Saturday, July 26, 2025

RBSE Class 9 Science Chapter 5 The Fundamental Unit of Life Solutions

This post contains all the main and important topics which have complete and detailed solutions of Chapter 5 the fundamental unit of life .These solutions are based on the latest Rajasthan Board syllabus and prescribe NCERT book.

RBSE Class 9 Science Chapter 5 The Fundamental Unit of Life Solutions


Board

RBSE

Subject

Science

Chapter

The   fundamental unit of life

No. of Intext questions

 

No. of End exercise questions

 

Prescribed Book

 NCERT Science

 

 

The Fundamental Unit of Life Questions- Answer

 

                                              

Intext Questions


 Answers of Questions on Page 51

 

Q.1 Who discovered cell, and how?

Ans.     

Robert Hooke (1165) discovered the cell. He examined a fine slice of a cork under a self-manufactured primitive microscope. He observed that the slice of cork resembled the structure of a honey comb. These were actually dead cell walls observed by Robert Hooke. He named these tiny compartment cellulae now termed cells.


 

Q.2 Why is the cell called the structural and functional

unit of life?

Ans.     

Cell is the structural unit of life because; all living organisms are made up of cells. Cell is functional unit of life because functions of life like nutrition, respiration, excretion and reproduction etc. are performed by cell only. 


Answers of Questions on Page 53

 


Q.1 How do substances like CO2 and  water move in and out of the cell? Discuss.

Ans.     

Carbon dioxide (CO2) moves in and out of the cells by the process of diffusion. In this movement particles of various substances move from the region of the higher concentration to the region of the lower concentration.

 

Water moves in and out of the cells by osmosis. This is the movement of water from the region of its higher concentration to the region of its lower concentration through a semi-permeable membrane. 


 

Q.2 Why is plasma membrane called a selectively permeable membrane?

Ans.     

Plasma membrane allows the movement of only selected molecules across it, so it is called selectively permeable membrane. For example, It allows the entry of gases through diffusion and water through osmosis. Larger molecules may pass through the plasma membrane by an active process. Plasma membrane is impermeable to certain other materials. That’s why, it is selectively permeable. 

 

Answers of Questions on Page 55


 Q.1 Fill in the gaps in the following table illustrating differences between prokaryotic and eukaryotic cells.


differences between prokaryotic and eukaryotic cells.
Answer



Answers of Questions on Page 57

 

Q.1 Can you name the two organelles, we have studied that contain their own genetic material?

Ans.     

Yes, mitochondria and chloroplast.

 

Q.2 If the organisation of a cell is destroyed due to some physical or chemical influence, what will happen?

Ans.     

If organisation is destroyed or plasma membrane is disturbed the cell would not be able to maintain the internal environment and chemical uniqueness. It will lead to death of the cell, Lysosomes would cause autolysis of the cell.

 

Q.3 Why are lysosomes known as suicide bags?

Ans.     

Lysosomes are membrane-bound sacs which contain hydrolytic enzymes. If lysosomes burst, enzymes are released and digest other organelles of the same cell. Therefore, they are known as ‘suicide bags’.

 

Q.4 Where are proteins synthesised inside the cell?

Ans.     

Proteins are synthesized over the ribosomes. 

 

 

Answers of End Exercise Questions on Page 59


Q.1 Make a comparison and write down ways in which plant cells are different from animal cells.

Ans.


Difference between plant cell and animal cell

Q.2 How is a prokaryotic cell different from a eukaryotic cell?

Ans. 


 
Q.3 What would happen if the plasma membrane ruptures or breaks down?

Ans.     

If plasma membrane is ruptures or break down, the cell would not be able to maintain the internal environment and chemical uniqueness. It will lead to death of the cell. Lysosomes would causes autolysis of the cell.

 

Q.4 What would happen to the life of a cell if there was no Golgi apparatus?

Ans.     

Golgi apparatus packages and dispatch enzymes, hormones and other necessary lipids and proteins secreted by ER to target inside and outside of the cell.

The digestive enzymes which remain concealed in lysosome will remain free in the cytoplasm killing the other cell organelles. So in absence of Golgi apparatus cell would die.

 

Q.5 Which organelle is known as the powerhouse of the cell? Why?

Ans.     

Mitochondria are known as the powerhouse of the cell because the energy required for various life activities is released by mitochondria in the form of ATP molecule. Mitochondria contain enzymes that are needed for oxidation of food present in the cells to CO2 and water. Oxidation of food releases energy which is used to form high energy ATP molecules. ATP is known as energy currency of the cell and these are used as cellular fuel. 

 

Q.6 Where do the lipids and proteins constituting the cell membrane get synthesized?

Ans.     

Proteins are synthesized over ribosomes which are attached to rough endoplasmic reticulum while lipids are synthesized over smooth endoplasmic reticulum.

 

Q.7 How does an Amoeba obtain its food?

Ans.     

Amoeba is unicellular organism. It acquires its food by the process of endocytosis.  Plasma membrane of Amoeba is flexible which helps it to engulf food particles. Phagosome combines with lysosome to produce digestive or food vacuole. Digestion occurs in food vacuole. The digested food passes into surrounding cytoplasm. The undigested residue is thrown out of the cell. 





Q.8 What is osmosis?

Ans.     

Osmosis: Osmosis is the process of Diffusion of water from the region of its higher concentration (pure water or dilute solution) to the region of its lower concentration through a semi-permeable membrane is called osmosis.

 


Q.9 Carry out the following osmosis experiment:

Take four peeled potato halves and hollow each one out to make potato cups. One of these potato cups should be made from boiled potato. Put each potato cup in through containing water. Now

 (a) keep cup A empty.

 (b) Put one teaspoon sugar in cup B

(c) Put one teaspoon salt in cup C

(d) Put one teaspoon sugar in boiled potato cup D.

 Keep this set up for two hours. Then observe the four potato cups and answer the following:

Explain why water gathers in the hollowed portion of B and C.

Why is potato A necessary for this experiment.

Explain why water does not gather in the hollowed out portions A and D.

Ans.    

(i)   Water gathers in the hollowed portion B and C because living plasma membrane of potato cup acts as semi-permeable membrane. There is higher concentration of water in through than the sugar solution of B and salt solution of C potato cup respectively. So, by process of osmosis water moves into  potato cups B and C.


(ii)  Potato A functions as control experiment which indicates that the cavity does not induce movement of water.


(iii) Water does not gather in the potato cup A because it does not possess higher osmotic concentration than the cell of potato.

Potato cup D is boiled cup. It does not have living cell and the membrane of the potato cells have lost their permeability. As a result, when teaspoon of sugar is added into hollowed portion of boiled potato cup D, water does not come out from within the potato cells into the hollowed protein.


osmosis experiment of potato class 9 science

Q10. Which type of cell division for growth ands repair of body and which type is involved in formation of gametes?

Ans.

For growth and repair of body- Mitosis

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