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Chapter 2 Levels Of Organization Of Life Plant Tissue And Its Distribution Short Answer Type Questions

Question 1. Mention the correlation amongst cells, tissues, organs and body.

Answer:

Cells are the structural and functional unit of a living body. Cells of the same origin and function having similar or dissimilar structures form a tissue. One or more types of tissue when unite to perform a specific function, form a tissue system. Several tissue systems constitute an organ and various organs form a body.

Cell → Tissue → Organ → Organ system → Organism

2 What is the utility of tissues in multicellular organisms?

Answer:

The different utility of tissues in multicellular organisms is as follows:

1. Tissue brings division of labour to increase efficiency.
2. Tissues become organised to form organs and organ systems.
3. It decreases the workload of individual cells.
4. Chances of survival of the organisms increase due to higher efficiency and better organisation.

WBBSE Class 9 Life Science Short Answer Questions

Question 3. Represent the classification of meristematic tissue based on position, origin and function in the form of a chart.

Answer:

We can classify meristematic tissue in the following way:

Question 4. Distinguish between meristematic tissue and permanent tissue.

Answer:

Distinguishing features between meristematic tissue and permanent tissue are:

Key Short Answer Questions on Organic and Inorganic Molecules

Question 5 Distinguish between simple permanent tissue and complex permanent tissue.

Answer:

Distinguishing features between simple permanent and complex permanent tissue are:

Question 6. Mention the occurrence of parenchyma cells.

Answer:

The occurrence of parenchyma tissue is as follows:

1. It is seen in the epidermis of all plant parts.
2. It is present in the ground tissue of plants including the cortex, medulla and medullary rays.
3. The mesophyll tissue of leaves is composed of parenchyma.
4. It occurs in the endosperm of seeds.

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Question 7. Where do you find collenchyma tissue?

Answer:

Collenchyma tissue is mainly found in the hypodermis of the stem. The Midrib and petiole of the leaves and peduncle of flowers are made up of collenchyma.

Important SAQs for Class 9 Life Science Chapter 2

Question 8 Mention the different types of sclerenchyma, based on their features.

Answer:

Features of different types of sclerenchyma are as follows:

1. Sclerenchyma fibres are long and narrow cells with pointed ends.
2. Sclereids are broad with thick-walled cells which occur singly or in small groups.

 

Question 9. Where do you find sclerenchyma tissue in a plant?

Answer:

Components of sclerenchyma are found in the following parts of the plant:

1. Sclerenchyma fibres are present in the hypodermis, cortex, vascular bundles and pericycle.
2. Sclereids are found in seed coats.

Question 10 Why are some specific types of sclereids called stone cells?

Answer:

The deposition of lignin, cutin and suberin on the cell wall of some short and oval or spherical-shaped sclereids, makes them hard, like stones. The lumen of such cells is almost squeezed due to the deposition.

That is why, these special types of sclereids are called stone cells. Stone cells are responsible for providing mechanical support to the plants.

WBBSE Life Science And Environment Class 9 Solutions

Question 11. Mention the functions of the cork cambium and vascular cambium.

Answer:

Functions of cork cambium:

It takes part in the growth of the outer part of the plant body beyond the vascular bundle, to produce cortex and bark to replace ruptured epidermis.
Functions of vascular cambium: It takes part in the formation of the xylem and phloem within the vascular bundle.

Question 12 Write down the functions of the xylem.

Answer:

The main functions of the xylem are the conduction of water and solutes from roots to the different parts of the plants, providing mechanical support to the plant and in some cases, helping in the storage of food materials.

Question 13 Distinguish between tracheid and trachea.

Answer:

Distinguishing features between the tracheid and trachea are:

Practice Short Answer Questions for Life Science

Question 14 Distinguish between the sieve tube and the companion cell.

Answer:

Distinguishing features between the sieve tube and the companion cell are

Question 15 Distinguish between xylem and phloem.

Answer:

Distinguishing features between the xylem and phloem are:

Question 16 Distinguish between the trachea and sieve tube.

Answer:

Distinguishing features between the trachea and sieve tube are:

Chapter 2 Levels Of Organization Of Life Plant Tissue And Its Distribution  Short Answer Type Questions

Question 1. What is meant by epithelial tissue?

Answer:

Epithelial Tissue:-

The tissue, which typically covers the outer surface of the body as well as the inner and outer lining of internal organs, is known as epithelial tissue. It consists of one or more cell layers.

WBBSE Class 9 Life Science Question And Answer

Question 2 What is the basement membrane? What does it do?

Answer:

Basement membrane: The basement membrane is a typical acellular layer of epithelial tissue, composed of materials, somewhat similar to the matrix of connective tissue.

Function: The basement membrane holds the epithelial cells on it. It also helps the epithelium to remain attached to the surface of the connective tissue layer below it.

Question 3 Write the different types of epithelial tissue.

Answer:

It is of three types:

1. Surface protective epithelium,
2. Glandular epithelium,
3. Sensory or neurosensory epithelium.

The surface protective epithelium also has three types:

1. Simple
2. Stratified
3. Pseudostratified.

Concepts Related to Organic and Inorganic Molecules for SAQs

Question 4. Mention the types of simple epithelial tissues.

Answer:

Simple epithelial tissue is of different types:

These are:

1. Squamous epithelium
2. Cuboidal epithelium
3. Columnar epithelium
4. Ciliated epithelium.

Question 5. Mention the distribution of epithelial tissue.

Answer:

Distribution Of Epithelial Tissue:-

Epithelial tissue is present on the outer surface of the body (skin) and the inner lining of the oral cavity, intestine, blood vessels, nasal passage, respiratory tracts, alveoli, renal tubules, urinary bladder, uterus, fallopian tube and different glands.

WBBSE Class 9 Life Science Question And Answer

Question 6 Mention the two functions of simple epithelial tissue.

Answer:

Two functions of simple epithelial tissue are:

1. The tissue helps in the exchange of gaseous and liquid substances.
2. It protects the organs from friction.

Question 7. Mention the characteristics, distribution and function of simple squamous epithelium.

Answer:

Characteristics:

1. Cells of the tissue are larger, flattened and elongated.
2. The nucleus is flattened and oval.
3. The cells remain arranged on the basement membrane.

Distribution: Present in alveoli, peritonium, pleura, loop of Henle and Bowman’s capsule of Kidney.

Function:
1. The tissue helps in the exchange of gaseous and liquid substances.
2. Helps in filtration.
3. Protects the body from microorganisms.

Question 8 Mention the characteristics, distribution and function of cuboidal epithelium.

Answer:

Characteristics:

1. The cells of the tissues are equal in length and breadth.
2. the nucleus of the cell is oval-shaped.
3. The upper surface of the cell is polygonal.

Distribution: Present in the renal tubule, salivary glands, thyroid gland.

Function: Helps in secretion and defence.

Question 9 Mention the characteristics, distribution and function of columnar epithelium.

Answer:

Characteristics:

1. The length of the cell is greater than the breadth.
2. Cells remain arranged on the basement membrane hence called columnar tissue.
3. The nucleus is oval and large in size.
4. Cytoplasm is reticular.

WBBSE Class 9 Life Science Question And Answer

Distribution: Present in the stomach, small intestine, large intestine and in certain glands.

Function:
1. Secretion and defence.
2. Protection.

Question 10 Mention the characteristics, distribution and function of ciliated epithelium.

Answer:

Characteristics:

1. The cells of this tissue is somewhere columnar, somewhere cuboidal.
2. The cells of this tissue bear 28-30 hairlike appendages at their surface.
3. Cilia arise from the basal part.

Distribution: Present in alveoli and its’ adjacent part, uterus, oviduct, and ependymal cells (spinal cord).

Function:
1. Clears mucous, dust particles, and different types of microbes from the respiratory tract.
2. The cell helps to expel the ovum and spermatozoa.

Sample Short Answer Questions from WBBSE Class 9 Life Science

Question 11 Mention the characteristics, distribution and function of the stratified or compound epithelium.

Answer:

Characteristics:

1. The tissue is formed by 3 to 4 cell layers.
2. Cells of the upper layer are large, flattened and quadrangular.
3. Number of nucleus may be one or two.

Distribution: Present in the broadened part of the ureter, in the upper part of the urinary bladder and urinary duct.
Function:
1. Defence
2. Inhibit reabsorption of waste substances.

WBBSE Class Nine Life Science

Question 12 Write the distribution of different types of stratified epithelial tissue.

Answer:

Stratified squamous epithelium:

1. Keratinised hair, nails, horns, and the epidermis of the skin.
2. Non-keratinised-Pharynx, oesophagus, vagina, mouth cavity.

Stratified cuboidal epithelium: Sweat gland, conjunctiva.

Stratified columnar epithelium: Glottis, epiglottis, rectum.

Question 13 Write the characteristics, distribution and function of the pseudostratified epithelium.

Answer:

Characteristics:

1. This tissue though is made up of single-layered cells but the size of the cells is unequal hence it appears like a stratified layer.
2. Cells may be ciliated or non-ciliated.
3. The nucleus of the cells lies at a different plane.

Distribution: Present in the large duct of the salivary gland, urethra, etc.

Function: Protect associated organs and helps in the movement of some substances.

Question 14 What is meant by glandular epithelium?

Answer:

Glandular Epithelium:-

An epithelium, which has assumed secretory function is termed as glandular epithelium. It is present in all types of exocrine and endocrine gland and is associated with the secretion of various secretory substances.

Question 15 Write the distribution of sensory epithelium.

Answer:

Distribution Of Sensory Epithelium:-

WBBSE Class Nine Life Science

The sensory epithelium is found in nasal passages and taste buds.

Understanding Organic vs Inorganic Molecules for SAQs

Question 16 Give two roles of glandular epithelium.

Answer:

Roles Of Glandular Epithelium:-

1. Glandular epithelium present in the inner lining of the gastrointestinal tract secretes various digestive enzymes.
2. In endocrine glands, glandular epithelium secretes hormones.
Image

Question 17 What is meant by connective tissue?

Answer:

Connective Tissue:-

The tissue of mesodermal origin, composed of less cells and more acellular matrix, connecting different tissues is known as connective tissue.

Question 18 Schematically represent different types of connective tissues.

Answer:

Schematic representation of different types of connective tissue is given below:

Question 19 Mention the characteristics and distribution of areolar tissue.

Answer:

Characteristics: Semidistinct, white, with wide intracellular space.

Distribution: This tissue binds the skin with the underlying part.

Question 20 Mention the characteristics and distribution of adipose tissue.

Answer:

Characteristics:

1. Cells are large, rounded and polygonal.
2. The nucleus lies at the periphery and fat remains deposited at the central portion of the cell.

Distribution: Found everywhere in the body but maximum below the skin, mesentery membrane and also in the adjacent area of the kidney.

Question 21 Write the functions of areolar tissue.

WBBSE Class Nine Life Science

Answer:

Functions Of Areolar Tissue:-

1. provides strength and rigidity to the body.
2. Helps in bearing weight.
3. keep the organs in the proper place.
4. Helps to fill the intermediary place of tissue cells.

Question 22 Write the functions of adipose tissue.

Answer:

Functions Of Adipose Tissue:-

1. Resist the Injury.
2. To store fat in the body.
3. Conserve heat in the body.

Question 23 Define weight-bearing connective tissue. Classify it.

Answer:

Weight-Bearing Connective Tissue:-

The connective tissue which helps in bearing weight is called weight-bearing connective tissue or skeletal tissue. It is the hardest tissue.

They are of two types:

1. Cartilage,
2. Bone

Question 24 Write the functions of skeletal muscle.

Answer:

The functions of skeletal muscles are:

WBBSE Class Nine Life Science

1. Helps in the movements of different body parts.

2. Protects many vital soft organs of the body.

Question 25 Connective tissue different types of what do mean by fluid connective tissue.

Answer:

It is a unique type of mobile connective tissue originating from embryonic mesoderm, transferred from one part of the body to another through the cardiovascular system.

Example: Blood.

Study Guide for Class 9 Life Science Short Answer Questions

Question 26 Why blood is called fluid connective tissue?

Answer:

Blood Is Called Fluid Connective Tissue:-

Blood is mesodermal in origin, has fewer cells and more matrix, and it maintains connection among various parts of the body. On the other hand, the matrix of blood, i.e., plasma, is fluid in nature. Therefore, blood is called fluid connective tissue.

Question 27 What is meant by muscular tissue?

Answer:

Muscular Tissue:-

The tissue, which has the ability to contract and relax and is associated with movement, is known as muscular tissue.

Question 28 Mention one function of the tendon and ligament those function of tendon and.

Answer:

The function of the tendon is to connect muscles to bones. The function of the ligament is to connect a bone to another bone.

WBBSE Class Nine Life Science

Question 29 How many types of muscular tissues are found in higher animals?

Answer:

In higher animals three types of muscular tissues are found, these are:

1. voluntary or skeletal muscles,
2. smooth muscles and
3. cardiac muscles.

Question 30. Mention the distribution of muscular tissue.

Answer:

Distribution Of Muscular Tissue:-

1. Voluntary muscles are attached to bones.
2. Smooth involuntary muscles are present in the vital visceral organs, such as the oesophagus, intestine, urinary bladder, and stomach [3] Cardiac muscles are present in the heart.

Question 31 Write down the functions of different types of muscles.

Answer:

Functions Of Different Types Of Muscles:-

1. Skeletal muscles help in movement and locomotion.
2. Smooth muscles control the movement of the visceral organs like the stomach, intestine, urinary bladder, etc.
3. Cardiac muscles are responsible for rhythmic contraction and relaxation of the heart.

Question 32 What do you mean by voluntary or skeletal muscle? Write its functions.

Answer:

Skeletal Muscle:-

Muscles which are normally attached to the bones are called skeletal muscle.

Functions:
1. Contraction of these muscles is under the voluntary control (controlled willingly) of the nervous system. Thus it helps to maintain posture and stabilize bones and joints.
2. Skeletal muscle is associated with reflex action.
3. These muscles can contract rapidly and are responsible for quick movements and thereby coordinates the entire body.

WBBSE Class Nine Life Science

Question 33 Write the functions of unstriated muscles.

Answer:

Functions Of Unstriated Muscles:-

1. Unstriated muscle fibres present around the blood vessels, help to maintain blood pressure.
2. Unstriated muscle fibre in the digestive tract helps in the movement of food substances and thereby assists in digestion.
3. The presence of unstriated muscle in air passages regulates the inflow and outflow of air.
4. In the renal system unstriated muscle fibres propel the urine from the kidney to the urinary bladder.

Question 34 What do you mean by intercalated disc. State its significance.

Answer:

Intercalated Disc:-

Special fibrous discs are present at intervals of They are transmitting the signals of nerve cardiac muscle is known as the Intercalated disc. impulse between the cells of the heart.

Question 35 Define the haversian canal. Or, Write its distribution.

Answer:

Haversian Canal:-

Each osteon consists of a single central canal, known as a haversian canal, surrounded by concentric layers of calcified bone matrix. It allows the passage of blood vessels, lymphatic vessels and never fibres.

Question 36 Name single-nucleated and multinucleated muscle cells.

Answer:

Single-Nucleated And Multinucleated Muscle Cells:-

WBBSE Class Nine Life Science

The single-nucleated muscle cell is an unstriated muscle cell, present in the visceral organ. The multinucleated muscle cell is a striated muscle cell, present in the hands and legs.

Question 37 What is nervous tissue?

Answer:

Nervous Tissue:-

The tissue, which is responsible for receiving and transmitting impulses and thereby coordinating different parts of the body, is known as nervous tissue.

Question 38 What are the cellular components of nervous tissue? Where do you find those components?

Answer:

Cellular components of nervous tissue: Neurone and neuroglia are the two cellular components of nerve tissue.

Distribution of neurone and neuroglia: Neurones are present in the brain, spinal cord, sense organs and nerves. Several neurones, surrounded by connective tissue, form a nerve. Neuroglia cells are found in the brain and spinal cord as packing material of neurones, providing them with necessary support and insulation.

Question 39 Write the functions of nervous tissue.

Answer:

Functions Of Nervous Tissue:-

1. Nerve tissue receives external and internal stimuli and responds to them.
2. It carries impulses and makes the body aware of the changes in the environment.
3. It helps to maintain coordination among all organs within the body.

Question 40 Classify different types of animal tissue.

Answer:

Classification of animal tissue is given below:

Question 41 Define the term:
1. Axon-hillock
2. End brush.

WB Class 9 Life Science Question Answer

Answer:

1. Axon-hillock: The part of the cell body. from where the axon originates is called axon-hillock.
2. End brush: The terminal end of branches are nodular called terminal buttons or end brush. 45

Question 42 Write different membranes of the axon arranged in proper order.

Answer:

Neurilemma, myelin sheath and axolemma

Question 43 What are the nodes of Ranvier?

Answer:

Nodes Of Ranvier:-

The continuity of myelin sheath myelinated axon is interrupted by several constrictions. These are called nodes of Ranvier.

Question 44 What do you mean by synapse?

Answer:

Synapse:-

Synapse is the junctional region as anatomical border in nervous system where one neurone ends and the next neurone starts.

Question 45. Write the difference between striated and non-striated muscles.

Answer:

The differences between striated and non-striated muscles are:

Question 46. Write the difference between voluntary muscle and cardiac muscle.

Answer:

The differences between voluntary muscle and cardiac muscle are:

Chapter 2 Levels Of Organization Of Life Plant Tissue And Its Distribution Long Answer Type Questions

Question 1. What is meant by tissue? How plant tissues can be classified into different types?

Answer:

Tissue:
Tissue is the assemblage of a number of structurally similar or dissimilar cells having the same origin and function.

Classification of different plant tissues:

Wbbse Class 9 Life Science Solutions

Question 2 What is meant by meristem or meristematic tissue? Describe the characteristic features of the meristematic tissue with a simple diagram.

Answer:

Meristem or meristematic tissue:

Meristems or meristematic tissues are cells or groups of cells that are capable of undergoing cell division.
Characteristic features of meristematic tissue

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The characteristic features of meristematic tissue are as follows:

1. Cells are living, undifferentiated, polygonal, spherical, or oval in shape.
2. Cells are densely packed and without intercellular spaces.
3. The cell wall is thin, made up of cellulose.
4. The nucleus is large and distinct.
5. The cytoplasm is dense, and vacuoles are generally absent.
6. The cells are capable of undergoing cell division.

WBBSE Class 9 Life Science Long Answer Questions

Question 3 Describe the distribution of different meristematic tissues with their functions and support your answer with a diagram.

Wbbse Class 9 Life Science Solutions

Answer:

Distribution of meristematic tissues:

Based on occurrence, meristematic tissues can be sub-divided into three types, which are as follows:

1. Apical meristem: It occurs at the tip of roots and shoots.

Function: Apical meristem gives rise to the primary plant body and helps the root and shoot of the plant to grow in length.

2. Intercalary meristem: It occurs near the nodes of growing shoots, in between two layers of permanent tissues.

Function: This makes the young internodes longer and also helps in the growth of leaves.

Levels of Organisation of Life Long Answer Questions

3. Lateral meristem: It occurs along the lateral position of roots and stems of higher plants. It divides laterally and makes the plant thicker.

It is of two types:

1. Vascular cambium (fascicular cambium): It occurs within the vascular bundle.
2. Cork cambium (phellogen): It occurs outside the vascular bundle.

Function: Vascular cambium helps in the formation of secondary xylem and secondary phloem tissues and cork cambium is responsible for secondary growth that replaces the epidermis in roots and stems.

Question 4. What is meant by permanent tissue? Mention its distribution, characteristics and functions.

Answer:

Permanent tissues:

The plant tissues in which cells have lost their capability of undergoing cell division are known as permanent tissues.

Distribution of permanent tissue:

According to the function, permanent tissues are located in various regions within a plant body. simple permanent tissues are found below the epidermis. Parenchyma is found in the mesophyll of leaves and in the cortex of the stem and root. Collenchyma is generally found in the leaf stalks and leaf midribs.

Sclerenchyma is found in stems around the vascular bundles, hard covering of seeds and nuts, and in the leaf veins. Complex permanent tissues can be found throughout a plant body.

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Characteristics of permanent tissue:

1. Cells of these tissues do not divide any further.
2. These are mature cells, so they have attained definite size, shape, structure and perform a particular function.
3. Cells have larger vacuoles. Intercellular spaces are often present.
4. Cell walls are comparatively thick. Often ornamentations are present on cell wall.
5. These tissues comprise of either dead or living cells. In living cells, smaller nucleus with reduced protoplasm is observed.
6. Metabolic rate within the cells of this tissue is slower in comparison to that of meristematic cells.

Function: These tissues are involved in protection, support, transportation or secretion.

Important Long Answer Questions for Class 9 Life Science

Question 5. Classify simple permanent tissue by describing the characteristic features of each.

Answer:

Classification of Simple Permanent Tissue:

On the basis of their shapes, simple permanent tissues are classified into three groups-parenchyma, collenchyma, and sclerenchyma.

1. Parenchyma:
1. Cells are spherical, oval, or polyhedral.
2. Cell wall is thin and made up of cellulose.
3. Cells living with dense protoplasm.
4. Cell contains distinct nucleus and vacuoles.
5. Cells are with intracellular spaces.
6. Cells are of three types:
1. Chloroplast containing chlorenchyma
2. Air cavity containing aerenchyma
3. Tanins, oils and calcium oxalate crystal containing idioblast.

2 Collenchyma:
1. Simple tissue consisting of unevenly thick-walled living cells.
2. On the basis of cell wall thickenings, collenchyma is of the following three types:
1. Lamellar or plate-like
2. Lacular or tubular
3. Angular.

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3. Sclerenchyma:
1. Simple tissue consisting of evenly thickened-walled dead cells.
2. Cell wall contains lignin.
3. It is of two types:
1. Sclerenchyma fibers.
2. Sclereids.

Wbbse Class 9 Life Science Solutions

Question 6. Describe the characteristic features of parenchyma tissue with simple diagram. Mention its functions in a plant body.

Answer:

Characteristic features of parenchyma tissue:

The characteristic features of parenchyma tissue are as follows:

1. Cells are living and thin-walled, almost equal in size and shape.
2. Cells are loosely packed with distinct intercellular spaces.
3. Vacuoles are large. Cytoplasm becomes peripheral, forming a primordial utricle with a distinct nucleus.

Functions of parenchyma tissue:

The functions of parenchyma tissue are as follows:

1. Simple parenchyma cells occur in the ground tissue and store food.
2. Aerenchyma maintains buoyancy in floating and submerged aquatic plants.
3. Chlorenchyma takes part in photosynthesis.
4. Idioblasts store mineral crystals, oil, excretory matter, etc.
5. Parenchyma cells take part in gaseous exchange which can be performed because of the presence of intercellular spaces.
6. In the form of epidermis or epiblema, parenchyma protects all plant parts.

 

Question 7. Describe the characteristic features of collenchyma tissue with a diagram. Mention the function of this tissue.

Answer:

Characteristic features of collenchyma tissue:

The characteristic features of collenchyma tissue are as follows:

1. Cells are living and are of almost identical size. They are cylindrical, but in cross-section, appear polygonal.
2. Cell wall is made up of cellulose, hemicellulose, and pectin. The cell wall is unevenly thickened at the corners.
3. Less intercellular space is present.
4. Vacuole is large. The cytoplasm is present as a primordial utricle.
5. Chloroplast may be present.

Functions of collenchyma tissue:

The functions of collenchyma tissue are as follows:

1. Collenchyma tissue provides mechanical strength.
2. It provides flexibility to plant parts and prevents them from breaking.
3. This type of tissue helps to store food.
4. It also carries out photosynthesis.

Wbbse Class 9 Life Science Solutions

Question 8. Describe the characteristic features of sclerenchyma tissue. Mention the functions of this tissue.

Answer:

Characteristic features of sclerenchyma tissue:

The characteristic features of sclerenchyma tissue are as follows:

1. Mature Cells are dead, devoid of protoplasm and have a narrow lumen.
2. Cells are without inter-cellular space.
3. The cell wall is evenly thickened and highly lignified.
4. In some places, pits are present on the cell wall.
5. Some cells are thin, elongated and pointed. These are called sclerenchyma fibres. Some are wide with very thick cell wall, which are called sclereids.

Functions of sclerenchyma tissue

The functions of sclerenchyma tissue are as follows:

1. Sclerenchyma tissue provides mechanical strength.
2. It makes the plant parts rigid.
3. Sclereids especially form tough seed coats of legume fruits and the endocarp of a drupe.
4. This tissue also protects plant parts from getting wet.

Wbbse Class 9 Life Science Solutions

Question 9. Write down the structure of sclerenchyma fibres.

Answer:

The structure of sclerenchyma fibres is as follows:

1. Sclerenchyma fibres are very fine and long with two pointed ends.
2. Cells are without intercellular spaces and are compactly arranged sidewise to form bundles.
3. The cell wall is evenly thickened with bordered pits and the lumen is narrow.
4. Cells are dead and appear polygonal in cross-section.
5. The sclerenchyma fibres occurring in the xylem are called wood fibres. These fibres, when occur in phloem are called bast fibres.

Question 10 Compare the characteristic features of parenchyma, collenchyma and sclerenchyma.

Answer:

Comparison among parenchyma, collenchyma and sclerenchyma:

Question 11 Mention the living and non-living components of the xylem. Write down its function.

Answer:

Components of Xylem:

Xylem has four typical components. These are the tracheid, tracheae or vessels, xylem parenchyma and xylem fibres. Among them, the xylem parenchyma is the living component of the xylem, whereas, the rests are non-living components.

Characteristic features of xylem components:

The characteristic features of xylem components are as follows:

1. Tracheids are dead, elongated cells with two pointed ends. Unevenly lignified thickening of walls creates different patterns. Pits are present in the cell wall. These cells take part in water transportation throughout the plant body.
2. Vessels or tracheae are long, tubular dead cells without end walls. Lumen is wider than that of tracheids. The wall of the vessels possesses many pits. These cells also carry sap. Numerous cells are arranged in a row to form long continuous vessels.
3. Xylem fibres are composed of dead cells, which are very thin & long with pointed ends. The cell wall of xylem fibre is thick with a narrow lumen. These cells provide mechanical strength and rigidity to the plant body.
4. Xylem parenchyma is the only component of the xylem tissue which is composed of living cells. It has a thin cell wall and it contains protoplasm.

WBBSE Life Science And Environment Class 9 Solutions

Question 12 Give a brief description of the structure of the trachea. Mention the occurrence and functions of the trachea.

Answer:

Structure of tracheae or vessels:

The structure of the tracheae is as follows:

1. These cells are dead, long and tubular in shape with completely or partially open ends.
2. The wall is lignified with bordered pits. Ornamentations are often found on the wall due to uneven thickening.
3. The lumen present here, is the widest among, all xylem components.
4. Several tracheal cells remain arranged one after another to form a continuous tube due to the dissolution of end walls.

Occurrence of tracheae or vessels:

These xylem components occur in all angiosperms and a gymnosperm named Gnetum. Functions of trachea

The functions of the trachea are as follows:

1. It transports sap from roots to leaves.
2. Trachea provides mechanical support to the plant body.

Practice Long Answer Questions for Class 9 Life Science

Question 13 Give a brief description of the structure of the Xylem Parenchyma. Mention its occurrence and functions.

Answer:

Structure of xylem parenchyma:

The structure of xylem parenchyma is as follows:

1. These are living cells with cytoplasm and a small nucleus.
2. The cell wall is thin and composed of cellulose.
3. The cells are almost isodiametric and their lateral walls have few simple pits.

Occurrence of xylem parenchyma:

Xylem parenchyma is present in the vascular bundle of all angiosperms and most of the gymnosperms, except pines.

Functions of xylem parenchyma:

The functions of xylem parenchyma are as follows:

1. It helps in the transportation of sap and also helps in lateral transportation.
2. It stores nutrients like carbohydrates, fats and excretory matters like tannin, inorganic crystals, etc.

Question 14. Give a brief description of the structure of Xylem fibre. Mention its occurrence and functions.

Answer:

Structure of xylem fibres:

The structure of xylem fibres is as follows:

1. The cells of xylem fibre are dead, very fine with pointed ends.
2. Cells have very narrow lumen.
3. The cell wall is very thick due to heavy lignification and rigid with both simple and bordered pits.
4. Fibres are of two types-libriform fibre and tracheid fibre.

Occurrence of xylem fibres:

Xylem fibres are present in the vascular bundle of all angiosperms and most of the gymnosperms, except pines.

Functions of xylem fibres:

The functions of xylem fibres are as follows:

1. These provide mechanical support to the plant body.

2. These also store food material and certain excretory matters.

Key Concepts in Levels of Organisation for Long Answers

Question 15. What is phloem? Describe the distribution, characteristics and function of phloem.

Answer:

Phloem:

The organic food conducting complex tissue in vascular plants is known as phloem.

These are composed of four elements:

1. sieve tubes
2. companion cells
3. phloem fibre or bast fibre
4. phloem parenchyma.

Distribution/Location:

Phloem is present in vascular bundles of root, stem and leaves.

Characteristics:

1. These are complex, living permanent tissue.
2. All the cell elements of this tissue are living except phloem fibre.
3.

The cell wall is thin, composed of cellulose except for phloem fibre.

Function:

The main functions of the phloem are the conduction of food matters from leaves to different regions of the plant body and its storage.

WBBSE Life Science And Environment Class 9 Solutions

Question 16. Describe the characteristic features of these components.

Answer:

Characteristic features of phloem components:

The characteristic features of phloem components are as follows:

1. Sieve tubes are living cylindrical cells with perforated end walls, called sieve plates. The nucleus is absent in mature cells. Several sieve tubes are arranged in a row forming a long tube. It helps in the transportation and storage of food.
2. Companion cells are lens-shaped cells with prominent nuclei and dense cytoplasm. They are present on either side of the sieve tube. These help sieve tubes in the transportation of food.
3. Phloem parenchyma has granular cytoplasm and a thin cell wall made up of cellulose. This component of phloem stores organic and orgastic materials.
4. Phloem fibre is the only non-living component of phloem. It is elongated with lignified walls. Pits are present in the cell wall. Fibres provide mechanical support to plant parts.

Sample Long Answer Questions from WBBSE Class 9 Life Science

Question 17. Give a brief description of the structure of the sieve tube. Mention its occurrence and functions.

Answer:

Structure of sieve tube:

The structure of the sieve tube is as follows:

1. Sieve tubes are tubular in shape, arranged longitudinally one after another to form a continuous pipe.
2. The matured cells have cytoplasm but no nucleus inside.
3. The wall is thin and composed of cellulose.
4. The two terminal walls are well-perforated and are called sieve plates.
5. The connection between two sieve cells is made by cytoplasmic strands through sieve pores.

Occurrence of sieve tube:

Sieve tubes are present in pteridophytes and all flowering plants.

Functions of sieve tube:

The functions of sieve tubes are as follows:

1. They help in the transportation of food.
2. They also occasionally store food.

Question 18. Give a brief description of the structure of the companion cell. Mention its occurrence and functions.

Answer:

Structure of companion cell:

The structure of companion cells is as follows:

1. The cells are living, full of dense cytoplasm and with a distinct nucleus.
2. The cells have thin walls, made up of cellulose and appear triangular in cross-section.
3. Laterally, these cells are lens-shaped.
4. These cells keep a close association with the sieve tube through pits and plasmodesmata on the lateral wall.

Occurrence of companion cell:

Companion cells occur in the phloem of all angiosperms and in a single gymnosperm, named Gnetum sp.

Functions of companion cell:

The functions of companion cells are as follows:

1. The help in the transportation of food through a sieve tube.
2. They also store carbohydrates and help in lateral transport.

Question 19. Give a brief description of the structure of phloem parenchyma. Mention its occurrence and functions.

Answer:

Structure of phloem parenchyma:

The structure of phloem parenchyma is as follows:

1. The cell wall is thin and made up of cellulose. It is rarely lignified and pitted.
2. The shape of the cells is elongated, cylindrical and radially arranged with the plant axis.
3. The cytoplasm of these cells stores starch, resin, tannin, etc.

Occurrence of phloem parenchyma:

It can be observed in all dicot plants but monocot plants never possess phloem parenchyma. Pteridophytes and gymnosperms also have these cells in the phloem.

Functions of phloem parenchyma:

The functions of phloem parenchyma are as follows:

1. It helps in food transport.
2. It stores different organic matter and excretory substances.
3. It helps in the lateral transport of organic food matter.

WBBSE Life Science And Environment Class 9 Solutions

Question 20. Give a brief description of the structure of phloem fibre. Mention its occurrence and functions.

Answer:

Structure of phloem fibre:

The structure of phloem fibre is as follows:

1. These cells are non-living, with a very fine and hollow lumen.
2. The cells are long with pointed ends.
3. The cell wall is thick, well-lignified and commonly with simple pits.
4. The cells remain arranged one after another along the length.
2. Fibres are overlapped to form bundle.

Occurrence of phloem fibres:

Phloem fibres are present in angiosperms only.

Functions of phloem fibres:

The functions of phloem fibres are as follows:

1. These provide mechanical support to the plant body.
3. These also store food matter, like starch.

Chapter 2 Levels Of Organization Of Life Plant Tissue And Its Distribution  Long Answer Type Questions

Question 1. Describe the structure of epithelial tissue. Mention its functions.

Answer:

Structure of epithelial tissue:

1. The cells are present on a basement membrane made up of collagenous materials.
2. Cells are densely packed and are joined together by mucoproteins (a special type of glycoprotein).
3. Cells of this tissue are either arranged in a single layer or in multilayers.
4. Cells do not get a direct blood supply. They receive oxygen and nutrients from underlying tissues.

Functions of epithelial tissue:

1. Epithelial tissue provides protection to the animal body and its various organs.
2. Epithelial tissue like squamous epithelium, takes part in gaseous exchange.
3. Columnar epithelial cells help in absorption and secretion.
4. Certain cuboidal and glandular epithelial cells secrete enzymes and hormones.

WBBSE Class 9 Life Science Question And Answer

Question 2. Mention the distribution of connective tissue. Briefly mention the structure of connective tissues.

Answer:

Distribution of connective tissue:

1. Areolar tissue is present below the skin, between muscles, outer coatings of nerves and walls of blood vessels.
2. Fibrous tissues are present in tendons, ligaments, walls of arteries, trachea and larynx.
3. Adipose tissue is found below the skin, mammary glands, and surrounding vital organs like the heart, kidney, etc.
4. Bones and cartilage are found in the skeletal parts.
5. Blood and lymph are present in the circulatory system.

Structure of connective tissue:

1. Connective tissue originates from the mesoderm layer of the embryo.
2. It possesses fewer cells, which remain loosely placed in the intercellular matrix.
3. Cells of connective tissue are of various types with different sizes, shapes, intra and intercellular components and functions.
4. Some fibrous materials like collagen, elastin etc. may be present in the matrix.
5. The matrix may be soft, jelly-like (areolar and adipose tissue), liquid (blood, lymph), rigid (bone), or elastic (cartilage).

Question 3 Briefly describe the structure of muscular tissue. Distinguish between muscular tissue and nervous tissue.

Answer:

Structure of muscular tissue:

1. Muscle cells are commonly called muscle fibres. These are thin, elongated, cylindrical or spindle-shaped.
2. Bundles of muscle fibres, surrounded by connective tissue, constitute a muscle.
3. Muscle fibres may be uninucleated, multinucleated, unbranched or branched.
4. The cytoplasm of muscle cells is called sarcoplasm, which remains surrounded by sarcolemma. Within sarcoplasm, several longitudinal contractile proteins are present, which help in the contraction and relaxation of muscles.

Differences between muscular tissue and nervous tissue:

WBBSE Class 9 Life Science Question And Answer

Question 4. Mention the functions of different types of connective tissues. Distinguish between epithelial tissue and connective tissue.

Answer:

Functions of connective tissue:

1. Areolar tissue acts as packing material between the organs.
2. Adipose tissue stores fat for future use, keeps the body warm and acts as a cushion to protect the body against mechanical injury.
3. Bones and cartilages form the skeleton to give mechanical support to the body of the vertebrates.
4. Fibrous tissue provides elasticity and mechanical support.
5. Blood and lymph act as transporting fluid, carrying nutrients, hormones, respiratory gases, etc. to different parts of the body.

Differences between epithelial and connective tissue:

Question 5. Describe the structure of a neurone.

Answer:

Structure of a neurone:

1 Neurone has two parts, the cell body or neurocytoma and some processes.
2 Neurocyton or cell body is covered by a typical cell membrane surrounding the protoplasm.
3 Protoplasm has a distinct nucleus and cytoplasm with various cell organelles.
4 Apart from mitochondria, Golgi body, ER etc., the cytoplasm of a neurone has some nucleoprotein granules, known as nissl granules.
5 Processes of a neurone are axon and dendron.
6 Axon is the longer part with fewer branching. A few axons have an extra thick insulating cover on it, called myelin sheath.
7 Myelin sheath is interrupted by several constrictions. These are called nodes of Ranvier.
8 A special type of cell called Schwann cell, is also found along, the length of the axon.
9 The axon ends with a few branches, commonly called as end brush.
10 The dendron is shorter and well-branched. These branches are known as dendrites.

Study Guide for Class 9 Life Science Long Answer Questions

Question 6. Compare the features of voluntary, involuntary and cardiac muscle.

Answer:

Comparison among voluntary, involuntary and cardiac muscle:

Question 7. Distinguish between:
1. Axon and Dendron
2. Sarcolemma and neurolemma.

Answer:

Differences between axon and dendron:

Differences between sarcolemma and neurolemma:

Chapter 2 Levels Of Organization Of Life Plant Tissue And Its Distribution Multiple Choice Questions

Question 1. Which of the following does not have a tissue system?

1. Amoeba
2. Volvox
3. Sponges
4. All of these

Answer:  4. All of these

Question 2. An organism possesses different types of tissues and organs due to

1. Organogenesis
2. Differentiation
3. Cell division
4. None of these

Answer: 2. Differentiation

Question 3. Cells of tissue always have

1. The similarity in size and shape
2. Same life span
3. Same function
4. Different origin

Answer: 3. Same function

Question 4. Cells of meristematic tissues are

1. Of the same size and shape
2. Capable of division
3. Undifferentiated
4. All of these

Answer: 4. All of these

WBBSE Class 9 Life Science MCQs Chapter 2

Question 5. Meristematic tissues are seen in

1. Green leaves
2. Matured fruit
3. Root tip
4. Shoot

Answer: 3. Root tip

Question 6. Stems of trees become thick by the activity of

1. Lateral meristem
2. Intercalary meristem
3. Primary meristem
4. Apical meristem

Answer: 1. Lateral meristem

Question 7 Intercalary meristem is found in

1. Root apex
2. Stem apex
3. Nodes
4. Internodes

Answer: 4. Internodes

Question 8. A tissue has cells with no intercellular space and a vacuole in the cytoplasm. This tissue is a

1. Xylem tissue
2. Parenchyma tissue
3. Meristematic tissue
4. Collenchyma tissue

Answer: 3. Meristematic tissue

Question 9. Cells of a tissue having a large and prominent nucleus and are capable of undergoing division can be identified as a

1. Meristem
2. Parenchyma
3. Collenchyma
4. Sclerenchyma

Answer: 1. Meristem

Important MCQs on Levels of Organization of Life

Question 10. Cells of this tissue are thin-walled, densely packed, capable of undergoing division and are located at the tip of roots. This is

1. Parenchyma
2. Collenchyma
3. Intercalary meristem
4. Apical meristem

Answer: 4. Apical meristem

Question 11. Intercalary meristem remains

1. At the apex of shoots and roots
2. In vascular bundle
3. In between two permanent tissue layers
4. On the surface of the plant body

Answer: 3. In between two permanent tissue layers

Question 12. Rapid elongation of a bamboo stem occurs due to the activity of

1. Lateral meristem
2. Intercalary meristem
3. Apical meristem
4. Cambium

Answer: 2. Intercalary meristem

Question 13. Formation of bark involves

1. Apical meristem
2. Intercalary meristem
3. Vascular cambium
4. Cork cambium

Answer: 4. Cork cambium

Question14. Permanent tissues are composed of

1. Undifferentiated cells
2. Identical cells
3. Growing cells
4. Matured cells

Answer: 4. Matured cells

Question 15. Cells of permanent tissue are

1. Thin-walled and full of cytoplasm
2. Without vacuoles
3. Unable to divide
4. Capable of cell division

Answer: 3. Unable to divide

Practice MCQs for Class 9 Life Science

Question 16. Which simple permanent tissue is composed of non-living cells?

1. Xylem
2. phloem
3. Sclerenchyma
4. Collenchyma

Answer: 3. Sclerenchyma

Question 17. Parenchyma cells containing orgastic materials are called

1. Aerenchyma
2. Parenchyma
3. Idioblasts.
4. Collenchyma

Answer: 3. Idioblasts.

Question 18. The tissue taking part in photosynthesis belongs to

1. Parenchyma
2. Collenchyma
3. Sclerenchyma
4. Meristematic tissue

Answer: 1. Parenchyma

Question 19. Which tissue takes part in storing food in the plant body?

1. Parenchyma
2. Sclerenchyma
3. Phloem
4. Xylem

Answer: 1. Parenchyma

Question 20 Epidermis and ground tissue of a plant body are typically made up of

1. Parenchyma
2. Collenchyma.
3. Sclerenchyma
4. Aerenchyma

Answer: 1. Parenchyma

Question 21 Buoyancy of aquatic plants is maintained by—

1. Parenchyma
2. Collenchyma
3. Sclerenchyma
4. Aerenchyma

Answer: 4. Aerenchyma

Question 22. Ray cells are the kind of—

1. Parenchyma
2. Companion cell
3. Sieve tube
4. Trachea

Answer: 1. Parenchyma

Key Concepts in Chapter 2 for MCQs

Question 23. The flexibility in plants is due to a tissue called—

1. Chlorenchyma
2. Parenchyma
3. Sclerenchyma
4. Collenchyma

Answer: 4. Collenchyma

Question 24. Cells of this tissue have typical angular thickening; this simple permanent tissue is called

1. Parenchyma
2. Collenchyma
3. Sclerenchyma
4. Xylem

Answer: 2. Collenchyma

Question 25. Cells with thick and highly lignified cell wall are seen in

1. Parenchyma
2. Collenchyma
3. Sclerenchyma
4. Aerenchyma

Answer: 3. Sclerenchyma

Question 26. The crispy nature of pears and apples is due to

1. Parenchyma
2. Xylem
3. Sclerenchyma
4. Collenchyma

Answer: 3. Sclerenchyma

Question 27. A stone cell is a modification of

1. Parenchyma
2. Collenchyma
3. Sclerenchyma
4. Aerenchyma

Answer: 3. Sclerenchyma

Question 28. Cells of sclerenchyma tissue have

1. Evenly thick cell wall with a hollow lumen
2. Cell wall with angular thickening and no intercellular space
3. Thin cell-walled living cells
4. Large intercellular spaces

Answer: 1. Evenly thick cell wall with a hollow lumen

Question 29. The husk of the coconut is made up of

1. Collenchyma
2. Sclerenchyma
3. Apical meristem
4. Intercalary meristem

Answer: 2. Sclerenchyma

Question 30. The cells of cork are dead and have a chemical in their walls that makes them impervious to gases and water. The chemical is—

1. Lignin
2. Suberin
3. Cutin
4. Wax

Answer: 1. Lignin

Sample MCQs from WBBSE Class 9 Life Science

Question 31. Which are complex permanent tissues?

1. Parenchyma and collenchyma
2. Collenchyma and sclerenchyma
3. Sclerenchyma and xylem
4. Xylem and phloem

Answer: 4. Xylem and phloem

Question 32. The gymnosperm where the trachea is found, is

1. Pinus sp.
2. Gnetum sp.
3. Cycas sp.
4. Ginkgo sp.

Answer: 2. Gnetum sp.

Question 33. The Tracheae of the xylem are

1. Elongated cells with pointed ends and pits on the cell wall
2. Elongated hollow tubular cells
3. Thin elongated fibre-like cells
4. Elongated living cells

Answer: 2. Elongated hollow tubular cells

Question 34. Strong, tough woods are rich in

1. Xylem parenchyma
2. Trachea
3. Xylem fibre
4. Tracheid

Answer: 3. Xylem fibre

Question 35 The cells involved in water transportation in plants are

1. Tracheids
2. Trachea
3. Xylem fibres
4. Both 1 and 2

Answer: 4. Both 1 and 2

36 Mechanical strength of a plant is provided by-

1. A Sieve tubes 
2. Companion cells
3. Parenchyma
4. Phloem fibres

Answer: 4. Phloem fibres

37 What are the main components of the vascular bundle?

1. Parenchyma
2. Sclerenchyma
3. Xylem
4. Xylem and Phloem

Answer: 4. Xylem and Phloem

 

Chapter 2 Levels Of Organization Of Life Plant Tissue And Its Distribution  Multiple Choice Questions

Question 1. Protection is the main function of

1. Epithelial tissue
2. Muscular tissue
3. Nervous tissue
4. None of these

Answer: 1. Epithelial tissue

Question 2. Histology is the study of—

1. Cells
2. Bones and muscles
3. Blood
4. Tissues

Answer: 4. Tissues

Question 3. Rapid healing of wounds is found in

1. Epithelial tissue
2. Muscular tissue
3. Connective tissue
4. Nervous tissue

Answer: 1. Epithelial tissue

Question 4. The adjacent epithelial cells are held together by means of

1. Microsomes
2. Liposomes
3. Glyoxysomes
4. Desmosomes

Answer: 2. Desmosomes

Question 5. The inner lining of blood vessels are made up of—

1. Muscular tissue
2. Epithelial tissue
3. Connective tissue
4. None of these

Answer: 4. None of these

Question 6. The similarity between areolar and adipose tissue is—

1. Both provide protection
2. Both are connective tissues
3. Both help in the coordination
4. All of these

Answer: 2. Both are connective tissues

Chapter 2 Life Science Quiz Questions

Question 7. The animal tissue which stores fat is—

1. Blood
2. Areolar tissue
3. Muscle tissue
4. Adipose tissue

Answer: 4. Adipose tissue

Question 8 Camel’s hump is made up of—

1. Skeletal tissue
2. Muscular tissue
3. Cartilage
4. Adipose tissue

Answer: 4. Adipose tissue
WB Class 9 Life Science Question Answer

Question 9. Animal body is structurally much more complex compared to that of plants, because

1. Animals can move
2. Animals can feed on others
3. Animals have well-differentiated organs and organ systems
4. Animals can survive in air, earth and water

Answer: 3. Animals have well-differentiated organs and organ systems

Question 10. Embryonic connective tissue is derived from—

1. Ectoderm
2. Endoderm
3. Mesenchyma
4. Mesoglea

Answer: 3. Mesenchyma

Question 11. Which tissue is called the coordinating tissue?

1. Epithelial tissue
2. Muscle tissue
3. Nervous tissue
4. Blood

Answer: 3. Nervous tissue

Question 12. Which of the following is a conducting tissue?

1. Muscle tissue
2. Bone tissue
3. Adipose tissue
4. Blood

Answer: 4. Blood

Question 13. Which of the following tissues has no role in the protection of the animal body?

1. Blood
2. Epithelial tissue
3. Nerve tissue
4. All of these

Answer: 3. Nerve tissue

Question 14. The walls of thick blood vessels are made up of—

1. Epithelial tissue and muscular tissue
2. Nervous tissue and epithelial tissue
3. Only muscular tissue
4. All of these

Answer: 1. Epithelial tissue and muscular tissue

Question 15. Which tissue acts as the shock absorber in our body?

1. Epithelial tissues
2. Bones
3. Muscles
4. Adipose tissues

Answer: 4. Adipose tissues

Question 16. Epithelium of which region is involved in gaseous exchange?

1. Trachea
2. Bronchus
3. Bronchiole
4. Alveolus

Answer: 4. Alveolus

Question 17. The tissue, which does not have direct blood supply is—

1. Epithelial tissue
2. Nervous tissue
3. Muscular tissue
4. All of these

Answer: 1. Epithelial tissue

Question 18. Which tissue takes part in the production of digestive enzymes?

1. Muscle tissue
2. Nervous tissue
3. Squamous epithelium
4. Glandular epithelium

Answer: 4. Glandular epithelium

Question 19. Which of the following tissues may have a ciliated lining?

1. Muscular tissue
2. Epithelial tissue
3. Connective tissue
4. Nervous tissue

Answer: 2. Epithelial tissue

Question 20. Which of the following has the slowest growth rate?

1. Connective tissue
2. Epithelial tissue
3. Nervous tissue
4. None of these

Answer: 3. Nervous tissue

Question 21. Which type of tissue forms glands?

1. Epithelial
2. Muscular
3. Nervous
4. Connective

Answer: 1. Epithelial

Question 22. The inner lining of our mouth is made up of

1. Blood and muscle
2. Epithelial tissue
3. Blood cells
4. All of these

Answer: Epithelial tissue

Question 23. Which part of body’s weight is formed by connective tissue?

1. 40%
2. 30%
3. 20%
4. 60%

Answer: 2. 30%

WB Class 9 Life Science Question Answer

Question 24. The only connective tissue without fibroblasts is

1. Areolar connective tissue
2. Bone
3. Cartilage
4. Blood

Answer: 4. Blood

Question 25. Which of the following cells of connective tissue secret antibodies?

1. Mast cells
2. Reticular cells
3. Adipose cells
4. Plasma cells

Answer: 4. Plasma cells

Question 26. The mast cells secrete the following

1. Heparin
2. Serotonin
3. Histamine
4. All of these

Answer: 4. All of these

Question 27 The liquid connective tissue contains no

1. Fibre
2. Matrix
3. Cell
4. All of these

Answer: 1. Fibre

Question 28 Collagen fibres of connective tissue are

1. White
2. Yellow
3. Colourless
4. Red

Answer: 1. White

Study Tips for Class 9 Life Science MCQs

Question 29. The types of fibres found in connective tissues are

1. White
2. Elastic fibres
3. Reticular fibres
4. All of these

Answer: 4. All of these

Question 30. Collagen is

1. Lipid
2. Carbohydrate
3. Globular protein
4. Fibrous protein

Answer: 4. Fibrous protein

Question 31. The tissue that supplies food to all other tissues of our body is

1. Muscles
2. Nerves
3. Blood
4. All of these

Answer: 2. Nerves

Question 32 Blood is a type of

1. Epithelial tissue
2. Connective tissue
3. Muscular tissue
4. Nervous tissue

Answer: 2. Connective tissue

Question 33 The percentage of plasma in the blood is about

1. 45%
2. 49%
3. 65%
4. 55%

Answer: 4. 55%

Question 34. Mast cells are linked to

1. Neural tissue
2. Areolar connective tissue
3. Endocrine glands
4. Exocrine glands

Answer: 2. Areolar connective tissue

Question 35 Bone is a

1. Specialised connective tissue
2. Weight-carrying tissue
3. Very high-density tissue
4. All of these

Answer: 4. All of these

WB Class 9 Life Science Question Answer

Question 36 Haversian canal is present in

1. Bones
2. Blood vessels
3. Muscles
4. All of these

Answer: 1. Bones

Question 37. The ends of two bones are connected by

1. Muscles
2. Tendons
3. Ligaments
4. Cartilage

Answer: 3. Ligaments

Question 38 Which covers cartilage?

1. Pericardium
2. Perichondrium
3. Perineurium
4. Periosteum

Answer: 2. Perichondrium

Question 39 Cartilage is formed by

1. Osteoblast
2. Fibroblast
3. Chondrocytes
4. Osteocytes

Answer: 3. Chondrocytes

Question 40 Cartilage is present in

1. Teeth
2. Cranium
3. Nail
4. Knee

Answer: 4. Knee

Question 41 Tendons and ligaments are made of

1. Special connective tissue
2. Epithelial tissues
3. Dense regular connective tissue
4. Loose conductive tissue

Answer: 3. Dense regular connective tissue

Question42. A tissue with a higher volume of the intercellular matrix than cells is

1. Epithelial tissue
2. Connective tissue
3. Muscle tissue
4. Nervous tissue

Answer: 2. Connective tissue

Question 43. Movement of different body parts involves

1. Muscular tissue
2. Nerves
3. Both 1 and 2
4. None of these

Answer: 3. Both 1 and 2

Question 44. The contractile protein of muscle is

1. Tubulin
2. Myosin
3. Actin
4. Tropomyosin

Answer: 3. Actin

Question 45. Actin and myosin are components of

1. Nerve
2. Blood
3. Muscle
4. Bone

Answer: 3. Muscle

Question 46. Contractile proteins are seen in

1. Only in muscle tissues
2. Only in connective tissues
3. All connective tissues and muscle tissues
4. Only in epithelial tissues

Answer: 1. Only in muscle tissues

Question 47. Smooth muscles are

1. Involuntary
2. Voluntary
3. Striated
4. None of the above

Answer: 1. Involuntary

Question 48. Involuntary muscles are seen in

1. Stomach
2. Urinary bladder
3. Walls of blood vessels
4. All of these

Answer: 4. All of these

WB Class 9 Life Science Question Answer

Question 49. Involuntary striated muscles are found in the walls of

1. Lungs
2. Heart
3. Kidney
4. Blood vessels

Answer: 2. Heart

Question 50. Cardiac muscle is

1. Smooth
2. striated
3. Involuntary
4. Both 2 and 3

Answer: 4. Both 2 and 3

Question 51. Intercalated discs are found in

1. Skeletal muscle
2. Smooth muscle
3. Both 1 and 2
4. Cardiac muscle

Answer: 4. Cardiac muscle

Question 52. The cytoplasm of muscle cells is called

1. Sarcomere
2. Sarcoplasm
3. Neuroplasm
4. Neuroglia

Answer: 2. Sarcoplasm

Question 53. Sarcolemma is the

1. The cell membrane of nerve cells
2. The cytoplasm of muscle cells
3. The cell membrane of muscle cells
4. The cytoplasm of nerve cells

Answer: 3. The cell membrane of muscle cells

Question 54. Our body movement is controlled by

1. Cardiac muscles.
2. Involuntary muscles
3. Voluntary muscles
4. All of these

Answer: 3. Voluntary muscles

Question 55. Which of the following tissues show contraction and expansion from the start to the end of our life?

1. Involuntary muscles
2. Voluntary muscles
3. Cardiac muscles
4. Neurons

Answer: 3. Cardiac muscles

Question 56. Neurones are held or surrounded by

1. Acellular matrix
2. Basement membrane
3. Plasma
4. Neuroglia

Answer: 4. Neuroglia

Question 57. The cytoplasm inside the axon is called

1. Sarcoplasm
2. Axoplasm
3. Toxoplasma
4. None of these

Answer: 2. Axoplasm

Question 58. Voluntary movement of our limbs involves

1. Only muscles
2. Muscles and bones only
3. Bones and nerves only
4. Muscles, bones and nerves

Answer: 4. Muscles, bones and nerves

WB Class 9 Life Science Question Answer

Question 59. Nucleated cells found in neurilemma are

1. Nissl granules
2. Plasma cells
3. Cell body
4. Schwann cells

Answer: 4. Schwann cells

Question 60. Cells with many projections is the common feature of

1. Neurones
2. Muscle cells
3. Epithelial cells
4. Blood cells

Answer: 1. Neurones

Question 61. Receiving external stimuli is the function of

1. Nerves
2. Muscles
3. Epithelium
4. None of these

Answer: 1. Nerves

Question 62. Which of the following is part of a nerve cell?

1. Sarcolemma
2. Node of Ranvier
3. Myofibrils
4. Myofilaments

Answer: 2. Node of Ranvier

Question 63. Axon and Dendron are involved in

1. Muscle contraction
2. Neural transport
3. Nutrient transport
4. Both 1 and 2

Answer: 2. Neural transport

Question 64. Syncytial cells are typically seen in

1. Voluntary muscle fibres
2. Involuntary muscle fibres
3. Cardiac muscle fibres
4. Neurones

Answer: 1. Voluntary muscle fibres

Question 65 Schwann cell is related to

1. Axon
2. Dendron
3. Cell body
4. Muscle

Answer: 1. Axon

WB Class 9 Life Science Question Answer

Question 66 Is End brush is related to

1. Axon
2. Dendron
3. Cell body
4. None of these

Answer: 1. Axon

Question 67 A syncytial tissue is

1. Cartilage
2. Epithelium
3. Cardiac muscle
4. Skeletal muscle

Answer: 2. Epithelium

Question 68 White fibre is found in

1. Skin
2. Bones
3. Collagen
4. Muscles

Answer: 1. Skin

Chapter 2 Levels Of Organization Of Life Organic And Inorganic Molecules Summary Multiple Choice Questions

Question 1. The most abundant element within a living body is

1. Carbon, water, and oxygen
2. Carbon and nitrogen
3. Water.
4. Oxygen, hydrogen, carbon, and nitrogen

Answer: 4. Oxygen, hydrogen, carbon, and nitrogen

Question 2. In plants, the medium of transport is

1. Water
2. Phloem
3. Xylem
4. Both A and B

Answer: 1. Water

Question 3. HCI in the stomach helps in the digestion of

1. Protein
2. Lactose
3. Maltose
4. Fructose

Answer: 1. Lactose

Question 4. Acidic chyme in the stomach is neutralized by

1. Bile salt
2. Sodium bicarbonate
3. NaOH
4. KOH

Answer: 2. Sodium bicarbonate

WBBSE Class 9 Organic and Inorganic Molecules MCQs

Question 5. Which of the following is not a strong acid?

1. HNO₃
2. HCI
3. H₂CO₃
4. H₂SO₄

Answer: 3. H₂CO₃

WBBSE Class 9 Life Science Question And Answer

Question 6. An example of weak alkali is

1. NH₄OH
2. NaOH
3. KOH
4. None of these

Answer: 1. NH₄OH

Question 7. The percentage of mineral salts present in cellular components is

1. 10-30%
2. 1-3%
3. 0.1-0.3%
4. 0.01-0.03%

Answer: 2. 1-3%

Question 8. A biomacromolecule is

1. Glucose
2. Peptide
3. Lipid
4. Protein

Answer: 1. Glucose

Important MCQs on Organic Molecules for Class 9

Question 9. Which one is an organic acid?

1. h₂so₄
2. hno₃
3. HCI
4. Maleic acid

Answer: 4. Maleic acid

Question 10. Which of the following is not an organic macromolecule?

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

Answer: 3. Nucleotide

WBBSE Class 9 Life Science Question And Answer

Question 11. The main energy-generating biomolecule is

1. Protein
2. Carbohydrate
3. Fat
4. Vitamin

Answer: 2. Carbohydrate

Question 12. In which of the following biomolecules do carbon, hydrogen, and oxygen maintain a ratio of 1:2:1?

1. Nucleotide
2. Protein
3. Fatty acid
4. Carbohydrate

Answer: 4. Carbohydrate

Question 13. The simple structural formula of carbohydrates is

1. c_n(H₂O)_n-1
2. (C₆H₁₀O₅)_n
3. (CH₂0)_n
4. R-COOH

Answer: 3. (C₆H₁₀O₅)_n

Inorganic Molecules MCQs for Class 9 Life Science

Question 14. The simplest form of sugar is

1. Glucose
2. Sucrose
3. Cellulose
4. Lactose

Answer: 1. Glucose

Question 15. Which of the following is not a hexose sugar?

1. Glucose
2. Galactose
3. Ribose
4. Fructose

Answer: 3. Ribose

Question 16. Which of the following carbohydrates is not a keto sugar?

1. Erythrose
2. Fructose
3. Xylulose
4. Ribulose

Answer: 1. Erythrose

Question 17. The main sugar present in honey is

1. Glucose
2. Fructose
3. Sucrose
4. Maltose

Answer: 2. Fructose

Question 18. The sugar present in sugarcane juice is

1. Fructose
2. Glucose
3. Maltose
4. Sucrose

Answer: 2. Sucrose

Question 19. Commonly used table sugar is

1. Maltose
2. Lactose
3. Sucrose
4. Glucose

Answer: 3. Sucrose

Question 20. The sugar present in the ONA molecule is composed of

1. 6-Carbon
2. 5-Carbon
3. 4-Carbon
4. 1-Carbon

Answer: 2. 5-Carbon

Practice MCQs for Class 9 Life Science Chapter 2

Question 21. Besides the amino group, the other functional group present in an amino acid is

1. Hydroxyl group
2. Carboxyl group
3. Aldehyde group
4. Ketone group

Answer: 2. Carboxyl group

Question 22. The number of amino acids taking part in protein synthesis is

1. 10
2. 20
3. 30
4. 40

Answer: 2. 20

Question 23. An essential amino acid is

1. Valine
2. Glutamic acid
3. Argentine
4. Glycine

Answer: 1. Valine.

Question 24. The simple structural formula of an amino acid is

1. R-CHNH₂COOH
2. NH₂-R = CO
3. R-COOK
4. R-NH₂

Answer: 1. R-CHNH₂COOH

Question 25. A sulfur-containing amino acid is

1. Serine
2. Valine
3. Methionine
4. Isoleucine

Answer: 2. Methionine

Question 26. A hydrophobic amino acid is

1. Leucine
2. Tyrosine
3. Histidine
4. Serine

Answer: 1. Leucine

Question 27. The two functional groups present in amino acids are

1. Amin and Ketone
2. Amino and Carboxyl
3. Amino and Aldehyde
4. Amino and Hydroxyl

Answer: 2. Amino and Carboxyl

West Bengal Board Class 9 Life Science Book Solution

Question 28. The important structural element of amino acids is

1. N
2. O
3. H
4. Na

Answer: 1. N

Question 29. Each fatty acid has a hydrocarbon chain ending with

1. Hydroxyl group
2. Aldehyde group
3. Ketone group
4. Carboxyl group

Answer: 4. Carboxyl group

Question 30. Carboxyl group An essential fatty acid is

1. Stearic acid
2. Oleic acid
3. Linolenic acid
4. All of these

Answer: 3. Linolenic acid

Key Concepts for MCQs on Organic and Inorganic Molecules

Question 31. A chromosome is a

1. Combination of many nucleotides
2. Nucleoprotein substance
3. Combination of many proteins
4. Combination of proteins and lipids

Answer: 1. Combination of many nucleotides

Question 32. Which of the following share the same class with glucose, sucrose, and maltose?

1. Myoglobin
2. Amino acid
3. Starch
4. Haemoglobin

Answer: 3. Starch

Question 33. Glycogen and starch are

1. Monosaccharides
2. Disaccharides
3. Oligosaccharides
4. Polysaccharides

Answer: 4. Polysaccharides

Question 34. A starch molecule is formed by combining

1. Glucose
2. Maltose
3. Galactose
4. Lactose

Answer: 1. Glucose

West Bengal Board Class 9 Life Science Book Solution

Question 35. The monosaccharide present in glycogen is

1. Fructose
2. Cellulose
3. Glucose
4. Galactose

Answer: 3. Glucose

Question 36. In which organ is glucose stored as glycogen?

1. Pancreas
2. Liver
3. Spleen
4. Kidney

Answer: 2. Liver

Question 37. Which of the following carbohydrates can be not digested in the human intestine?

1. Glycogen
2. Cellulose
3. Maltose
4. Inulin

Answer: 2. Cellulose

Question 38. The walls of the xylem become rigid due to the presence of

1. Glycogen
2. Chitin
3. Cellulose
4. Lignin

Answer: 4. Lignin

Sample MCQs from WBBSE Class 9 Life Science

Question 39. The main component of plant cell wall is—

1. Cellulose
2. Glycogen
3. Glucose
4. Lipid and protein

Answer: 1. Cellulose

Question 40. The main component of fungal cell wall is—

1. Inulin
2. Chitin
3. Cellulose
4. Pectin

Answer: 2. Chitin

Question 41. Which of the following is known as animal starch?

1. Glucose
2. Cellulose
3. Inulin
4. Glycogen

Answer: 4. Glycogen

Question 42. The structural component of a simple protein molecule is—

1. Peptide
2. Peptone
3. Amino acid
4. Nucleic acid

Answer: 1. Peptide

Question 43. Which of the following compounds is essentially a protein structure?

1. Hormone
2. Enzyme
3. Co-enzyme
4. Prostaglandin

Answer: 2. Enzyme

Question 44. The two radicals present in protein molecules are—

1. Amino and ketone
2. Amino and carboxyl
3. Carboxyl and aldehyde
4. Aldehyde and ketone

Answer: 2. Amino and carboxyl

West Bengal Board Class 9 Life Science Book Solution

Question 45. Which of the following is a simple protein?

1. Haemoglobin
2. Nucleoprotein
3. Glycoprotein
4. Globulin

Answer: 4. Globulin

Question 46. The bond present in protein molecules is—

1. Covalent bond
2. Peptide bond
3. Electrovalent bond
4. Glycosidic bond

Answer: 2. Peptide bond

Question 47. Which of the following is produced after the hydrolysis of a polypeptide?

1. Fatty acid
2. Amino acid
3. Lactic acid
4. Nucleic acid

Answer: 2. Amino acid

Question 48. Which is not a conjugated protein?

1. Proteose
2. Nucleoprotein
3. Metalloprotein
4. Glycoprotein

Answer: 1. Proteose

Question 49. Haemoglobin is a—

1. Simple protein
2. Conjugated protein
3. Derived protein
4. Colloidal protein

Answer: 2. Conjugated protein

Question 50. The protein component of a hemoglobin molecule is

1. Haem
2. Globin
3. Both
4. None of these

Answer: 2. Globin

Question 51. The non-protein component of a hemoglobin molecule is

1. Magnesium
2. Calcium
3. Copper
4. Iron

Answer: 4. Iron

Question 52. Which of the following is not a fibrous protein?

1. Haemoglobin
2. Elastin
3. Keratin
4. Elastin

Answer: 2. Elastin

Question 53. Which has a close association with fibrous protein?

1. Centrosome
2. Golgi body
3. Endoplasmic reticulum
4. Mitochondria

Answer: 1. Centrosome

West Bengal Board Class 9 Life Science Book Solution

Question 54. Which is a chromoprotein?

1. Gleadin
2. Keratin
3. Haemoglobin
4. Elastin

Answer: 3. Haemoglobin

Question 55 An example of contractile protein is

1. Keratin
2. Collagen
3. Haemoglobin
4. Myosin

Answer: 4. Myosin

Question 56. One useful lipoprotein for humans is

1. LDL
2. HDL
3. VLDL
4. DL

Answer: 2. HDL

Question 57. Which of the following is a derived protein?

1. Haemoglobin
2. Albumin
3. Globulin
4. Peptone

Answer: 1. Haemoglobin

Question 58. The cell membrane is composed of

1. Proteins and lipids
2. Proteins and polysaccharides
3. Proteins, lipids, and carbohydrates
4. All of these

Answer: 1. Proteins and lipids

Question 59. Lipid is an

1. Acidic compound
2. Alcoholic compound
3. Ester
4. Aldehyde

Answer: 3. Ester

Question 60. The simple structural formula of lipids is

1. C-ROOH
2. R-CHO
3. R-COOH
4. R=CO

Answer: 3. R-COOH

Question 61. An essential component of lipids is—

1. Nucleic acid
2. Malic acid
3. Fatty acid
4. Amino acid

Answer: 3. Fatty acid

Question 62. The functional bond that helps to form a lipid molecule is—

1. Ester bond
2. Hydrogen bond
3. Peptide bond
4. Sulfide bond

Answer: 1. Ester bond

Question 63. The highest calorific value is seen in which of the following four nutrients?

1. Protein
2. Carbohydrate
3. Fat
4. Vitamin

Answer: 3. Fat

Chapter 2 Life Science Quiz Questions

Question 64. Wax is a type of—

1. Carbohydrates
2. Glycoproteins
3. Lipids
4. Lipoproteins

Answer: 2. Glycoproteins

Question 65. During hibernation, energy is supplied to the organism by—

1. Carbohydrate
2. Protein
3. Vitamin
4. Fat

Answer: 4. Fat

Question 66. DNA is a

1. Single-stranded chain of nucleotides
2. Double-stranded chain of polypeptides
3. Double-stranded chain of nucleotides
4. Double-stranded chain of amino acids

Answer: 3. Double-stranded chain of nucleotides

Question 67. In a DNA molecule, hydrogen bonding occurs between—

1. Adenine and guanine
2. Thymine and cytosine
3. Adenine and cytosine
4. Guanine and cytosine

Answer: 4. Guanine and cytosine

West Bengal Board Class 9 Life Science Book Solution

Question 68. The sugar present in DNA is—

1. Triose
2. Pentose
3. Hexose
4. Heptose

Answer: 2. Pentose

Question 69. Nitrogenous bases, present in both DNA and RNA, are—

1. Adenine, guanine, cytosine
2. Adenine, guanine, thymine
3. Adenine, thymine, uracil
4. Adenine, guanine, uracil

Answer: 1. Adenine, guanine, cytosine

Question 70. Which of the following carbohydrates is present in RNA?

1. Ribulose
2. Deoxyribose
3. Ribose
4. None of these

Answer: 3. Ribose

Chapter 2 Levels Of Organization Of Life Organic And Inorganic Molecules

Multiple Choice Questions

Question 1. Which of the following combinations of vitamins are fat soluble?

1. Vit. A Vit. B and Vit. K
2. D Vit. A Vit. B and Vit. C
3. Vit. A Vit. D and Vit. E
4. Vit. B, Vit. C and Vit. P

Answer: 3. Vit. A Vit. D and Vit. E

Question 2. Which combination includes all macroelements?

1. Calcium, magnesium, and boron
2. Sodium, potassium, and iodine
3. Sodium, molybdenum, and iron
4. Potassium, calcium, and phosphorus

Answer: 4. Potassium, calcium, and phosphorus

Question 3. A vitamin related to blood coagulation is

1. Vit. A
2. Vit. E
3. Vit. D
4. Vit. K

Answer: 4. Vit. K

Question 4.  Which combination of vitamins and minerals is related to the formation of bones and teeth?

1. Vit. A and phosphorus
2. Vit. D and calcium
3. Vit. C and calcium
4. Vit. D and sodium

Answer: 2. Vit. D and calcium

Question 5. To get vitamin K, you will have to eat

1. Guava
2. Lettuce
3. Butter
4. Tomato

Answer: 2. Lettuce

Question 6. Pellagra is caused due to the deficiency of

1. Vit. B₆
2. Vit. B₅
3. Vit. B₃
4. Vit. B₁₂

Answer: 2. Vit. B₅

Question 7. Pernicious anemia occurs due to a deficiency of

1. Vit. B₆
2. Vit. B₅
3. Vit. B₃
4. Vit. B₁₂

Answer: 4. Vit. B₁₂

Question 8. Chlorosis in plants can be seen in the deficiency of

1. Calcium
2. Magnesium
3. Oxygen
4. Sodium

Answer: 2. Magnesium

Question 9. Name the vitamin that helps in developing immunity against common cough and cold.

1. Retinol
2. Pantothenic acid
3. Ascorbic acid
4. Calciferol

Answer: 3. Ascorbic acid

Question 10. Which of the following food items should one take to prevent xerophthalmia?

1. Papaya
2. Pulses
3. Carrot
4. Beans

Answer: 3. Carrot

Question 11. Which vitamin can reduce the chance of fetal death?

1. Vit. B₁₂
2. Vit. E
3. Vit. K
4. Vit. B₆

Answer: 2. Vit. E

Question 12. Which combination of elements is widely used in making fertilizers?

1. N, C, H
2. N, P, K
3. N, Fe, Mg
4. Mn, K, C

Answer: 2. N, P, K

Question 13. A microelement helping in the fixation and assimilation of nitrogen

1. Molybdenum
2. Magnesium
3. Manganese
4. Potassium

Answer: 1. Molybdenum

Question 14. The disease caused by a deficiency of iodine is

1. Night blindness
2. Beriberi
3. Goitre
4. Anaemia

Answer: 3. Goitre

Question 15. The provitamin of vitamin A is

1. Beta carotene
2. Retinol
3. Calciferol
4. Pyrithiamine

Answer: 1. Beta carotene

Study Tips for Class 9 Organic and Inorganic Molecules MCQs

Question 16. The contraction of muscles is controlled by

1. Magnesium
2. Calcium
3. Phosphorus
4. Iron

Answer: 2. Calcium

Question 17. Which of the following vitamins is insoluble in fat?

1. Vitamin A
2. Vitamin C
3. Vitamin D
4. Vitamin K

Answer: 2. Vitamin C

Question 18. Which of the following vitamins is insoluble in water?

1. Vitamin C
2. Vitamin P
3. Vitamin M
4. Vitamin E

Answer: 4. Vitamin E

Question 19. A water-soluble vitamin is

1. Vitamin A
2. Vitamin C
3. Vitamin D
4. Vitamin E

Answer: 2. Vitamin C

Question 20. The biomolecule that prevents the action of vitamins is called

1. Pseudo vitamin
2. Antivitamin
3. Provitamin
4. All of these

Answer: 2. Antivitamin

Question 21. Which of the following is an antivitamin?

1. Galactoflavin
2. Riboflavin
3. Thiamin
4. Cyanocobalamin

Answer: 1. Galactoflavin

Question 22. Vitamin A is produced in the liver from

1. Ergosterol
2. Avidin
3. Carotene
4. Citral

Answer: 3. Carotene

Question 23. 95% of vitamin A, absorbed in the human body is stored in

1. Kidney
2. Lungs
3. Liver
4. Stomach

Answer: 3. Liver

Question 24. The disease caused due to deficiency of vitamin A is

1. Sterility
2. Osteomalacia
3. Rickets
4. Night blindness

Answer: 4. Night blindness

Question 25.  Xerophthalmia occurs due to a deficiency of vitamin

1. C
2. A
3. E
4. K

Answer: 2. A

Question 26. Osteomalacia is caused due to deficiency of

1. Vitamin C
2. Vitamin A
3. Vitamin D
4. Vitamin K

Answer: 3. Vitamin D

Question 27. Deficiency of which vitamin in children does result in rickets?

1. Vit. D
2. Vit. A
3. Vit. C
4. Vit. K

Answer: 1. Vit. D

Question 28. Tetany occurs due to a deficiency of

1. Vitamin C
2. Vitamin D
3. Vitamin E
4. Vitamin K

Answer: 2. Vitamin D

Question 29. The vitamin that is known as anti sterility factor is

1. Calciferol
2. Phylloquinone
3. Tocopherol
4. Retinol

Answer: 2. Tocopherol

Question 30. Which of the following vitamins is known as the ‘Antihaemorrhagic factor’?

1. Vit. K
2. Vit B₅
3. Vit. D
4. Vit. C

Answer: 1. Vit B₅

Question 31. Which vitamin does help in blood clotting?

1. Vit. A
2. Vit. D
3. Vit. E
4. Vit. K

Answer: 4. Vit. K

Question 32. Which vitamin does help in maintaining normal prothrombin levels in blood?

1. Vit. K
2. Vit. B
3. Vit. B₅
4. Vit. C

Answer: 1. Vit. K

Question 33. Deficiency of which vitamin does result in pernicious anemia?

1. Vit. B₂
2. Vit. B₅
3. Vit. B₁₂
4. Vit. B₆

Answer: 3. Vit. B₁₂

Question 34. PP factor is

1. Vit. A
2. Vit. B₁₂
3. Vit. D
4. Vit. B₃

Answer: 4. Vit. B₃

Question 35. Megaloblastic anemia occurs deficiency of

1. Pyridoxine
2. Folic acid
3. Niacin
4. Biotin

Answer: 2. Folic acid

Question 36. Deficiency of which vitamin does cause beriberi?

1. Vit. B₁
2. Vit B₂
3. Vit B₅
4. Vit. B₁₂

Answer: 1. Vit. B₁

Question 37. The chemical name of vitamin B₁ is

1. Niacin
2. Thiamin
3. Pyridoxine
4. Riboflavin

Answer: 2. Thiamin

Question 38. The chemical name of vitamin C is

1. Tocopherol
2. Ascorbic acid
3. Retinol
4. Thiamine

Answer: 2. Ascorbic acid

Question 39. The disease that is caused due to deficiency of vitamin C is

1. Rickets.
2. Osteomalacia
3. Scurvy
4. Beriberi

Answer: 3. Scurvy

Question 40. Biotin was previously known as

1. Vitamin G
2. Vitamin H
3. Vitamin M
4. Vitamin K

Answer: 2. Vitamin H

Question 41. Which of the following sets of vitamins are antioxidants?

1. B₁,B₆, B₁₂
2. A, E, C
3. D, K, B₂ 
4. B_1, B₅, B₆

Answer: 2. A, E, C

Question 42. One macro-element for the human body is

1. Zn
2. Cu
3. Ca
4. Cr

Answer: 3. Ca

Question 43. Which one of the following is a microelement?

1. N
2. P
3. K
4. Mo

Answer:

4. Mo

Question 44. Which one is required for blood coagulation?

1. P
2. K
3. Na
4. Ca

Answer: 4. Ca

Question 45. The disease caused in animals due to deficiency of iodine is

1. Night blindness
2. Beriberi
3. Goiter
4. Anaemia.

Answer: 3. Goiter

Question 46. Helps in the synthesis of thyroxine

1. Ca
2. K
3. P
4. I

Answer: 4. 1

Question 47. Which mineral helps in hemoglobin?

1. Calcium
2. Potassium
3. Magnesium
4. Iron

Answer: 4. Iron

Question 48. Deficiency of which mineral element does result in anemia?

1. Magnesium
2. Iron
3. Calcium
4. Phosphorus

Answer: 2. Iron

Question 49. Which mineral does help in the transmission of nerve impulses and contraction of heart muscles?

1. Sodium
2. Iron
3. Copper
4. Iodine

Answer: 1. Sodium

 

Chapter 2 Levels Of Organization Of Life Organic And Inorganic Molecules Short Answer Type Questions

Question 1. What are vitamins?

Answer:

Vitamins:-

Vitamins are special components of food that are present in very little quantities, but they perform an elementary role in various physiological activities and in the development of immunity against different diseases.

Examples: Vit. A Vit. B, Vit. C, Vit. D, Vit. K, etc.

Question 2. What is meant by antivitamin? Give an example.

Answer:

Antivitamin:-

Certain organic compounds hinder the functions of some vitamins or denature some vitamins completely. These compounds are known as antivitamins.

Example: Galactoflavin is an antivitamin, which hinders the action of vitamin B₁₂ or riboflavin.

Question 3. What is a pseudovitamin? Give an example.

Answer:

Pseudovitamin:-

A pseudovitamin is a substance that has a chemical structure similar to that of a vitamin but lacks the usual physiological effects of a vitamin. Example—Methylcobalamin is the pseudovitamin of vitamin B₁₂.

WBBSE Class 9 Organic and Inorganic Molecules Short Answer Questions

Question 4. What is a Provitamin?

Answer:

Provitamin:-

The organic compound from which a vitamin is synthesized in the body of a living organism is called a provitamin.

Example: Vitamin A is synthesized in the liver from the liver from provitamin β-carotene.

Question 5. Mention the functions of vitamin A in the human body.

Answer:

The functions of vitamin A in the human body are as follows:

1. Vitamin A helps to maintain the health of the eye, tear gland, and retina.

2. It helps in maintaining healthy skin and muscle.

Key Short Answer Questions on Organic Molecules

Question 6. Why vitamin A is called antixerophthalmic vitamin?

Answer:

Xerophthalmia is defined as the condition characterized by excessive and abnormal dryness of the eyeball, accompanied by conjunctivitis. This occurs basically due to the deficiency of vitamin A. Since vitamin A prevents Xerophthalmia, therefore it is called an antixerophthalmic vitamin.

Question 7. Mention the functions of vitamin D in the human body. Mention its sources.

Answer:

Functions of Vit.D:

1. Vitamin D helps in the uptake of phosphorus and calcium from the intestine.

2. It helps in the formation of teeth and bones.

Sources of Vit.D:

The sources of vitamin D are milk, cabbage, vegetable oil, cod liver oil, etc.

 

Question 8.  why vitamin D is called antirachitic vitamin?

Answer:

Ricket is a disease caused by vitamin D deficiency. Since vitamin D helps in the prevention of the disease, therefore it is called antiricketic vitamin.

Question 9.  Which vitamin is called anti sterility vitamin? Mention the main functions of this vitamin.

Answer:

Antisterility vitamin:

Vitamin E is called anti sterility vitamin.

Functions of vitamin E:

1. Vitamin E helps in the development of the embryo, reproductive organs, and muscles.

2. It helps to inhibit unwanted oxidation in the body by substances called free radicals.

Inorganic Molecules Short Answer Questions for Class 9

Question 10. Which vitamin is called antihaemorrhagic vitamin? Mention the functions of this vitamin.

Answer:

Antihaemorrhagic vitamin:

Vitamin K is called the antihaemorrhagic vitamin.

Functions of vitamin K:

1. Vitamin K helps in prothrombin formation and blood coagulation.

2. It helps in the generation of energy in mitochondria.

Question 11. Which vitamin is called antiscorbutic vitamin? Mention the functions of this vitamin.

Answer:

Antiscorbutic vitamin:

Vitamin C is called antiscorbutic vitamin since it helps in preventing the disease scurvy.

The function of vitamin C:

1. It protects the body against some infections like common cough and cold.

2. It helps to keep bones and cartilage healthy.

3. It catalyzes the metabolism of carbohydrates.

Question 12.  Mention the functions of Vitamin B₃.

Answer:

The functions of vitamin B₃ are as follows:

1. It catalyzes the transformation of carbohydrates to lipids.

2. It helps to stimulate the central nervous system.

3. It helps in cellular respiration and metabolism.

WBBSE Class Nine Life Science

Question 13. Which two vitamins help in cellular respiration? What is the similarity between iron and vitamin B₁₂?

Answer:

Vitamin B₁ and B₂ help in cellular respiration.

Both iron and vitamin B₁₂ help in the formation of red blood cells.

Question 14. Mention one function of chlorine. Write a function of manganese.

Answer:

The function of chlorine:

Chlorine helps to maintain the acid-base balance in the body.

The function of manganese:

Manganese regulates the normal level of carbohydrates in the blood.

Practice Short Answer Questions for Life Science Chapter 2

Question 15. How do minerals control membrane permeability?

Answer:

Potassium (K) increases the membrane permeability of living cells whereas calcium (Ca) restricts it. Thus, mineral elements play an important role in controlling membrane permeability in the body.

Question 16. Mention some plant and animal sources of | food that are rich in magnesium.

Answer:

Plant sources of magnesium:

The plant sources of magnesium are green vegetables, grains, groundnut, bean, soybean, peas, etc.

Animal sources of magnesium:

The animal sources of magnesium are fish, chicken, egg, milk, etc.

 

Question 17. Mention some plant and animal sources of food that are rich in iron.

Answer:

Plant sources of iron:

The plant sources of iron are pulses, whole-wheat flour, spinach, lettuce, banana, etc.

Animal sources of iron:

The animal sources of iron are fish, eggs, mutton, liver, etc.

 

WBBSE Class Nine Life Science

Question 18. Which elements and vitamins help in the formation of our skeletal structure?

Answer:

Calcium (Ca) and phosphorus (P) are the main building components of bones and teeth. Similarly, vitamin D and vitamin C are the vitamins which also help in the formation o tee and bones. Thus, these elements and vitamins take part in the formation of the skeletal structure of the human body.

Question 19. Mention two animal sources and a plant source of calcium.

Answer:

Two animal sources of calcium are fish and egg and a plant source of calcium is pea.

Important Concepts for Short Answers on Organic and Inorganic Molecules

Question 20. What is the function of sodium in the human body?

Answer:

The functions of sodium in the human body are as follows:

1. It helps to maintain the cardiac cycle, blood pressure, blood volume, and acid-base balance.

2. It helps in the conduction of nerve impulses.

3. It also helps to maintain the density of urine.

Question 21. Mention a plant source and an animal source of sodium.

Answer:

A plant source of sodium is vegetables and an animal source of sodium is butter.

 

Question 22. Which diseases are caused due to deficiency of vitamins A, G, D, and B₁₂?

Answer:

Deficiency of Vitamin A – Xerophthalmia.

Deficiency of Vitamin C – Scurvy.

Deficiency of Vitamin D – Rickets.

Deficiency of Vitamin B₁₂ – Pernicious anemia

Question 23. Mention deficiency diseases of one water soluble and one fat soluble vitamins.

Answer:

Vitamin C is a water-soluble vitamin. Its deficiency causes scurvy.

Vitamin D is a fat soluble vitamin. Deficiency of this vitamin causes rickets in children.

Question 24 Name the vitamins, which act as antioxidants.  Mention the significance of antioxidants.

Answer:

Vitamins acting as antioxidants:

Vitamins A, C, E, and P act as antioxidants.

Significance of antioxidants: Free radicals induce cell aging. Antioxidants destroy free radicals and thus help to keep our bodies fit.

Sample Short Answer Questions from WBBSE Class 9 Life Science

Question 25 Mention the functions of the vitamin B complex. 

Answer:

The functions of the vitamin B complex are:

1. Vitamins B and B help in amino acid metabolism.

2. Vitamin B₂ helps in the activation of other vitamins.

3. Vitamin B₃ and B₅ take part in the formation of NADP and Coenzyme A respectively, which take part in different metabolic reactions.

4. Vitamin B₆, B₇, and B₁₂ take part in fat metabolism.

5. Vitamin B₉, and B₁₂ help in DNA synthesis.

Question 26 What happens in case of folic acid deficiency?

Answer:

In the case of folic acid deficiency, the following anemia Megaloblastic occurs-

1. and Leucopoenia.

2. Weakening of muscles.

3. Loss of weight and disruption of mental stability.

Question 27 What is meant by macronutrients?

Answer:

The elements, which are essentially required in larger quantities to maintain normal growth and nutrition and deficiency which are distinctly noticeable in our body, are called macronutrients. Example-Calcium, phosphorus, etc.

Question 28 Name the macronutrients, required for the human body.

Answer:

Following are the macronutrients required for the human body-Calcium, phosphorus, magnesium, sodium, potassium, etc.

Question 29 What is meant by micronutrients?

Answer:

The elements which are required in little quantities for normal growth and nutrition and deficiency of which are not distinctly noticeable in our body, are called micronutrients. Example-Molybdenum, boron, etc.

Question 30. Name some micronutrients required for the human body.

Answer:

Following are some of the micronutrients required for the human body-Iron, copper, boron, zinc, iodine, etc.

Question 31. Mention two important roles of magnesium. 

Answer:

Two important roles of magnesium are:

1. It takes part in the formation of bones and teeth.

2. It controls muscle contraction and the function of the nervous system.

Study Guide for Class 9 Life Science Short Answer Questions

Question 32 Mention the importance of potassium. 

Answer:

The importance of potassium is:

1. It regulates heart rate and muscle contraction.

2. It directly takes part in neural transmission and guides different cellular reactions.

Question 33 Mention the relation between calcium and he relation betwee vitamin D.

Answer:

Vitamin D helps in calcium absorption in the body. In the absence of this vitamin, calcium uptake in bones and teeth is hindered. Thus vitamin D helps in adding calcium to bones and teeth.

Question 34 What will happen, if the level of sodium drops in the blood?

Answer:

In case of deficiency of sodium in the blood, hyponatremia may occur. In this situation, there will be a severe scarcity of water in the body followed by a sharp decline in blood pressure.

Understanding Organic vs Inorganic Molecules for SAQs

Question 35. What is the importance of iodine in human nutrition?

Answer:

Similar question:

Mention one importance of iodine. Iodine is an essential component of thyroxine hormone. This hormone plays a very important role in controlling the metabolic rate of our body. Deficiency of this hormone causes goiter. Thus, iodine is one of the most important micro-elements needed for nutrition in humans.

Question 36. How does the increased level of fluorine in drinking water cause harm to the human body?

Answer: 

Increased levels of fluorine in drinking water may cause damage to teeth and bones. The enamel of the teeth becomes weak and turns brownish in colour. It also results in the formation of a cavity leading to a condition called dental fluorosis.

Apart from this, fluorine forms a cementing layer on the spine and bones of the legs, resulting in the loss of their natural flexibility. In addition to this, high fluoride ingestion can also cause a range of gastrointestinal symptoms like nausea, pain, and vomiting.

Moreover, excess fluoride level in the body results in polyuria (frequent urination), polydipsia (excessive thirst), and constipation followed by diarrhea.

 

 

Chapter 2 Levels Of Organization Of Life Organic And Inorganic Molecules Summary Long Answer Type Questions

Question 1. Schematically represent the list of molecules, which are important for life.

Answer:

Important molecules of life

WBBSE Class 9 Life Science Solutions

Question 2. Briefly describe the roles of water in living organisms. Mention the importance of different gases and salts in living organisms.

Answer:

Roles of water in living organisms:

1. The body of a living organism consists of 70-90% water.

2. Water acts as the medium of all cellular reactions within protoplasm.

3. In plants, water helps in many physiological processes, like photosynthesis, the ascent of sap, germination of seeds, and transpiration. 

4. In animals, water is the major component of body fluid.

It maintains salt and water balance and helps in the processes of digestion, excretion, etc.

5. In starfish sea urchins and other echinoderms, water helps in locomotion also.

Read and Learn More Class 9 Life Science Long Answer Questions

WBBSE Class 9 Organic and Inorganic Molecules Long Answer Questions

Importance of different gases in living organisms

Oxygen and carbon dioxide are the two most biologically important gases. 

Their importance is as follows-

1. Oxygen is essential for respiration in all aerobic organisms. It helps to oxidize food and liberate energy. 

2. Carbon, which is the raw material of photosynthesis, is obtained by autotrophs in the form of carbon dioxide.

Importance of salts in living organisms:

1. Salts maintain osmoregulation in the body of living organisms.

2. Salts control the production of thyroid hormones. 

3. Salts help to form the structure of bones.

Key Long Answer Questions on Organic Molecules

3 What is a carbohydrate? Classify carbohydrates according to their structure.

Answer:

Carbohydrate

A carbohydrate is a biomolecule, made up of carbon, hydrogen, and oxygen, where hydrogen and oxygen usually maintain a ratio of 2:1.

Organisms break down carbohydrates to produce energy for cellular processes. 

The general formula of carbohydrate is C_n(H₂O)_n.

Classification of carbohydrates:

Structurally carbohydrates are of four types. 

These are-

1. Monosaccharides: 

Monosaccharides are the simplest form of carbohydrates that do not hydrolyze further into smaller units.

Example Glucose, fructose, galactose, etc.

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2 Oligosaccharides: 

Oligosaccharides are the type of carbohydrates, which are composed of 2-9 molecules of monosaccharides, joined by glycosidic bonds. 

According to the number of molecules of monosaccharides present, oligosaccharides can be classified into disaccharides, trisaccharides, tetrasaccharides, pentasaccharides, etc.

Examples are Sucrose (disaccharide), raffinose (trisaccharide), stachyose (tetrasaccharide), verbascose (pentasaccharide), etc.

3 Polysaccharides: 

Polysaccharides are composed of ten to numerous molecules of monosaccharides. 

Example-Cellulose, glycogen, inulin, dextrin, starch, etc.

Question 4. Briefly mention the main characteristic features of carbohydrates and their importance in the living body.

Answer:

Main characteristic features of carbohydrates:

1. Carbohydrates are colorless, odorless, and mostly water-soluble (polysaccharides are insoluble in water) organic compounds. 

2. Smaller carbohydrates (monosaccharides and disaccharides) are sweet tasting, hence, they are known as sugars.

3. Carbohydrates behave as reducing molecules due to the presence of aldehyde and ketone in them. 

4. In larger carbohydrate molecules, monosaccharide units may arrange in either a linear or circular manner.

Importance of carbohydrates in the living body:

The importance of carbohydrates in the living body is as follows-

1. Energy production:

Monosaccharides (glucose and fructose) act as fuel to fulfill the body’s energy needs. 

The calorific value of carbohydrates is 4.1 kcal/g.

2 Structural function: 

Structural components of cell walls, cell coats, and blood group antigens are carbohydrates.

3 Synthesis of biomolecules: Glucose and other sugars are transformed into fats and amino acids by some physiological processes.

4. Bowel formation: Most animals are incapable of digesting cellulose.

So it is accumulated in the intestine as roughage, which in turn, helps in bowel formation.

5 Brain development: Galactose, derived from milk sugar (lactose), helps in brain development in infants.

6 Prevention of ketosis: Very low intake of carbohydrates causes the breakdown of fat and production of ketone bodies. 

This causes a disease called ketosis. Regular intake of carbohydrates prevents the chance of ‘ketosis.

Inorganic Molecules Long Answer Questions for Class 9

Question 5. Describe in brief the chemical structure of carbohydrates.

Answer:

Chemical structure of the carbohydrate:

Carbohydrates are the most abundant biomolecule on earth.

1 Structural components:

Carbohydrate consists of carbon (C), hydrogen (H), and oxygen (O) atoms, usually with a ratio of 1:2:1.

2 Chemical formula:

The general formula of carbohydrates is C_n (H₂O)_n. For example, the formula of glucose is C₆H1₂O₆.  But there are some exceptions also. Such as the chemical formula of rhamnose is C6H1205

3 Chemical group:

The basic carbohydrate molecule possesses an aldehyde or ketone group and one hydroxyl group in every carbon atom except the one involved in the carbonyl group. The chemical structure of glucose and fructose is given here.

 Isomerism Glucose and fructose have the same chemical formula, but because of their different chemical structure, they possess different physical and chemical properties. This phenomenon is known as isomerism.

 

Question 6. Classify monosaccharides based on the number of carbon atoms. Mention the characteristic features of monosaccharides.

Answer:

Classification of monosaccharides:

Based on the number of carbon atoms, monosaccharides can be classified into the following types. 

1. Triose: These monosaccharides are composed of three carbon atoms. Example- Glyceraldehyde.

2 Tetrose: These monosaccharide molecules have four carbon atoms. Example-Erythrose. 

3 Pentose: Five carbon atoms are present in a pentose monosaccharide. Example-Ribose.

4. Hexose: This is the most commonly occurring monosaccharide, which is composed of six carbon atoms. Example-Glucose, fructose, etc.

5 Heptose: Few monosaccharides are of this type, which has seven carbon atoms.

Example: Sedoheptulose.

Characteristic features of monosaccharides:

The characteristic features of monosaccharides are as follows

1. These are crystalline solids at room temperature and are quite soluble in water. Monosaccharides are colorless, sweet substances. 

2. These are reducing sugars, and reducing mild oxidizing agents because they have free ketone or aldehyde groups.

3. These produce glycoside bonds when reacting with alcohol and form enediol compounds when reacting with base.

WBBSE Class 9 Life Science Solutions

Question 7. What Is amino acid? Mention the functions of amino acids.?

Solution:

Amino acid:

The organic compounds, composed of at least one amino group (-NH₂) and one carboxyl group (-COOH), are called amino acids.

In an amino acid molecule, a central carbon atom remains attached with one amino group, one carboxyl group, one hydrogen atom, and one variable group Amino (R). Amino acids act as the structural unit of proteins.

Examples: Methionine, alanine, etc.

Functions of amino acid

Structural function: 

Amino acids take part in the formation of protoplasm and different structural proteins, like keratin, elastin, etc. in living organisms.

2 Controlling of biochemical reactions: 

Amino acids play an important role in enzyme formation, which controls various biochemical reactions in our body.

3 Haemoglobin formation: 

Certain amino acids and iron atoms unite to form hemoglobin which is the oxygen and carbon dioxide transporting metalloprotein of blood.

4 Hormone production: 

Certain amino acids unite to produce proteinaceous hormones, like ACTH, insulin, etc.

5 Antibody formation: 

Some amino acids take part in antibody formation and thus help in developing immunity.

6 Nitrogen storage: 

Amino acids store nitrogen in the form of amides.

7. Neoglucogenesis:

In the case of protein deficiency in the human body, amino acids produce glucose by the process of neoglucogenesis.

Question 8. Schematically represent the classification of protein.

Answer:

Classification of protein

Important Concepts in Organic and Inorganic Molecules

Question 9. Mention different important functions of proteins in the human body. Write down the roles of lipids in life processes.

Answer:

Role of Proteins in the human body

1. Proteins are the building materials of a living cell. 

2. Proteins are directly involved in the development of the embryo, growth, healing of wounds, repair of damaged tissues, etc. 

3. Proteins are the main structural components of animal cell membranes and cell organelles, different body tissues, different enzymes, hormones and antibodies, and several other substances.

4. Nucleoproteins constitute chromosomes, which carry genes. 

5. Protein is also a major source of energy. The calorific value of protein is 4.1 kcal/g.

6. Broken non-nitrogenous amino acids produce carbohydrates and fats through the process of deamination and transamination. 

7. Proteins act as a buffer solution to maintain the pH of the body. 

8. In mammals, proteins play an important role in the production of milk during lactation.

Roles of lipids in life processes:

The roles of lipids in life processes are as follows-

1. Lipids act as the reserve food materials of plants and animals. 

2. Fat can generate maximum heat energy. Its calorific value is 9.3 kcal/g. Animals like frogs, snake, etc. store fat in the adipose cells under their skin, which protect them against extreme cold. 

3. Fat deposits in the body of desert animals (such as camels) are oxidized to produce metabolic water, to counter extreme dryness.

Question 10. Give a brief account of different proteins based on their nutritional value along with their sources.

Answer:

Different proteins based on nutritional value:

The nutritional value of proteins depends upon the number of essential amino acids present in it.

1. First-class proteins: 

The proteins which contain all essential amino acids in such a proportion that is necessary for building our body, are treated as first class proteins.

Sources-Different animal proteins like milk, meat, fish, egg, etc.

WBBSE Class 9 Life Science Solutions

2 Second class proteins:

The proteins which may contain essential amino acids but not in such a proportion, that is necessary for building the body, or lack a few essential amino acids, are known as second-class proteins.

Sources-Pulses, gram, rice, wheat, etc.

3 Third class proteins: These proteins do not contain essential amino acids, hence, play no role as body building material, these are merely catabolised to generate heat. 

Source-Gelatin.

Practice Long Answer Questions for Life Science Chapter 2

Question 11. Mention two biological importance of fatty acids. Mention the role of essential fatty acids in our body.

Answer:

Importance of fatty acids

Two biological importance of fatty acids are as follows:

1. Fatty acids are the units of fat, which is one of the most important structural components of the body. 

2. Products of many fatty acids act as hormones.

Role of essential fatty acids:

The role of essential fatty acids in our body is mentioned below.

1. Essential fatty acids are responsible for keeping the skin glowing and wrinkle-free. 

2. These help in maintaining the membrane permeability of skin cells.

3. These help in maintaining a steady supply of milk in the mammary glands of lactating mothers.

4. Essential fatty acids help to maintain water balance in the body. 

5. These fatty acids help in growth and extend reproductive life. 

6. These help in transporting cholesterol in the blood. 

7. Function of the kidney is further supported due to the presence of some essential fatty acids.

 Question 12. Describe the structure of a nucleotide and explain different structural components of nuclotide with schematic diagram. Mention the main roles of nucleotides in life processes.

Answer:

Structure of nucleotide:

Nucleotides are the units of nucleic acids. Several Phosphate group nucleotide monomers join in a linear sequence to constitute a nucleic acid molecule. A nucleotide is composed of three components- 

1. A pentose (5C) sugar

2. A nitrogenous base

3. A phosphate group. A nucleotide monomer without phosphate is called a nucleoside. Practically, A phosphate group holds two successive nucleosides together.

Nucleotides have two basic types of nitrogenous bases:

1. Purines (including adenine and guanine), 

2. Pyrimidines (include thymine, cytosine, and uracil).

Pentose sugar also of two types:

1. ribose

2. deoxyribose.

Schematic representation of different structural components of a nucleotide

 Roles of nucleotides in life processes:

The main roles of nucleotides in life processes are as follows:

1. Nucleotides play an important role in cell signaling and metabolism. 

2. The specific arrangement of nucleotides on a nucleic acid stores genetic information for performing all the biochemical activities in all living organisms.

WBBSE Class 9 Life Science Solutions

Question 13. Mention the types of nucleotides.

Answer:

Types of nucleotides:

Nucleotides are composed of pentose sugar, nitrogen bases, and phosphoric acid. The variation in the constituting ribose sugar and nitrogen bases causes the formation of different types of nucleotides. 

1. Based on pentose sugar: 

The pentose sugar, present within nucleotide, can be either ribose sugar or deoxyribose sugar. According to this, the nucleotides are termed ribonucleotide or deoxyribonucleotide respectively.

2 Based on nitrogen bases:

1. Based on nitrogenous bases, deoxyribonucleotides can be divided into four groups- dATP, dGTP, dTTP, and dCTP. A deoxyribonucleotide that is composed of one Adenine base, one Deoxyribose sugar, and a phosphate radical is called dATP or deoxyadenosine triphosphate.

Similarly, guanine, thymine, and cytosine-containing deoxyribonucleotides are known as dGTP or deoxyguanosine triphosphate, dTTP or deoxythymine triphosphate and dCTP or deoxycytidine triphosphate respectively. 

2. Ribonucleotides act as structural units of RNA molecules. Similarly, ribonucleotides are also of four types. As ATP or adenosine triphosphate, GTP or guanosine triphosphate, UTP or uracil triphosphate, and CTP or cytosine triphosphate.

Sample Long Answer Questions from WBBSE Class 9 Life Science

Question 14. What is nucleic acid? Schematically describe the classification of nucleic acid.

Answer:

Nucleic acid:

The biological macromolecules, which are the polymers of nucleotides, present in all living cells and responsible for determining and regulating the genetic characteristics of an organism, are known as nucleic acid.

Example: Deoxyribonucleic acid [DNA] and ribonucleic acid [RNA]

Question 15. Write down the structure of the RNA molecule. Describe the function of RNA molecules.

Answer:

Structure of RNA molecule

1. ORNA is a single-stranded polymer of ribonucleotides.

2. RNA is composed of five carbon containing ribose sugar, nitrogen bases, and a phosphate group.

3. The nitrogenous bases present in RNA are adenine [A], guanine [G], uracil [U], and cytosine [C].

4. RNA molecules may fold upon themselves to form a complex structure.

The function of RNA molecule

1. All physiological functions of the body of an organism are regulated by proteins. mRNA molecule is responsible for the synthesis of protein molecules. rRNA and tRNA also help in protein synthesis.

2. In RNA virus, RNA acts as its genetic material and is transmitted during its replication.

Index:

A = Adenine, G = Guanine

C=Cytosine, U = Uracil

Structure of RNA

 

Question 16. Schematically represent the different components of a DNA molecule. Briefly describe the structure of a DNA molecule.

Answer:

Components of a DNA molecule

Structure of a DNA molecule:

A DNA molecule is a double-stranded, coiled, helical structure, running in opposite directions and made up of several nucleotide units. Many nucleotide monomers join in a linear sequence in two parallel strands to constitute a DNA molecule. The structural unit of DNA is composed of a sequence of deoxyribonucleotides. 

WBBSE Class 9 Life Science Solutions

Such a nucleotide is composed of three components:

1. A five-carbon containing deoxyribose sugar, 

2. Any one of the four nitrogenous bases (viz. adenine, guanine, thymine, and cytosine)

3. A phosphate group. Practically, two successive nucleosides are held Adenine Thymine together by a phosphate group to constitute a DNA strand. The two strands of a DNA molecule are zipped together by weak hydrogen bonds.

Here, adenine joins with thymine by two hydrogen bonds (A = T) and guanine joins with cytosine by three hydrogen bonds (G ≡ C).

Question 17. Mention the similarities and dissimilarities of DNA and RNA.

Answer:

Similarities between DNA and RNA

The similarities between DNA and RNA are as follows:

1. Both DNA and RNA are nucleic acids.

2. Both are made up of pentose sugar, nitrogenous base, and phosphate. 

3. Both are treated as bio-macromolecules. 

4. DNA and RNA carry the same types of purines, i.e. adenine and guanine.

5. Cytosine is present in both these molecules.

Dissimilarities between DNA and RNA:

Chapter 2 Levels Of Organization Of Life Organic And Inorganic Molecules

Long Answer Type Questions

Question 1. What is meant by vitamin? Schematically mention different types of vitamins.

Vitamin

The special component of food, which are present in very little quantities, but perform an elementary role in various physiological activities and help in developing immunity against different diseases are known as vitamins.

Different types of vitamins

Based on solubility vitamins can be divided into two types.

These are:

1. Fat-soluble vitamins – vitamins A, D, E, and K.

2. Water soluble vitamins – vitamin B complex, C and P.

Question 2. Mention some important features of vitamins.

Some important features of vitamin

1. Synthesis:

Most of the vitamins are synthesized in the plant body.  A few are synthesized in the animal body (such as Vitamin A, D, K, and B₁₂).

2. Daily requirement:

Vitamins act in very little quantities; therefore, the daily requirement of vitamins is very low.

3. Storage:

Vitamins are stored in very little quantity. Fat-soluble vitamins are stored in adipose tissue below the skin. Vitamin C is stored in the adrenal cortex.

4. Fate:

Vitamins are not digested. These are absorbed intact. However, during metabolic processes, these are partially denatured.

5. Solubility:

Some vitamins like vitamins B and C are soluble in water. Vitamins A, D, E, and K are soluble in fat and organic solvents, like ether, chloroform, etc.

WB Class 9 Life Science Question Answer

6. Help in enzymatic activity:

Some vitamins act as coenzymes and thus play an important role in enzymatic activity.

7. Role in metabolic reaction:

The requirement for vitamins is directly proportional to metabolic rate. Therefore, the daily requirement of vitamins for a physically active person or a pregnant woman is higher than for a normal person.

Understanding Organic vs Inorganic Molecules for Long Answers

Question 3. Write down the names, sources, and roles of different fat-soluble vitamins in the human body. 

Answer:

Names, sources, and roles of different fat-soluble vitamins in the human body

WBBSE Class Nine Life Science

Question 4. Mention the chemical names and deficiency diseases of different fat-soluble vitamins.

Answer:

Names and deficiency diseases of fat-soluble vitamins

Question 5. Mention names, sources, and functions of different minerals important for the human body.

Answer:

Names, sources, and functions of different minerals important for the human body

 

Question 6. Mention chemical names of different water-soluble vitamins and their deficiency diseases.

Answer:

WBBSE Class Nine Life Science

Question 7. Differentiate between water-soluble vitamins and fat-soluble vitamins.

Answer:

Differences between water-soluble vitamins and fat-soluble vitamins

 

Question 8. Based on physiological function classify different minerals.

Answer:

Classification of minerals based on physiological function

Based on physiological function, minerals can be classified into six types:

1. Body-forming minerals:

Calcium, phosphorus, and magnesium play vital roles in the formation of bones and teeth.

2. Body fluid regulating minerals:

Sodium, potassium, chlorine, etc., control the volume of blood, tissue fluids, cerebrospinal fluid, and cytoplasm.

3. Transporting minerals:

Certain minerals like iron, copper, etc., help in transportation. Iron takes part in the formation of hemoglobin which carries oxygen and carbon dioxide.
4. Minerals regulating enzymatic activity:

Calcium, magnesium, and iron regulate the functioning of different enzymes.

5. Hormone synthesizing minerals:

Iodine directly takes part in the synthesis of thyroxine hormone.

6. Vitamin synthesizing minerals:

Cobalt takes part in the synthesis of vitamin B₁₂

Study Guide for Class 9 Life Science Long Answer Questions

Question 9. Mention names, sources, and functions of different minerals important for the human body.

Answer:

Names, sources, and functions of different minerals important for the human body

WBBSE Class Nine Life Science

Question 10. What do you understand by the terms macro-elements and micro-elements? Mention general role of different minerals on physiological processes in the human body.

Answer:

Macro-elements

The elements, which are required in large quantities for proper growth and development of the human body, are known as macro-elements.

Examples: Sodium (Na), potassium (K), chlorine (CI), calcium (Ca), phosphorus (P), etc.

Micro-elements

The elements, which are required in minute quantities for proper growth and development of the human body, are known as micro-elements. 

Examples: Iron (Fe), boron (B), iodine (I), molybdenum (Mo), zinc (Zn), manganese (Mn), copper (Cu), etc.

The general role of different minerals on physiological processes in the human body

Different minerals play different roles in physiological processes in the human body, which are as follows:

1. As cofactors of enzymes:

Different minerals like iron, copper, manganese, zinc, etc., act as cofactors of different enzymes.

2. Maintenance of acid-base balance:

Certain elements like sodium, potassium, chlorine, etc., maintain acid-base balance within the body.

3. Maintenance of water balance:

Sodium helps in maintaining water balance within the body.

4. Conduction of nerve impulse:

Sodium and potassium play a very important role in the conduction of nerve impulses.

5. Control membrane permeability:

Elements like calcium and potassium control the membrane permeability of our body.

6. Role in blood coagulation:

Calcium acts as an essential blood-coagulating factor.

7. Formation of skeletal structure:

Calcium and phosphorus are the main building components of bones and teeth.