NCERT Solutions for Class 9 Science Chapter 5 The Fundamental Unit Of Life are provided here with simple step-by-step explanations. These solutions for The Fundamental Unit Of Life are extremely popular among class 9 students for Science The Fundamental Unit Of Life Solutions come handy for quickly completing your homework and preparing for exams. All questions and answers from the NCERT Book of class 9 Science Chapter 5 are provided here for you for free. You will also love the ad-free experience on Meritnation’s NCERT Solutions. All NCERT Solutions for class 9 Science are prepared by experts and are 100% accurate.
Page No 33:
Question 1:
Which of the following can be made into crystal?
(a) A Bacterium
(b) An Amoeba
(c) A Virus
(d) A Sperm
Answer:
Crystallization of virus is transforming them into organized solid particles. For the process of crystallization very low temperature is needed which can stop the metabolic and other functions of a living cell. As virus lives on the border line of living organisms, it is non living in nature unless they find a host cell, they can be crystallized easily.
Hence, the correct answer is option (c).
Page No 33:
Question 2:
A cell will swell up if
(a) The concentration of water molecules in the cell is higher than the concentration of water molecules in surrounding medium
(b) The concentration of water molecules in surrounding medium is higher than water molecules concentration in the cell
(c) The concentration of water molecules is same in the cell and in the surrounding medium
(d) Concentration of water molecules does not matter
Answer:
When a cell is placed in a hypotonic solution where the concentration of water molecules in surrounding medium is higher than the concentration of water molecules in the cell, it will swell up due to the process of endosmosis.
Hence, the correct answer is option (b).
Page No 33:
Question 3:
Chromosomes are made up of
(a) DNA
(b) protein
(c) DNA and protein
(d) RNA
Answer:
Chromosomes are highly condensed form of chromatin which is made up of single molecule of DNA and proteins. Chromosomal proteins help in DNA packaging within a small space of nucleus.
Hence, the correct answer is option (c).
Page No 33:
Question 4:
Which of these options are not a function of Ribosomes?
(i) It helps in manufacture of protein molecules
(ii) It helps in manufacture of enzymes
(iii) It helps in manufacture of hormones
(iv) It helps in manufacture of starch molecules
(a) (i) and (ii)
(b) (ii) and (iii)
(c) (iii) and (iv)
(d) (iv) and (i)
Answer:
Ribosomes play an important role in the synthesis of protein molecules and all enzymes are made up of unique chains of amino acids.
All the hormones are not made up of protein, few of them are lipid derivatives also.
The starch molecules are synthesized by plastids.
Hence, the correct answer is option (c).
Page No 34:
Question 5:
Which of these is not related to endoplasmic reticulum?
(a) It behaves as transport channel for proteins between nucleus and cytoplasm
(b) It transports materials between various regions in cytoplasm
(c) It can be the site of energy generation
(d) It can be the site for some biochemical activities of the cell
Answer:
In a cell, mitochondria performs the function of energy generation. This is not the function of endoplasmic reticulum.
Hence, the correct answer is option (c).
Page No 34:
Question 6:
Following are a few definitions of osmosis
Read carefully and select the correct definition
(a) Movement of water molecules from a region of higher concentration to a region of lower concentration through a semipermeable membrane
(b) Movement of solvent molecules from its higher concentration to lower concentration
(c) Movement of solvent molecules from higher concentration to lower concentration of solution through a permeable membrane
(d) Movement of solute molecules from lower concentration to higher concentration of solution through a semipermeable membrane
Answer:
The correct definition of osmosis is 'Movement of water molecules from a region of higher concentration to a region of lower concentration through a semipermeable membrane.'
Hence, the correct answer is option (a).
Page No 34:
Question 7:
Plasmolysis in a plant cell is defined as
(a) break down (lysis) of plasma membrane in hypotonic medium
(b) shrinkage of cytoplasm in hypertonic medium
(c) shrinkage of nucleoplasm
(d) none of them
Answer:
When a plant cell is kept in hypertonic medium, exosmosis occurs which means water leaves the cell resulting in shrinkage of cytoplasm. This process is defined as plasmolysis.
Hence, the correct answer is option (b).
Page No 34:
Question 8:
Which of the following are covered by a single membrane?
(a) Mitochondria
(b) Vacuole
(c) Lysosome
(d) Plastid
Answer:
Mitochondria and chloroplast are double membrane bound organelles whereas lysosomes and vacuoles both are single membrane bound organelles.
Hence, the correct answer is both option (b) and (c).
Page No 34:
Question 9:
Find out the false sentences
(a) Golgi apparatus is involved with the formation of lysosomes
(b) Nucleus, mitochondria and plastid have DNA; hence they are able to make their own structural proteins
(c) Mitochondria is said to be the power house of the cell as ATP is generated in them.
(d) Cytoplasm is called as protoplasm
Answer:
The term cytoplasm and protoplasm are often used interchangeably but both are different from each other. Protoplasm is a colorless material which comprises the living part of the cell, that is the nucleus, cytoplasm and other cell organelles. So, the cytoplasm is a part of protoplasm.
Hence, the correct answer is option (d).
Page No 34:
Question 10:
Find out the correct sentence
(a) Enzymes packed in Lysosomes are made through RER (rough endoplasmic reticulum).
(b) Rough endoplasmic reticulum and smooth endoplasmic reticulum produce lipid and protein respectively.
(c) Endoplasmic reticulum is related with the destruction of plasma membrane.
(d) Nucleoid is present inside the nucleoplasm of eukaryotic nucleus.
Answer:
Rough endoplasmic reticulum performs the function of synthesis of protein due to the presence of ribosomes. These proteins are enzymes which are packed in lysosomes.
Rough endoplasmic reticulum and smooth endoplasmic reticulum produce protein and lipid respectively. Smooth endoplasmic reticulum is related with the formation of plasma membrane. Nucleoid is an irregularly shaped region present inside the prokaryotic cell.
Hence, the correct answer is option (a).
Page No 35:
Question 11:
Which cell organelle plays a crucial role in detoxifying many poisons and drugs in a cell?
(a) Golgi apparatus
(b) Lysosomes
(c) Smooth endoplasmic reticulum
(d) Vacuoles
Answer:
Smooth endoplasmic reticulum is the cell organelle which plays a crucial role in detoxifying poisons and drugs from the liver cells of vertebrate.
Hence, the correct answer is option (c).
Page No 35:
Question 12:
The proteins and lipids, essential for building the cell membrane, are manufactured by
(a) rough endoplasmic reticulum
(b) golgi apparatus
(c) plasma membrane
(d) mitochondria
Answer:
Rough endoplasmic reticulum is the cell organelle where the production of protein take place and that of lipids in smooth endoplasmic reticulum.
Hence, the correct answer is (a).
Page No 35:
Question 13:
The undefined nuclear region of prokaryotes are also known as
(a) nucleus
(b) nucleolus
(c) nucleic acid
(d) nucleoid
Answer:
The undefined nuclear region of prokaryotes is also known as nucleoid. The prokaryotic cell lacks the true nucleus and a circular DNA lies naked in the cytoplasm of the cell.
Hence, the correct answer is option (d).
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Question 14:
The cell organelle involved in forming complex sugars from simple sugars are
(a) endoplasmic reticulum
(b) ribosomes
(c) plastids
(d) golgi apparatus
Answer:
Golgi apparatus is involved in the formation of complex sugars from simple sugars.
Hence, the correct answer is option (d).
Page No 35:
Question 15:
Which out of the following is not a function of vacuole?
(a) Storage
(b) Providing turgidity and rigidity to the cell
(c) Waste excretion
(d) Locomotion
Answer:
Out of all, locomotion is not the function of vacuole. For locomotion, cilia or flagella are present on the single celled organisms.
Hence, the correct answer is option (d).
Page No 35:
Question 16:
Amoeba acquires its food through a process, termed
(a) exocytosis
(b) endocytosis
(c) plasmolysis
(d) exocytosis and endocytosis both
Answer:
Endocytosis is the process of ingestion of food particles inside the cell which also occurs in amoeba to acquire food.
Hence, the correct answer is option (b).
Page No 35:
Question 17:
Cell wall of which one of these is not made up of cellulose?
(a) Bacteria
(b) Hydrilla
(c) Mango tree
(d) Cactus
Answer:
Hydrilla, Mango and cactus all are plants, so their cell wall is made up of cellulose. On the other hand, the cell wall of bacteria is made up of polysaccharide, peptidoglycan.
Hence, the correct answer is option (a).
Page No 36:
Question 18:
Silver nitrate solution is used to study
(a) endoplasmic reticulum
(b) golgi apparatus
(c) nucleus
(d) mitochondria
Answer:
Silver nitrate solution is used to stain Golgi apparatus as it is dynamic in nature and actively uptakes the stain. This method is known as silver staining method. It helps to clearly observe the vesicles of Golgi apparatus against the colourless background.
Hence, the correct answer is option (b).
Page No 36:
Question 19:
Organelle other than nucleus, containing DNA is
(a) endoplasmic reticulum
(b) golgi apparatus
(c) mitochondria
(d) lysosome
Answer:
In a cell, other than nucleus, organelles like mitochondria and chloroplast contain their own DNA.
Hence, the correct answer is option (c).
Page No 36:
Question 20:
Kitchen of the cell is
(a) mitochondria
(b) endoplasmic reticulum
(c) chloroplast
(d) golgi apparatus
Answer:
In plants, the food is prepared inside the chloroplast by the process of photosynthesis and thus it is known as the kitchen of the cell.
Hence, the correct answer is option (c).
Page No 36:
Question 21:
Lipid molecules in the cell are sythesized by
(a) smooth endoplasmic reticulum
(b) rough endoplasmic reticulum
(c) golgi apparatus
(d) plastids
Answer:
Lipid molecules are synthesized in smooth endoplasmic reticulum, whereas proteins are synthesized in rough endoplasmic reticulum.
Hence, the correct answer is option (a).
Page No 36:
Question 22:
Cell arises from pre-existing cell was stated by
(a) Haeckel
(b) Virchow
(c) Hooke
(d) Schleiden
Answer:
Rudolf Virchow proposed that the cell arises from pre-existing cells. This point was added by him in the cell theory.
Hence, the correct answer is option (b).
Page No 36:
Question 23:
Cell theory was given by
(a) Schleiden and Schwann
(b) Virchow
(c) Hooke
(d) Haeckel
Answer:
The cell theory was given by Schleiden and Schwann which states that all the plants and animals are composed of cells and that the cell is the basic unit of life.
Hence, the correct answer is option (a).
Page No 36:
Question 24:
The only cell organelle seen in prokaryotic cell is
(a) mitochondria
(b) ribosomes
(c) plastids
(d) lysosomes
Answer:
As the organelles found in prokaryotic cell are not bound by any membrane and out of all given options, the only cell organelle seen in prokaryotic cell are ribosomes as they are not surrounded by any membrane.
Hence, the correct answer is option (b).
Page No 36:
Question 25:
Organelle without a cell membrane is
(a) ribosome
(b) golgi apparatus
(c) chloroplast
(d) nucleus
Answer:
The cell organelle without a membrane is ribosome. Golgi apparatus, chloroplast and nucleus are double membrane-bound organelles.
Hence, the correct answer is option (a).
Page No 37:
Question 26:
1 µm is
(a) 10–6 m
(b) 10–9 m
(c) 10–10 m
(d) 10–3 m
Answer:
1 µm is equal to 10–6 m.
Hence, the correct answer is option (a).
Page No 37:
Question 27:
Lysosome arises from
(a) endoplasmic reticulum
(b) golgi apparatus
(c) nucleus
(d) mitochondria
Answer:
Golgi apparatus is involved in the formation of lysosomes.
Hence, the correct answer is option (b).
Page No 37:
Question 28:
Living cells were discovered by
(a) Robert Hooke
(b) Purkinje
(c) Leeuwenhoek
(d) Robert Brown
Answer:
Robert Hooke discovered the dead cells of the bark of a tree under his self made microscope whereas, Leeuwenhoek was the one who observed the living cells using his primitive microscope.
Hence, the correct answer is option (c).
Page No 37:
Question 29:
Select the odd one out
(a) The movement of water across a semi permeable membrane is affected by the amount of substances dissolved in it.
(b) Membranes are made of organic molecules like proteins and lipids
(c) Molecules soluble in organic solvents can easily pass through the membrane.
(d) Plasma membranes contain chitin sugar in plants
Answer:
Plasma membrane of plants contain cellulose instead of chitin sugars.
Hence, the correct answer is option D.
Page No 37:
Question 30:
Why are lysosomes known as ‘suicide-bags’ of a cell?
Answer:
Page No 37:
Question 31:
Do you agree that “A cell is a building unit of an organism”. If yes, explain why?
Answer:
Yes, a cell is a building unit of an organism because it is a fundamental structural and functional unit of life. Cells performing similar function forms a tissue and group of tissue forms organs and organs forms the organ system which further forms an organism. In a single cell organism, the single cell performs all the essential life processes.
Page No 37:
Question 32:
Why does the skin of your finger shrink when you wash clothes for a long time?
Answer:
The soap solution in which clothes are washed is a concentrated- hypertonic solution which makes the water moves out of the cells of the fingers which eventually shrinks the fingers due to exosmosis when the clothes are washed for long.
Page No 37:
Question 33:
Why is endocytosis found in animals only?
Answer:
Endocytosis is the process of ingestion of foreign material by the cells through the plasma membrane. Endocytosis is found only in animals because cell wall is absent in animals. Hence the movement of substances inside the cell is easier in animals than in plants due to the barrier of cell wall in plant cells.
Page No 37:
Question 34:
A person takes concentrated solution of salt, after sometime, he starts vomiting. What is the phenomenon responsible for such situation? Explain.
Answer:
On the consumption of concentrated salt solution, the cells of the alimentary canal of the person undergoes exosmosis due to the hypertonic condition outside the cell of the alimentary canal and causes dehydration which results in vomiting.
Page No 37:
Question 35:
Name any cell organelle which is non membranous.
Answer:
Ribosomes are the non membranous cell organelles.
Page No 37:
Question 36:
We eat food composed of all the nutrients like carbohydrates, proteins, fats, vitamins, minerals and water. After digestion, these are absorbed in the form of glucose, aminoacids, fatty acids, glycerol etc. What mechanisms are involved in absorption of digested food and water?
Answer:
Absorption is the process in which nutrients are absorbed from the small intestine and are taken to blood and lymph. This process is facilitated by the simple diffusion method where molecules move from higher concentration to lower concentration region. Thus, absorption of digested food takes place by the process of diffusion and that of water takes place by osmosis.
Page No 38:
Question 37:
If you are provided with some vegetables to cook. You generally add salt into the vegetables during cooking process. After adding salt, vegetables release water. What mechanism is responsible for this?
Answer:
After adding salt to the vegetables, it releases water due to the process of exosmosis. In this process, the external environment becomes hypertonic and the concentration of water outside the cell is lower than inside the cell. As a result, the water diffuses out from the cells of the vegetables.
Page No 38:
Question 38:
If cells of onion peel and RBC are separately kept in hypotonic solution, what among the following will take place? Explain the reason for your answer.
(a) Both the cells will swell.
(b) RBC will burst easily while cells of onion peel will resist the bursting to some extent.
(c) a and b both are correct.
(d) RBC and onion peel cells will behave similarly.
Answer:
When a cell is kept in hypotonic solution, water moves inside the cell, thus endosmosis occur. Since RBCs does not have a plasma membrane, they will swell to an extent and then will burst out. On the other hand, because of the presence of cell wall, the plant cell will just swell due to endosmosis and will not burst.
Hence the correct answer is option C.
Page No 38:
Question 39:
Bacteria do not have chloroplast but some bacteria are photoautorophic in nature and perform photosynthesis. Which part of bacterial cell performs this?
Answer:
The pigments and enzymes involved in photosynthesis are found in the infoldings (vesicles) of plasma membrane of most of the photosynthetic bacteria. These vesicles trap sunlight to carry out the process of photosynthesis.
Page No 38:
Question 40:
Match the following A and B
| (A) | (B) | ||
| (a) | Smooth endoplasmic reticulum | (i) | Amoeba |
| (b) | Lysosome | (ii) | Nucleus |
| (c) | Nucleoid | (iii) | Bacteria |
| (d) | Food vacuoles | (iv) | Detoxification |
| (e) | Chromatin material and nucleolus | (v) | Suicidal bag |
Answer:
| (A) | (B) | ||
| (a) | Smooth endoplasmic reticulum | (i) | Detoxification |
| (b) | Lysosome | (ii) | Suicidal bag |
| (c) | Nucleoid | (iii) | Bacteria |
| (d) | Food vacuoles | (iv) | Amoeba |
| (e) | Chromatin material and nucleolus | (v) | Nucleus |
Page No 38:
Question 41:
Write the name of different plant parts in which chromoplast, chloroplast and leucoplast are present.
Answer:
Plastids are present only in plant cells which are of two types:
- Chromoplasts (coloured plastids)
- Leucoplasts (white or colourless plastids)
Chloroplast is found in the green part of the plant i.e. in leaves
Leucoplast are found in the colourless part of the plant i.e in the seeds, tuber and roots.
Page No 38:
Question 42:
Name the organelles which show the analogy written as under
(a) Transporting channels of the cell________
(b) Power house of the cell________
(c) Packaging and dispatching unit of the cell________
(d) Digestive bag of the cell________
(e) Storage sacs of the cell________
(f) Kitchen of the cell________
(g) Control room of the cell________
Answer:
(a) Endoplasmic reticulum
(b) Mitochondria
(c) Golgi apparatus
(d) Lysosome
(e) Vacuoles
(f) Chloroplast
(g) Nucleus
Page No 38:
Question 43:
How is a bacterial cell different from an onion peel cell?
Answer:
| Bacterial cell | Onion peel cell |
| It is a prokaryotic cell | It is a eukaryotic plant cell |
| Membrane bound organelles are absent | Membrane bound organelles are present |
| Vacoule is absent | Vacoule is present |
| Cell wall is made up of peptidoglycan | Cell wall is made up of cellulose |
Page No 38:
Question 44:
How do substances like carbon dioxide (CO2) and water (H2O) move in and out of the cell?
Answer:
Substances like carbon dioxide move in and out of the cell through the process of diffusion and water moves in and out of the cell through the process of osmosis.
Page No 38:
Question 45:
How does amoeba obtain its food?
Answer:
Amoeba obtain its food with the help of pseudopodia (false feet) which extends out from the body and surrounds the food particle and engulfing it in the food vacoule. This process of ingestion of food in amoeba is known as endocytosis. 
Page No 38:
Question 46:
Name the two organelles in a plant cell that contain their own genetic material and ribosomes.
Answer:
The two cell organelles in a plant cell that contain their own genetic material and ribosomes are Chloroplast and Mitochondria.
Page No 38:
Question 47:
Why are lysosomes also known as “scavengers of the cells”?
Answer:
Lysosomes are known as “scavengers of the cells” because of the presence of strong digestive enzymes which destroys all the worn out particles or harmful pathogens which are not useful to the cell. It works as a waste disposal system of the cell.
Page No 38:
Question 48:
Which cell organelle controls most of the activities of the cell?
Answer:
The nucleus of the cell is responsible for most of the activities of the cell (mainly due to the presence of genetic material).
Page No 39:
Question 49:
Which kind of plastid is more common in
(a) roots of the plant
(b) leaves of the plant
(c) flowers and fruits
Answer:
(a) Roots of the plant contains leucoplast which are colourless plastids and act as storage of food.
(b) Leaves of the plant contain chloroplast which contain green pigment chlorophyll and helps in photosynthesis.
(c) Flowers contain coloured plastids, chromoplast that attract pollinators.
Page No 39:
Question 50:
Why do plant cells possess large sized vacuole?
Answer:
Usually mature plant cells found to have large sized vacuole as it helps to maintain the turgidity of the cell, due to the presence of cell sap in the vacuole. The large sized vacuole provides rigidity, turgidity and support to the plant cell.
Page No 39:
Question 51:
How are chromatin, chromatid and chromosomes related to each other?
Answer:
Chromatin is a fine thread like long structure found in the nucleus prior to the division of the cell. At the time of division, these chromatin material condense to form chromosomes which are nothing but supercoiled chromatin threads. When the fully condensed chromosomes are formed, it possess two arms which are known as chromatids.
Page No 39:
Question 52:
What are the consequences of the following conditions?
(a) A cell containing higher water concentration than the surrounding medium.
(b) A cell having low water concentration than the surrounding medium.
(c) A cell having equal water concentration to its surrounding medium.
Answer:
(a) The cell will loose water and will shrink due to exosmosis.
(b) The cell will gain water and will swell due to endosmosis.
(c) No changes will be seen in the size of the cell.
Page No 39:
Question 53:
Draw a plant cell and label the parts which
(a) determines the function and development of the cell.
(b) packages materials coming from the endoplasmic reticulum.
(c) provides resistance to microbes to withstand hypotonic external media without bursting.
(d) is site for many biochemical reactions necessary to sustain life.
(e) is a fluid contained inside the nucleus.
Answer:
(a) Nucleus - It determines the function and development of the cell.
(b) Golgi apparatus - It packages materials coming from the endoplasmic reticulum.
(c) Cell wall - It provides resistance to microbes to withstand hypotonic external media without bursting.
(d) Cytoplasm - It is site for many biochemical reactions necessary to sustain life.
(e) Nucleoplasm - It is a fluid contained inside the nucleus.
Page No 39:
Question 54:
Illustrate only a plant cell as seen under electron microscope. How is it different from animal cell?
Answer:
Plant cell-
| Plant cell | Animal cell |
| Cell wall is present | Cell wall is absent |
| Plastids are present | Plastids are absent |
| Centrioles are absent. | Centrioles are present. |
| A large vacoule is present | Small vacoules are present. |
| Lysosomes are rarely present. | Lysosomes are present. |
Page No 39:
Question 55:
Draw a neat labelled diagram of an animal cell.
Answer:
An animal cell-
Page No 39:
Question 56:
Draw a well labelled diagram of an eukaryotic nucleus. How is it different from nucleoid?
Answer:
Eukaryotic nucleus
| Nucleus | Nucleoid |
| It is bound by double nuclear membrane | Nuclear membrane is absent |
| It contains nucleolus and nucleoplasm | It does not contain nucleolus and nucleoplasm |
| Spherical shaped structure | Irregularly shaped structure |
| It is found in eukaryotes | It is found in prokaryotes |
| It has number of chromosomes | It has a single chromosome |
Page No 39:
Question 57:
Differentiate between rough and smooth endoplasmic reticulum. How is endoplasmic reticulum important for membrane biogenesis?
Answer:
| Rough endoplasmic reticulum | Smooth endoplasmic reticulum |
| RER possess ribosomes on its membrane, hence looks rough. | SER do not possess any ribosomes on its membrane, hence looks smooth. |
| It is involved in the process of protein synthesis. | It is involved in the process of lipid synthesis. |
Membrane biogenesis is the formation of cell membrane with the help of protein and lipids. Smooth ER helps in the formation of lipids and rough ER helps in the formation of proteins which jointly helps in the formation of cell membrane. Hence endoplasmic reticulum plays crucial role in the formation of cell membrane.
Page No 39:
Question 58:
In brief state what happens when
(a) dry apricots are left for sometime in pure water and later transferred to sugar solution?
(b) a Red Blood Cell is kept in concentrated saline solution?
(c) the Plasma-membrane of a cell breaks down?
(d) rheo leaves are boiled in water first and then a drop of sugar syrup is put on it?
(e) golgi apparatus is removed from the cell?
Answer:
(a) On leaving the dry apricots in pure water, endosmosis occurs and the apricots swells but after they are soaked in sugar solution, they undergo exosmosis and shrinks.
(b) RBC in concentrated saline water will loose water from it and shrink eventually.
(c) The cell dies upon the breaking of the plasma membrane as it looses its crucial components which helps in the functioning of the cell.
(d) When rheo leaves or any leaf is boiled, the plant cell dies. Hence there will be no change in the cells of the leaf and it will not undergo plasmolysis when sugar syrup is dropped on it.
(e) On removal of golgi aparatus, the function of modification and packaging of material will not occur and the formation of all type of vesicles will also stop.
Page No 39:
Question 59:
Draw a neat diagram of plant cell and label any three parts which differentiate it from animal cell.
Answer:
The plant cell have a cell wall, chloroplast and large sized vacuole which are absent in an animal cell.
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