NCERT Class 10 Chapter 7 Life Process CBSE Board Sample Problems Short Answer

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What are the components of the gastric juice? Write their functions?


Gastric juice contains three components:

Hydrochloric acid enzyme pepsin and mucus. Their functions are:

  • Hydrochloric acid in the stomach is used to make the medium acidic to facilitate the action of the enzyme pepsin and to kill germs if any.

  • Enzyme pepsin digests proteins to convert them in to peptones.

  • The mucus helps to protect the stomach wall from its own secretions of hydrochloric acid.


What are the end products formed during fermentation in yeast? Under what conditions a similar process takes place in our body that leads to muscle cramps?


  • The end products formed during anaerobic respiration or fermentation in yeast are carbon dioxide and ethanol along with ATP. A similar process is seen in our body when there is lack of oxygen in muscles, leading to the muscle fatigue.

  • It results due to the accumulation of lactic acid produced during anaerobic respiration of glucose. The energy or ATP produced during anaerobic respiration is much less as compared to aerobic respiration.


Give reason:

(i) Water enter continuously into the root xylem?

(ii) Bile does not contain any enzyme but it is essential for digestion.


  • Cells of root are in close contact with soil and so actively take up ions. The ion concentration increases inside the root and hence osmotic pressure increases the movement of water from the soil into the root which occurs continuously.

  • The bile salts breakdown the fat present in the food into smaller globules.

  • This increases the efficiency of enzymes in the small intestine to digest the food effectively.


Why does absorption of digested food occur mainly in the small intestine?


  • Inner lining of small intestine is provided with villi which increases the surface area for absorption.

  • Wall of intestine is richly supplied with blood vessels which take the absorbed food to each and every cell of the body.


Why is blood circulation in human heart called double circulation?


The blood circulation in human heart is called double circulation because the blood passes through the heart in one complete cycle of the body i.e. once through the right half in the form of deoxygenated blood and once through the left half in the form of oxygenated blood.


Draw and label the parts of the human excretory system.


The human excretory system

The Human Excretory System

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Give reason

Separation of oxygenated and de-oxygenated blood is necessary in mammals.

The rate of breathing in a fish is faster than a pigeon.

We experience pain in our muscles after a strenuous physical exercise


  • Mammals are warm blooded hence lot of energy is required to maintain a constant body temperature (1)

  • A fish breathes in oxygen dissolved in water and the percentage of oxygen dissolved in water is less as compared to atmosphere. (1)

  • Due to lack of oxygen anaerobic respiration occurs resulting in formation of lactic acid. Accumulation of lactic acid causes pain in the muscles. (1)