Chapter 1 The Fundamental Unit Of Life
Cell
Have you ever seen a cell?
Take an onion bulb. Peel off the skin from its inner side using forceps. Then, place individual layers in a watch glass containing water. Carefully transfer each layer on a clean glass slide using a paint brush. Add one-two drops of iodine solution on the material to stain the cell for visualization. Place a cover slip on the material in such a way that no bubbles are formed. Observe the slide under the microscope.
What do you observe?
You will observe a number of rectangular chambers under the microscope (as shown in the given figure). Each chamber is a cell here. You will find a similar pattern and structure in each slide.
Read And Learn More NEET Biology Class 9 Question And Answers
What are cells? Who named them so?
All living organisms are made up of cells. The Cell is the structural and functional unit of life. It is the smallest living entity found in living organisms.
The term cell was introduced by Robert Hooke in 1665, while examining a slice of cork through his microscope. Cork is obtained from the bark of a tree. Under a compound microscope, he observed many small compartments resembling a honeycomb. He termed these as cells. The given table lists some properties of cells.
WBBSE Class 9 Fundamental Unit of Life Q&A
Properties of cell
- The Cell is the smallest living unit of life.
- It is so small that it is not visible to the naked eye.
- The shape of the cell varies in different organisms and within an organism.
- Size of cells also differs.
- All living cells exhibit certain basic properties like respiration, growth, metabolism etc.
- Cells originate from a pre-existing cell. A mother cell divides to produce daughter cells. Hence, cells exhibit cell division.
Cell is the basic unit of life. All cells vary in their shape, size, and activity they perform. In fact, the shape and size of the cell is related to the specific functions they perform.
The table given below lists the shape and size of certain cells.
Amoeba is a simple, unicellular organism. Larger animals are more evolved than unicellular Amoeba. Do you know the reason for this?
Have you ever tried to know how multicellular organisms evolve?
Multicellular organisms have several advantages over unicellular organisms.
- As division of labour exists in multicellular organisms, a variety of tasks can be performed efficiently. This gives the organism a wide range of adaptability to survive.
- In multicellular organisms, dead cells play an important role. For example, dead epidermal cells in the skin of animals protect the underlying cells.
Do you know what division of labour is?
Division of labour suggests the specialized functions of organs. All organs, tissues, or cells cannot carry out all the functions. They are evolved to carry out a specific set of functions. Each organ system coordinates with the other to carry out functions required for life. Therefore, by dividing the work or function, they minimize the load of carrying out all functions and therefore, they work or function efficiently.
Let us learn more about unicellular and multicellular cells.
Organisms are often grouped as unicellular or multicellular organisms. Unicellular organisms represent a single cell, while multicellular organisms are made up of numerous cells.
Some Interesting Facts:
- The smallest cell in the universe is the Mycoplasma, a type of bacteria. Its diameter is 0.1 µm.
- The smallest cell in the human body, in terms of volume, is the sperm cell.
The table given below lists the characteristics of some unicellular and multicellular organisms with a few examples.
Understanding Cell Structure and Function
Cells can also be classified on the basis of their cellular complexity.
Based on their sub-cellular organization and cellular complexity, cells can be classified as prokaryotes and eukaryotes. Animals, plants, fungi, protozoans, and algae, all are composed of eukaryotic type of cells, while bacteria are prokaryotes in nature. Prokaryotes are unicellular organisms, while eukaryotes are usually multicellular organisms. Yeast is exceptionally a unicellular eukaryote. The table given below lists the characteristic features of both prokaryotes and eukaryotes.
Chapter 1 The Fundamental Unit Of Life Worksheet 1
Question 1. Robert Hooke was the first scientist who coined the term ‘cell’. Which cell did he observe under the microscope?
- Fiber
- Cork
- Root
- Leaf
Answer. 2. Cork
Question 2. Which of the following organisms is multi-cellular?
- Hydra
- Amoeba
- Paramecium
- Dinoflagellate
Answer. 1. Hydra
Question 3. All living organisms are made up of cells. Cells are often referred to as the ‘building blocks’ of life. Which of the following organisms is not a unicellular organism?
- Bacteria
- Coral
- Yeast
- Archaea
Answer. 2. Coral
Question 4. Organisms that are made up of many cells are called multi-cellular organisms; whereas organisms that are made up of only a single cell that performs all functions are called unicellular organisms. Which of the following organisms is unicellular?
- Pine
- Algae
- Sundew
- Amoebae
Answer. 4. Amoebae
Step-by-Step Guide to Cell Biology Questions
Question 5. Multicellular organisms are made of a large number of cells, wherein each cell performs a specific function. Which of the following organisms is not multicellular?
- Plants
- Protists
- Monkey
- Mushrooms
Answer. 2. Protists
Question 6. Which of the following organisms is not multicellular?
- Banyan tree
- Pea plant
- Diatom
- Leech
Answer. 3. Diatom
Question 7. An organism made up of a single cell is known as a unicellular organism. Which of the following organisms is not unicellular?
- Bacterium
- Mushroom
- Paramecium
- Dinoflagellate
Answer. 2. Mushroom
Question 8. In a multicellular organism, different cells are specialized to perform different functions. Which of the following organisms is multicellular?
- Diatom
- Bacteria
- Euglena
- Hydra
Answer. 4. Hydra
Question 9. In a unicellular organism, the single cell performs all the functions necessary for its survival. Which of the following organisms is unicellular?
- Pine
- Moss
- Amoeba
- Earthworm
Answer. 3. Amoeba
Question 10. Prokaryotes are distinguished from eukaryotes by the
- presence of cell wall
- absence of nucleus
- presence of ribosomes
- absence of chloroplasts
Answer. 2. absence of nucleus
Question 11. Which of the following statements about prokaryotes is true?
- All prokaryotes have a cell wall
- Nucleus is absent in all prokaryotes
- Prokaryotes are larger than eukaryotes
- Ribosomes are larger in prokaryotes as compared to eukaryotes
Answer. 2. Nucleus is absent in all prokaryotes
Practice Questions on The Fundamental Unit of Life
Question 12. Which arrow diagram correctly illustrates the arrangement of cell organelles starting from the outermost layer of plant cells?
- Plasma membrane cell wall cytoplasm nucleus
- Cell wall plasma membrane cytoplasm nucleus
- Cell wall cytoplasm plasma membrane nucleus
- Plasma membrane cytoplasm cell wall nucleus
Answer. 2. Cell wall plasma membrane cytoplasm nucleus
Question 13. Living organisms are grouped into eukaryotes and prokaryotes on the basis of
- ribosomes
- nucleus
- plasma membrane
- chloroplast
Answer. 2. nucleus
Question 14. In multi-cellular organisms, cells are usually
- independent of each other
- dependent upon each other
- incapable of transporting substances
- incapable of multiplication
Answer. 2. dependent upon each other
Question 15. Plant cells can perform certain functions which animal cells cannot perform. The function unique to a plant cell is the
- exchange of gases
- absorption of water
- production of starch
- transport of nutrients
Answer. 3. production of starch
Question 16. Cells perform the essential life functions in an animal body. Which of the following functions is not performed by animal cells?
- Digestion
- Respiration
- Protein synthesis
- Carbohydrate synthesis
Answer. 4. Carbohydrate synthesis
Question 17. As compared to plant cells, animal cells are found in a variety of shapes. Animal cells are found in a verity of shapes because of the presence of a flexible
- vacuole
- nucleus
- cell wall
- cell membrane
Answer. 4. cell membrane
Question 18. Vacuole is cell structure present in both plant and animal cells. Which of the following statements about plant and the animal cell vacuoles is true?
- The plant cell has many small vacuoles, but the animal cell has one large vacuole.
- The plant cell has one large vacuole, but the animal cell has many small vacuoles.
- The plant as well as the animal cell has many small vacuoles.
- The plant as well as the animal cell has one large vacuole.
Answer. 2. The plant cell has one large vacuole, but the animal cell has many small vacuoles.
Question 19. Which of the following processes does not occur in animal cells?
- Photosynthesis
- Respiration
- Excretion
- Osmosis
Answer. 1. Photosynthesis
Question 20. Animal cells are found in a verity of shapes because of the presence of a flexible
- Vacuole
- Nucleus
- Cell wall
- Cell membrane
Answer. 4. Cell membrane
Chapter 1 The Fundamental Unit Of Life Cell Wall, Plasma Membrane, And Cytoplasm
We know that a cell contains a cell wall, a plasma membrane, and a cytoplasm.
Can you identify the plasma membrane and the cytoplasm in a cell?
Collect a small piece of onion. Peel off the skin (also called epidermis) from the concave side of the onion using forceps. Place this thin layer of onion skin in a watch glass containing water. Transfer it on a clean glass slide using a paint brush and add a drop of iodine solution to it. Mount a cover slip on the material in such a way that no bubbles are formed inside. Observe it under the microscope.
What do you observe?
You will observe cells. There is a clear boundary around cells, which is the plasma membrane. A small, dark coloured, round-shaped structure can be seen inside the cell. This is the nucleus of cells. The entire space (apart from the nucleus) is enclosed by the plasma membrane.
The basic component of cells is the protoplasm and plasma membrane. Protoplasm consists of the cytoplasm and the nucleus. Cytoplasm is the cellular matrix in which the nucleus is suspended. However, in bacteria, cellular materials are surrounded by the bacterial cell wall.
In plant cells, the outermost covering also constitutes the cell wall, beneath which the plasma membrane lies.
Let us study the plasma membrane, the cell wall, and the cytoplasm in detail.
The plasma membrane is the outermost covering in animal cells. However, in plant cells and in certain unicellular organisms, the outermost covering is the cell wall. The plasma membrane is a selectively permeable lipid bilayer.
Lipids and proteins are major components of the cell membrane. However, a small amount of carbohydrates can also be found in the plasma membrane. The plasma membrane is flexible in nature.
The table given below lists the various functions of the plasma membrane.
Let us explore the process of diffusion and osmosis in detail.
Diffusion
Do you know how nutrients are absorbed in the digestive tract?
In the digestive tract, food is broken down into simpler products such as glucose. Nutrients are then absorbed by the intestinal cells through a process known as diffusion.
Do you know how oxygen reaches the cells in the human body?
The inhaled air contains oxygen. In the lungs, oxygen diffuses through the blood capillaries and reaches the red blood cells. There, it binds with haemoglobin to form oxy-haemoglobin. Oxy-haemoglobin is then circulated throughout the body. In tissues, where oxygen concentration is lesser than blood or the red blood cells, oxygen diffuses out of it and enters into tissues and then into cells.
Osmosis
Osmosis is the movement of water molecules across a semi-permeable membrane from a higher to a lower concentration.
Plasma membrane acts as a semi-permeable membrane. Water moves in and out of cells through osmosis to maintain the amount of water in cells and in the outside environment.
How does water move from one region to another?
Solutions can be of three types: isotonic, hypotonic, and hypertonic. Let us explore the differences between these solutions.
Let us perform an experiment to understand osmosis using raisins or apricots.
Take raisins in three breakers. Pour pure water in the first beaker, isotonic solution in the second, and a high concentrated salt solution in the third beaker.
What do you observe?
After five minutes, you will observe that the raisins swell up in the first beaker. Pure water does not contain salt. Thus, to maintain equilibrium, water enters into the raisins. This swells up the raisins. In the second beaker, you will see no change in the raisins. An isotonic solution contains similar salt concentration as that of raisins. This produces osmotic balance. Hence, no change can be observed. In the third beaker, you will observe that the raisins shrink. This beaker contains a hypertonic solution. To maintain equilibrium, water moves out of the raisins. This shrinks the raisins. Excessive shrinkage results in the breakdown of the membrane. This phenomenon is called plasmolysis.
Artificial kidney dialysis!
An artificial dialysis must be performed when the kidneys stop functioning. Artificial kidney dialysis uses the cellulose membrane, which acts as a semi-permeable membrane. Such a system filters blood through osmosis and diffusion (as the kidneys do). This keeps the body activity normal.
Differences between osmosis and diffusion Can you distinguish between diffusion and osmosis?
The table given below lists some distinguishing characteristics of diffusion and osmosis.
Plasma membrane of cells acts as semi-permeable membrane. It allows the movement of water and gaseous molecules freely (diffusion). However, it does not allow the movement of other larger molecules such as sugar, amino acids, etc. All such molecules are transported across the membrane by facilitated diffusion (with the help of other carrier proteins) and active transport (with the expenditure of energy).
Do you know why brine is used to preserve food?
Brine is a high salt concentration solution. Perishable food items such as fish, meat, etc. are preserved for a longer period of time in such solutions. Brine is hypertonic for bacteria. Therefore, water comes out of bacterial cells, causing dehydration. This kills the bacteria. Thus, bacterial contamination is prevented.
Cell wall
The cell wall is the outermost rigid structure in plant cells. The main component providing structural strength to the cell wall is cellulose. However, the bacterial cell wall is mainly composed of peptideglycan. The table given below lists the various functions of the cell wall.
Functions of cell wall:
- It protects intracellular organelles from the outside environment.
- It can withstand dilute hypotonic media and prevents bursting of cells. Therefore, plant cells withstand changes in environmental concentration better than animal cells.
- Plasma membrane establishes communication between cells.
Cytoplasm
The cytoplasm is the inner content of the cell membrane, which is separated from the nucleus. It includes cytosol, organelles, and inclusions. Cytosol is a soft and sticky, semi-transparent fluid in which various cell organelles are suspended. Inclusions are stored nutrients.
The table given below lists various functions of the cytoplasm.
Functions of Cytoplasm:
- It is the region where many cellular activities take place.
- It mostly consists of water and it balances the water content in the cell.
- It contains cytoskeleton, which maintains the shape and movement of cells.
- Cytoplasmic streaming or circulation of the cytoplasm helps in the proper distribution of cellular organelles during cell division, growth, etc.
Do you know what cybrid is?
Cybrids are cytoplasmic hybrids. Plasma membrane of cells (of different origins) is broken down to obtain cytoplasm. These naked cells are then fused to obtain hybrid cells called cybrids. Cybrids are often known as heterokaryon as they contain the nucleus from different origins. Cybrids are important for research purposes.
Chapter 1 The Fundamental Unit Of Life Worksheet 2
Question 1. Which of the following functions holds true for plasma membrane?
- It protects and gives structural support to cells
- It contains the genetic material
- It regulates substances moving in and out of cells
- It maintains the shape of cells
Answer. 3. It regulates substances moving in and out of cells
Question 2. The nucleus of a cell is a membrane-bound organelle that contains the genetic material i.e., DN(A) The cellular material present outside the nucleus is called cytoplasm. Which membrane separates the components of nucleus and cytoplasm?
- Protoplasm
- Nucleolus
- Plasma membrane
- Nuclear envelope
Answer. 4. Nuclear envelope
Question 3. Which organelle forms the outermost layer in animal cells?
- Mitochondria
- Plasma membrane
- Cell wall
- Nuclear membrane
Answer. 2. Plasma membrane
Question 4. The flow of molecules in and out of a cell is regulated by
- cell membrane
- mitochondria
- golgi body
- nucleus
Answer. 1. cell membrane
Question 5. Emily reads about a cell structure made up of proteins and lipids. This structure holds the constituents of the cell together. Which cell structure is described here?
- Golgi apparatus
- Cell membrane
- Cytoplasm
- Lysosome
Answer. 2. Cell membrane
Question 6. Osmosis is the movement of molecules from a region of higher concentration to a region of lower concentration. Which of the following processes does not involve osmosis?
- Turgidity of living cells
- Exchange of gases through stomata
- Absorption of water by roots
- Opening and closing of stomata
Answer. 2. Exchange of gases through stomata
Question 7. A hypotonic solution is one that contains a low concentration of the solute relative to the comparative solution. A hypertonic solution is one that contains a high concentration of the solute relative to the comparative solution. Isotonic solution is a solution whose solute concentration is equal for both the solutions under comparison. Osmosis occurs when a cell is placed in a solution hypertonic to it. Which of the following observations would be recorded if an animal cell is placed in a solution hypotonic to it?
- There would be a drop in the intercellular pressure
- There would be a gain in the extra cellular pressure
- There would be a movement of contents from the solution to the cell
- There would be a movement of contents from the cell to the solution
Answer. 3. There would be a movement of contents from the solution to the cell
Question 8. Cell bursting occurs when cell is immersed in a solution.(x is isotonic to cells) Which alternative completes the given sentence?
Answer.
3.
Question 9. Human cells are observed to be spherical when placed in an isotonic solution that has 0.9% salt concentration.
What will be the effect of the solution on the cells?
- They will shrink in size
- They will increase in size
- They will burst because of pressure
- They will neither increase nor decrease in size
Answer. 4. They will neither increase nor decrease in size
Question 10. A red blood cell is placed in a hypotonic solution. It is observed that
- water enters the cell
- oxygen enters the cell
- water moves out of the cell
- oxygen moves out of the cell
Answer. 1. water enters the cell
Question 11. Which of the following biomolecules is not a component of animal cells?
- Lipid
- Protein
- Glucose
- Cellulose
Answer. 4. Cellulose
Question 12. A cell structure in the plant cell is made up of cellulose and protects the cell from physical injury. The described cell structure is the
- cell wall
- chloroplast
- mitochondrion
- cell membrane
Answer. 1. cell wall
Question 13. In the given figure, label X represents the
- cell membrane
- cytoplasm
- cell wall
- nucleus
Answer. 3. cell wall
Question 14. Cell wall is the outermost covering of the plant cell. Its main function is to
- provide support to the cell
- provide energy for the cell
- take part in lipid synthesis
- take part in protein synthesis
Answer. 1. provide support to the cell
Examples of Questions on Cell Organelles
Question 15. The presence of a thick cell wall is one of the important factors that differentiate plant cells from animal cells. The cell wall surrounds the cell or plasma membrane. The presence of cell wall allows plant cells to
- exhibit mobility
- synthesize their own food
- separate internal contents of the cell
- withstand changes in their surroundings
Answer. 4. withstand changes in their surroundings
Question 16. The given figure shows a labeled plant cell. In the given figure, the cytoplasm is labeled as
- 1
- 2
- 3
- 4
Answer. 4. 4
Question 17. Cell wall is the most distinguishing feature of plant cells. Which of the following functions is not performed by plant cell wall?
- Manufacturing proteins
- Giving support to the cell
- Providing shape to the cell
- Protecting cellular contents
Answer. 4. Protecting cellular contents
Question 18. The cells of which of the following organisms have a cell wall, chloroplast, and a prominent vacuole?
- Sea kelp
- Sting ray
- Star fish
- Sea urchin
Answer. 1. Sea kelp
Question 19. Cytoplasm is composed of all cell organelles except nucleus. The contents of nucleus are separated from cytoplasm by the nuclear membrane. Nucleus and nuclear membrane together form nucleoplasm. Cytoplasm and nucleoplasm are together referred to as
- protoplast
- cytonucleus
- protoplasm
- nucleolus
Answer. 3. protoplasm
Question 20. Cytoplasm is a water-like substance that is present outside the nucleus and contains all cellular organelles. In animal cells, it occupies nearly half of a cell’s volume. It occupies less space in plant cells. Cytoplasm occupies less space in plant cells because of the
- presence of cell wall
- presence of vacuoles
- absence of cell wall
- absence of vacuoles
Answer. 2. presence of vacuoles
Chapter 1 The Fundamental Unit Of Life Nucleus: Structure And Function
We often hear of scientists producing clones.
Do you know what clones are? Do you know how clones are created?
Cloning refers to an identical copy of something. In biology, clones signify genetically identical organisms. The nucleus holds the genetic material. Therefore, if the nucleus is similar in two cells, then they would be similar. Hence, clones are produced by obtaining the nucleus from the cells of donor organisms.
The nucleus, thus obtained, is reintroduced inside the cell whose nucleus is removed. These cells are allowed to grow by providing all the required conditions. Some of these cells divide, producing a zygote. This zygote is then placed inside the uterus of a female recipient to give birth to a baby. Thus, the baby born is identical to the donor organism (whose nucleus is used) and is said to be a clone of the donor.
Have you ever seen a nucleus?
Nucleus is visible under a light microscope. It is acidic in nature. Any basic stain can be used to see the nucleus. Take a toothpick and spool out the materials gently from the inner surface of your cheek. Spread the materials on a clean glass slide and dry it. Add a few drops of methylene-blue solution to the material for staining. After staining, place a cover slip on the material and observe under the microscope.
What do you observe?
You will observe numerous round-shaped cells, which are light blue in colour. Inside each cell, a nucleus can be observed as a dark blue coloured structure.
The nucleus is the largest organelle present in the eukaryotic cells. In mammalian cells, the size of the nucleus typically varies from 11 to 22 µm in diameter. It is spherical in shape.
How are chromosomes and genetic material present in cells?
Thus, the nucleus controls all life activities. The entire segment of the DNA present is not always functional. The functional regions are calledgenes.
Role of the nucleus in cellular reproduction and heredity
Genetic material is present inside the nucleus. The nucleus plays an important role in cellular reproduction as it divides and passes the genetic material to the offspring. The genetic material decides both the appearance and the function of cells. Therefore, heredity depends upon the division of nucleus.
Chapter 1 The Fundamental Unit Of Life Vacuoles
Do you know what vacuoles are?
Vacuoles are membrane-bound structures, which are believed to store ergastic substances of cells. In plant cells, vacuoles are large in size, while in animal cells vacuoles are small. The table given below lists some functions of vacuoles.
Functions of vacuoles:
- They help in the removal of unwanted structural debris.
- They store all the waste products of cells.
- They maintain the turgor pressure within cells.
- In Amoeba, food vacuoles store food.
Chapter 1 The Fundamental Unit Of Life Endoplasmic Reticulum
Endoplasmic reticulum, or ER, is an interconnected network of membranous structureslike tubules, vesicles, and cisternae. Cisternae are the flattened disk-like membranous structures. Tubules are tubular in shape, while vesicles are sac-like structures.
There are two types of endoplasmic reticulum, namely smooth endoplasmic reticulum (SER) and rough endoplasmic reticulum (RER). When ribosomes get attached to the surface of smooth endoplasmic reticulum, it becomes rough endoplasmic reticulum.
Functions of smooth endoplasmic reticulum
- Smooth ER synthesizes fats and lipids.
- It also takes part in the metabolism of carbohydrates.
- It actively participates in drug detoxification.
- It maintains the calcium ion concentration in the cytosol.
Functions of rough endoplasmic reticulum
- Most of the lysosomal proteins are produced in the rough ER.
- It transports proteins to various destinations like the plasma membrane.
- This is the major site of glycosylation (addition of carbohydrates in proteins).
Chapter 1 The Fundamental Unit Of Life Worksheet 3
Question 1. Endoplasmic reticulum forms a tubular network throughout the cell. The main function of the endoplasmic reticulum is to
- synthesize glucose in the cell
- synthesize lipids in the cell
- store water in the cell
- store food in the cell
Answer. 2. synthesize lipids in the cell
Question 2. Lysosomes are involved in the autolysis of cells and cell organelles. They also digest themselves when worn out. They disintegrate or fuse with other vacuoles to release lytic enzymes at the site of action. Lysosomes are also known as
- power generators
- recycling centres
- suicidal bags
- dictyosomes
Answer. 3. suicidal bags
Question 3. A certain cell organelle controls various activities of the cell such as protein synthesis. It also contains the hereditary information of an organism. The described cell organelle is the
- nucleus
- ribosome
- chloroplast
- mitochondrion
Answer. 1. nucleus
Question 4. Which cell organelle does the highlighted region represent?
- Endoplasmic reticulum
- Golgi apparatus
- Lysosome
- Centriole
Answer. 1. Endoplasmic reticulum
Question 5. Nucleus is one of the most important cell organelles in the cell. It performs the function of
- controlling the activities of the cell
- protecting the cell from physical injury
- forming spindle fibers during cell division
- removing old cell organelles from the cell
Answer. 1. controlling the activities of the cell
Question 6. The vacuoles present in animal cells are
- small, centrally located, and a few in number
- large, centrally located, and a few in number
- small, scattered, and more in number
- large, scattered, and more in number
Answer. 3. small, scattered, and more in number
Question 7. Joshua draws the diagram of a cell organelle. The function of this organelle is to carry out the transport of substances within the cell. Which cell organelle is drawn by Joshua?
- Endoplasmic reticulum
- Cell membrane
- Ribosome
- Vacuole
Answer. 1. Endoplasmic reticulum
Question 8. Michael reads about a cell structure in his science book. This structure stores the waste material of the cell. This cell structure is the
- vacuole
- lysosome
- chloroplast
- mitochondrion
Answer. 1. vacuole
Question 9. Lysosomes are responsible for the destruction of foreign bodies and dead and worn-out cell organelles. They also digest themselves when worn out.Which of the following substances is present in lysosomes?
- Proteins
- Fatty acids
- Hydrolyses
- Nucleic acids
Answer. 3. Hydrolyses
Question 10. Which cell structures are present on the surface of the endoplasmic reticulum as well as scattered throughout the cytoplasm?
- Centrioles
- Ribosomes
- Lysosomes
- Mitochondria
Answer. 2. Ribosomes
Conceptual Questions on Applications of Cell Biology
Question 11. The old and worn out cell organelles are removed by the
- lysosome
- ribosome
- nucleus
- vacuole
Answer. 1. lysosome
Question 12. A certain cell organelle is surrounded by a single membrane and contains enzymes. This organelle is the
- nucleus
- lysosome
- chloroplast
- mitochondria
Answer. 2. lysosome
Question 13. Vacuoles are cell structures present in both plant and animal cells. Vacuoles perform the function of
- storing genetic information of the organism
- storing water, food, and waste
- producing proteins
- producing lipids
Answer. 2. storing water, food, and waste
Question 14. The membranous system which helps in the synthesis of fat and proteins and forms vacuoles and vesicles is considered to be the extension of infolded plasmalemma. The given membrane system is known as
- endoplasmic reticulum
- Golgi apparatus
- mitochondria
- microtubules
Answer. 1. endoplasmic reticulum
Question 15. The intracellular digestion of macromolecules in a cell is performed by a membranous bag which contains hydrolases. This bag is known as a
- chromosome
- nucleosome
- phagosome
- lysosome
Answer. 4. lysosome
Chapter 1 The Fundamental Unit Of Life Golgi apparatus
Golgi apparatus are the membrane-bound, sac-like structures called cisternae. They are arranged parallel to each other in stacks. They were discovered by Camillo Golgi in 1898. Golgi body is usually composed of five-eight cisternae in stacks. Vesicles leave the Golgi body from one end known as the cis face. The other end is known as the trans face. The table given below lists some functions of the Golgi apparatus.
Functions of Golgi apparatus:
- It involves the transport of lipids in cells.
- It involves the formation of lysosomes.
- It also takes part in glycosylation and phosphorylation of certain proteins.
- It plays an important role in the production of proteoglycans. Proteoglycans are the molecules present in the extra cellular matrix of animal cells.
Chapter 1 The Fundamental Unit Of Life Mitochondria And Lysosomes
Mitochondrion is a membrane-enclosed organelle found in eukaryotic cells.
Mitochondria are responsible for the production of most of the energy (or ATP) in cells. Therefore, mitochondria are also known as the power house of cells. A mitochondrion is composed of two lipid membranes, enclosing the matrix. The inner membrane gets folded to form numerouscristae. Cristae are the main site for ATP production. Mitochondrial matrix contains mitochondrial DNA and ribosomes.
Functions of mitochondria:
- They produce energy required for cells in the form of ATP.
- They also regulate the free calcium ion concentration in the cytosol.
- They participate in apoptosis or programmed cell death.
Lysosomes are the membrane-bound vesicles, which contain digestive (hydrolytic) enzymes like acid hydrolase. They digest a variety of substances including worn out organelles, food particles, viruses, and bacteria. They are also known as ‘suicide-bags’ of cells as they burst out and release hydrolytic enzymes in the cytosol, where cells are heavily injured.
Functions of lysosomes:
- They digest macromolecules by phagocytosis, endocytosis, or autophagy
- They also take part in auto-cell lysis.
Chapter 1 The Fundamental Unit Of Life Plastids
Do you know what plastids are?
Plastids are major organelles found in plant cells and algae. There are two major types of plastids, namely chromoplasts and leucoplasts.
Chromoplasts are coloured plastids, while leucoplasts are white or colourless plastids. Chromoplasts contain coloured pigments like carotene (orange), xanthophylls (yellow) etc. These pigments are responsible for the colour of plants. Unlike chromoplasts, leucoplasts lack pigments.
Chloroplasts are plastids containing the pigment called chlorophyll. A chloroplast is enclosed by two lipid membranes.
The inner matrix is called the stroma. Thylakoids are the sub-organelles arranged in stacks within the stroma to form grana. The thylakoids are believed to be the main site for photosynthesis. Plastids also contain their own DNA and ribosomes.
Functions of plastids:
- They carry out the process of photosynthesis.
- They contribute to the colour of leaves, flowers etc.
Chapter 1 The Fundamental Unit Of Life Worksheet 4
Question 1.
The cell organelle that is the site for cellular respiration is labeled
- 1
- 2
- 3
- 4
Answer. 2. 2
Question 2. Which cell organelle does the highlighted region represent?
- Plasma membrane
- Golgi apparatus
- Ribosome
- Nucleus
Answer. 2. Golgi apparatus
Question 3. Mitochondria contain their own genetic material for replication. They are also known as semi-autonomous organelles. Which other cell organelle is semi-autonomous?
- Plastids
- Ribosomes
- Golgi complex
- Endoplasmic reticulum
Answer. 1. Plastids
Question 4. Golgi apparatus is made up of stacks of flattened sacs that resemble the endoplasmic reticulum in structure. The main function of the Golgi apparatus is to
- package materials for transport outside the cell
- produce lipids and proteins in the cell
- perform cellular respiration
- perform photosynthesis
Answer. 1. package materials for transport outside the cell
Question 5. A certain cell organelle stores and modifies the substances produced by the cell. The change makes the produced substances active. Which cell organelle is described here?
- Endoplasmic reticulum
- Golgi apparatus
- Mitochondrion
- Ribosome
Answer. 2. Golgi apparatus
Question 6. Chloroplast is the cell organelle present only in the plant cell. Chloroplast is involved in the production of
- glucose
- proteins
- lipids
- water
Answer. 1. glucose
Question 7. Which of the following functions is performed by the mitochondria?
- Synthesizes proteins
- Cellular respiration
- Cellular transport
- Stores genes
Answer. 2. Cellular respiration
Question 8. Which of the following structures is not found in animal cells?
- Lysosome
- Ribosome
- Vacuole
- Plastid
Answer. 4. Plastid
Question 9. Which of the following statements about mitochondrial respiration is false?
- Energy is produced by the mitochondria.
- Glucose is utilized by the mitochondria.
- CO2 is released by the mitochondria.
- O2 is released by the mitochondria.
Answer. 4. O2 is released by the mitochondria.
Question 10. Annie sees a plant which has green leaves as well as leaves with white patches. Annie analyses that photosynthesis is affected in the white patches of the leaves. The white patches appear as a result of the damage to the
- mitochondria
- chloroplast
- ribosome
- vacuole
Answer. 2. chloroplast
Question 11. Mitochondria are double membrane bound cell organelles. Mitochondria are involved in the production of
- glucose
- oxygen
- energy
- proteins
Answer. 3. energy
Question 12. Semi-autonomous organelles are those which can replicate on their own. These organelles contain the genetic information to carry out protein synthesis required for replication. Which of the following organelles is semi-autonomous?
- Ribosomes
- Golgi bodies
- Mitochondria
- Endoplasmic Reticulum
Answer. 3. Mitochondria
Question 13.
The cell organelle that performs photosynthesis is labeled
- 1
- 2
- 3
- 4
Answer. 3. 3
Question 14. Chloroplasts perform the function of
- osmosis
- respiration
- transpiration
- photosynthesis
Answer. 4. photosynthesis
Key Terms Related to Cell Biology for Class 9
Question 15. Which of the following processes does not occur in animal cells?
- Photosynthesis
- Respiration
- Excretion
- Osmosis
Answer. 1. Photosynthesis
Question 16. Which of the following statements about mitochondria is true?
- Glucose is prepared by the mitochondria.
- Glucose is utilized by the mitochondria.
- CO2 is utilized by the mitochondria.
- O2 is produced by the mitochondria.
Answer. 2. Glucose is utilized by the mitochondria.
Chapter 1 The Fundamental Unit Of Life Competitive Worksheet
Question 1. The first person to observe a cell under microscope was
- M. Schleiden
- T. Schwann
- Robert Hook
- A.V.Leeuwenhoek
Answer. 3. Robert Hook
Question 2. Cell theory was propounded by
- Morgan
- Halden
- Schleiden and Schwann
- Robert Hooke
Answer. 3. Schleiden and Schwann
Question 3. The word cell was coined by
- Robert hooke
- Weismann
- Cuvier
- Darwin
Answer. 1. Robert hooke
Question 4. Nucleus discovered by
- Robert Hooke
- Robert Brown
- Dujardin
- Purkinje
Answer. 2. Robert Brown
Question 5. Smallest cells so far known are
- Bacteria
- blue green algae
- PPLOs
- human egg
Answer. 3. PPLOs
Question 6. Which of the following is the longest cell of animal kingdom?
- Bacteria
- Nerve cell
- Virus
- Muscle cell
Answer. 2. Nerve cell
Question 7. Which one of the following is an example of prokaryotic cell?
- Typical plant cell
- Typical animal cell
- Bacteria
- None of these
Answer. 3. Bacteria
Question 8. What is cytology?
- Study of cytoplasm
- Study of structure and composition of cell
- Study of animal cell only
- Study of cell only
Answer. 2. Study of structure and composition of cell
Question 9. Who coined term protoplasm?
- Leeuwenhoek
- Purkinje
- Robert hooke
- Robert Brown
Answer. 2. Purkinje
Question 10. Cell is
- Functional unit of life
- Structural unit of life
- Hereditary unit of life
- all of the above
Answer. 4. all of the above
Question 11. Plasma membrane is made up of
- Proteins and carbohydrates
- Proteins and lipids
- Proteins and nucleic acids
- Proteins, some nucleic acids and lipids
Answer. 2. Proteins and lipids
Question 12. Plant cell wall is mainly composed of
- Sugars
- Cellulose
- Proteins
- lipids
Answer. 2. Cellulose
Question 13. Nucleus was discovered of
- Robert Brown
- Robert Hooke
- A.V. Leeuwenhoek
- Schwann
Answer. 1. Robert Brown
Question 14. A solution is said to be hypotonic when
- Concentration of medium is higher than that of the cell
- Concentration of medium is equal to that of the cell
- Concentration of medium is lower than that of the cell
- None of the above are correct.
Answer. 3. Concentration of medium is lower than that of the cell
Question 15. Cell wall shows
- Complete permeability
- semipermeability
- Differential permeability
- impermeability
Answer. 1. Complete permeability
Question 16. Plasma membrane is
- Impermeable
- formed of cellulose
- selectively permeable
- nonselective
Answer. 3. selectively permeable
Question 17. Ribosome was named by
- Palade
- Porter
- de Duve
- Koliker
Answer. 1. Palade
Question 18. Ribosome consist of
- DNA and protein
- RNA and protein
- RNA and amino acids
- RNA and DNA
Answer. 2. RNA and protein
Question 19. The solution having concentration equal to the concentration of solution of inside the cell is called as
- Isotonic solution
- hypotonic solution
- Hypertonic solution
- all of the above
Answer. 1. Isotonic solution
Question 20. If a cell will be placed in hypotonic solution what will happen to it ?
- The cell will swell and burst
- The cell will become flaccid
- It will remain unchanged
- None of the above
Answer. 1. The cell will swell and burst
Question 21. What is more abundant in smooth endoplasmic reticulum?
- Cistemae and vesicle
- Tubules
- Tubules and vesicles
- Cistemae
Answer. 2. Cistemae and vesicle
Question 22. Mitochondria are concerned with
- Kreb cycle
- C, cycle
- glycolysis
- none of the above
Answer. 1. Kreb cycle
Question 23. Which of the following organelle is the site of Kreb cycle?
- Ribosome’s
- Lysosomes
- eukaryotic cells
- Nucleus
Answer. 3. eukaryotic cells
Question 24. Mitochondria are absent in
- Prokaryotic cells
- RBC of mammals
- eukaryotic cells
- (A) and (B) Both
Answer. 4. (1) and (2) Both
Question 25. Mitochondria stores energy in from of
- Heat energy
- ATP
- light energy
- none of the above
Answer. 2. ATP
Question 26. The ATP synthesizing units of Mitochondria are
- Oxysomes
- peroxysomes
- glyoxysomes
- lysosomes
Answer. 1. Oxysomes
Question 27. Lipid synthesis is performed by
- Rough ER
- smooth ER
- both of above
- none of the above
Answer. 3. both of above
Question 28. Who observed Mitochondria at first?
- Porter
- Palade
- Koliker
- Camilo Golgi
Answer. 3. Koliker
Question 29. Detoxification of body is done by?
- Mitochondria
- lysosomes
- Smooth endoplasmic reticulum
- rough endoplasmic reticulum
Answer. 3. Smooth endoplasmic reticulum
Question 30. Golgi apparatus is made of
- Cisternae
- vesicles
- golgian vacuoles
- all of the above
Answer. 4. all of the above
Question 31. Which of the following is called as ‘Suicidal bags’ ?
- Centrosome
- Lysosome
- Microsome
- Mesosomes
Answer. 2. Lysosome
Question 32. Eukaryotic ribosomes are
- 30s
- 50s
- 80s
- 70s
Answer. 3. 80s
Question 33. Plastids that are white in colour (Pigment free)
- chloroplast
- lysosome
- leucoplast
- Chromoplast
Answer. 3. leucoplast
Question 34. Striking difference between a plant cell and an animal cell is due to the presence
- mitochondria
- plasma membrane
- cell wall
- ribosome
Answer. 3. cell wall
Question 35. Tonoplast is the membrane surrounding the
- cytoplasm
- vacuole
- nucleus
- mitochondria
Answer. 2. vacuole
Question 36. Lysosomes are responsible for
- protein synthesis
- digestion of organic molecules
- fat synthesis
- fat emulsification
Answer. 2. digestion of organic molecules
Question 37. In prokaryotic cell
- nucleus is developed
- membrane bounded organelles are present
- double membrane bounded organelles are absent
- none of these
Answer. 3. double membrane bounded organelles are absent
Question 38. A typical plant cell contains
- cell well
- plastids
- large vacuole
- all of the above
Answer. 4. all of the above
Question 39. The waste disposal system of cell is formed by
- lysosomes
- peroxysomes
- mitochondria
- glyoxysomes
Answer. 1. lysosomes
Question 40. In which cell Centriole is absent?
- plant cell
- Animal cell
- Both of above
- None of above
Answer. 1. plant cell