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NCERT · Class 10 · Science

Chapter 5: Life Processes

Practice each question, then open the answer or worked solution.

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Textbook exercises

33 questions
Q31Written answer

Describe double circulation in human beings. Why is it necessary?

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Worked solution

Ans: Double circulation is a process of blood circulation in which blood flows twice through the heart.

It constitutes of two steps:

1. Pulmonary circulation.

2. Systemic circulation.

Pulmonary circulation starts from the right ventricle and ends in the left atrium after the process of oxygenation occurs from the lungs.

While the systemic circulation starts from the left ventricle and ends in the right atrium after the materials get exchanged throughout the body.



Importance Of Double Circulation:

The oxygen is supplied more efficiently to the body cells when there is a separation of oxygenated and deoxygenated blood. The efficient oxygen supply in human beings is very useful for the maintenance of high blood pressure for various processes and also provides pure blood to reach various parts of the body.


Q32Written answer

What are the differences between the transport of materials in the xylem and phloem?

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Ans: The differences between the transport of materials in the xylem and phloem are:

Transport Of Materials In Xylem

Transport Of Materials In Phloem

(i) They help in the transportation of water.

(i) They help in the transportation of water and minerals.

(ii) Xylem elements consist of vessels and tracheids.

(ii) Phloem elements consist of sieve tubes and companion cells.

(iii) Transportation starts from the roots to various parts of the plant.

(iii) Transportation starts from the leaves and then moves towards the roots.

(iv) Helps in providing water and minerals to all parts of the plant.

(iv) Helps in providing nutrients to all parts of the plant.


Q33Written answer

Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.

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Ans: The comparison of alveoli in the lungs and nephrons in the kidneys are:

                            Alveoli

                      Nephron

Structure

(i) Alveoli are air-sacs that are present in the lungs in the form of balloon-like structures.

(ii) The cell walls of alveoli are thin, only one cell thick and composed of an extensive network of blood capillaries.

Structure

(i) Nephrons are present inside the kidneys in the form of tubular structures.

(ii) Nephrons consist of three main parts - glomerulus, bowman’s capsule, and a long renal tube. They are composed of a cluster of thin-walled capillaries.

(Image will be uploaded soon)

(Image will be uploaded soon)

Function

(i) The gaseous exchange of oxygen and carbon dioxide occurs in between the blood of the capillaries that are present around the alveoli and the gases that are present in the alveoli. 

In alveoli, there is no selective reabsorption.

Function

(i) Nephron helps in the process of filtration of the blood and removal of wastes. The solutes and excess water is filtered out when the filtration starts in the nephron. The selective reabsorption of essential molecules like amino acids, sodium salts, glucose, and water occurs before the formation of the final filtrate (urine).

(ii) The exchange of gases for the process of respiration takes place in alveoli.

(ii) The basic filtration unit for excretion is nephrons.