14. Name a cell organelle that increases in number during the G₂ phase.
Answer: Mitochondrion is the cell organelle which increases in number during the G₂ phase.

Question 15. How many daughter cells will be available after five consecutive mitotic divisions of an animal cell?
Answer: After five consecutive mitotic divisions of an animal cell, 32 daughter cells will be available.

Question 16. Which substance produce spindle fibre in blant cell?
Answer: Microtuble

Question 17. What is the role of the centrosome in animal cell division?
Answer: Centrosomes produce spindle fibres during cell division in animal cells.

Question 18. Which cell organelle supplies phospholipids during membrane formation in cell division?
Answer: Smooth endoplasmic reticulum

Wbbse Class X Life Science

Question 19. Write down the name of a substance helping in cell division.
Answer: Growth hormone

Question 20. In which type of cell division chromosome is not seen?
Answer: Amitosis

Question 21. What type of cell division is the binary fission of Amoeba?
Answer: Amitosis

Question 22. Which type of cell division helps in the healing of the body?
Answer: Mitosis

Question 23. Which phase of cell division is called the quiescent phase?
Answer: Go phase

Question 24. Name two cells which are present permanently in Go stage.
Answer: Nerve cells and Muscle cells of the heart.

Question 25. Name one enzyme controlling cell cycle.
Answer: Cyclin Dependent Kinase (CDK).

Question 26. How many cells will be produced if a cell undergoes five mitotic divisions successively?
Answer: 32

Question 27. Which is the longest and shortest phase of Interphase?
Answer: Longest phase-G₁, shortest phase-G₂

 

Chapter 2 Cell Division And Cell Cycle Fill In The Blanks

Question 1. The whole body of an organism is formed from a single _______.
Answer: Cell

Question 2. The process of synthesis of DNA from another DNA is called _______.
Answer: Replication

Question 3. The membrane-less cytoplasmic organelle that plays an important role in protein synthesis is known as _______.
Answer: Ribosome

Question 4. Energy generated within mitochondria remains stored in _______ molecules.
Answer: ATP

Wbbse Class X Life Science

Question 5. _______ cell division is called equational division.
Answer: Mitotic

Question 6. Amitosis is a _______ cell division.
Answer: Direct

Question 7. Meiosis it is a _______ division.
Answer: Equational

Question 8. Cell organelles become doubled in phase.
Answer: G

Question 9. DNA synthesis takes place in _______ phase of the cell cycle.
Answer: S

Question 10. _______ phase of cell division is called the dormant phase.
Answer: Go phase

 

Chapter 2 Cell Division And Cell Cycle State True Or False

Question 1. Ribosome helps in protein synthesis.
Answer: True

Question 2. Uncontrolled cell division results in to cancer.
Answer: True

Question 3. The go stage is seen in all somatic cells.
Answer: False

Question 4. Mitochondria supply the necessary energy for cell division.
Answer: True

Wbbse Class 10 Life Science Solutions

Question 5. Amitotic cell division occurs in neurone.
Answer: False

Question 6. Mitotic cell division occurs in the germ mother cell.
Answer: False

Question 7. Chromosome number decreases in daughter cells after meiosis.
Answer: True

Question 8. The mitotic division is known as the equational division.
Answer: True

Question 9. Meiosis plays important role in the alternation of generations.
Answer: True

 

Chapter 2 Cell Division And Cell Cycle Match The Columns

Question 1.

Answer: 1. E, 2. C, 3. B, 4. D, 5. F, 6. G

Question 2.

Answer: 1. B, 2. C, 3. A, 4. E, 5. D, 6. G

Chapter 2 Cell Division And Cell Cycle Find The Odd One Out

Question 1. Spindle fibre formation, Energy generation, Protein production, O₂ conduction
Answer: Oxygen conduction

Question 2. Amitosis, Direct cell division, Amoeba, Human
Answer: Human

Question 3. Reductional division, Gamete formation, Crossing over, Somatic cell formation
Answer: Somatic cell formation

Question 4. Interphase, Metaphase, Anaphase, Prophase
Answer: Interphase

Wbbse Class 10 Life Science Solutions

Question 5. G₁, S, G₂, M
Answer: M

Question 6. Cell number increase, Healing, Reproduction, Circulation
Answer: Circulation

Question 7. Uncontrolled cell division, Tumour formation, RBC formation, Cancer
Answer: RBC formation

Chapter 2 Cell Division And Cell Cycle Fill In The Blanks By Looking At The First Pair

Question 1. Mitochondria: Energy supply in cell division:: Centrosome: __________.
Answer: spindle fibre formation

Question 2. Spindle fibre formation in animal cell : Centrosome: Spindle fibre formation in plant cell: __________.
Answer: Microtubule

Question 3. Mitosis: equational division:: Meiosis: __________.
Answer: Reductional division

Question 4. Somatic cell formation: Mitosis :: Gamete formation: __________.
Answer: Meiosis

Question 5. Sperm formation: Mitosis: Growth of embryo: __________.
Answer: Mitosis

Wbbse Class 10 Life Science Solutions

Question 6. G phase: Interphase :: Metaphase: __________.
Answer: M phase

Question 7. Mitosis: Radicle:: __________:Spore mother cell.
Answer: Meiosis

Question 8. Mitosis: Radicle :: Meiosis __________.
Answer: Spore mother cell

Chapter 2 Cell Division And Cell Cycle Among The Four Concepts Given, Three Of Them Belong To One Find That

Question 1. Yeast, Paramoecium, Amitosis, Bacteria
Answer: Amitosis

Question 2. Growth of embryo, Spore mother cell formation, Mitosis, Healing
Answer: Mitosis

Question 3. G₁, phase, S phase, Interphase, G₂ phase
Answer: Interphase

Question 4. Ribose sugar, Phosphate, N₂ base, RNA.
Answer: RNA

Wbbse Class 10 Life Science Solutions

Question 5. Sperm production, Egg production, Meiosis, Pollen formation
Answer: Meiosis

Question 6. N₂ base, DNA, phosphate, Deoxyribose sugar
Answer: DNA

Question 7. H2A, H2B, H4, Histone
Answer: Histone

Chapter 2 Continuity Of Life Chromosome Summary

WBBSE Class 10 Chromosome Structure Overview

• Cell division and reproduction maintain the continuity of life. Ceil contain a nucleus which in turn contain chromosome. The DNA in the chromosome is> the reservoir of genetic information.
• A particular portion or sequence of DNA, that controls one or more characters of an organism is called a gene. It is also known as a basic physical and functional unit of heredity.
• Chromosome is a condensed form of DNA. Hence it is of two types—autosomes and allosomes. Autosomes are mainly responsible for controlling somatic characteristics whereas allosomes are responsible for sexual features. In the human body, 22 pairs of autosomes are there, whereas allosomes are only one pair.
• In males,-allosomes are heterologous in nature and comprise with two different types of chromosome-X and Y. In female, allosomes are homologous in nature and comprise of similar type of chromosome-X and X.

Read and Learn More WBBSE Solutions for Class 10 Life Science And Environment

• The physical structure of a chromosome is mainly comprised of chromatids, centromere, secondary constriction and telomere. The chemical components of chromosomes are DNA, histone and non-histone protein.
• DNA or deoxyribonucleic acid is a large molecule mainly composed of two polynucleotide chains, that coil around with each other and form a helical structure. This DNA is chemically composed of N₂ bases, pentose sugar and phosphate. The N₂ bases of DNA are of two types-purines (adenine and guanine) and pyrimidine (cytocine and thymine).
• Other than DNA, RNA also carries genetic information in the case of lower organisms {mainly bacteria and viruses). This RNA or ribonucleic acid is produced or originates from DNA, mainly composed of a single polynucleotide chain and is very unstable in nature.
• Like DNA, it is also comprised with N₂ base, pentose sugar and phosphate. But in RNA pyrimidine base uracil replaces the thymine.
  When the cell is in a quiescence state, the chromosome remains in chromatin form in the cell. On the basis of staining and function, chromatin is of two types-euchromatin and heterochromatin.

Chapter 2 Continuity Of Life Chromosome Long Answer Type Questions

Question 1. Explain the inter-relationships among Chromosomes, DNA and gene. Distinguish between euchromatin and heterochromatin on the following two aspects: Coiling, Activity.
Or,
Distinguish between euchromatin and heterochromatin.

Answer:

Inter-relationships among Chromosomes, DNA and gene:

There are fine thread-like structures present in the nucleus of cell. These are intermingled twisted ladder-like double-stranded structures. These structures are DNA which are large biomolecules. They occur inside the nucleus in a completely coiled manner.

In an undivided state of cells, the partially uncoiled DNA is called nuclear fibre or chromatin fibre. During cell division, DNA gets coiled. DNA strand surrounds protein molecules firmly and forms a dense coiling.

This coiled structure is called a chromosome. Actually, chromatin fibre and chromosome are respectively the less and much-coiled structures of DNA.

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WBBSE Class 10 History Long Answer Questions	WBBSE Solutions for Class 10 Life Science And Environment
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WBBSE Class 10 History Very Short Answer Questions	WBBSE Solutions for Class 10 Physical Science and Environment
WBBSE Class 10 History Multiple Choice Questions

 

Life Science Class 10 Wbbse

Difference between euchromatin and heterochromatin

Types of Chromosomes in Humans

Question 2. Describe the physical structure of the eukaryotic chromosome. Or, Describe the morphological features of the chromosomes of an eukaryotic cell.

Part Question, Explain the importance of the following parts of a eukaryotic chromosome:

1. Centromere,
   
2. Telomere.

Answer:

The physical structure of eukaryotic chromosome:

The morphological features of a chromosome appear ‘most distinctly under a microscope during the metaphase stage of cell division. From this study, we can find 5 parts of a chromosome. These parts are described below.

1. Chromatids:

In a metaphase chromosome, two identical and longitudinal strands are seen. These are chromatids. Two chromatids of the same chromosome are called sister chromatids, which remain attached to a constricted region or centromere.

Each chromatid carries one or few very fine filaments along its length. These are called chromonemata (singular—chromonema). Each chromonema is composed of a longitudinally arranged coiled DNA.

Along each chromonema, everal spherical linearly arranged bead-like structures are seen, which are called chronometers.

2. Primary constriction and centromere:

Each chromosome has a distinct constricted region at which the sister chromatids remain attached to each other. This is known as primary constriction.

At e primary constriction, a round plate-like and dense heterochromatin structure is seen, which is called the centromere. The centromere has a few adhesive points, called kinetochores, which attach to the spindle fibres during metaphase.

The DNA present in the .centromere is genetically inactive in nature.

3. Secondary constriction:

Other than primary constriction, there are one or a few constricted regions in the chromosomes. These are called secondary constrictions. Generally, the nucleolus is seen affixed to the secondary constriction.

During the telophase of cell division, this region helps to reorganise the nucleolus. Therefore, secondary constriction is also known as nucleolar organiser region or NOR.

4. Satellite:

In a few chromosomes, a bulb-shaped terminal portion is seen beyond the secondary constriction. This is called a satellite or SAT body. The chromosomes with SAT body are called SAT chromosomes.

5. Telomere:

The terminal portions of a chromosome are called telomeres. These are genetically inactive regions of a chromosome. During interphase, telomeres help in DNA replication.

It also prevents the joining of a chromosome with another and controls the ageing and death of a cell.

Life Science Class 10 Wbbse

Question 3. Draw the morphology of an ideal eukaryotic chromosome and label the following parts:

1. Chromatid,
2. Centromere,
3. Nucleolar organizer,
4. Telomere.

Answer:

Question 4. Classify chromosomes based on the position of the centromere. Describe each type.

Answer:

Classification of chromosomes based on the position of the centromere

Based on the position of centromere, chromosomes can be classified into the following types—

1. Metacentric chromosome,
2. Sub-metacentric chromosome,
3. Acrocentric chromosome and
4. Telocentric chromosome.

Description of different types of chromosomes:

Different types of chromosomes have been described below.

1. Metacentric chromosome:

In this type of chromosome, the centromere is located at its middle. The two arms appear almost identical. During anaphasic movement, this type of chromosome appears as the English letter ‘V’.

Life Science Class 10 Wbbse

2. Sub-metacentric chromosome:

The Centromere of this type of chromosome is located slightly away from the ie centre. The two arms are unequal in length; one arm is slightly longer than the other, tiling anaphasic movement, this type of chromosome appears as the English letter ‘L’.

3. Acrocentric chromosome:

In this type of chromosome, the centromere is located near one end of it. Here, one arm is very long and another one is very short. During anaphasic movement, this type of chromosome appears like the English letter J.

4. Telocentric chromosome:

This type of chromosome has its centromere at one terminal end. During anaphasic movement, this chromosome appears like the English letter ‘I’.

Question 5. Distinguish between

1. Chromosome and chromatid,
2. Centromere and centrosome.

Answer:

Differences between chromosome and chromatid

Differences between centromere and centrosome

Life Science Class 10 Wbbse

Question 6. Describe the chemical structure of chromosomes.

Answer:

Chemical structure of chromosome:

A eukaryotic chromosome is composed of nucleic acid (DNA and RNA), proteins (basic and acidic) and metallic ions like calcium (Ca²⁺), magnesium (Mg²⁺) etc. Eukaryotic chromosomes contain 90% DNA and histone proteins.

The remaining 10% comprises RNA and acidic (non-histone) proteins.

1. Deoxyribonucleic acid (DNA):

It is a double-stranded helically coiled self-replicating macromolecule, 88 of deoxyribose (pentose) sugars, nitrogenous bases and phosphate molecules. Physically, this molecule appears as a spiral staircase.

The handrail-like portion of this molecule PhyS1Cposed of pentose sugars and phosphates. The steps are made up of pairs of nitrogenous bases, each pair includes one purine and one pyrimidine. Purines are adenine (A) and guanine (G).

Pyrimidines are thymine (T) and cytosine (C) In DNA, adenine joins with thymine and guanine joins with cytosine with two and three weak hydrogen bonds respectively.

2. Ribonucleic acid (RNA):

It is a single-stranded macromolecule, having few loops along the length. RNA is composed of ribose sugars, phosphates and nitrogenous bases. Like DNA, RNA also includes adenine, guanine and cytosine but instead of thymine, it contains uracil (U).

3. Histone and non-histone proteins:

The basic proteins of chromosomes are known as histones. Due to their basic nature, they can easily combine with acidic DNA molecules to provide stability.

Five types of histones are seen in a chromosome. These are H1, H2A, H2B, H3 and H4. Besides these, a few acidic non-histone proteins are also present in chromosomes.

4. Metallic ions:

These include calcium (Ca²⁺) and magnesium (Mg²⁺) ions, which help to maintain the integrity of the chromosome.

Question 7. Distinguish between DNA and RNA

Answer:

Differences between DNA and RNA

Functions of Chromosomes in Genetic Continuity

Chapter 2 Continuity Of Life Chromosome Short Answer Type Questions

Question 1. State the relation between chromosomes and gene.

Answer:

The relation between chromosomes and gene:

A chromosome is a dense, coiled form of DNA and a gene is a specific sequence of DNA, that can be translated to form a particular protein, which can be expressed in an organism. The number of genes is constant in a particular chromosome.

Not only the number, in a particular chromosome the nature of the gene is also constant. If a particular portion of a chromosome will be deleted mistakenly then the particular gene of that region will also be deleted which leads to mutational abnormality.

Question 2. What is a chromosome?

Answer:

Chromosome:

Chromosome is the self-replicating thread or rod-shaped nucleoprotein structure, present within the nucleus of eukaryotic cells. Chromosome carries genes and thereby controls all features and activities of any organism.

Wbbse Class 10 Life Science Solutions

Question 3. What are autosomes?

Answer:

Autosomes:

Autosomes are the chromosomes, which are present in the nucleus of the cell and regulate all physical features of an organism. Out of 23 pairs of chromosomes in a human somatic cell, 22 pairs are autosomes.

Question 4. Write the name of any two structural parts of the eukaryotic chromosome.

Answer:

Two structural parts of eukaryotic chromosome are chromatids and centromere.

Question 5. Mention the types of chromosomes.

Answer:

Functionally, chromosomes can be classified into two types. These are—

1. Autosomes or Somatic chromosomes and
2. Allosomes or sex chromosomes.

Question 6. What are allosomes?

Answer:

Allosomes:

The chromosomes present in the nucleus other than autosomes which mainly carry the sex-determining factors, are called allosomes. Human allosomes are of two types—X and Y chromosomes.

Question 7. What is meant by homologous chromosomes?

Answer:

Homologous chromosomes:

In a diploid (2n) cell, all chromosomes are present in pairs. Both the chromosomes of a pair have identical length, and size and carry the same set .of genes.

Each of these pairs of chromosomes is called a homologous chromosome.

Common Chromosomal Abnormalities in Humans

Question 8. What Is Chromatid?

Answer:

Chromatid:

During metaphase, each chromosome splits along the length into two identical thread-like portions, which remain attached to each other at a distinct constriction, called centromere. Each of these two filamentous parts of a chromosome is called a chromatid.

Question 9. What is Chromoneme?

Answer:

Chromoneme:

Chromonema filaments densely coil to form several equidistant bead-like structures serially aligned along its length. These dense granular structures are called chromomeres.

Wbbse Class 10 Life Science Solutions

Question 10. What is meant by chromatin reticulum?

Answer:

Chromatin reticulum:

The delicate network of very fine coiled, thread-like nucleoprotein structures, present in the nucleus of the cell, which shows affinity towards basic dyes, is called chromatin reticulum.

Before cell division, these chromatin reticular coils densely to take the shape of chromosomes.

Question 11. What is meant by primary constriction?

Answer:

Primary constriction:

The lightly stained, constricted part of a chromosome, at which the two chromatids remain attached, is called primary constriction. The region of primary constriction carries the centromere.

It is also the region where the spindle fibres bind during metaphase.

Question 12. What is meant by secondary constriction?

Answer:

Secondary constriction:

Apart from primary constriction, there may be one or few lightly stained constricted points, present on chromosomes. Each of these constrictions is called secondary constriction. The nucleolar organiser region (NOR) is associated with secondary constriction region.

Question 13. What is meant by NOR?

Answer:

NOR:

NOR stands for nucleolar organiser region. It is a chromosomal region around which the nucleolus forms. NOR includes active RNA genes which give rise to secondary constrictions of metaphase chromosomes.

Wbbse Class X Life Science

Question 14. What is meant by constitutive heterochromatin? Where does this occur?

Answer:

Constitutive heterochromatin:

The type of heterochromatin, which always remains within the nuclei of nil types of cells, is called constitutive heterochromatin.

Occurrence of constitutive heterochromatin:

This occurs in the centromere, telomere and nucleolar organiser regions.

Question 15. What is meant by facultative heterochromatin? Where does this occur?

Answer:

Facultative lieterochromatin:

Wbbse Class 10 Life Science Solutions

The type of heterochromatin, which occurs in certain cell types for a brief period of time, is called facultative heterochromatin.

Occurrence of facultative heterochromatin:

This occurs in the nucleus of human female somatic cells as Barr body.

Question 16. What is meant by coiled heterochromatin?

Answer:

Coiled heterochromatin:

In certain cells, during interphase, some heterochromatin fibres occur in coiled form. These are called coiled heterochromatin. These heterochromatin fibers help in gene regulation and are present equally in all cells.

Question 17. What is meant by haploid cells?

Answer:

Haploid cells:

The cells, in which all types of chromosomes occur in an unpaired state, are called haploid cells. The chromosome number of these cells is indicated as (n).

Example: Human spermatozoa and ova are haploid cells.

Question 18. What is meant by diploid cells?

Answer:

Diploid cells:

The cells, in which all types of chromosomes occur in the paired state, are called diploid cells. The chromosome number of these cells is indicated as (2n).

Example: Human somatic or body cells are diploid in nature.

Question 19. what are meant by 44XY and 44XX chromosomes?

Answer:

44XY and 44XX chromosomes:

In human somatic cells, there are 46 chromosomes. Out of these, male body cells have 44 autosomes and XY as two sex chromosomes whereas in females, diere are 44 autosomes and XX as two sex chromosomes.

Therefore, 44XY and 44XX constitute the chromosome number of a human male and female respectively.

Wbbse Class 10 Life Science Solutions

Question 20. Distinguish between primary and secondary constriction.

Answer:

Differences between primary and secondary constriction are—

Question 21. Distinguish between autosome and sex chromosome of humans based on the following features: Nature, Number.
Or,
Distinguish between autosome and allosome.

Answer:

Differences between autosome and allosome are—

Wbbse Class 10 Life Science Solutions

Question 22. What is meant by euchromatin?

Answer:

Euchromatin:

The loosely coiled chromatin fibres, which are lightly stained by basic dyes in a resting nucleus, carry active genetic material and take part in the synthesis of RNA, are called euchromatin. All functional genes of a cell are present in euchromatin.

Question 23. What is heterochromatin?

Answer:

Heterochromatin:

The densely coiled chromatin fibres, which are deeply stained by basic dyes and carry less genetic material are called heterochromatin. These chromatin fibres take part in regulating genes and maintaining chromosomal integrity.

Question 24. What is a gene?

Answer:

Gene:

The specific segment of a DNA molecule that acts as the structural and functional unit of heredity is called a gene. It carries the code for the synthesis of a particular protein within a living cell.

Genes are responsible for determining different characteristics of a living organism.

Question 25. What is locus?

Answer:

Locus:

Every gene is located in a specific position of a particular chromosome. This specific position of the gene on this particular chromosome is known as the locus of that gene.

Mitosis and Meiosis in Chromosome Division

Question 26. What is a nucleotide?

Answer:

Nucleotide:

The structural unit of a nucleic acid molecule, composed of one nitrogenous base, one pentose sugar and a phosphate group, is known as a nucleotide.

The number of nucleotides present in the nucleic acid conventionally determines the size of the nucleic acid.

Question 27. What is nucleoside?

Answer:

Nucleoside:

The structural subunit of a nucleic acid molecule, composed of one nitrogenous base and a pentose sugar, is known as a nucleoside. Phosphodiester bonds join several nucleosides one after another to form a nucleic acid strand.

Question 28. Distinguish between nucleoside and nucleotide.

Answer:

Differences between nucleoside and nucleotide are—

Question 29. What are histone proteins?

Answer:

Histone proteins:

The basic structural proteins, which bind to DNA to make it stable, are called histone proteins. There are five different histone proteins present in chromosomes. These are HI, H2A, H2B, H3 and 114.

Question 30. What are non-histone proteins?

Answer:

Non-histone proteins:

The acidic proteins associated with DNA molecules are known as non-histone proteins. These proteins help in the regulation of genes.

Question 31. What is meant by deoxyribonucleotide?

Answer:

Deoxyribonucleotide:

The structural unit of a DNA molecule, composed of one nitrogenous base, one deoxyribose sugar and a phosphate, is called deoxyribonucleotide.

Example:

Deoxyadenosine monophosphate, deoxyguanosine monophos¬phate, deoxycytidine monophosphate and deoxythymidine monophosphate.

Question 32. What is meant by ribonucleotide?

Answer:

Ribonucleotide:

The structural unit of an RNA molecule, composed of one nitrogenous base, one ribose sugar and a phosphate group, is called ribonucleotide.

Example: Adenosine monophosphate, guano-sine monophosphate, cytidine monophosphate and uridine monophosphate.

Question 33. What is the full form of DNA? Where does it occur?

Answer:

1. Full form of DNA: Deoxyribonucleic acid.
2. Occurrence of DNA: DNA occurs in chromosomes of the nucleus, mitochondria and plastids in eukaryotic cells. In prokaryotic cells, it occurs as the nucleoid. It also occurs in DNA viruses as genetic material.

Wbbse Class 10 Life Science Solutions

Question 34. Mention the components of DNA.

Answer:

DNA consists, of three components.

These components are—

1. Nitrogenous bases (such as adenine, guanine, thymine and cytosine),
2. Deoxyribose sugar and
3. Phosphate molecule.

Question 35. What is the full form of RNA? Where does it occur?

Answer:

1. Full form of RNA: Ribonucleic acid.
2. Occurrence: RNA occurs in nucleus ribosomes in eukaryotic cells. In prokaryotic cells, it occurs in ribosomes. RNA also occurs as genetic material in RNA viruses.

Question 36. Mention the components of RNA.

Answer:

RNA consists of three components.

These components are

1. Nitrogenous bases [such as adenine (a), guanine (g), cytosine (c) and uracil (u)],
2. Ribose sugar and
3. Phosphate molecule.

Question 37. Mention the types of RNA present in living cells.

Answer:

RNA is of three types.

These are—

1. Messenger RNA or mRNA,
2. Ribosomal RNA or rRNA and
3. Transfer rna or trna.

Role of Chromosomes in Cell Division

Question 38. What is a nucleosome? State its significance.

Answer:

Nucleosome:

In eukaryotes,, the basic structural organization of DNA packaging, where the DNA strand wound around the eight histone proteins (octamer) and looks like with a thread wrapped around a spool.

The eight histone proteins that are coiled by DNA are H2A, H2B, H3, and H4.

Significance Of Nucleosome:

Nucleosome is a packaging technique, that allows the DNA to be wrapped into the small area of a cell.

 

Chapter 2 Continuity Of Life Chromosome Very Short Answer Type Questions Multiple Choice Questions And Answers [Mcq]

Question 1. The term ‘chromosome’ was coined by—

1. Robert Hook
2. Darwin
3. Waldeyer-ITartz
4. Lamarck

Answer: 3. Waldeyer-ITartz

Question 2. The nucleolar organiser region refers to—

1. Primary constriction
2. Secondary constriction
3. Nucleolus
4. Nucleoplasm

Answer: 2. Secondary constriction

Question 3. At which region of a chromosome is the centromere situated?

1. Primary constriction
2. Secondary constriction
3. Telomere
4. Satellite

Answer: 1. Primary constriction

Question 4. The number of types of histone proteins presents in chromosomes are—

1. Two
2. Three
3. Five
4. Six

Answer: 3. Five

Question 5. The chromosome, whose centromere is located at the middle, is known as—

1. Telocentric chromosome
2. Acrocentric chromosome
3. Metacentric chromosome
4. Sub-metacentric chromosome

Answer: 3. Metacentric chromosome

Wbbse Class 10 Life Science Solutions

Question 6. Chromosomes in human somatic cells are—

1. Diploid
2. Haploid
3. Tetraploid
4. Triploid

Answer: 1. Diploid

Question 7. Many mitotic divisions are required to give rise to 128 cells from a single cell.

1. 7 times
2. 14 times
3. 16 times
4. 32 times

Answer: 1. 7 times

Question 8. The nitrogenous base, that is absent in RNA molecules, is called—

1. Adenine
2. Guanine
3. Cytosine
4. Thymine

Answer: 4. Thymine

Question 9. Which of the following is not a structural component of DNA?

1. Deoxyribose sugar
2. Uracil base
3. Thymine base
4. Phosphoric acid

Answer: 2. Uracil base

Question 10. Identify the correct feature of amitosis cell division. Occurs in germ mother cell of sexually reproducing organism

1. It is called indirect cell division
2. Chromosome and spindle fibre are formed
3. Chromosome and spindle fibre are not formed.

Answer: 2. It is called indirect cell division

Question 11. The number of chromatids present in a chromosome is—

1. 4
2. 2
3. 6
4. 8

Answer: 2. 2

Question 12. The number of chromosomes in a human germ cell is—

1. 46
2. 50
3. 23
4. 10

Answer: 3. 23

Wbbse Class 10 Life Science Solutions

Question 13. The chromosome, which has a centromere located at one end, is called—

1. Metacentric chromosome
2. Sub-metacentric chromosome
3. Acrocentric chromosome
4. Telocentric chromosome

Answer: 4. Telocentric chromosome

Question 14. The number of autosomes in the human somatic cells is—

1. 44
2. 46
3. 23
4. 22

Answer: 1. 44

Question 15. The number of autosomes in human germ cells is—

1. 44
2. 23
3. 22
4. 46

Answer: 3. 22

Question 16. The ratio of autosomes and X chromosomes in the somatic cell of a female is—

1. 44: 1
2. 44: 2
3. 23: 1
4. 44: 0

Answer: 2. 44: 2

Question 17. The ratio of autosomes and Y chromosomes in the somatic cell of a female is—

1. 44: 0
2. 44: 1
3. 44: 2
4. 23: 1

Answer: 1. 44 : 0

Question 18. The ratio of autosomes and X chromosomes in the somatic cell of a male is—

1. 44: 0
2. 44: 1
3. 44: 2
4. 23: 1

Answer: 2. 44: 1

Question 19. The point on primary constriction of a chromosome, that joins with a spindle fibre during cell division, is—

1. Chromomere
2. Centromere
3. Chromatid
4. Centrosome

Answer: 2. Centromere

Question 20. Any constriction on a chromosome, other than that carrying the centromere, is called—

1. Secondary constriction
2. Primary constriction
3. Main constriction
4. Second constriction

Answer: 1. Secondary constriction

Wbbse Class 10 Life Science Solutions

Question 21. The bulbous or swelled portion of a chromosome, beyond the secondary constriction, is called—

1. Stem body
2. Centromere
3. SAT body
4. Centrosome

Answer: 2. Centromere

Question 22. The main structural protein that forms the chromosome in eukaryotic cells is—

1. Albumin
2. Histone
3. Keratin
4. Globulin

Answer: 2. Histone

Question 23. A number of structural units, which combine to construct any ribonucleic and deoxyribonucleic acid molecule, is called—

1. Phosphate
2. Nitrogenous base
3. Pentose sugar
4. Nucleotide

Answer: 4. Nucleotide

Question 24. The term ‘gene’ was coined in 1909 by—

1. Remak
2. Farmer
3. Johannsen
4. Pasteur

Answer: 3. Johannsen

Wbbse Class X Life Science

Question 25. The nitrogenous base absent in DNA is—

1. Cytosine
2. Guanine
3. Adenine
4. Uracil

Answer: 4. Uracil

Question 26. The pair of parallel fibres present along the length of a chromosome is called—

1. Chromatid
2. Chromosphere
3. Chromonema
4. Chromomere

Answer: 1. Chromatid

Question 27. The percentage of DNA present in a chromosome is—

1. 50 %
2. 90%
3. 33.3%
4. 100%

Answer: 3. 33.3%

Question 28. The end portion of a chromosome is called—

1. Chromomere
2. Telomere
3. Centromere
4. Chromatid

Answer: 2. Telomere

Question 29. Each chromatid is composed of two parallel fibres along its length. Each of these fibres is called—

1. Chromatid
2. Chromosphere
3. Chromonema
4. Chromomere

Answer: 3. Chromonema

Question 30. Which of the following is the carrier of genes or genetic material?

1. Mesosome
2. Polysome
3. Chromosome
4. Ribosome

Answer: 3. Chromosome

Question 31. A purine nitrogenous base is—

1. Adenine
2. Cytosine
3. Thymine
4. Uracil

Answer: 1. Adenine

Wbbse Class X Life Science

Question 32. Which of these is not a pyrimidine nitrogenous base?

1. Thymine
2. Cytosine
3. Uracil
4. Guanine

Answer: 4. Guanine

Question 33. A nitrogenous base and a pentose sugar constitute a—

1. RNA
2. Nucleotide
3. Nucleoside
4. DNA

Answer: 3. Nucleoside

 

Chapter 2 Continuity Of Life Chromosome Answer In A Single Word Or Sentence

Question 1. Name the two terminal ends of a chromosome.
Answer: Telomeres

Question 2. Which amino acids are mostly present in histone protein?
Answer: Basic amino acids like lysine, arginine etc. are mostly present in histone protein.

Question 3. How many chromosomes are present in a human somatic cell?
Answer: A human somatic cell contains 46 chromosomes.

Question 4. Give an example of a haploid cell.
Answer: Germ cell or gamete (sperm and ovum)

Question 5. Give an example of a diploid cell.
Answer: Zygote

Question 6. Give an example of a triploid cell.
Answer: The endosperm of angiosperms plant is an example of a triploid cell.

Question 7. How many autosomes are there in a human spermatozoon?
Answer: Autosomes

Question 8. Mention the nitrogenous bases present in DNA.
Answer: The nitrogenous bases present in DNA molecules are adenine (A), guanine (G), cytosine (C) and thymine (T).

Question 9. Mention the nitrogenous bases present in RNA.
Answer: The nitrogenous bases present in RNA molecules are adenine (A), guanine (G), cytosine (C) and uracil (U).

Question 10. Name the nitrogenous base that is present in RNA instead of thymine.
Answer: Uracil

Question 11. Which component is present in nucleotide but absent in nucleoside?
Answer: Phosphate radical ‘is present in nucleotide but absent in nucleoside

Question 12. What is Kinetochore?
Answer:

Kinetochore

A disc-shaped protein structure associated with the centrosome of a chromosome, during cell division, to which microtubules of the spindle are attached.

Wbbse Class X Life Science

Question 13. Which portion of the chromosome is genetically inactive and takes deep stain?
Answer: Heterochromatin region of a chromosome is genetically inactive and takes deep stain.

Question 14. Who coined the term chromosome?
Answer: Von Waldeyer and Hartz

Question 15. What is Karyotype?
Answer:

Karyotype

Karyotype is a picture of all the chromosomes of an organism.

Question 16. Where do you find NOR?
Answer: NOR is present in between the centromere and telomere of the short arm of chromosomes 13, 14, 15, 21, 22.

Question 17. What is the distance between two nucleotides in the DNA?
Answer: 3.4A

Question 18. What is the full form of RNA?
Answer:

Form of RNA

Ribonucleic acid

Question 19. What is the structural unit of chromosomes?
Answer:

The structural unit of chromosomes

Nucleosome

Chromosomal Disorders Explained for Class 10

Question 20. What is the function of Euchromatin?
Answer:

Function of Euchromatin

Euchromatin contains more DNA and contains the gene for controlling characters.

Question 21. Which structure bind chromosome with spindle fibre?
Answer: Centromere

Question 22. What are the types of chromatin?
Answer:

Types of chromatin

Chromatin is of two types heterochromatin and euchromatin.

 

Chapter 2 Continuity Of Life Chromosome Fill In The Blanks

Question 1. __________ carries the characteristic features of any organism from one generation to the next.
Answer: DNA

Question 2. DNA is a large __________ molecule.
Answer: Organic

Question 3. A gene is located on a specific __________ of a chromosome.
Answer: Locus

Question 4. The sex-determining chromosome or sex chromosome is also known as __________.
Answer: Allosome

Question 5. The y chromosome carries __________ genes.
Answer: Holandric

Wbbse Class X Life Science

Question 6. Gametes are __________ in nature.
Answer: Haploid

Question 7. The __________ is located at the junction of two chromatids.
Answer: Centromere

Question 8. Somatic cells is __________ in nature.
Answer: Diploid

Question 9. The tiny bead-like structures along the length of a chromonema are called __________.
Answer: Chromomeres

Question 10. NOR is the region of __________ constriction.
Answer: Secondary

Question 11. The terminal portion of the chromosome is called __________.
Answer: Telomere

Question 12. Adenine and guanine is __________ type of N2 base.
Answer: Purine

Question 13. N₂ base + phosphate + Pentose sugar = __________.
Answer: Nucleotide

Question 14. Nucleotide = Nucleoside + __________.
Answer: Phosphate

Question 15. Pentose sugar of RNA is __________.
Answer: Ribose

Question 16. The distance between two strands of DNA is __________.
Answer: 10A

Wbbse Class X Life Science

Question l7. Non-histone proteins contain __________ protein in high amounts.
Answer: Acidic

Question 18. Production of DNA from a DNA is called __________.
Answer: Replication

Question 19. Cytosine, thymine and uracil are __________ types of N₂ base.
Answer: Pyrimidine

Question 20. Chromosome with satellite is called __________.
Answer: Sat chromosome

Question 21. The region of the chromosome containing the gene is called __________.
Answer: Locus

Question 22. A chromosome is the condensed coiled structure of __________.
Answer: DNA

Question 23. Adenine is a __________ type of nitrogenous base.
Answer: Purine

Chapter 2 Continuity Of Life Chromosome State True Or False

Question 1. DNA is a small organic molecule.
Answer: False

Question 2. Within the nucleus, DNA lies in a linear fashion.
Answer: False

Question 3. DNA is a double-stranded molecule.
Answer: True

Question 4. DNA molecules loosely coiled protein molecules.
Answer: False

Question 5. Chromatin reticulum and chromosomes are two different states of coiling of the DNA molecule.
Answer: True

Question 6. The autosome number of a human somatic cell is 44.
Answer: True

Question 7. The number of sex chromosomes in human somatic cells is 2.
Answer: True

Question 8. Human spermatozoa are diploid in nature.
Answer: False

Wbbse Class X Life Science

Question 9. Human ova are haploid in nature.
Answer: True

Question 10. DNA is composed of ribose sugars.
Answer: False

Question 11. RNA is composed of deoxyribose sugars.
Answer: False

Question 12. Germ cells contain a haploid number of chromosomes.
Answer: True

Question 13. In DNA, adenine is linked with guanine by hydrogen bonds.
Answer: False

 

Chapter 2 Continuity Of Life Chromosome Match The Columns

Question 1.

Answer: 1. D, 2. C, 3. B, 4. A, 5. F, 6. E

Question 2.

Answer: 1. D, 2. A, 3. B, 4. C, 5. E, 6. G

 

Chapter 2 Continuity Of Life Chromosome Find The Odd One Out

Question 1. DNA, RNA, Protein, Gene
Answer: Protein

Question 2. Acentric chromosome, -Metacentric chromosome, Telocentric chromosome, Acrocentric chromosome
Answer: Acentric chromosome

Question 3. Arginine, Histidine, Lysine, Tryptophan
Answer: Tryptophan

Question 4. Chromatids, Chromomeres, Centrosome, Centromere
Answer: Centrosome

Question 5. DNA, Histone protein, Non-histone protein, Ribosome
Answer: Ribosome

Question 6. Adenine, Cytosine, Uracil, Guanine
Answer: Uracil

Question 7. Secondary Constriction, Klnetoebore, Mitochondria, Chromatid
Answer: Mitochondria

Question 8. Adenine, Guanine, Thymine, Vitamin
Answer: Vitamin

Question 9. Pentose sugar, Phosphate, N₂ base, Auxin
Answer: Auxin

Question 10. Active gene, HNA production, Heterochromnlin, Lossdensed
Answer: Heterochromnlin

 

Chapter 2 Continuity Of Life Chromosome Fill In The Blanks By Looking At The First Pair

Question 1. Human Autosome: 44:: Human sex chromosome: ______.
Answer: 2

Question 2. Human chromosome in the somatic cell:: 46:: Human chromosome in germ cell: ______.
Answer: 23

Question 3. Heterochromatin : Inactive :: Euchromalin : ______.
Answer: Active

Question 4. XY: Male sex chromosome:: XX: ______.
Answer: Female Sex chromosome

Question 5. Adenine: Purine:: Thymine: ______.
Answer: Pyrimidine

Question 6. Histone: Alkaline:: Non-histone: ______.
Answer: Acidic

Question 7. Nucleosome: Chromosome:: Nucleotide:: ______.
Answer: Nucleic acid

 

Chapter 2 Continuity Of Life Chromosome Among The Four Concepts Given, Three Of Them Belong To One Find That

Question 1. Centromere, Chromosome, Primary Constriction, Secondary Constriction
Answer: Chromosome

Question 2. Chromosome, DNA, Histone protein, Non-histone protein
Answer: Chromosome

Question 3. Pyrimidine, N₂ base, Adenine, Guanine
Answer: N2 base

Question 4. Pyrimidine, Cytoeine, Thymine, Uracil
Answer: Pyrimidine

Question 5. N₂ base, DNA, Phosphate, Deoxyrihose sugar
Answer: DNA

Question 6. Ribose sugar, Phosphate, N₂ base, RNA
Answer: RNA

Question 7. H2A, H2B,H4, Histone
Answer: Histone

Chapter 1 Locomotion As A Type Of Response In Animals Summary

• The movement of the whole organism from one place to another is termed as locomotion. Animals move from one place to another place due to various reasons.
• Some of the reasons are—the search of food, to protect itself, search of habitat, search of mate or reproduction, etc Amoeba moves through pseudopodia, Paramoecium uses cilia, and Euglena uses flagella for locomotion.
• Fishes swim by the help of V-shaped myotome muscles and paired or unpaired fins. Birds use feathers i.e. remiges of the wing and rectrices of tail and flight muscles like pectoralis major, coracobrachialis and pectoralis minor for flight.

Read and Learn More WBBSE Solutions for Class 10 Life Science And Environment

• Locomotion in humans is termed as bipedal locomotion. This bipedal locomotion involves movement by two rear limbs or legs. The semicircular canal of inner ear and cerebellum helps in body balance during movement.
• Movable joints and skeletal muscles have a huge importance in human locomotion, The synovial fluid present in the joint prevents, friction. Examples of synovial joints are—ball and socket joints, hinge joints, pivot joints, etc.
• An example of a hinge joint is the joint of the knee and elbow. An example of ball and socket joint is the hip and shoulder joint.
• In flexion movement, two bones come near each other and in extension movement, two bones move distant from each other. The movement of any part away from the midline of the body is abduction and the movement towards the midline of the body is adduction.
• Rotation refers to movements made about the longitudinal axis and in the transverse plane, Different types of muscles help in these types of movements.
• Example-Biceps (flexor muscle), triceps (extensor muscle), deltoids (abductor’s muscle), adductor longus (adductor muscle).

Chapter 1 Locomotion Long Answer Type Questions

Life Science Class 10 Wbbse

Question 1. Briefly explain the driving forces of locomotion.
Or,
State the importance of locomotion in living organisms.

Similar question, A resting animal attempts to move. Mention four probable reasons behind it.

Answer:

Driving forces of locomotion:

The driving forces of locomotion are mentioned below.

1. Search of food:

Unlike plants, animals are not capable of synthesising their own food. Therefore animals have to roam around in search of food resources.

2. Escaping predation:

Among animals, a prey-predator interaction continues all the time. Here the aggressor is called the predator and the victims are called the preys.

To avoid predation’ preys have to flee from the predator. Therefore, locomotion is essential for preys to escape predation.

3. Migration:

Due to environmental changes, various species move from one place to another this is called migration. To avoid natural calamities, epidemics and other adversities, animals migrate to favourable places. This is a driving force of locomotion.

For example: during rain ants upward in search of a dry habitat.

WBBSE Solutions for Class 10 History	WBBSE Solutions for Class 10 Geography and Environment
WBBSE Class 10 History Long Answer Questions	WBBSE Solutions for Class 10 Life Science And Environment
WBBSE Class 10 History Short Answer Questions	WBBSE Solutions for Class 10 Maths
WBBSE Class 10 History Very Short Answer Questions	WBBSE Solutions for Class 10 Physical Science and Environment
WBBSE Class 10 History Multiple Choice Questions

 

4. Searching for favourable habitat:

Animals always look out for places with adequate food, water, ambient temperature, light, etc. This is also a purpose of animal locomotion.

5. Searching for a mating partner and favourable mating place:

Animals and a few plants perform locomotion in search of favourable places for reproduction. Animals roam around in search 1 o suitable mating partners for successful reproduction.

Question 2. How is locomotion dependent upon movement? State the differences between movement and locomotion.

Answer:

Dependence of locomotion on movement:

Locomotion is a process by which an organism changes its overall position in response to a stimulus or spontaneously.

Whereas, the physical activity by which an organism move any of its body parts either spontaneously or in response to stimulus without changing its position, is called movement.

A living form has to move its organs or cellular components in order to perform locomotion. Therefore, locomotion without movement is impossible but the movement of organs is completely independent of locomotion.

Differences between movement and locomotion

Life Science Class 10 Wbbse Question 3.

Briefly describe the method of amoeboid movement.
Or,
Describe the role of pseudopodia in the locomotion of Amoeba. Distinguish between cilia and flagella.

Answer:

Amoeboid movement:

The method of amoeboid movement is mentioned here.

1. The locomotory organ of Amoeba is the pseudopodium. Density of cytosol changes within the cell body of an Amoeba by external stimulation. Cytosol with lower density moves faster than the denser portion. As the cytosol flows to hit the cell membrane, it protrudes to develop a pseudopodium. There are numerous pseudopodia developed in an amoeboid cell.
2. The tip of these pseudopodia attach with the substratum and cytosol continues to flow into them.
3. Gradually the whole protoplasm flows towards the direction of the pseudopodia and the posterior portion of the cell retracts accordingly. This type of movement by pseudopodia is called amoeboid movement.

 

 

Differences between Cilia and Flagella

WBBSE Class 10 Locomotion Overview

Question 4. Briefly describe the locomotory mechanism of Euglena. Mention the differences between locomotion in Amoeba and Euglena.

Answer:

Locomotory mechanism of Euglena:

1. The locomotory organ of Euglena is a flagellum. This is a microscopic, long and fine filamentous cytoplasmic projection. Euglena moves in water by beating of the flagellum, therefore this movement is called flagellar movement The locomotory mechanism of Euglena is described as follows—
2. Euglena beats I’LS flagellum sidewise like a whip or rotates it around the longitudinal axis.
3. Movement of the flagellum generates turbulence in water and Euglena moves in opposition to its flagellum.
4. Euglena has a photosensitive eyespot This helps it to sense light and guide it during locomotion towards the illuminated zone of the water body.

Life Science Class 10 Wbbse

 

Differences between locomotion of Amoeba and Euglena

 

Question 5. Briefly describe the method of locomotion in Paramoecium. Mention a few ciliated cells other than Paramoecium.

Answer:

Locomotary mechanism of Paramoecium:

The locomotory organs of Paramoecium are cilia. These are tiny, very fine and densely arranged filamentous structures present all over the outer surface of its cell body. The method locomotion in Paramoecium through cilia is mentioned here.

1. All cilia show a synchronised whiplash movement. The first phase of this movement is the effective stroke, during which the cilium bends sharply in one direction.
2. Effective stroke is followed by a slow recovery stroke during which the cilium curls back loosely to its previous direction.
3. By the coordinated movement of all cilia, a continuous wave moves across the ciliated cell surface. This ciliary wave applies a thrust in the surrounding liquid medium and pushes the Paramoecium through it. This type of movement is known as ciliary movement.

 

Types of Locomotion in Animals

Ciliated cells other than Paramoecium:

Other than Paramoecium, Vorticella is another unicellular organism that possesses cilia. Among multicellular organisms, the cells of the inner lining of the trachea, olfactory cells of the nose and hair cells of the internal ear have cilia.

Question 6. Describe with a diagram, the mechanism of locomotion in fish. Mechanism of locomotion in fish.

Answer:

The locomotory organs of fish are its fish:

Life Science Class 10 Wbbse

Besides these, myotome muscles and, the swim bladder also help in locomotion. The method of locomotion in fish is described here—

1. Fish has seven fins, of which pectoral and pelvic fins are paired whereas dorsal, anal and tail, fins are unpaired. Role of each of these fins are mentioned as follows—

1. Pectoral and pelvic fins help the fish in going up and down in the water. These fins also keep the fish steady at the floor of the water body during rest.
2. The dorsal fin and anal fin keep the fish steady and prevent it from rollover during swimming.
3. Tail fin beats to create a thrust in water to move the fish forward. It also helps it to change direction during swimming.

2. ‘V-shaped myotome muscles of a fish, present at two sides of the vertebral column contact alternately in a synchronised fashion. This muscular action creates a lateral undulating movement in its body that helps the fish in swimming.

3. Swim bladder of a fish maintains its buoyancy by making instantaneous and voluntary changes in gas volume and thereby helps it to stay at different levels of water.

 

 

Question 7. Describe the roles of different flight-assisting body parts of birds.

Answer:

Role of different flight-assisting body parts of birds:

Birds are primary volant animals. Most of birds perform locomotion by flight. The role of different flight-assisting body parts of birds are explained here—

1. Birds have a spindle-shaped body, which helps to overcome air resistance.
2. The bones of birds are hollow inside, hence are very light. These bones are called pneumatic bones, which keep the body lighter and thus facilitate flight.
3. The lungs of birds are associated with 9 air sacs. These sacs hold extra air to reduce specific gravity and supply oxygen during high flight.
4. The forelimbs of birds are modified into wings. It is outwardly convex and inwardly concave. This shape facilitates in holding air during flight.
5. The edge of each wing has 23 and the edge of the tail has 12 l^rge ore-shaped flight feathers. These are called remiges and rectrices respectively.’The feathers have barbs, barbules and interlocking hooks, which keep the feather intact even in heavy air thrust.
6. To beat continuously, the wings are fitted with strong flight muscles. The Pectoralis major, pectoralis minor and coach brachialis are the three flight muscles, which help in the flight of birds.

Life Science Class 10 Wbbse

Difference Between Remiges And Rectrices

Question 8. Describe the mechanism of bipedal locomotion in man.

Answer:

Bipedal locomotion in man:

Human locomotion occurs by bipedal movement. Two legs take part in this locomotion hence it is called bipedal locomotion. Leg bones, bone joints and various leg muscles act in a coordinated fashion in this locomotion.

The mechanism of bipedal locomotion is described here—

1. At first, the upper portion of the body tends to move forward while the two legs remain anchored on the ground.
2. As the upper portion approaches forward, it tends to fall. To avert it, one leg, for instance, the left leg moves forward and places the foot ahead. At this moment, the right leg holds the body weight.
3. As the left foot touches the ground, the right knee folds and the heel is lifted With this movement, the upper portion of the body progresses forward and shifts its weight to the left leg.
4. Now, the right toe is lifted from the ground and the foot is placed ahead of the left leg. In this process, the two legs alternately move up and down and hence, move forward to aid in walking.
5. To maintain body balance, two hands swing forward and backwards alternately. When one leg moves forward the opposite hand extends.
6. The cerebellum and the semi-circular canals of the internal ear also play important roles in keeping body balanced during bipedal movement.

 

 

Wbbse Class 10 Life Science Solutions

Question 9. What is meant by movable or synovial joint? Describe it in brief.

Answer:

Movable or synovial joint:

The bone joint in which the bones are articulated in a movable manner and offer some degree of free movement is called a movable joint.

The point of articulation between two bones of a movable joint has a thin space, which remains filled with synovial fluid. Therefore, this type of joint is also called a synovial joint

Description of movable or synovial joint:

The description of movable or synovial joint is given here.

1. In this joint, the articulated ends of the bones remain attached to each other by thin but strong ligaments.
2. The heads of the bones remain coated with a thin fibrous tissue membrane called the synovial membrane.
3. The fine space present in between the membrane-coated ends of the two bones is known as synovial space.
4. The space remains filled with an aqueous lubricating fluid called synovial fluid.
5. The synovial fluid protects the bone ends against frictional wearing and supplies nutrition to the surrounding tissues.
6. The ends of bones are covered by thick cartilaginous tissue, called articular cartilage. It allows the bones to glide over each other with minimum friction.
7. There are different types of movable joints—ball and socket joint, hinge joint, angular joint, saddle joint, pivot joint, etc.

Difference Between Remiges And Rectrices

 

Functions of Muscles in Locomotion

Question 10. Give a brief description of the mechanism with examples of human skeletal muscles, involved in

1. Flexion,
2. Extension,
3. Abduction,
4. Adduction and
5. Rotation.

Answer:

The action of some human skeletal muscles:

Difference Between Remiges And Rectrices

Wbbse Class 10 Life Science Solutions

Question 11. Distinguish between flexion and extension. Mention the differences between abduction and adduction.

Answer:

Differences between flexion and extension

 

Differences between abduction and adduction

Difference Between Remiges And Rectrices

Chapter 1 Locomotion Short Answer Type Questions

Question 1. What is locomotion?

Answer:

Locomotion:

Locomotion is a physical activity by which an organism changes its overall position in response to a stimulus or spontaneously.

Question 2. What is meant by response in animals?

Answer:

Response in animals:

Response in animals means the movement of body parts or changing the overall position by an animal, involving the activity of muscles and bones.

Question 3. What are pseudopodia?

Answer:

Pseudopodia:

Pseudopodia are temporary finger-like protrusions of protoplasm with cell membrane from the surface of amoeboid cells for the purpose of feeding and locomotion.

Question 4. What are cilia?

Answer:

Cilia:

Cilia are minute, numerous hair-like projections emerging from the surface of some unicellular organisms, which perform rhythmic beating for locomotion.

Question 5. What are flagella?

Answer:

Flagella:

Flagella are fine, slender, whip-like projections of some unicellular organisms, used for the purpose of swimming.

Question 6. What does amoeboid movement mean?

Answer:

Amoeboid movement

Amoeboid movement is a locomotory movement of unicellular organisms, executed by means of pseudopodia. Protozoans like Amoeba and blood cells like neutrophils perform the amoeboid movement.

Question 7. How does Paramoecium perform ciliary movement?

Answer:

Paramoecium has numerous densely arranged cilia along its cell membrane. All its cilia beat in a coordinated manner to create an undulating wave along the cell surface. This ciliary wave helps it to swim in the water bodies.

Wbbse Class 10 Life Science Solutions

Question 8. What is ciliary movement?

Answer:

Ciliary movement:

The locomotion of unicellular organisms by rhythmic beating of cilia beating in a liquid medium is called ciliary movement etc. Paramoecium, and Vorticella, perform a ciliary movement.

Question 9. What is flagellar movement?

Answer:

Flagellar movement:

The locomotion of a unicellular organism by whipping or rotating of flagella in any liquid medium is called flagellar movement. Euglena, Trypanosoma, etc. perform flagellar movement.

Wbbse Class 10 Life Science Solutions

Question 10. What is myotome muscle?

Answer:

Myotome muscle

The ‘V-shaped muscle present on two sides of vertebra of fish extending from head to tail is called myotome muscle. These muscle helps in swimming.

Question 11. Mention the location of myotome muscles. State their functions.

Answer:

Location of myotome muscles:

Myotome muscles are located at the two lateral sides of the body of a fish, extending from the back of the operculum to the base of the tail fin.

Functions of myotome muscles:

These muscles at lateral sides, contract and expand alternately in a synchronised manner to create an undulating movement of the body. The thrust that is created, helps the fish to move forward in water.

Wbbse Class 10 Life Science Solutions

Question 12. Mention the roles of the fins of fish.

Answer:

Fins of fish perform the following functions-

1. Pectoral and pelvic fins help the fish to move up and down in the water.
2. Dorsal fins keep the body steady and prevent rolling over.
3. The tail fin helps in propelling the fish through water and changing direction during locomotion.
4. The anal fin maintains the stability of the fish in the water while swimming.

 

 

Question 13. What would have happened to a bony fish if it had not developed any paired fin?

Answer:

If a bony fish had not developed any of its paired fins, like pectoral and pelvic fins, it would not have been able to move up and down in water and cannot remain steady in a stationary condition.

Question 14. What would have happened to a bony fish if it had not developed a swim bladder?

Answer:

If a bony fish had not developed a swim bladder, it would fail to maintain its buoyancy. In this situation, it could not go at different depths of the water body and not even stay stationary at a certain depth.

If it had to survive, it would have to stay at the floor of the water body.

Wbbse Class 10 Life Science Solutions

Question 15. Mention the functions of the tail fin of a fish.

Answer:

The functions of tail fin of a fish are as follows—

1. The tail fin gives the ultimate thrust on the water to push the body forward (propulsion).
2. The tail fin controls the direction of movement of the fish while swimming.

Question 16. What are flight feathers? Mention their types.

Answer:

Flight feathers:

The larger feathers, which are arranged along the inner edge of wings and end of the tail of a bird, are called flight feathers.

Types of flight feathers:

The flight feathers are of two types—the remiges present in the wings and the rectrices along the end of the tail.

Question 17. What are flight muscles?

Answer:

Flight muscles:

The voluntary muscles attached to the wings and tail of birds, which help in beating of wings and rotating of the tail during flight, are called flight muscles.

Example: Pectoralis major, pectoralis minor, coracobrachialis.

Question 18. How do the feathers remain intact in air pressure?

Answer:

A feather has numerous lateral filamentous barbs. Each barb develops lateral barbules and microscopic hooks from both the sides. These hooks interlock the barbules and thereby the barbs as well.

Due to this cross interlocking of the barbs and barbules, the feathers remain intact in wind pressure, if any portion of it splits, it rejoins at once at the two opposing hooks that encounter each other.

Wbbse Class 10 Life Science Solutions

Question 19. Differentiate between remiges and rectrices.

Answer:

Differences between remiges and rectrices are—

 

Question 20. Why is human locomotion called bipedal locomotion?

Answer:

The locomotory organs of humans are two legs. By continuous and synchronised movement of these two legs, a man moves from one place to an order. Therefore, human locomotion is called bipedal locomotion.

Question 21. What is skeletal muscle? Give two examples of muscle helping in locomotion.

Answer:

Skeletal muscle:

The muscle attached to bones by tendon and helps in locomotion are called skeletal muscle.

Example: Biceps femoris and gastrocnemius.

Question 22. Mention how the skeletal muscles help in human movement and locomotion.

Answer:

Skeletal muscles remain attached to different movable bones of different limbs. By the voluntary contraction of these muscles, the concerned limbs move. Thus, skeletal muscles help in human movement and locomotion.

Skeletal System and Locomotion

Question 23. Why is the movable bone joint called the synovial joint?

Answer:

In between the joining ends of two bones of a movable joint, there remains a thin space. A lubricating fluid is present in it, called synovial fluid. Therefore, this type of bone joint is called a synovial joint.

Question 24. What are the functions of synovial fluid?

Answer:

The functions of synovial fluid are—

1. The synovial fluid prevents the decay of bones due to friction.
2. Synovial fluid nourishes the cartilage present in the joint.

Question 25. What is a tender?

Answer:

Tender:

A tendon is a fibrous connective tissue which attaches muscle to bone. These are generally bright white in colour.

Question 26. What is a hinge joint?

Answer:

Hinge joint:

The bone joint, in which the bones move at an angle of 180° in a single plane, is called the hinge joint. For example—The elbow and knee are hinge joints.

 

Wbbse Class 10 Life Science Solutions

Question 27. Mention the characteristics of the hinge joint.

Answer:

Characteristics of hinge joint are as follows—

1. One bone of this joint has a round head and the other has a concave head.
2. The bones move at a maximum angle of 180° only in one plane.

Question 28. What is a bait and socket joint?

Answer:

Bait and socket joint:

The movable joint in which one bone with a partially spherical head is articulated with a cup¬shaped cavity of another bone is called the ball and socket joint.

This allows multidirectional movement and rotation. This type of joint is present in the shoulder and hip.

Question 29. Mention the characteristics of bail and socket joints.

Answer:

Characteristics of ball and socket joints are as follows—

1. One bone of this joint has a spherical head (ball) and the other bone has a cup-shaped end (socket).
2. In this joint, the socket remains fixed but the ball-ended bone can rotate almost at any direction.

 

 

wbbse class 10 life science question answer

Question 30. What is rotator muscle?

Answer:

Rotator muscle:

The muscle, which helps an organ to rotate around a central axis, is called the rotator muscle.

Example: Piriformis muscle of the lower limb.

Question 31. What is flexor muscle?

Answer:

Flexor muscle:

The muscle, which contracts to fold a limb, is called flexor muscle.

Example: Biceps muscle of the upper arm.

Question 32. What is extensor muscle?

Answer:

Extensor muscle:

The muscle, which contrasts to extend a folded limb, is called the extensor muscle.

Example: Triceps muscle of the upper arm.

Question 33. What is the abductor muscle?

Answer:

Abductor muscle:

The muscle, which contracts to pull a limb away from the body’s axis, is called abductor’s muscle.

Example: Gluteus maximus muscle of the hip, deltoid muscle of the shoulder.

wbbse class 10 life science question answer

Question 34. What is the adductor muscle?

Answer:

Adductor muscle:

The muscle, which contracts to pull a limb close to the body’s axis, is called adductor muscle.

Example: Adductor longus muscle of the thigh.

Human Locomotion Mechanism

Chapter 1 Locomotion Very Short Answer Type Questions Multiple Choice Questions And Answers [Mcq]

Question 1. The overall change in position of an organism from one place to another is called—

1. Movement
2. Locomotion
3. Transportation
4. Displacement

Answer: 2. Locomotion

Question 2. Which of the following organisms performs locomotion by means of pseudopodia?

1. Amoeba
2. Cockroach
3. Paramoecium
4. Butterfly

Answer: 1. Amoeba

Question 3. Paramoecium performs locomotion by—

1. Flagella
2. Cilia
3. Pseudopodia
4. Muscular foot

Answer: 2. Cilia

wbbse class 10 life science question answer

Question 4. _______ performs locomotion by flagella.

1. Cockroach
2. Euglena
3. Paramoecium
4. Amoeba

Answer: 2. Euglena

Question 5. The number of fins found in bony fishes is—

1. One
2. Five
3. Seven
4. Nine

Answer: 3. Seven

Question 6. Myotome muscles are present in—

1. Fishes
2. Bats
3. Dragonflies
4. Pigeons

Answer: 1. Fishes

Question 7. While swimming, which of the following helps in changing direction in fish?

1. Caudal fin
2. Dorsal fin
3. Anal fin
4. Pelvic fin

Answer: 1. Caudal fin

Question 8. Which of the following is the locomotory organ in a human body?

1. Hand
2. Leg
3. Forelimb
4. Tail

Answer: 2. Leg

Question 9. Which of the following organisms is not capable of locomotion?

1. Coral
2. Cockroach
3. Spider
4. Snail

Answer: 1. Coral

Question 10. The organ which helps fishes to float in water, is called—

1. Fins
2. Air bladder
3. Operculum
4. Lateral line sense organ

Answer: 2. Air bladder

Question 11. A plant, which is capable of locomotion, is

1. Fern
2. Cuscuta
3. Chlamydomonas
4. Mucor

Answer: 3. Chlamydomonas

Question 12. An animal, which is not capable of locomotion, is—

1. Starfish
2. Earthworm
3. Sponge
4. Hydra

Answer: 3. Sponge

Question 13. Where do you find the ball and socket joints?

1. Shoulder
2. Knee
3. Thumb
4. Elbow

Answer: 1. Shoulder

Question 14. In which of the following, a hinge joint is seen?

1. Waist
2. Shoulder
3. Elbow
4. Skull

Answer: 3. Elbow

wbbse class 10 life science question answer

Question 15. In which of the following, an immovable joint is seen?

1. Waist
2. Shoulder
3. Skull
4. Elbow

Answer: 3. Skull

Question 16. The type of movement, which is seen in humans, is called—

1. Bipedal movement
2. Amoeboid movement
3. Ciliary movement
4. Flagellar movement

Answer: 1. Bipedal movement

Question 17. Which of the following animals performs locomotion by means of swimming?

1. Hydra
2. Sponge
3. Fish
4. Amoeba

Answer: 3. Fish

Question 18. Which of the following animals performs locomotion by means of flight?

1. Earthworm
2. Snail
3. Bird
4. Lizard

Answer: 3. Bird

Question 19. Locomotory organ of fish—

1. Fin
2. Swim bladder
3. Lateral line sense organ
4. Undulating membrane

Answer: 1. Fin

Question 20. The bone, which is absent in hands, is—

1. Radius
2. Ulna
3. Humerus
4. Femur

Answer: 4. Femur

Question 21. Sunlight plays an important role in the movement of which animal?

1. Amoeba
2. Paramoecium
3. Both 1 and 2
4. Euglena

Answer: 4. Euglena

Question 22. Tibia, femur and patella unite at—

1. Pelvic girdle
2. Knee
3. Elbow
4. Ankle

Answer: 2. Knee

wbbse class 10 life science question answer

Question 23. Hip joint is the union of—

1. Femur and pelvic girdle
2. Femur and scapula
3. Humerus and scapula
4. Radius and ulna

Answer: 1. Femur and pelvic girdle

Question 24. Shoulder joint involves—

1. Scapula and humerus
2. Humerus and ulna
3. Femur and tibia
4. Pelvic girdle and femur

Answer: 1. Scapula and humerus

Question 25. Ligaments, tendons and bone joints are part of the—

1. Respiratory system
2. Musculature
3. Skeletal system
4. Circulatory system

Answer: 3. Skeletal system

Question 26. The number of remiges present in each wing of a pigeon is—

1. 11
2. 13
3. 19
4. 23

Answer: 4. 23

Question 27. The number of rectrices present in the tail of the pigeon is—

1. 6
2. 8
3. 12
4. 16

Answer: 3. 12

Question 28. Which of the following muscles is not a flight muscle of a pigeon?

1. Pectoralis major
2. Pectoralis minor
3. Myotome
4. Coraco brachialis

Answer: 3. Myotome

Question 29. Myotome muscles are seen in—

1. Human body
2. Fish
3. Whale
4. Toad

Answer: 2. Fish

Question 30. The skeletal muscle that aids in the folding of a limb is called—

1. Rotator
2. Flexor
3. Extensor
4. Abductor

Answer: 2. Flexor

Question 31. The skeletal, muscle that aids in the unfolding of a folded limb is called—

1. Rotator
2. Flexor
3. Extensor
4. Abductor

Answer: 3. Extensor

Question 32. The skeletal muscle that aids a limb to move away from the body axis is called—

1. Rotator
2. Flexor
3. Extensor
4. Abductor

Answer: 4. Abductor

Question 33. The skeletal muscle that aids in pulling a limb close to the body axis ifc called—

1. Rotator
2. Flexor
3. Extensor
4. Adductor

Answer: 4. Adductor

Question 34. The skeletal muscle that aids in rotating a limb is called—

1. Rotator
2. Flexor
3. Extensor
4. Abductor

Answer: 1. Rotator

Question 35. The muscle helping in flexion is—

1. Triceps
2. Biceps
3. Deltoid
4. Rotator

Answer: 2. Biceps

Question 36. The muscle that helps in adduction is—

1. Triceps
2. Biceps
3. Deltoid
4. Latissimus dorsi

Answer: 4. Latissimus dorsi

Question 37. An abductor’s muscle is —

1. Deltoid
2. Biceps
3. Triceps
4. Stapedius

Answer: 1. Deltoid

Question 38. Match the words of column-A with that of column B and select which of the following options is correct—

1. 1. A, 2. B, 3. C
2. 1. B, 2. C, 3. A
3. 1. C, 2. A, 3. B
4. 1, C, 2. A, 3. C

Answer: 3. 1. C, 2. A, 3. B

Common Disorders Affecting Locomotion

Chapter 1 Locomotion Answer In a single Word Or Sentence

Question 1. Name the locomotory organ of Amoeba.
Answer: Pseudopodia

Question 2. What is the locomotory organ of Euglena?
Answer: Flagellum

Question 3. What are the locomotory organs of a fish?
Answer: Fins

Question 4. What are the locomotory organs of a bird?
Answer: A pair of wings and two legs are the locomotory organs of a bird.

Question 5. Name the muscle that helps in locomotion of a fish.
Answer: Myotome muscles

Question 6. Name the paired fins of a fish.
Answer: Pectoral and pelvic fins

Question 7. Name the unpaired fins of a fish.
Answer: Caudal, dorsal and anal fins

Question 8. Which fin helps a fish to change its direction during swimming?
Answer: Caudal or tail fin

Question 9. Which organ of a fish helps it to float in water?
Answer: Swim bladder

Question 10. What will happen to a fish if all its fins are tied with a thread?
Answer: A fish will not be able to swim and keep its balance in water if all its fins are tied with a thread.

Question 11. when does Amoeba grow its pseudopodia?
Answer: During movement and food capturing, Amoeba grows its pseudopodia.

Question 12. Which type of locomotion does an adult human perform?
Answer: Bipedal locomotion

Question 13. Name a voluntary muscle.
Answer: Biceps

Question 14. Which type of muscle is the biceps?
Answer: Flexor muscle

Question 15. Name an extensor muscle.
Answer: Triceps

Question 16. How do you denote the point of contact ‘ between two bones?
Answer: The point of contact between two bones is called the bone joint.

Question 17. Name the structure, which connects two bones in a bone joint.
Answer: Ligament

Question 18. Where do you find hinge joints?
Answer: We find hinge joints in the elbow and knee.

Question 19. Where do you find ball and socket joints?
Answer: We find ball and socket joints in the shoulder and hip.

Question 20. Which characteristic feature of muscle fibres helps in movement and locomotion?
Answer: Contractibility of muscle fibres helps in movement and locomotion.

Question 21. Which type of joint is the knee joint?
Answer: Hinge joint

Question 22. Which fins help a fish to move up and down in the water?
Answer: Pectoral and pelvic fins

Question 23. Name the ‘V-shaped muscles present at both sides of the lateral line of a fish.
Answer: Myotome muscles

Question 24. Which muscle helps in extending a folded, limb?
Answer: Extensor muscles

Question 25. Which muscle helps to rotate a body part?
Answer: Rotator muscles

Question 26. Which muscle does help to move a limb away from the axis of the body?
Answer: Abductor’s muscles

Question 27. Name the flight feathers present along the posterior edge ot wings of a bird.
Answer: Remiges

Question 28. Name the large feathers present at the tail end of a bird.
Answer: Rectrices

Question 29. Name a unicellular organism having a photosensitive eyespot.
Answer: Euglena

Question 30. Which flight muscle helps a bird to move downward during the flight?
Answer: Pectoralis major

Question 31. Which flight muscle helps a bird to move upward during flight?
Answer: Pectoralis minor

Question 32. Which part of the internal ear helps to maintain body balance?
Answer: Semicircular canals

Locomotory Organs in Different Animals

Chapter 1 Locomotion Fill In The Blanks

Question 1. One of the objectives of ________ is the search for food.
Answer: Locomotion

Question 2. Chlamydomonas is a ________ capable of locomotion.
Answer: Plant

Question 3. The locomotory organ of Amoeba is ________.
Answer: Pseudopodium

Question 4. Paramoecium moves in ________ the direction to the movement of cilia.
Answer: Opposite

Question 5. The ________ of Euglena helps in determining the direction of its movement.
Answer: Eyespot

Question 6. The ________ present in Euglena can sense die presence of sunlight.
Answer: Eyespot

Question 7. The swim bladder of bony fish helps to maintain its ________.
Answer: Buoyancy

Question 8. ________ are the main locomotory organs of fishes.
Answer: Fins

Question 9. The ________ muscles of fish help it in swimming.
Answer: Myotome

Question 10. ________ fin of fish gives it stability in water.
Answer: Anal

Question 11. Pectoral and ________ fins are paired fins of a fish.
Answer: Pelvic

Question 12. The muscles, which help a bird in flying are called ________ muscles
Answer: Flight

Question 13. During bipedal locomotion, two ________ help in maintaining the stability of the human body.
Answer: Hands

Question 14. Articular hyaline cartilage is present in ________ joints.
Answer: Synovial

Question 15. In a hinge joint, the articulated bones can move at an angle of ________ in a single plane.
Answer: 180

Question 16. The hip joint involves pelvic girdle and ________.
Answer: Femur

Question 17. The muscles helping in the movement of bones are called ________ muscles.
Answer: Skeletal

Question 18. Sternocleidomastoid is a muscle that helps in ________ movement.
Answer: Rotational

Question 19. ________ muscle of hand contracts to fold the arm.
Answer: Biceps

Question 20. ________ muscle helps in the extension of the arm.
Answer: Triceps

Question 21. ________ muscle is ‘Y shaped.
Answer: Myotome

Question 22. The elbow joint is a ________ joint.
Answer: Hinge

 

Chapter 1 Locomotion State True Or False

Question 1. The movement of any limb away from the body axis is called a flexor.
Answer: False

Question 2. Joints of the knee and elbow are examples of hinge joints.
Answer: True

Question 3. The synovial fluid protects the movable bone ends against friction.
Answer: True

Question 4. Fins of birds help in flight.
Answer: False

Question 5. The tail feathers of birds are called remiges.
Answer: False

Question 6. During locomotion in man, the cerebellum helps in maintaining body balance.
Answer: True

Question 7. The tail fin of fish helps in changing direction during swimming.
Answer: True

Question 8. The biceps is example of an extensor muscle.
Answer: False

Question 9. Fins with fin rays are seen only in bony fishes.
Answer: True

Question 10. Byespot is present in Amoeba.
Answer: False

Question 11. Flagella help in the locomotion of Amoeba.
Answer: False

Question 12. Paramoecium is a sessile organism.
Answer: False

Question 13. Corals are incapable of locomotion.
Answer: True

Question 14. The skull bones are movably articulated with each other.
Answer: False

Question 15. In the ball and socket joint, the bones can move in more than two axes.
Answer: True

Question 16. Flagella is the locomotory organ of Paramoecium.
Answer: True

 

Chapter 1 Locomotion Match The Columns

Question 1.

Answer: 1. B, 2. D, 3. G, 4. A, 5. E, 6. C

Question 2.

Answer: 1. E, 2. C, 3. D, 4. F, 5. A, 6. B

 

Chapter 1 Locomotion Find The Odd One Out

Question 1. Pectoral fin, Caudal fin, Anal fin, Dorsal fin
Answer: Pectoral fin

Question 2. Amoeba, Cilia, Flagella, Fins
Answer: Amoeba

Question 3. Extensor digitorum, Myotome, Gastrocnemius, Biceps femoris
Answer: Myotome

Question 4. Synovial membrane, Ligament, Synovial fluid, Tendon
Answer: Tendon

Question 5. Gastrocnemius muscle, Pectoralis major, Coracobrachialis, Pectoralis minor
Answer: Gastrocnemius muscle

Question 6. Eye, Cerebellum, Semicircular Canal, Otolith
Answer: Eye

Question 7. Rotator, Extensor, Flexor, Fin
Answer: Fin

Question 8. Extensor muscle, Abductor muscle, Adductor muscle, Heart muscle
Answer: Heart muscle

 

Chapter 1 Locomotion Fill In The Blanks By looking At The First pair

Question 1. Flagellar movement: Euglena :: Ciliary movement:
Answer: Paramoecium

Question 2. Fish: Fins :: Amoeba:
Answer: Pseudopodia

Question 3. Biceps: Flexion of hand:: Triceps:
Answer: Extension of hand

Question 4. Pelvic girdle: Femur:: Pectoral girdle:
Answer: Humerus

Question 5. Elbow: Hinge joint:: Shoulder:
Answer: Ball and socket joint

Question 6. Pulling hand close to body axis: Latissimus dorsi:: Moving hand away from the body axis:
Answer: Deltoid

Question 7. Wings: Remiges :: Tail:
Answer: Rectrices

Question 8. Pectoralis major: Flight :: Biceps femoris :
Answer: Walking

 

Chapter 1 Locomotion Among The Four Concepts Given, Three Of Them Belong To One Find That

Question 1. Ciliary movement, Lateral undulation of the tail, Aquatic locomotion, Flagellar movement
Answer: Aquatic movement

Question 2. Ball and socket joint, Biceps femoris, Lifting of the leg, Extensor digitorum
Answer: Lifting of legs

Question 3. Changing flight direction, Twelve rectrices, Tail of a flying bird, Contraction of tail muscles
Answer: Changing flight direction

Question 4. Expansion of dorsal fin, Movement of pectoral fins, Maintaining body balance, Expansion of pelvic fins
Answer: Maintaining body balance

Question 5. Socket joint, Synovial joint, Hinge joint, Hip joint
Answer: Synovial joint

Question 6. Remiges, Rectrices, Flight feather, Quill
Answer: Flight feather

 

Chapter 1 Locomotion Advanced Questions And Answers

Question 1. What is a crescograph?

Answer:

Crescograph

Crescograph is a highly sensitive device, invented by Sir Jagadish Chandra Bose to detect even the mildest sensitivity of plants., This instrument is used to create impulses in the plant body and to record the response shown by it.

With this instrument, he performed experiments on the touch-me-not plant and telegraph plant.

Question 2. What is nyctinasty?

Answer:

Nyctinasty

The induced movement of curvature in plants, which is controlled by the intensity of both light and heat, are spread widely in hot and bright sun in midday but folds in late afternoon as the intensity of heat and light starts decreasing.

Question 3. What is meant by the Richmond-Lang effect?

Answer:

Richmond-Lang effect

Cytokinin hinders the denaturation of chlorophyll, proteins and nucleic acids of leaves and thus delays their immature shedding.

By this process, it protects other organs of a plant from early senescence and keeps them fresh for a longer time. This is called the Richmond-Lang effect.

Question 4. Mention the opposite actions of auxin and cytokinin.

Answer:

The opposite actions of auxin and cytokinin

Auxin enhances the growth of apical buds and maintains apical dominance, whereas, cytokinin prevents these actions. On the other hand, cytokinin promotes the growth of axillary buds but auxin prevents it.

Question 5. Mention two applications of animal hormone.

Answer:

Two applications of animal hormones are as follows—

1. By the application of pituitary hormone extract, fishes can be induced for breeding.
2. In case of acute breathing distress, adrenaline provides instant relief.

Question 6. Mention names, nature and function of 12 pairs of cranial nerves of humans.

Answer:

Question 7. What is acetabulum?

Answer:

Acetabulum

The socket-shaped portions of each pelvic girdle, located lateral to the hip region, in which the head of the femur fits, is called the acetabulum. The acetabulum and head of the lemur lit in a ball and socket joint.

Question 8. What is meant by synaptic delay?

Answer:

Synaptic delay

Synaptic delay is the brief period of time which is required for transmission of a nerve impulse horn one neurone to the next, across a synapse.

Chapter 1 Eye As A Sense Organ In Human Accommodation Defects Of Vision And Corrective Measures Summary

• The eye is a human sense organ which acts as a light receptor organ and helps in vision. The structural, components of the eye are—the eyeball, protective structures and eye muscles.
• The eyeball is composed of three layers. The outer fibrous layers is composed of sclera and cornea. The middle layer is composed of the choroid containing blood capillaries, ciliary bodies, and iris. The innermost neural layer is the retina.
• It is composed of rod and cone cells. Inside the eye, there is a biconvex lens behind the iris. The eyeball has three chambers. The front chamber is located between the cornea and iris; the middle chamber is located between the iris and lens and contains aqueous humour.
• The posterior vitreous chamber, located between the lens and retina contains vitreous humour. The protective parts of the eye are the conjunctiva, eyelid and lacrimal glands. The eyeball is connected by the eye muscle inside the eye socket.

Read and Learn More WBBSE Solutions for Class 10 Life Science And Environment

• Monocular vision is a type of vision in which one eye of the animal moves and sees objects independently of the other eye. Most preys have this type of vision.
• On the other hand, binocular vision is a type of vision where both eyes of an animal are used at the same time. Most predatory animals including humans employ this type of vision.
• The elasticity of ciliary muscle and lens helps the eye to produce the right image from different distances perfectly. This is called accommodation. Ciliary muscles change the curvature of the lens, which helps the lens to change its focal length and keep objects in focus.
• There are some important disorders related to the eyes. These are myopia (short-sightedness), hyperopia or hypermetropia (long-sightedness), and presbyopia.
• Accumulation of pigment due to the breakdown of protein in the lens causes loss of clear vision. It is called a cataract.

Chapter 1 Eye As A Sense Organ In Human Long Answer Type Questions

wbbse class 10 life science question answer

Question 1. Describe the structure of the human eyeball and mention its function.
Or,
Describe the structure and function of the human eyeball.

Similar question, Draw a neat diagram of the vertical section of the eyeball of the human eye and label the following parts—

1. Cornea,
2. Lens,
3. Vitreous humour,
4. Retina.

Answer:

Human eyeball:

It js a spherical, fluid-filled portion of the eye. It has two types of structural components—

1. The eye coats:

The structure and function of each component of the eye coats are as follows—

1. The eye has three coats—fibrous outer coat, vascularised medial coat and neural inner coat.
2. The fibrous outer coat has two portions, its posterior 5/6th opaque portion is called the sclera and the anterior 1 /6th transparent portion is known as the cornea, the sclera is rigid that keeps the shape of the eye intact. Cornea is a refractive medium that acts as a front window of the eye.
3. The vascularised medial coat is known as choroid. It is black in colour due to the accumulation of melanin pigment. The cornea is rich in blood capillaries.
4. The anterior extension of the choroid forms the ciliary body and iris. The ciliary body is a muscular extension of the choroid that holds the lens in position. It remains attached with the suspensory ligament. The pigmented muscular extension of the choroid that is present behind the cornea is called the iris. It has a round aperture at the centre to allow light to enter the eye. This aperture is known as the pupil. Contraction and expansion of iris muscles change the diameter of the pupil to regulate the exposure on the retina.
5. The neural inner coat known as the retina is composed of two types of photosensitive cells—rod cells and cone cells. The rod cells are sensitive to dim light and the cone cells sense bright light.
6. fust opposite to the pupil, the retina has a tiny depressed spot, called the macula lutea of yellow spot. This spot contains cone cells only and is capable of creating the sharpest image in bright light. The region of the retina from which the optic nerve emerges is devoid of any photosensitive cells. Therefore, this spot is incapable of sensing light, hence it is called the blind spot.

2. Refractive medium:

The structure and function of each component of the refractive medium is as follows—

1. The refractive media of eye are—cornea, aqueous humour, lens and vitreous humour.
2. Cornea is a transparent convex layer, present in front the eye as a window glass.
3. The thin anterior chamber of eye between the cornea and the lens is filled with a watery fluid called aqueous humour.
4. Behind the iris, a transparent circular biconvex lens is present, that is held in position by suspensory ligaments and ciliary muscles. The lens creates the image on the retina.
5. The posterior chamber of the eyeball behind the lens is filled with a viscous matrix, called vitreous humour. Both aqueous and vitreous humour maintains the pressure inside the eyeball and supply nutrition to different parts of the eye.

WBBSE Class 10 Eye as a Sense Organ Overview

WBBSE Solutions for Class 10 History	WBBSE Solutions for Class 10 Geography and Environment
WBBSE Class 10 History Long Answer Questions	WBBSE Solutions for Class 10 Life Science And Environment
WBBSE Class 10 History Short Answer Questions	WBBSE Solutions for Class 10 Maths
WBBSE Class 10 History Very Short Answer Questions	WBBSE Solutions for Class 10 Physical Science and Environment
WBBSE Class 10 History Multiple Choice Questions

 

Question 2. Mention two importance of accommodation in daily life. How does the eye accommodate to see a distant and a nearer object?

Answer:

Importance of accommodation:

Two importance of accommodation in our daily life is mentioned below.

1. While driving a car, the driver has to follow close objects like pedestrians and change over to a distant objects like traffic signals instantly.
2. While in the classroom; we look at the blackboard and the very next moment read or write something from the book or on tire paper over the desk.

Mechanism of accommodation to view distant and nearer objects:

Accommodation enables the eye to see any object from both close and long distances. The mechanism is mentioned below.

1. Seeinq a distant object:

To see a distant object, some sequential adjustments occur inside the eyeball. These are mentioned here.

Ciliary muscles relaxed → Curvature of the lens decreases → Lens becomes thin → Focal length of the lens increases →’The image is formed on the retina.

wbbse class 10 life science question answer

2. Seeing a nearer object:

To see a nearer object, following sequential adjustments occur inside the eyeball.

Ciliary muscles contract → Curvature of the lens increases → Lens becomes thick → Focal length of the lens reduces → The image is formed on the retina.

Question 3. Give a brief idea on hypermetropia.

Similar question, ‘A person can see distant objects distinctly but is unable to visualise a near object in a perfect way’—Predict what would be the probable cause and suggest the corrective measure for such problem. Write a note on the cataract.

Answer:

Hypermetropia:

Hypermetropia is a visual impairment in which a person can see any distant object but is unable to find the nearer objects clearly.

1. Characteristic feature:

In this disease, the diameter of the eyeball becomes anteroposteriorly compressed or the cornea becomes too much flattened. As a result, the image is formed beyond the retinal surface. So the patient finds a blurred image of the nearer objects.

2. Remedy:

To rectify hypermetropia, ophthalmologists recommend (+ve power) a convex glass lens. This glass lens creates an image on the retinal surface and makes the vision clear.

Cataract:

Usually due to ageing, deficiency of certain proteins in the eye lens makes it opaque. This condition is called cataracts.

1. Characteristic feature:

The opacity of the lens increases gradually to make the vision blurred.

2. Remedy:

To solve the problem of cataracts, an eye surgeon can replace the defective lens with a synthetic plastic lens by surgical procedure.

Functions of the Human Eye for Class 10

Question 4. Write a brief note on myopia. What do you know about presbyopia?

Answer:

Myopia:

Myopia is a visual impairment, in which a person can see nearer objects clearly but is unable to see distant objects.

1. Characteristic feature:

In this disease, the diameter of the eyeball becomes anteroposteriorly enlarged or the cornea is too much curved. As a result, the eyeball becomes elliptical, and the image is formed ahead of the retinal surface.

Therefore, the patient views a blurred image of the distant object.

2. Remedy:

To rectify myopia, ophthalmologists recommend a (-ve power) concave glass lens. This glass lens creates an image on the retinal surface and makes the vision clear.

Presbyopia Meaning:

After attaining the age of 40, most people lose the elasticity of the lens. In this situation, the accommo¬dation capacity reduces significantly. The visual impairment caused is known as presbyopia.

1. Characteristic feature:

A patient suffering from presbyopia cannot see nearer objects clearly. They face problems in reading, writing and dealing with finer tools.

2. Remedy: Presbyopia can be rectified by using the bifocal lens.

 

Chapter 1 Eye As A Sense Organ In Human Short Answer Type Questions

Question 1. What are sense organs?

Answer:

Sense organs:

The special receptor organs present in the animal body, which are capable of sensing only specific types of stimulus and transmitting the impulses to the central nervous system, are known as sense organs.

There are five sense organs, viz—ear, skin, eye, nose and tongue.

Structure of the Human Eye Explained

Question 2. Briefly describe the sclera of the eye. Mention its function.

Answer:

Sclera of the eye:

Sclera is the opaque fibrous coat, covering about 5/6 th portion of the eye from its posterior side. It is white in colour, rigid and composed of collagen fibres.

Function of Sclera of the eye:

Sclera provides shape to the eye and protects it from external injuries.

Question 3. What is a choroid? Mention its function.

Answer:

1. Choroid: The melanin-rich, dark-coloured layer of the eye, that is present in between the retina and sclera is called the choroid.
2. Function of choroid: Choroid supplies nutrition to different parts of the eye. It is black, therefore, prevents reflection inside the eyeball and absorbs undesired rays.

Question 4. Where is the retina located? Mention its function.

Answer:

1. Location Of Retina: Retina is located on the inner back wall of the eye.
2. Function Of Retina: Retina receives the visual stimulation by its photosensory cells and sends the visual impulse to the brain.

Question 5. Briefly describe the lens of human eye. Mention its function.

Answer:

Similar question, Mention one function of lens of the human eye.

The lens of the human eye:

It is a transparent, biconvex, elastic structure located behind the iris. It remains suspended steadily by suspensory ligaments behind the pupil of the eye.

Function:

The lens creates an image on the retina by the refraction of incident rays of light entering in to the eye.

wbbse class 10 life science question answer

Question 6. Briefly describe the cornea. Mention its function.

Answer:

Cornea:

The cornea is the 1 /6th portion of the fibrous protective layer of eye. It is a convex, transparent refractive layer present in front of the eye.

function of Cornea:

Cornea acts as a refractive medium to allow light to enter in to the eye. It operates as a condenser of incident light.

Question 7. What is a yellow spot? Mention its function.

Answer:

Yellow spot:

The spot-on retina just opposite to the pupil is highly rich in cone cells. This spot is capable of receiving the brightest and most piominent image of any object. This region is known as macula densa or yellow spot.

Function of Yellow spot:

The yellow spot is the portion of the eye that is specialised for seeing things with maximum clarity.

Life Science Class 10 Wbbse

Question 8. What is fovea centralis?

Answer:

Fovea centralis:

The centre of a yellow spot on the human retina has a tiny depression that contains only cone cells. This region of the retina is called the fovea centralis.

Importance of the Eye in Human Perception

Question 9. What is blind spot?

Answer:

Blind spot:

The spot on the retina, from which the optic nerve emerges and has no photosensitive cells. Therefore, this spot does not receive any stimulus from light. This spot on the retina is known as a blind spot.

Question 10. What is aqueous humour? Mention its function.

Answer:

Aqueous humour:

Aqueous humour is the transparent watery medium that is present in the anterior chamber of the eye in between the cornea and the lens.

Function Of Aqueous humour::

Aqueous humour is a refractive medium of the eye that maintains internal pressure of the anterior chamber and provides nutrition to different parts of it.

Life Science Class 10 Wbbse

Question 11. What is vitreous humour? Mention its function.

Answer:

Vitreous humour:

Vitreous humour is the transparent viscous medium that is present in the posterior chamber ol eye in behind the lens.

Function of Vitreous humour:

Vitreous humour is a refractive medium of eye that maintains internal pressure of the posterior chamber and maintains the perfect shape of the eye.

Question 12. Write the names of the different refractive mediums of eyeballs in proper sequence.

Answer:

The refractive mediums of the eyeball from outside to inside are—cornea → aqueous humour→lens→vitreous humour.

Question 13. What are eye muscles?

Answer:

Eye muscles:

The five strips of muscles, which bind the eyeball to the inner wall of the orbit or eye socket of the skull, are called eye muscles. The eye muscles control both voluntary and involuntary eye movements.

Question 14. State the location of the tear gland. Mention its function.

Answer:

Tear Gland Location:

The tear gland is located below the upper eyelid of each eye.

Tear Gland Function:

The tear gland releases a watery secretion to keep the exposed surface of the eye wet and clean it from dirt. It contains an enzyme (called lysozyme) that protects the eye against external germs.

 

 

Life Science Class 10 Wbbse

Question 15. What will happen if the tear glands stop secreting?

Answer:

If tear glands stop secreting, the surface of the eye will become dry and coarse. Dirt will settle on the eye and will damage the eye surface. Lack of the enzyme lysozyme will make the eye vulnerable to bacterial attack.

Question 16. What is monocular vision? Name a few animals with monocular vision.

Answer:

1. Monocular vision: In certain animals, two different images of two different objects are formed in two different eyes. As a result, the animal spots two different objects by its two eyes at a time. This is called monocular vision.
2. Animals with a monocular vision: Frogs, horses, most birds, fishes, etc.

Question 17. What is binocular vision? Name a few animals with binocular vision.

Answer:

Binocular vision:

In certain animals, the same image of a single object is formed in both eyes at a time. As a result, the animal spots the complete image of the same object by both of its. eyes. This is called binocular vision.

Animals with binocular vision:

A few animals with binocular vision are men, tigers, owls, etc.

Life Science Class 10 Wbbse

Question 18. What is an accommodation of the eye?

Answer:

Accommodation of the eye:

Accommodation is the unique ability of the eye to focus objects from different distances perfectly and instantly on the retinal surface. This is done by a quick change in curvature of the lens with the help of ciliary muscles and suspensory ligaments.

Question 19. How does the eye accommodate seeing a nearer object?

Answer:

To accommodate the eye to see a nearer object the ciliary muscles contract and suspensory ligaments relax to increase the curvature of the lens. As a result, the lens becomes thicker and its focal length reduces to create a clear image on the retinal surface.

Question 20. How does the eye accommodate seeing a distant object?

Answer:

To accommodate the eye to see an object located at a distance, the ciliary muscles relax and suspensory ligaments contract to decrease the curvature of the lens. As a result, the lens becomes thinner and its local length reduces to create a clear image on retinal surface.

Question 21. Mention the names of few visual problems

Answer:

The names of few visual problems are– myopia, hypermetropia, cataract, presbyopia, astigmatism, etc.

Question 22. What is myopia? Mention the cause of myopia.

Answer:

Myopia:

The visual Impairment in which a person can see the closer objects, but unable to visualise the distant objects clearly, is called myopia.

Myopia Cause:

In case of myopia, either the shape of the eyeball is too long or the cornea is too much curved. So, the light coming from any distant source creates the image a little ahead of retinal surface to make the distant vision blurred.

Life Science Class 10 Wbbse

Question 23. What is hypermetropia? Mention its cause.

Answer:

Hypermetropia:

The visual impairment in which a person can visualise the distant objects but is unable to see the closer objects clearly is called hypermetropia.

Hypermetropia Cause:

In the case of hypermetropia either the shape of the eyeball is too short or the cornea is too fiat. As a result, the light coming from a closer source creates the image a little behind the retinal surface to make the near vision blurred.

Question 24. What is presbyopia?

Answer:

Presbyopia:

The natural ability of accommodation of human eye decreases gradually after the age of 40 to 45 due to hardening or loss of elasticity of the lens, causing long-sightedness.

In this ageing-related visual impairment, individuals face a problem in reading and writing. This disease is called presbyopia.

Question 25. What is a cataract?

Answer:

Cataract:

Sometimes the lens of the human eye becomes opaque. Due to this condition, individuals lose clear vision. This visual impairment is called cataract and ii not treated in time, it may cause complete loss of vision.

Question 26. For correction of which defects in the vision of the eye, spectacles of convex and concave lenses are used?

Answer:

Spectacles of convex lenses are used in hyperopia and spectacles of concave lenses are in myopia.

 

Chapter 1 Eye As A Sense Organ In Human Very Short Answer Type Questions Multiple Choice Questions And Answers [Mcq]

Question 1. Which one of the following is a retinal cell?

1. Rod cell
2. Hepatocyte
3. Schwann cell
4. Mast cell

Answer: 1. Rod cell

Question 2. Rhodopsin is present in—

1. Cone cell
2. Rod cell
3. Cell body
4. Carrier cell

Answer: 2. Rod cell

Question 3. The aperture through which light enters into the eyeball is called—

1. Pupil
2. Cornea
3. Choroid
4. Cochlea

Answer: 1. Pupil

Question 4. The transparent outer covering of the eyeball is called—

1. Cornea
2. Sclera
3. Choroid
4. Retina

Answer: 1. Cornea

Question 5. The innermost layer and the most delicate layer of the eyeball where the photoreceptors are located are—

1. Choroid
2. Sclera
3. Retina
4. Cornea

Answer: 3. Retina

Question 6. Which one of the following helps in low-light vision?

1. Cone cell
2. Rod cell
3. Carrier cell
4. Transporter cell

Answer: 2. Rod cell

Question 7. The lens used for distant vision is—

1. Thick lens
2. Thin lens
3. Lens of identical curvature
4. All of these

Answer: 2. Thin lens

Question 8. The shape of the human eye lens is—

1. Concave
2. Convex
3. Bi-convex
4. Bi-concave

Answer: 3. Bi-convex

Question 9. The spot of the retina without rod and cone cells is called—

1. Black spot
2. Yellow spot
3. Fovea
4. Blind spot

Answer: 4. Blind spot

Question 10. An enzyme present in tears is—

1. Amylase
2. Maltase
3. Lysozyme
4. Sucrase

Answer: 3. Lysozyme

Question 11. Near-sightedness is called—

1. Presbyopia
2. Hypermetropia
3. Myopia
4. Cataract

Answer: 3. Myopia

Question 12. The vision problem in which an image is formed behind the retina is palled—

1. Myopia
2. Hyperopia
3. Presbyopia
4. Cataract

Answer: 2. Hyperopia

Question 13. Which of the following is not a refractory medium of an eye?

1. Lens
2. Cornea
3. Sclera
4. Aqueous humour

Answer: 3. Sclera

Question 14. Which of the following gives different colour to the eye?

1. Cornea
2. Iris
3. Lens
4. Choroid

Answer: 2. Iris

Question 15. The area of eye with the most excellent vision is—

1. Lens
2. Cornea
3. Fovea centralis
4. Optic disk

Answer: 3. Fovea centralis

Question 16. The meeting point of the retina and the optic nerve is called—

1. Yellow spot
2. Choroid
3. Eyespot
4. Blind spot

Answer: 4. Blindspot

Question 17. Which nerve receives the visual stimulus?

1. Olfactory
2. Optic
3. Auditory
4. None of the above

Answer: 2. Optic

Question 18. The liquid present in the chamber between the cornea and the lens is—

1. Perilymph
2. Endolymph
3. Aqueous humour
4. Vitreous humour

Answer: 3. Aqueous humour

Question 19. Which of the following has monocular vision?

1. Owl
2. Monkey
3. Tiger
4. Frog

Answer: 4. Frog

Question 20. Feco surgery is done in—

1. Ear
2. Eye
3. Skin
4. Tongue

Answer: 2. Eye

Common Eye Disorders for Class 10 Students

Chapter 1 Eye As A Sense Organ In Human Answer In A Single Word Or Sentence

Question 1. Name the three layers of a human eye.
Answer: Sclera, choroid and retina

Question 2. What is the other name of blind spot?
Answer:

The other name of blind spot is Optic disc

Question 3. Which portion of human eye protects it from mechanical injury by dust particles?
Answer: Conjunctiva

Question 4. What is the main function of the human eye?
Answer: Vision.

Question 5. What is sclera?
Answer:

Sclera

Sclera is the outermost protective layer of human eye.

Question 6. Which nerve connects the human eye with the brain?
Answer: Optic nerve

Question 7. Through which opening does light enter in to the eyeball?
Answer: Pupil

Question 8. Which part of the eyeball makes the pupil narrow or wide?
Answer: Iris

Question 9. In which organ do you find the cornea?
Answer: Eye

Question 10. Which protective layer of eye becomes transparent to form the cornea?
Answer: Sclera

Question 11. What is the function of the fluid present in the intermediate chamber between lens and retina of the eyeball?
Answer: The fluid present in the intermediate chamber between lens and the retina is vitreous humour which helps to absorb shocks to the eye and maintains the shape of the eye.

Question 12. Which parts of the body protect the eyes from mechanical injury and airborne particles?
Answer: The two eyelids protect the eyes from mechanical injury and airborne particles.

Question 13. Which type of lens is used to correct myopia?
Answer: Concave lens

Life Science Class 10 Wbbse

Question 14. Which type of lens is used to correct hypermetropia?
Answer: Convex lens

Question 15. At which minimum distance does an object comes under the range of distant vision?
Answer: An object at a minimum distance of 6 metres comes under the range of distant vision.

Question 16. In which eye problem, a person faces difficulty in viewing objects placed at a longer distance?
Answer: Myopia

Question 17. In which eye problem, a person faces difficulty in viewing objects placed at a close distance?
Answer: Hypermetropia

Question 18. Name an ageing-related eye disease.
Answer: Presbyopia

Practice Questions on Eye as a Sense Organ

Question 19. Which type of lens is used to rectify presbyopia?
Answer: Bifocal lens

Question 20. Which protective layer is directly connected to the eyeball?
Answer: Conjunctive

Question 21. In which disease the protein of the lens is degraded?
Answer: Cataract

wbbse class 10 life science question answer

Question 22. What are the pigments of rod and cone cells?
Answer: The pigment of the rod cell is rhodopsin and the pigment of the cone cell is iodopsin.

Question 23. What are the components of tears?
Answer:

Components of tears

The components of the tear are water, minerals, amino acid, antibody and lysozyme.

Question 24. Why image is not formed in the blind spot?
Answer: Due to the absence of light-sensitive rod and cone cells image is not formed in the blind spot.

Chapter 1 Eye As A Sense Organ In Human Fill In The Blanks

Question 1. The retina is composed of rod and _________ cells.
Answer: Cone

Question 2. Other than human being owl has _________ vision.
Answer: Binocular

Question 3. Image of any visible object is formed on the _________ of an eye.
Answer: Retina

Question 4. Rod cells contain _________ pigments.
Answer: Rhodopsin

Wbbse Class 10 Life Science Solutions

Question 5. The concave spot of the retina from which the optic nerve emerges is called _________ spot.
Answer: Blind

Question 6. The centre of the retina lying opposite to the pupil of eye is called _________ spot, where the brightest image is formed.
Answer: Yellow

Question 7. The l/6th part of the sclera in front of the eye remains transparent, which is called _________.
Answer: Cornea

Question 8. The protective layer, just below the sclera of the eye is called _________.
Answer: Choroid

Question 9. The cavities of a skull in which the two eyeballs are lodged are called _________.
Answer: Orbit

Question 10. The thin and transparent fibrous layer above the cornea is called _________.
Answer: Conjunctiva

Question 11. The faintly saline watery discharge from the eye is called _________.
Answer: Tear

Question 12. At the centre of the yellow spot, there is a tiny depression called _________.
Answer: Fovea centralis

Question 13. The gel-like substance present in between the lens and retina is known as _________ humour.
Answer: Vitreous

Question 14. In disease, the lens becomes opaque.
Answer: Cataract

Question 15. Loss of accommodation capacity of a lens, due to ageing, results in to _________ disease.
Answer: Presbyopia

Question 16. The process of necessary adjustment of the focal length of the lens in the human eye is called _________.
Answer: Accommodation

Wbbse Class 10 Life Science Solutions

Chapter 1 Eye As A Sense Organ In Human State True Or False

Question 1. The white outer protective layer of the eye is known as the choroid.
Answer: False

Question 2. Light enters in to the eyeball through the pupil.
Answer: True

Question 3. Sclera regulates the fluctuation in the size of the pupil.
Answer: False

Question 4. The lens of the human eye is biconvex.
Answer: True

Question 5. Tear glands are the protective parts of the eye.
Answer: True

Question 6. Human vision is binocular.
Answer: True

Question 7. The lens becomes thick to see a distant object.
Answer: False

Question 8. A concave lens is used to rectify myopia.
Answer: True

Question 9. To rectify presbyopia bifocal lens is to be used.
Answer: True

Question 10. The inability of accommodation by lens causes cataracts.
Answer: False

Question 11. Choroid helps in the accommodation of the eye by changing the curvature and shape of the lens.
Answer: False

Wbbse Class 10 Life Science Solutions

Chapter 1 Eye As A Sense Organ In Human Match The columns

Question 1. 

Answer: 1. B, 2. D, 3. F, 4. C, 5. A, 6. G

Question 2.

Answer: 1. B, 2. D, 3. A, 4. C, 5. F, 6. E

 

Chapter 1 Eye As A Sense Organ In Humans Find The Odd One Out

Question 1. Aqueous humour, Lens, Cornea, Choroid
Answer: Choroid

Question 2. Cataracts, Xerophthalmia, Presbyopia, Myopia
Answer: Xerophthalmia

Question 3. Aqueous humour, Lens, Cornea, Conjunctiva
Answer: Conjunctiva

Question 4. Vision of a chameleon,  Vision of a monkey,  Vision of a cow,  Vision of a horse
Answer: Vision of a monkey

Question 5. Increase in thickness of the lens, Nearsightedness, Contraction of the ciliary muscle, and Increase in focal length of the lens.
Answer: Increase in focal length of a lens

 

Chapter 1 Eye As A Sense Organ In Human Fill In The Blanks By Looking At The First Pair

Question 1. Chemical impulse: Taste:: Light impulse :
Answer: Vision

Question 2. Ear: Auditory nerve:: Eye :
Answer: Optic nerve

Question 3. Dim light: Rod cells:: Bright light:
Answer: Cone cells

Wbbse Class 10 Life Science Solutions

Question 4. Eyelid: Protecting eye:: Lens:
Answer: Refractory medium

Question 5. Vitreous chamber: Vitreous humour Anterior chamber:
Answer: Aqueous humour

Question 6. Human: Binocular vision : Cow:
Answer: Monocular vision

Question 7. Myopia: Concave lens:: Hyperopia:
Answer: Convex lens

 

Chapter 1 Eye As A Sense Organ In Humans Among The Four Concepts Given, Three Of Them Belong To One Find That

Question 1. The protective layer, Conjunctiva, Sclera, Cornea
Answer: Protective layer

Question 2. Yellow spot, Retina, Blindspot, Rod and cone cells
Answer: Retina

Wbbse Class 10 Life Science Solutions

Question 3. Cornea, Sclera, Eyeball, Iris
Answer: Eyeball

Question 4. Human, Owl, Binocular vision, Hawk
Answer: Binocular vision

Question 5. Contraction of the ciliary muscle, Change in the curvature of the lens, Change in focal length of the lens, and Visual accommodation.
Answer: Visual accommodation

Question 6. Cataract, Myopia, Visual impairment, Hypermetropia
Answer: Visual impairment

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Chapter 1 Neural Control And Co-Ordination Nervous Pathway Neurone Neuroglia And Nerves Types Of Nerve Ganglia Synapse Summary

Animals can respond to the environment without chemical secretion. The nervous system allows the organism to interact with its environment, appropriately. Different organs of the body are directly connected to the nervous system.

The actions of these organs are controlled by the nervous system. This is known as neural coordination. We respond in respect to various types of external and internal stimuli through a specific neural pathway.

This neural pathway is—stimulus-receptor-nerve centre-effector-response. Like we open the door by the activity of muscle (effector) after hearing (sound receptor) the doorbell (stimulus). Here, our brain functions as a nerve centre.

The unit of the nervous system is the neurone. The three structural parts of the neurone are the dendron,’ the cell body and the axon. It helps in sending and receiving the stimulus.

There are neuroglia or glial cells which act as a matrix of neurones and also help in the defence of the nervous system, nutrition of neurones and fast transportation of stimulus.

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The long projection of neurones or axons gets covered by different membranes and forms the nerve. The cell bodies of the neurones of the peripheral nervous system form a cluster and is covered by connective tissue.

This is known as nerve ganglion. It controls the function of the oesophagus, digestive glands, etc. The junction of two neurone is called the synapse.

Nerve impulses are transmitted from one neurone to another by synapse with the help of neurotransmitters (acetylcholine, dopamine, etc).

Chapter 1 Neural Control And Co-Ordination Long Answer Type Questions

Question 1. What do you understand by the terms neural control and neural co-ordination? Explain how neural control and neural co-ordination are established in the case of running.

Answer:

Neural control and neural co-ordination:

Wbbse Class 10 Life Science Solutions

Neural control is the process by which the nervous system controls all physiological processes as well as movements in order to maintain an equilibrium between the organism and its environment.

Neural co-ordination is the process by which nervous system co-ordinates various physiological and metabolic functions of an organism with muscle contraction, movements, locomotion, hormone and neurotransmitter release, etc. is called neural coordination.

Neural control and neural co-ordination during running:

A suitable example where neural control and co-ordination is established is running. During running, an increased demand of energy and oxygen occurs.

To meet this increased energy and oxygen demand, both the force and frequency of respiration and cardiac output is increased. These events lead to increased mobilisation of oxygen and glucose in the muscle cells, resulting in increased metabolic rate in these cells, which leads to alteration of levels of oxygen and carbon dioxide in the blood.

This is sensed by the brain which then sends signals to the spinal cord and the respiratory muscles (diaphragm, intercostal muscles) thus changing the rate of respiration.

In this way, the nervous system co-ordinates with different systems of the body in order to control a definite function.

WBBSE Class 10 Neural Control Overview

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Question 2. Describe the nervous path with example.

Answer:

Nervous path:

The nervous system of our body receives external and internal stimuli and makes us respond accordingly. For this coordination, the body needs a nervous path, which is built in the following way.

At first, the sensory organs or receptors receive sensory stimulation from any external or internal stimulus. This stimulus generates a nerve impulse in the receptor cells. The sensory nerve then carries it to the central nervous system.

Within the central nervous system, a sensory impulse is analysed and is converted into a motor impulse. Then a motor nerve carries this motor impulse to a specific effector organ. The effector organs like glands, muscles, etc.

Then respond according to the nature of the command from the central nervous system. Example—When a doorbell rings, the sound stimulates the auditory nerves. Soon this sensory impulse is sent to the brain.

Now brain sends a motor impulse to limbs. Accordingly, we move to the door and open it by voluntary action of legs and hands.

Question 3. Briefly describe the two main components of the nervous system and mention their functions.

Answer:

Wbbse Class 10 Life Science Solutions

Main components of the nervous system and their functions:

The two main components of the nervous system are—

1. Neurone and
2. Neuroglia.

1. Neurone:

Neurone is the structural and functional unit of the nervous system. Each neurone is composed of a cell body and several projections. The cell body contains a distinct nucleus and other common cell organelles like mitochondria, Golgi bodies, etc.

The cytoplasm of neurone especially carries Nissl granules and neurofibrils. Centrosome is present in an inactive state. The projections of a neurone are of two types—axon and dendron.

Axon is longer, unbranched, and may or may not be covered with a specialised myelin layer. It does not contain Nissl granules. Dendron is shorter, branched and contains Nissl granules.

Function of Neurone::

Neurone helps in the transmission of nerve impulses.

2. Neurogjia:

Neuroglial cells are modified connective tissue cells, which form a supporting medium for neurones within the central nervous system. About 90% of the total cellular components of the central nervous system are made up of neuroglia.

There are different types of neuroglia, such as microglia, oligodendroglia, astrocyte, etc. Neuroglial cells are incapable of transmitting nerve impulse.

Function of Neurogjia:

The functions of neuroglia are as follows—

1. Neuroglial cells act as supporting cells of the central nervous system.
2. Certain phagocytic neuroglial cells kill pathogens to protect neurones.
3. Few of these cells take part in preparing the medullary layer over the axon.

Question 4. Describe the relationship between neurone, nerve fibre and nerve with a suitable diagram.

Answer:

Relation between neurone, nerve fibre and nerve:

The relation between neurone and nerve is as follows—

1. The structural and functional unit of the nervous system is called the neurone. An ideal neurone is composed of the axon, a dendron and a cell body. It receives impulse by dendron and then through the axon the impulse is transmitted to the next neurone or to any effector tissue.

On the other hand, a membrane-bound axon is called a nerve fibre. The fibrous membrane that covers the axon surface is called the endoneurium. Some of these nerve fibres unite to form a thin bundle, which is sheathed by another fibrous membrane, called perineurium.

A number of such bundles then come together to form a thick bundle, which is then coated by a blood vessel containing a connective tissue layer, epineurium, to form a nerve.

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2. The afferent nerves carry nerve impulses from receptors to the central nervous system and the efferent nerves carry impulses from the central nervous system to the effector organs.

These efferent and afferent nerves are composed of sensory and motor neurones respectively. Therefore, it becomes clear that both neurones and nerves are meant for transmitting nerve impulses.

Practically, the structural elements of nerves, that is, the neurones carry the nerve impulse. So, it can be concluded that nerves, nerve fibres and neurones are closely related to each other.

Functions of the Nervous System in Animals

Question 5. Describe the structure of a typical neurone. Similar question, Draw a neat diagram of neurone and label the following parts—

1. Dendron,
   
2. Node of Banvier,
   
3. Myelin sheath,
4. Schwann cell.

Answer:

Structure of a typical neurone:

A typical neurone has two structural components—

1. Cell body or cyton and
2. Projections.

1. Cell body or cyton:

The structural features of the cell body of a neurone is as follows—

1. The largest, round or star-shaped portion of the neurone is called cell body.
2. The cell body contains thick protoplasm, called neuroplasm, surrounded by a cell membrane.
3. This cell bears a distinct nucleus within it
4. Neuroplasm contains different cell organelles like mitochondria, Golgi bodies, etc. Other than these, numerous typical nucleoprotein granules, called Nissl granules are present in the neuroplasm.
5. Fine thread-like neurofibrils remain scattered within the neoplasm.
6. The centrosome is present in an inactive state, therefore, neurones cannot undergo mitosis.

Wbbse Class 10 Life Science Solutions

2. Projections:

The projections of a neurone are of two types

1. Axon and
2. Dendron.

The structural features of these two projections are given below.

Axon:

The structural features of the axon is as follows—

1. The longer and unbranched protoplasmic projection of a neurone is called an axon.
2. Axon emerges from a conical portion of the cell body, called the axon hillock.
3. The semi-liquid cytoplasm present in the axon is called axoplasm, which is externally lined by a cell membrane called axolemma.
4. Axoplasm does not contain Nissl granules.
5. In several neurones, the axon has an extra lipid-rich insulating coat outside the axolemma, called myelin sheath.
6. The myelin sheath has a number of periodic gaps, which are called nodes of Ranvier.
7. A few tiny nucleated cells remain associated with myelin sheath, these are known as Schwann cells.
8. The neurones with myelin sheath are called medullated nerve fibres whereas the axons having no myelin sheath are called non-medullated nerve fibres.
9. Axon terminally gives off a few fine branches, this portion is called the end brush. The end of each branch swells to form a synaptic knob or end button.

Dendron:

The structural features of dendron is as follows—

1. The shorter and branched protoplasmic projection of a neurone is known as a dendron. Branches of dendrons are known as dendrites.
2. The base of each dendrone is wide but it gets terminally finer and branched.
3. Neuroplasm, neurofibrils and Nissl granules are present in the dendron, but it does not have, any myelin sheath.

Wbbse Class 10 Life Science Solutions

Question 6. Mention classification of neurone on. the basis of function. Mention the main functions of the axon and dendron.

Answer:

Classification of neurone:

On the basis of function, neurones are of three types—

1. Sensory neurone:

The neurones, which carry sensory impulses from the environment, are called sensory neurones. These neurones transfer nerve impulses from sense organs and receptors to the brain or spinal cord (nerve centres). Therefore, these are also known as afferent neurones.

2. Motor neurone:

The neurones, which carry motor impulses from the central nervous system (brain or spinal cord) to the effector organs or tissues, are called motor neurones.

As these neurone carry impulses from the brain or spinal cord (nerve centres) to effector organs, hence these are also known as efferent neurones.

3. Inter-neurone:

The nerve cells present in the central nervous system, which transfer impulses from sensory neurons to motor neurones are called inter-neurones. These neurones are also known, as adjustor or relay neurones.

Functions of axon and dendron:

1. Axon:

Axon transmits nerve,e impulses from cell body of a neurone to the next neurone or any effector organ.

2. Dendron:

Dendron receives1 one nerve impulse from any sensory cell or another neurone and sends it to the cell body of the neurone.

Question 7. Distinguish between axon and dendron.

Answer:

Differences between axon and dendron

 

Chapter 1 Neural Control And Co-Ordination Short Answer Type Questions

Question 1. Illustrate with the help of a word diagram the nervous pathway of the way you will open the door by hearing the doorbell.

Answer:

The nervous pathway of the way you will open the door by hearing the doorbell:

When someone rings the bell at the door, we listen to the bell with our ears and open die door. In this case, the receptors present in our ear receive the stimulus and send it to the central nervous system (CNS).

CNS processes that stimulus and sends motor signals to our body parts (muscles of hands and legs) and as a result, we open the door.

Question 2. What is meant by coordination?

Answer:

Coordination:

Coordination is a process of organised regulation of the activities of different organs and organ systems of a living body to enable them to work together effectively and thereby maintain a balance between the external and internal environment of the body.

In, animals both the nervous system and hormones and in plants only hormones play a role in coordination.

Wbbse Class 10 Life Science Solutions

Question 3. Define the nervous system.

Answer:

Nervous system:

The organ system made up of neurones and neuroglia, that helps the body to interact with the changes in the environment by receiving and responding to external stimuli as well as maintaining physical coordination among all other organs and organ systems of the body, is known as nervous system.

Question 4. What would have happened to the higher organisms if they had no nervous system?

Answer:

The body of higher organisms is composed of different organs and organ systems. Nervous system maintains co-ordination among the activities of these components.

In the absence of nervous system, the total system of functional coordination in the higher organisms would have been disrupted.

Structure of Neurons Explained

Question 5. Mention differences between the endocrine system and nervous system.

Or,

Distinguish between the functions of hormones and the nervous system on the following parameters: Nature of function, Pace of function, Time span of function, and Fate.

Answer:

Differences between the endocrine system and nervous system

 

Question 6. What is a nerve?

Life Science Class 10 Wbbse

Answer:

Nerve:

A bundle of nerve fibres accompanied by blood vessels and sheathed by three different connective tissue layers is called a nerve. It carries nerve impulses to different directions in the body.

Question 7. Name the sheaths of a nerve.

Answer:

The sheaths of a nerve

A nerve remains covered by three different sheaths. Endoneurium is the outermost sheath that covers a bundle of nerve fibres. The perineurium is the second layer that collectively covers few of such bundles.

A thicker, blood vessel-carrying outer sheath, called epineurium, covers the entire nerve.

Question 8. What are the functions of the nerve?

Answer:

The functions of nerve are as follows—

Afferent nerves carry nerve impulses from receptors to the central nervous system.

Efferent nerves carry impulses from the central nervous system to the effector organs.

Question 9. Why is the neurone called the structural and functional unit of nervous system?

Answer:

The structural components of nervous system are the brain, spinal cord and nerves. All of these are composed of cellular units known as neurones.

Therefore, the neurone is treated as the structural unit of the nervous system. The main function of the nervous system is to transmit nerve impulses. A single neurone also performs the same function. Therefore, it is treated as the functional unit of the nervous system.

Question 10. Why the neurones are unable to divide?

Answer:

In animal cells, centrosomes play vital role in cell division. The neurones possess inactive centrosomes. That is why the neurones cannot divide.

Question 11. Mention one functional difference between an axon and a dendron.

Answer:

Functional difference between an axon and a dendron

Axon sends nerve impulses from cell body to the next neurone or effector organ or tissue. Dendron, on the . other hand, receives nerve impulses from a previous neurone or receptor and sends it to the cell body.

Reflex Action in Humans

Question 12. What is neuroglia?

Answer:

Neuroglia:

Neuroglia or glial cells are the cells of the central nervous system that provide support, protection and insulation to the neurones. But they are incapable of transmitting nerve impulses.

Dendrocytes, oligodendrocytes and astrocytes are different types of glial cells.

Question 13. Distinguish between neurone and neuroglia.

Answer:

Differences between neurone and neuroglia—

 

Question 14. What is nerve ganglion?

Answer:

Nerve ganglion:

Aggregation of cell bodies of a number of neurones, covered by a sheath of connective tissue, appear as distended regions along a nerve. Such a swollen region is called a nerve ganglion.

Question 15. what is a nerve impulse?

Answer:

Nerve impulse:

The nerve impulse is an electrochemical signal that travels along a nerve fibre at a fast speed from one neurone to the next due to momentary alteration of ionic concentration at two sides of the neurilemma.

Life Science Class 10 Wbbse

Question 16. What is a synapse?

Answer:

Synapse:

Synapse is the junction between two nerve cells or neurones, across which nerve impulses pass from one neurone to the next by diffusion of a neurotransmitter. In this junction, the impulse¬sending neurone is called pre-synaptic neurone and the impulse-receiving neurone is called post-synaptic neurone.

 

Question 17. State the function of synapse.

Answer:

The function of synapse:

Synapse transmits information between neurones or neurones and their target cells. They also act as valves to ensure that impulses pass across them in one direction only.

Question 18. Write a note on neurotransmitters.

Answer:

Neurotransmitters:

Neurotransmitters are certain biochemical substances, which are secreted within the synaptic cleft from the pre-synaptic neurone to cany nerve impulse from it to the post-synaptic neurone. Some of the most important neurotransmitters are—acetylcholine, adrenaline, dopamine, etc.

 

Question 19. Mention differences between sensory neurones and motor neurones.

Answer:

Differences between the sensory neurone and motor neurone—

 

Question 20. What are afferent nerves?

Answer:

Afferent nerves:

The nerves, which carry sensory impulses from the receptor to the central nervous system, are called afferent nerves.

Examples: Olfactory nerve, optic nerve, auditory nerve, etc.

 

Life Science Class 10 Wbbse

Question 21. What are efferent nerves?

Answer:

Efferent nerves:

The nerves, which carry motor impulses from the central nervous system to the effector organs or tissues, are called efferent nerves.

Examples: Trochlear nerve, hypoglossal nerve, etc.

Question 22. What are mixed nerves?

Answer:

Mixed nerves:

The nerves, which are composed of both sensory and motor neurones and are capable of carrying impulses in both ways, are known as mixed nerves.

Examples: Vagus nerve, facial nerve, etc.

Question 23. Mention the characters of afferent nerves.

Answer:

The characteristics of afferent nerves are as follows—

1. These nerves are composed of sensory neurones.
2. These nerves carry impulses from receptors to the central nervous system.

Question 25. Mention the characters of mixed nerves.

Answer:

The characters of mixed nerves are as follows—

1. These nerves are composed of both sensory and motor neurones.
2. Mixed nerves carry sensory impulses from the sense organs to the central nervous system and motor impulses from the central nervous system to the effector organs or tissues.

Central vs Peripheral Nervous System

Question 26. What are effectors?

Answer:

Effectors:

The organs, glands, muscles or tissues of the body, which respond to motor impulses by performing specific functions, are called effectors.

Example: Voluntary muscles, different glands, etc.

Life Science Class 10 Wbbse

Question 27. What is a receptor?

Answer:

Receptor:

There are certain cells or organs, which can sense any change in the internal or external environment and

Question 28. Differentiate sensory, motor and mixed nerves.

Answer:

Differences among sensory nerve, motor nerve and mixed nerve—

 

Chapter 1 Neural Control And Co-OrdinationVery Short Answer Type Questions Multiple Choice Questions And Answers [MCQ]

Question 1. The portion of a neurone from which the axon emerges is called—

1. Axis cylinder
2. Axon hillock
3. Dendrite
4. Dendron

Answer: 2. Axon Hillock

Nerve Cell Diagram Class 10 Wbbse

Question 2. The portion of a nerve cell that is devoid of Nissl granules is—

1. Dendrite
2. Axon
3. Cell body
4. All of these

Answer: 2. Axon

Question 3. An effector is

1. Ear
2. Muscles
3. Skin
4. Nose

Answer: 2. Musules

Question 4. Physical co-ordinator in the animal body is—

1. Hormone
2. Heart
3. Nervous system
4. Circulatory system

Answer: 3. Nervous system

Life Science Class 10 Wbbse

Question 5. The membrane that surrounds the axoplasm is called—

1. Axolemma
2. Neurilemma
3. Plasmalemma
4. Pleura

Answer: 1. Axolemma

Question 6. Which of the following is a neurotransmitter?

1. Glycogen
2. Glucose
3. Lipid
4. Acetylcholine

Answer: 4. Acetylcholine

Question 7. Which of the following is a motor nerve?

1. Vagus
2. Oculomotor
3. Facial
4. Trigeminal

Answer: 2. Oculomotor

Nerve Cell Diagram Class 10 Wbbse

Question 8. The multicellular organism that does not have a nervous system is—

1. Tapeworm
2. Roundworm
3. Starfish
4. Sycon

Answer: 4. Sycon

Question 9. The structural and functional unit of the nervous system is—

1. Nephron
2. Neurone
3. Axon
4. Neuroglia

Answer: 2. neurone

Question 10. Which of the following is related to the Schwann cell?

1. Dendrite
2. Axon
3. Cell body
4. Synapse

Answer: 2. Axon

Question 11. The Vagus nerve is a type of—

1. Motor nerve
2. Mixed nerve
3. Sensory nerve
4. Spinal nerve

Answer: 2. Mixed nerve

Question 12. The branches of dendron are called

1. Dendrites
2. End plates
3. Myelin sheath
4. Axon

Answer: 1. Dendrites

Nerve Cell Diagram Class 10 Wbbse

Question 13. The optic nerve is a type of—

1. Motor nerve
2. Sensory nerve
3. Mixed nerve
4. Efferent nerve

Answer: 2. Sensory nerve

Question 14. Which of the following is a motor nerve?

1. Hypoglossal nerve
2. Auditory nerve
3. Olfactory nerve
4. Optic nerve

Answer: 1. Hypoglossal nerve

Question 15. The cell bodies of neurones unite to form—

1. Neuroglia
2. Nerve ganglion
3. Axon
4. Synapse

Answer: 2. Nerve ganglion

Question 16. The nucleus of a neurone is present in—

1. Axon
2. Neurocyton
3. Dendron
4. Axon hillock

Answer: 2. Neurocyton

Question 17. Any change in the internal or external environment that may generate a response in a living organism is called—

1. Receptor
2. Response
3. Sensation
4. Impulse

Answer: 4. Impulse

Question 18. The reaction, shown by an organism by the action of a stimulus is called—

1. Effect
2. Sensation
3. Response
4. Reception

Answer: 3. Response

Nerve Cell Diagram Class 10 Wbbse

Question 19. The ability of any organism to respond to a stimulus is called—

1. Effector
2. Sensitivity
3. Excitability
4. Receptor

Answer: 2. Sensitivity

Question 20. The broader portion of a neurone that carries the nucleus is called—

1. Cell body
2. Nissl body
3. Axon
4. Dendrite

Answer: 1. Cell body

Question 21. The cytoplasm of axon is known as—

1. Ectoplasm
2. Endoplasm
3. Axoplasm
4. Neuroplasm

Answer: 3. Axoplasm

Question 22. The packing cells of the nervous system is called—

1. Neurilemma
2. Axolemma
3. Neuroglia or glial cell
4. Neurone

Answer: 3. Neuroglia or glial cell

Question 23. Which of the following is a neuroglial cell?

1. Astrocyte
2. Oligodendrocyte
3. Microcyte
4. All of these

Answer: 4. All of these

Question 24. The cell that helps in the protection of the nervous system is called—

1. Neurone
2. Astrocyte
3. Schwann cell
4. Nephron

Answer: 2. Astrocyte

Question 25. The cell that forms the myelin sheath is called—

1. Neurone
2. Astrocyte
3. Schwann cell
4. Podocyte

Answer: 3. Schwann cell

Life Science Class 10 Wbbse

Question 26. The part of the neurone that is covered by myelin sheath is called—

1. Axon
2. Dendron
3. Cell body
4. End brush

Answer: 1. Axon

Question 27. The nerve that carries impulses from the central nervous system to the effector organ is called—

1. Sensory nerve
2. Afferent nerve
3. Motor nerve
4. Mixed nerve

Answer: 3. Motor nerve

Question 28. The nerve that carries impulses from sensory organs to central nervous system is called—

1. Motor nerve
2. Efferent nerve
3. Sensory nerve
4. Mixed nerve

Answer: 3. Sensory nerve

Question 29. The outermost covering of a nerve is called—

1. Endoneurium
2. Endomysium
3. Perineurium
4. Perimysium

Answer: 3. Perineurium

Question 30. Which of the following is present in between two neurones?

1. CSP
2. Lymph
3. Neurotransmitter
4. Blood

Answer: 3. Neurotransmitter

Question 31. The region where two neural projections come close to each other is called—

1. Synapse
2. Synopsis
3. Nerve ending
4. Nerve terminal

Answer: 1. Synapse

Question 32. Neurilemma coats—

1. Axis cylinder
2. Cell body
3. Medullary sheath
4. Endoneurium

Answer: 3. Medullary sheath

Role of Neurotransmitters in Nerve Impulses

Chapter 1 Neural Control And Co-Ordination Answer In A Single Word Or Sentence

Question 1. Which is the structural and functional unit of the nervous system?
Answer: Neurone

Question 2. What is the name of the conical portion of the cell body of a neurone from where the axon emerges?
Answer: Axon Hillock

Question 3. What are the fine and branched ends of an axon called?
Answer: End brush

Question 4. Where is the myelin sheath found?
Answer: Myelin sheath is found on the outer surface of axons of myelinated or medullated neurones.

Question 5. Write one function of the myelin sheath.
Answer: The main function of the myelin sheath is to facilitate the conduction of electrical impulses through the nerve cells.

Question 6. Name two systems of the human body that perform the coordinating function.
Answer: Nervous system and endocrine system

Question 7. Name the main parts of a neurone.
Answer:

The main parts of a neurone include-

1. Cell body,
2. Dendron and
3. Axon.

Question 8. Which cytoplasmic material is seen only in neurones?
Answer: Nissl granules

Question 9. Name the point of connection between two successive neurones.
Answer: Synapse

Question 10. Which chemical substance is released from the end brush of neurone?
Answer: Neurotransmitter

Question 11. Name the supporting cells that are present only in central nervous system.
Answer: Neuroglia

Question 12. Which type of stimulus do pressure, heat and light belong to?
Answer: External stimulus

Question 13. Which type of stimulus do hunger, thirst and pain belong to?
Answer: Internal stimulus

Question 14. What is the cell body of a neurone called?
Answer: Neurocyton or perikaryon

Question 15. Name the dense cytoplasm present in the cell body of the neurone.
Answer: Neuroplasm

Question 16. Name the fine fibrillar materials present in the cytoplasm of nerve cells.
Answer: Neurofibrils

Question 17. What do you mean by neurotransmitter?
Answer: Neurotransmitters are chemicals that help in the transmission of nerve impulses throughout the nervous system.

Question 18. Name any two motor nerves.
Answer: Trochlear and hypoglossal nerves

Question 19. Name the swollen region of nerves, made up of a cluster of cell bodies of neurones.
Answer: Nerve ganglion

Question 20. What is the main function of nerve fibre?
Answer: The main function of nerve fibre is to transmit nerve impulses.

Question 21. Where the Schwann cells are located?
Answer: Schwann cells are located in the axon of the neurones.

Common Disorders of the Nervous System

Chapter 1 Neural Control And Co-Ordination Fill In The Blanks

Question 1. The long, unbranched projection of the neurone is called _______.
Answer: Axon

Question 2. The regions of a medullated neurone, devoid of myelin sheath are called nodes of _______.
Answer: Ranvier

Question 3. The _______ is inactive in neurons, that is why these cells never divide.
Answer: Centrosome

Question 4. The junction of two neurones is known as _______.
Answer: Synapse

Question 5. The _______ of the cell body of a neurone is called neuroplasm.
Answer: Cytoplasm

Question 6 The membrane of the synaptic knob is known as _______ membrane.
Answer: Pre-synaptic

Question 7. As nerve impulse reaches the pre-synaptic region, _______ is secreted from the axon end brush.
Answer: Acetylcholine

Question 8. The parts of the living body, which receive stimuli from the environment, are called _______.
Answer: Receptor

Question 9. The parts of a living body, which respond to stimuli, are called _______.
Answer: Effector

Question 10. The fine fibrillar structures, named _______ extend from neuroplasm to dendrons and axons.
Answer: Neurofibril

Question 11. The small, fine filamentous protoplasmic projection of the cell body are called _______.
Answer: Dendron

Question 12. The conical region of the cell body ” from which the axon emerges is called _______.
Answer: Axon Hillock

Question 13. The nerves composed of both sensory and motor neurones is called _______ nerve.
Answer: Mixed

Question 14. The main function of _______ is to carry nerve impluse.
Answer: Neurone

Question 15. Nucleated _______ cells are present in between the myelin sheath and neurilemma.
Answer: Schwann

 

Chapter 1 Neural Control And Co-Ordination State True Or False

Question 1. Skeletal muscles are an example of an effector.
Answer: True

Question 2. Vagus is a mixed nerve.
Answer: True

Question 3. The centrosome of neurone is active in nature.
Answer: False

Question 4. Nissl granules are present only in muscle cells.
Answer: False

Question 5. Golgi bodies of neurones are inactive in nature.
Answer: False

Question 6. Schwann cells are present on dendrons.
Answer: False

Question 7. Axon is a terminal motor projection.
Answer: True

Question 8. The end brush is present at the terminal portion of the axon.
Answer: True

Question 9. Axon emerges from axon hillock.
Answer: True

Question 10. Acetylcholine and adrenaline are neurotransmitters.
Answer: True

 

Chapter 1 Neural Control And Co-Ordination Match The Columns

Question 1.

Answer: 1. B, 2. D, 3. A, 4. C, 5. F, 6. E

Question 2.

Answer: 1. C, 2. D, 3. A, 4. F, 5. B, 6. E

 

Chapter 1 Neural Control And Co-Ordination Find The Odd One Out

Question 1. Axolemma, Axoplasm, Nissl granules, Schwann cell
Answer: Nissl granules

Question 2. Nerve ganglion, Receptor, Effector; Nerve centre
Answer: Nerve ganglion

Question 3. Axolemma, Neurilemma, Neuroplasm, Node ofRanvier
Answer: Neuroplasm

Question 4. Neurofibril, Neuroplasm, Neurocyton, Neuroglia
Answer: Neuroglia

Question 5. Node of Ranvier, Myelin sheath, Axolemma, Dendron
Answer: Dendron

Question 6. Axon, Nerve fibre, Nerve, Nerve ganglion
Answer: Nerve ganglion

 

Chapter 1 Neural Control And Co-Ordination Fill In The Blanks By Looking At The First Pair

Question 1. Projection of neurone : Axon :: Cell body of neurone: ________
Answer: Neurocyton

Question 2. Aggregation of axons : Nerves :: Aggregation of cell bodies: ________
Answer: Ganglion

Question 3. Optic nerve: Afferent nerve:: Oculomotor nerve: ________
Answer: Efferent nerve

Question 4. Olfactory nerve : Sensory nerve :: Vagus nerve: ________
Answer: Mixed nerve

Question 5. Axon: Axoplasm :: Neurocyton: ________
Answer: Neuroplasm

Question 6. Receptor: Sensory neurone:: Effector: ________
Answer: Motor neurone

Question 7. Neruohormone: Vasopressin :: Neurotransmitter ________
Answer: Acetylcholine

Question 8. Mixed nerve: Vagus:: Sensory nerve: ________
Answer: Optic nerve

Question 9. A small projection of neurone: Dendron:: Long projection of neurone: ________
Answer: Axon

 

Chapter 1 Neural Control And Co-Ordination Among The Four Concepts Given Three Of Them

Question 1. Neuroglia, Dendrocyte, Oligodendrocyte, Astrocyte
Answer: Neuroglia

Question 2.Pre-synaptic knob, Post-synaptic knob, Synaptic cleft, Synapse
Answer: Synapse

Question 3. Astrocyte, Oligodendrocyte, Neuroglia, Epididymal cell
Answer: Neuroglia

Question 4. Nerve, Acceptor, Effector, Neural pathway
Answer: Neural pathway

Question 5. Axon, Neurone, Dendron, Axoplasm
Answer: Neurone

Chapter 1 Types Of Nervous System Brain And Spinal Cord Reflex Action And Reflex Arc Summary

• The human nervous system can be divided into three divisions like—central nervous system, peripheral nervous system and autonomic nervous system. The central nervous system is composed of the brain and spinal cord.
• Cranial nerves arising from, the brain and spinal nerves arising from the spinal cord together form the peripheral nervous system. The autonomous nervous system is composed of sympathetic and parasympathetic nervous systems.
• The main portion of the brain is the cerebral cortex of the forebrain which controls intelligence, memory, auditory and visual sensations, speech, etc. The. thalamus of the forebrain recognises pain, touch, pressure, and heat.

Read and Learn More WBBSE Solutions for Class 10 Life Science And Environment

• Hypothalamus regulates the feeling of hunger and thirst. It also regulates the body temperature and is involved in emotional expression. The midbrain connects the forebrain and hindbrain. The pons of the hindbrain contract and expands the heart.
• The Cerebellum of the hindbrain controls the body balance and body posture. Medulla oblongata controls breathing, sneezing, salivation, engulfing, etc. Spinal cord functions as the central control centre of the reflex action.
• Reflex actions are defined as the automatic response to any kind of stimulus carried out by the spinal cord and which is sudden and spontaneous. The nervous or neural pathway through which reflex action takes place is called a reflex arc.
• Sneezing, coughing, blinking of an eye, etc. are inborn reflex actions. Playing a musical instrument, and salivation at the sight of favourite food are examples of conditioned or acquired reflex action.
• These reflex actions have great importance in daily life.

Chapter 1 Nervous SystemLong Answer Type Questions

WBBSE Class 10 Nervous System Overview

Question 1. Classification of the human nervous system. Give a brief description of each type of nervous system.

Answer:

Classification of the human nervous system:

The human nervous system can be classified into three types.

These are

1. Central nervous system (CNS),
2. Peripheral nervous system (PNS) and
3. Autonomic nervous system (ANS).

Description of different nervous systems:

A brief description of different nervous systems are given below.

1. Central nervous system:

This type of nervous system is composed of the brain and spinal cord. It is the main neural control centre of the human body.

This system controls ail intellectual activities of an individual and regulates the overall coordination of the body with any change in its internal and external environment.

2. Peripheral nervous system:

This type of nervous system is composed of 12 pairs of cranial nerves and 31 pairs of spinal nerves. This system coordinates the activities of the body by sensory and motor nerves connected with the central nervous system.

3. Autonomic nervous system:

This nervous system is composed of certain cranial and spinal nerves. Functionally, it is of two types—the sympathetic nervous system and the parasympathetic nervous system.

This nervous system controls the functions of all visceral organs, glands and involuntary muscles.

Wbbse Class 10 Life Science Solutions

WBBSE Solutions for Class 10 History	WBBSE Solutions for Class 10 Geography and Environment
WBBSE Class 10 History Long Answer Questions	WBBSE Solutions for Class 10 Life Science And Environment
WBBSE Class 10 History Short Answer Questions	WBBSE Solutions for Class 10 Maths
WBBSE Class 10 History Very Short Answer Questions	WBBSE Solutions for Class 10 Physical Science and Environment
WBBSE Class 10 History Multiple Choice Questions

 

Question 2. Give a brief description of the central nervous system of humans.

Answer:

The central nervous system of humans:

The central nervous system of humans is composed of the brain and the spinal cord. A brief description of these two are mentioned below.

1. Brain:

The brain of a human is divisible into three main parts—forebrain, midbrain and hindbrain.

Forebrain:

The structural features of the forebrain is as follows—

1. Forebrain is composed of the cerebrum, rhinencephalon,* corpus striatum, thalamus and hypothalamus. The first three combine to form telencephalon and the last two combine to form diencephalon.
2. Cerebrum is the largest part of the brain. It is divisible into two identical hemispheres. These hemispheres are interconnected by a nerve bundle, called corpus callosum.
3. The outer portion of the cerebrum is composed of grey matter and the inner portion is made up of white matter. The grey outer portion is called the cerebral cortex.
4. Below the cerebrum an oval structure called the thalamus is present; which is also made up of grey matter.
5. Hypothalamus is the smallest part of the forebrain present below the thalamus. It is composed of both white and grey matter.

Midbrain:

This portion of the human brain is located between the forebrain and the hindbrain. It is made up of two portions—tectum and cerebral peduncle.

Wbbse Class 10 Life Science Solutions

Hindbrain:

This is the posteriormost portion of the human brain. It is composed of two parts— metencephalon and myelencephalon or medulla oblongata. Metencephalon has two parts— the cerebellum, and pons. Out of these, the cerebellum is the largest portion of the hindbrain.

2. Spinal cord:

The structural features of the spinal cord are as follows—

1. It is a long tubular structure extending from the base of the medulla oblongata to the space between the first and second lumbar vertebrae through the neural canal of the vertebral column.
2. A total of 31 pairs of spinal nerves emerge laterally from the spinal cord. It is divisible into five regions— cervical (8 pairs), thoracic (12 pairs), lumber (5 pairs), sacral (5 pairs) and coccygeal (1 pair).
3. The central canal of the spinal cord is filled with cerebrospinal fluid.
4. The length of the spinal cord in healthy human adult males is about 45 cm and that of healthy adult females is about 42 cm.
5. The lower end of the spinal cord is tapering from which several fibrils grow.

Question 3. Mention the names, locations and functions of five different parts of the human brain in the form of a table.

Answer:

Names, locations and functions of five different parts of the human brain

Wbbse Class 10 Life Science Solutions

Question 4. Mention the location and functions of the following—

1. Midbrain,
2. Medulla oblongata.

Answer:

Midbrain or mesencephalon: The location and functions of the midbrain

Midbrain or mesencephalon Location:

Midbrain is located as a connective in between the forebrain and the hindbrain. It is a small area composed by the tectum and cerebral peduncle.

Midbrain or mesencephalon Functions:

The functions of the midbrain are as follows—

1. Midbrain coordinates the function of the forebrain and hindbrain.
2. The tectum portion of the midbrain acts as the reflex centre for vision and hearing.
3. The midbrain plays an important role to control body temperature.
4. It also helps to regulate muscle tension.
5. It coordinates the movement of voluntary muscles.

Medulla oblongata: The location and functions of medulla oblongata—

1. Medulla oblongata Location:

The Medulla oblongata is located below the pons and just above the spinal cord.

2. Medulla oblongata Functions:

The functions of medulla oblongata are as follows—

1. Medulla oblongata regulates breathing, contraction and relaxation of the heart, blood pressure, etc.
2. Controls salivation and vomiting.
3. Ninth to twelfth cranial nerves originate from this region.

Question 5. What is the reflex path? Name five Components of a reflex path and mention their functions.

Answer:

Reflex path:

The neural path, through which nerve impulse rotates to accomplish a reflex action, is known as the reflex path or reflex arc.

Central Nervous System vs Peripheral Nervous System

Components of the reflex path:

The reflex path has five components, which are mentioned below.

1. Receptor: The receptor generates a sensory nerve impulse in response of a stimulus.
2. Afferent neurone: This neurone carries sensory impulses from the receptor to the nerve centre.
3. Nerve centre: It is located in the grey matter of the spinal cord. Here, sensory impulse is converted into motor impulse and it is transferred from sensory neurone to motor neurone through inter-neurone.
4. Efferent neurone: It carries motor impulses from the nerve centre to the effector organ.
5. Effector: Muscles or glands are the effector organs, which show specific responses to specific stimuli.

 

Question 6. Briefly describe the functional activities of a simple reflex path or reflex arc with a common example. Similar question, Draw a diagram of a reflex arc and label the following parts:

1. Receptor,
2. Sensory nerve,
3. Nerve centre,
4. Motor nerve.

Answer:

Functional activities of a simple reflex arc:

If a thorn pricks our sole, we withdraw the foot at once. This is an example of a reflex action. The process of this reflex action occurs in the following way—

1. As the thorn pricks, the receptors in the skin below our soul sense the stimulus.
2. The receptors at once, generate a sensory impulse and sensory or afferent neurone (afferent nerve) carries it to the spinal cord (nerve centre).
3. Immediately, the sensory impulse is modified into a motor impulse and sensory or afferent neurone (afferent nerve) carries it to the spinal cord (nerve centre).
4. Immediately, the sensory impulse is modified into a motor impulse and it is conveyed to the motor or efferent neurone (efferent nerve) by an inter-neurone within the spinal cord.
5. The efferent neurone instantly carries the motor impulse to the leg muscles (effector).
6. The muscles of the leg act at once to lift the foot promptly to avert a deeper prick.

Wbbse Class 10 Life Science Solutions

Chapter 1 Nervous System Short Answer Type Questions

Question 1. What is the central nervous system?

Answer:

The central nervous system:

The main controlling part of the nervous system, which is composed of the brain and spinal cord, is known as the central nervous system.

Question 2. What is the peripheral nervous system?

Answer:

The peripheral nervous system:

The type of nervous system, which is composed of different cranial and spinal nerves, is known as the peripheral nervous system.

Question 3. What is the autonomic nervous system?

Answer:

The autonomic nervous system:

The type of nervous system, which is composed of certain cranial and spinal nerves, which control tire involuntary activities of different visceral organs, is known as the autonomic nervous system. Visceral activities such as breathing, heartbeat, digestive processes, etc. are controlled by the autonomic nervous system.

Question 4. Write the parts of the central nervous system and peripheral nervous system.

Answer:

The central nervous system consists of the brain and spinal cord and the peripheral nervous system consists of the sympathetic and parasympathetic nervous systems.

Question 5. What are the components of the peripheral nervous system?

Answer:

The components of the peripheral nervous system:

The nerves emerging directly from the central nervous system constitute the peripheral nervous system. The components of this nervous system include 12 pairs of cranial nerves and 31 pairs of ’ ‘ nerves.

Types of Nervous Systems in Animals

Question 6. what is meant by the sympathetic nervous system?

Answer:

The sympathetic nervous system:

The part of the autonomic nervous system that is composed of thoracic and lumbar nerves to control the functions of different visceral organs during emergency conditions (fight or flight response), is called the sympathetic nervous system.

Question 7. What is meant by the parasympathetic nervous system?

Answer:

The parasympathetic nervous system:

The part of the autonomic nervous system that is composed of cranial and sacral nerves to control functions of different visceral organs during the state of rest or relaxation (rest and digest response), is called the parasympathetic nervous system.

Question 8. What is the brain?

Answer:

Brain:

The brain is the largest and distended portion of the central nervous system, located at the anterior region of the spinal cord and remains protected within the skull. It controls all neural and intellectual activities and physiological functions in vertebrates.

Question 9. What is the cerebral cortex?

Answer:

Life Science Class 10 Wbbse

cerebral cortex:

The cerebral cortex is the thick and grey outer layer of the cerebrum, composed of cell bodies of neurones and acts as the controlling centre of memory, intelligence, thinking and all sensory activities.

Question 10. What is the thalamus?

Answer:

Thalamus:

Thalamus is a grey-coloured, paired oval structure, situated below the cerebral hemis¬pheres at two sides of the third ventricle and just above the midbrain. It acts as the relay centre or gatekeeper of the brain. It also senses pressure, pain, heat, etc.

Question 11. What is the hypothalamus?

Answer:

Hypothalamus:

Hypothalamus is the small portion of the forebrain located just below the thalamus and the third ventricle and acts as the controlling centre of temperature, hunger, thirst, emotions, etc.

Life Science Class 10 Wbbse

Question 12. What is the midbrain?

Answer:

Midbrain:

The midbrain or mesencephalon is the smallest part of the brain that connects the fore and hindbrain. This segment of the human brain is composed of two parts—the tectum and the cerebral peduncle.

Question 13. What is pons?

Answer:

Pons:

Pons is the part of the hindbrain, located below the midbrain at the ventral side of the fourth ventricle and above the medulla oblongata. It acts as a bridge between the midbrain and medulla oblongata.

Functions of the Autonomic Nervous System

Question 14. What is medulla oblongata?

Answer:

Medulla oblongata:

Medulla oblongata is the posteriormost portion of the brain, located below the pons and at the apex of the spinal cord. It acts as a control centre for sneezing, coughing, salivation, engulfing, vomiting, etc.

Life Science Class 10 Wbbse

Question 15. What is the cerebellum?

Answer:

Cerebellum:

Cerebellum is the largest part of the hindbrain, located at the dorsal side of the fourth ventricle which plays a major role in controlling the body’s balance and coordinating muscular activities.

Question 16. Mention two functions of the cerebral cortex.

Answer:

Two functions of the cerebral cortex are as follows

1. It acts as the controlling centre of memory, intelligence, analysing capacity, power of thinking, etc.
2. It also helps to control the sense of vision, smell, taste, heat, cold, touch, pain, etc.

Life Science Class 10 Wbbse

Question 17. Mention two functions of the thalamus.

Answer:

Two functions of the thalamus are as follows

1. It acts as the relay station for impulses travelling to and from the cerebrum, midbrain, cerebellum, and spinal cord.
2. It sends different sensory impulses to the concerned reception centres of the cerebral cortex.

Question 18. Mention two functions of the hypothalamus.

Answer:

Two functions of the hypothalamus are as follows

1. It controls hunger, thirst, sleep, mental stress, body temperature, consciousness, etc.
2. It also controls the secretion of different hormones from the pituitary gland.

Question 19. Mention two functions of the midbrain.

Answer:

Two functions of the midbrain are as follows—

1. It helps to coordinate the functions of the forebrain and hindbrain.
2. It also controls muscle contraction and maintains the equilibrium of the body.

Question 20. Mention two functions of the pons.

Answer:

Two functions of the pons are as follows

1. It controls facial expression, urination, breathing, and movement of the jaw and eyeballs.
2. It also maintains functional coordination between the cerebrum and cerebellum.

Life Science Class 10 Wbbse

Question 21. Mention two functions of the cerebellum.

Answer:

Two functions of the cerebellum are as follows—

1. It maintains body balance and posture.
2. It regulates the voluntary movement of body parts.

Question 22. What is the corpus callosum?

Answer:

The corpus callosum:

There is a thick bundle of nerves that transversely connects the two hemispheres of the brain. This bundle of nerves of cerebrum is known as the corpus callosum.

Question 23. What is the spinal cord?

Answer:

Spinal cord:

The spinal cord is the continuation of the medulla oblongata. It is a tubular, neural structure that extends through the neural canal of the vertebral column from the base of the medulla oblongata to a first or second lumbar vertebra and acts as the controlling centre for reflex action.

Question 24. Mention any two functions of spinal cord.

Answer:

Two functions of the spinal cord are as follows

The spinal cord acts as the controlling centre for reflex action.

It conducts sensory and motor information between the peripheral nervous system and the central nervous system.

Life Science Class 10 Wbbse

Question 25. Mention the location of the meninges.

Answer:

Meninges Location:

Meninges is located just outside the brain and spinal cord as a membranous outer covering.

Meninges  Functions:

The functions of meninges are as follows

1. Meninges protects the central nervous system from injury and infection.
2. Capillaries of the meninges supply blood to the skull and cerebral cortex.

Question 26. What is CSF?

Answer:

CSF:

A transparent and slightly alkaline fluid is present in the ventricles of the brain, the central canal of the spinal cord, sub-dural and sub-arachnoid space of the meninges. This is called CSF or cerebrospinal fluid.

Question 27. Mention the location of CSF.

Answer:

The location of CSF:

CSF or cerebrospinal fluid is present in the four ventricles of the brain, the central canal of the spinal cord, and the sub-dural and sub-arachnoid space of the meninges.

wbbse class 10 life science question answer

Question 28. Mention the functions of CSF.

Answer:

The functions of CSF or cerebrospinal fluid are as follows

1. CSF supplies nutrients and oxygen to the neural cells of the central nervous system.
2. It also acts as a cushion to protect the brain and spinal cord against external shocks and pressure.

Structure of Neurons in Different Animals

Question 29. Mention the differences between the cerebrum and cerebellum.

Answer:

Differences between cerebrum and cerebellum—

Question 30. What is reflex action?

Answer:

Reflex action:

The spontaneous, instantaneous and involuntary response to any external or internal stimulus is known as a reflex action. It is under the control of the spinal cord.

Question 31. What is meant by innate reflex actions?

Answer:

 Innate reflex actions:

The reflexes, which are inborn, not regulated consciously and are not conditioned through any regular activities, are called innate reflex actions.

Example: The building urge of a newborn baby, blinking of an eye.

wbbse class 10 life science question answer

Question 32. What is meant by acquired reflex actions?

Answer:

Acquired reflex actions:

Certain reflexes can be acquired by continuous practice or from experience. These are called acquired reflex actions.

Examples: Cycling, swimming, etc.

Question 33. Mention two salient features of innate reflex.

Answer:

Two salient features of innate reflex are as follows

1. This reflex is independent of any condition and it does not need any past experience.
2. This reflex is acquired by birth through generations.

Question 34. Mention two sailent features of acquried reflex.

Answer:

Two salient features of acquired reflex are as follows

1. This reflex is acquired by prolonged practice or through past experience.
2. This reflex may be lost partially or completely due to lack of practice.

wbbse class 10 life science question answer

Question 35. Categorize the following actions as natural or acquired reflex actions. Willingness of infants for breastfeeding, cycling, sneezing, and catching the ball by wicketkeeper with swiftness.

Answer:

1. Natural reflex action: Willingness of infants for breastfeeding, sneezing.
2. Acquired reflex action: Cycling, catching the ball by wicketkeeper with swiftness.

Question 36. Reflex actions occur when the following incidents happen in the everyday life of humans. Write the importance of these two reflex actions:

1. When food particles enter into the trachea
2. When foreign particles enter inside the nasal cavity.

Answer:

1. When food particles enter into the trachea, coughing occurs. Through coughing, the food particles are expelled out of the trachea along with pulmonary air.
2. When foreign particles enter inside the nasal cavity, sneezing occurs. Sneezing helps to expel the foreign particle from th6 nasal cavity.

Question 37. What is meant by intermediate neurone or connecting neurone or relay neurone?

Answer:

Intermediate neurone:

The specialised type of neurone, present in the central nervous system, that* interconnects sensory and motor neurones, is known as intermediate neurone or connecting neurone or relay neurone.

Question 38. Mention the differences between innate reflex and acquired reflex.

Answer:

Differences between innate reflex and acquired reflex are

Chapter 1 Nervous System Very Short Answer Type Questions Multiple Choice Questions And Answers [Mcq]

Question 1. The part of the human brain associated with controlling body temperature is—

1. Thalamus
2. Cerebellum
3. Hypothalamus
4. Medulla, oblongata

Answer: 3. Hypothalamus

wbbse class 10 life science question answer

Question 2. Which one of the following is the correct reflex arc?

1. Receptor→Effector→Efferent nerve→ Nerve centre→Afferent njerve
2. Nerve centre→Receptor→Afferent nerve→Effector→Efferent nerve
3. Efferent nerve → Receptor → Afferent nerve → Nerve centre → Effector
4. Receptor→ Afferent nerve →Nerve centre → Efferent nerve → Effector

Answer: 4. Receptor → Afferent nerve → Nerve centre → Efferent nerve → Effector

Question 3. Determine the number of cranial nerves in the human body—

1. 10 pairs
2. 31 pairs
3. 12 pairs
4. 21 pairs

Answer: 3. 12 pairs

Question 4. Select the correct pair

1. Cerebrum—Maintenance of balance of the body
2. Hypothalamus—Control of intelligence and emotion
3. Cerebellum—Control of body temperature
4. Medulla oblongata—Control of heartbeat and swallowing of food

Answer: 4. Medulla oblongata—Control of heartbeat and swallowing of food

wbbse class 10 life science question answer

Question 5. An example of a conditioned reflex is—

1. Approaching of goldfish towards the front wall of the aquarium (for collecting food) by viewing any man in front
2. Quick withdrawal of hand on touching any hot object
3. Suckling of milk by a baby
4. Watering of the eye while chopping an onion

Answer: 1. Approaching of goldfish towards the front wall of the aquarium (for collecting food) by viewing any man in front

Question 6. Cycling is a type of—

1. Innate reflex
2. Inborn reflex
3. Brain activity
4. Acquired reflex

Answer: 4. Acquired reflex

Question 7. Cerebrum is part of—

1. Forebrain
2. Midbrain
3. Hindbrain
4. Spinal cord

Answer: 1. Forebrain

wbbse class 10 life science question answer

Question 8. The number of spinal nerves in man is—

1. 10 pairs
2. 12 pairs
3. 31 pairs
4. 33 pairs

Answer: 3. 31 pairs

Question 9. The relay centre of the nervous system is—

1. Thalamus
2. Hypothalamus
3. Cerebrum
4. Cerebellum

Answer: 1. Thalamus

Question 10. The length of the human spinal cord is about—

1. 45 cm
2. 4.5 cm
3. 45 m
4. 4.5 m

Answer: 1. 45 cm

wbbse class 10 life science question answer

Question 11. Which of the following is the controlling organ of reflex action?

1. Brain
2. Nerve ganglion
3. Neuroglia
4. Spinal cord

Answer: 4. Spinal cord

Question 12. The portion of central holds CSF is—

1. Ventricles of brain
2. The central canal of the spinal cord
3. Both 1 and 2
4. Neurone

Answer: 3. Both 1 and 2

Question 13. The outermost covering of the central nervous system is called—

1. Pleura
2. Pericardium
3. Peritoneum
4. Meninges

Answer: 4. Meninges

Question 14. Which of the following is not a part of meninges?

1. Dura mater
2. Grey matter
3. Arachnoid mater
4. Pia mater

Answer: 2. Grey matter

Question 15. Which of the following is not a part of the hindbrain?

1. Pons
2. Cerebellum
3. Tectum
4. Medulla oblongata

Answer: 3. Tectum

Question 16. Corpus callosum is present in—

1. Cerebrum
2. Medulla oblongata
3. Cerebellum
4. Midbrain

Answer: 1. Cerebrum

Question 17. The mass of the spinal cord of a healthy adult man is about—

1. 15 gram
2. 35 grain
3. 75 gram
4. 95 gram

Answer: 2. 35 grain

Question 18. The smallest part of the brain is—

1. Cerebrum
2. Cerebellum
3. Optic lobe
4. Midbrain

Answer: 4. Midbrain

Question 19. The quantity of cerebrospinal fluid present in a healthy adult human being is—

1. 100 ml
2. 150 ml
3. 200 ml
4. 250 ml

Answer: 2. 150 ml

Question 20. The number of ventricles in the human brain is

1. 2
2. 3
3. 4
4. 5

Answer: 3. 4

Question 21. The mass of adult human cerebellum is about—

1. 150 gm
2. 250 gm
3. 350 gm
4. 450 gm

Answer: 1. 150 gm

Question 22. Which one is controlled by the cerebrum?

1. Memory
2. Heartbeat
3. Eyelid movement
4. Body Balance

Answer: 1. Memory

Question 23. Which part of the human brain regulates the body balance?

1. Cerebrum
2. Cerebellum
3. Thalamus
4. Hypothalamus

Answer: 2. Cerebellum

Question 24. The outermost layer of the meninges is—

1. Pia mater
2. Dura mater
3. Arachnoid mater
4. Grey mater

Answer: 2. Dura mater

Question 25. Which of the following is absent in the central nervous system?

1. Neurilemma
2. Axon
3. Axial filament
4. Cyton

Answer: 3. Axial filament

Question 26. Which of the following is developed from myelencephalon?

1. Cerebellum
2. Pons
3. Medulla oblongata
4. Thalamus

Answer: 3. Medulla oblongata

Question 27. The cavities inside the human brain are called—

1. Auricles
2. Central canals
3. Ventricles
4. Cranium

Answer: 3. Ventricles

Question 28. Which of the following is part of the hindbrain?

1. Diencephalon
2. Metencephalon
3. Mesencephalon
4. Telencephalon

Answer: 2. Metencephalon

Question 29. Which of the following is a part of the midbrain?

1. Telencephalon
2. Metencephalon
3. Mesencephalon
4. Myelencephalon

Answer: 3. Mesencephalon

wbbse class 10 life science question answer

Question 30. Which of the following is a part of the forebrain?

1. Telencephalon
2. Metencephalon
3. Mesencephalon
4. Myelencephalon

Answer: 1. Telencephalon

Question 31. The largest portion of the forebrain is called—

1. Cerebellum
2. Cerebrum
3. Thalamus
4. Hypothalamus

Answer: 2. Cerebrum

Question 32. The tube inside the spinal cord is called—

1. Ventricle
2. Central canal
3. Auricle
4. Fallopian tube

Answer: 2. Central canal

Question 33. The fluid present in the central canal is called—

1. Lymph
2. Cerebrospinal fluid
3. Neurohumour
4. Serum

Answer: 2. Cerebrospinal fluid

Chapter 1 Nervous System Answer In A Single Word Or Sentence

Question 1. Which portions of the human brain contain white matter and grey matter?
Answer: The outer portion of the human brain contains white matter and the inner portion is composed of grey matter.

Question 2. What are the gyrus and sulcus?
Answer: Cerebral cortex of the human brain has many folds and grooves. Each outward fold is called gyrus (plural—gyri) and each inward groove is called sulcus (plural—sulci).

Question 3. Which fluid is present inside the ventricles of the brain and central canal of the spinal cord?
Answer: Cerebrospinal fluid

Question 4. Name the three-layered outer covering of the brain.
Answer: Meninges

Role of Sensory and Motor Neurons

Question 5. Who was the first to suggest the concept of reflex action?
Answer: Ivan Pavlov

wbbse class 10 life science question answer

Question 6. What is the full form of CNS?
Answer: Central Nervous System

Question 7. What is the full form of PNS?
Answer: Peripheral Nervous System

Question 8. What is the full form of ANS?
Answer: Autonomic Nervous System

Question 9. Which is the largest part of the human brain?
Answer: Cerebrum

Question 10. State the location of white matter and grey matter in the spinal cord.
Answer: In the spinal cord, grey matter is present inside and white matter remains surrounding it.

Question 11. Name the protective layer surrounding the central nervous system.
Answer: Meninges

Question 12. Which type of nervous system controls the activities of all visceral organs?
Answer: Autonomic nervous system

Question 13. Which part of the nervous system controls the reflex action?
Answer: Spinal cord

Question 14. Which type of nervous system is constituted of the nerves coming out of the brain and spinal cord?
Answer: Peripheral nervous system

Question 15. Name the space between the dura mater and the arachnoid mater.
Answer: Sub-dural space

Question 16. Name the space between the arachnoid mater and the pia mater.
Answer: Sub-arachnoid space

Common Disorders Related to the Nervous System

Question 17. Name the two main parts of the human brain.
Answer: Telencephalon and diencephalon

Question 18. What is the cerebral peduncle?
Answer: Hie portion of human brain that connects thalamus with different parts of hindbrain and midbrain is called cerebral peduncle.

Question 19. Which is the longest nerve of the human body?
Answer: Sciatic nerve

Question 20. Which is the smallest cranial nerve?
Answer: Trochlear nerve

Question 21. Which part of the human brain is concerned with temperature regulation of the body?
Answer: Hypothalamus

wbbse class 10 life science question answer

Question 22. Which are the main portions of the human brain?
Answer: Forebrain, midbrain and hindbrain

Question 23. Which are the main two parts of the midbrain?
Answer: Cerebral peduncle and tectum

Question 24. Which are the two main portions of the hindbrain.
Answer: Metencephalon and myelencephalon

Question 25. Which type of reflex is the suckling of milk by a baby?
Answer: Inborn or innate reflex

Question 26. What is vermis?
Answer: The fibrous connector of the two cerebellar hemispheres is called the vermis.

Question 27. Name the three main parts of the hindbrain.
Answer: Cerebellum, pons and medulla

Question 28. Which part of the hindbrain regulates sneezing, coughing and vomiting?
Answer: Medulla oblongata

Question 29. Site an example of reflex action in daily life.
Answer: One example of reflex action in daily life is— the eyelids close, at once, when a sudden bright light or any object, like dust particles enters the eye.

Chapter 1 Nervous System Fill In The Blanks

Question 1. There are _________ pairs of cranial nerves in the human body.
Answer: 12

Question 2. The outer region of the cerebrum is called _________.
Answer: Reflex arc

Question 3. The brain of vertebrates remains protected inside the _________.
Answer: Skull

Question 4. The reflexes achieved by birth are called _________ reflex.
Answer: Innate

Question 5. The peripheral nervous system is composed of all the _________ emerging from the central nervous system.
Answer: Nerves

Question 6. The folds of the cerebrum are called _________.
Answer: Gyri

Question 7. The momentary involuntary actions in response to sensory stimulus, controlled by the spinal cord is called _________ action.
Answer: Reflex

Question 8. The outer region of the cerebrum is called _________.
Answer: Cerebral cortex

Question 9. The higher mental activities are controlled by the _________ of the human brain.
Answer: Cerebrum

Question 10. The largest part of the brain is _________.
Answer: Cerebrum

Question 11. _________ region of brain control body balance.
Answer: Cerebellum

Question 12. The two hemispheres of the cerebellum are connected by _________.
Answer: Vermis

Chapter 1 Nervous System State True Or False

Question 1. Supporting neurones are found only in the peripheral nervous system.
Answer: False

Question 2. The central nervous system controls the muscular activities of visceral organs.
Answer: False

Question 3. Midbrain is composed of the thalamus and hypothalamus.
Answer: False

Question 4. The outer coating of the brain and spinal cord is the meninges.
Answer: True

Question 5. The terminal part of the brain is the medulla oblongata.
Answer: True

Question 6. The urge of suckling just after birth is an acquired reflex.
Answer: False

Question 7. Grey matter is present on the outer side of the brain and spinal cord.
Answer: False

Question 8. Coughing is an acquired reflex.
Answer: False

Question 9. Hypothalamus helps to maintain body balance inhuman.
Answer: False

Chapter 1 Nervous System Match The Columns

Question 1.

Answer: 1. D, 2. A, 3. B, 4. C,5. G, 6. F

Question 2.

Answer: 1. C, 2. F, 3. A, 4. B,5. D, 6. E

Chapter 1 Nervous System Finds the Odd One Out

Question 1. Vagus nerve, Facial nerve, Glossopharyngeal nerve, Optic nerve
Answer: Optic nerve

Question 2. Swimming, Cycling ability, Hand-eye co-ordination during cricket batting, Sneezing
Answer: Sneezing

Question 3. Intelligence, Vision, Body Balance, Memory
Answer: Body balance

Question 4. Pons, Cerebellum, Cerebrum, Medulla
Answer: Cerebrum

Question 5. Filum terminale, Conas medullaris, Central canal, Brain
Answer: Brain

Question 6. Glossopharyngeal, Oculomotor, Trigeminal, Oxytocin
Answer: Oxytocin

Question 7. Cerebrum, Hypothalamus, Pons, Thalamus
Answer: Pons

Chapter 1 Nervous System Fill In The Blanks By Looking At The First Pair

Question 1. The suckling ability of newborn baby: Innate reflex:: Swimming ability: _______.
Answer: Conditioned reflex

Question 2. Spinal cord: Central nervous system:: Spinal nerve: _______
Answer: Peripheral nervous system

Question 3. Telencephalon: Forebrain:: Metencephalon: _______
Answer: Hindbrain

Question 4. Human cranial nerves: 12 pairs:: Human spinal nerves: _______
Answer: 31 pairs

Question 5. Corpus. callosum: Cerebrum :: Vermis: _______
Answer: Cerebellum

Question 6. Breathing control : Pons:: Body balance: _______
Answer: Cerebellum

Chapter 1 Nervous System Among The Four Concepts Given, Three Of Them Belong To One Find That

Question 1. Brain, Cerebrum, Cerebellum, Pons
Answer: Brain

Question 2. Thalamus, Cerebral cortex, Forebrain, Hypothalamus
Answer: Forebrain

Question 3. Pons, Cerebellum, Medulla oblongata, Hind brain
Answer: Hind brain

Question 4. Brain, Nervous system, Spinal cord, Cranial nerve
Answer: Nervous system

Question 5. Duramater, Piamater, Arachnoid mater, Meninges
Answer: Meninges

Question 6. Reflex arc, Sensory neurone, Motor neurone, Adjuster neurone
Answer: Reflex arc

Question 7. Control of reflex action, Control of breathing Function of the medulla oblongata, Regulation of heartbeat
Answer: Function of the medulla oblongata

Question 8. Suckling of milk, Digestive reflex, Innate reflex action, Contraction of a pupil under bright light
Answer: Innate reflex action