NCERT Class 10: Science-Exercise Solutions

Chapter 06-Life Process-Exercise Solutions

NCERT Book – Page Number- 113
Q.1. The kidneys in human beings are a part of the system for:
(a) nutrition.
(b) respiration.
(c) excretion.
(d) transportation.
Ans. (c) Excretion.
Q.2. The xylem in plants are responsible for:
(a) transport of water.
(b) transport of food.
(c) transport of amino acids.
(d) transport of oxygen.
Ans. (a) Transport of water.
Q.3. The autotrophic mode of nutrition requires:
(a) carbon dioxide and water.
(b) chlorophyll.
(c) sunlight.
(d) all of the above.
Ans. (d) All of the above
Q.4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in:
(a) cytoplasm.
(b) mitochondria.
(c) chloroplast.
(d) nucleus.
Ans. (b) Mitochondria.

Q.5. How are fats digested in our bodies? Where does this process take place?
Ans. Fats are present in the form of large globules in the small intestine. The small intestine gets the secretion in the form of bile juice and pancreatic juice respectively from the liver and the pancreas. The bile salts (from the liver) breakdown the large fat globules into smaller globules so that the pancreatic enzymes can easily act on them. This is referred to as emulsification of fats. It takes place in the small intestine.
Q.6. What is the role of saliva in the digestion of food?
Ans. Saliva is secreted by the salivary glands, located in our mouth. It moistens the food and forms easy swallowing. It contains a digestive enzyme called salivary amylase, which breaks down starch into simple sugars.
Q.7. What are the necessary conditions for autotrophic nutrition and what are its by-products?
Ans. Autotrophic nutrition takes place through the process of photosynthesis. Carbon dioxide, water, chlorophyll pigment, and sunlight are the necessary conditions required for autotrophic nutrition. Carbohydrates (food) and O2 are the by-products of photosynthesis.
$6CO_{2} + 6H_{2}O \rightarrow C_{6}6H_{12}O_{6} + 60_{2}$
Q.8. What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

Anaerobic respiration occurs in the roots of some waterlogged plants, some parasitic worms,
human muscles, and some micro-organisms such as yeast.
Q.9. How are the alveoli designed to maximise the exchange of gases?
Ans. The alveoli are the small balloon like structures present in the lungs. The walls of the alveoli consist of extensive network of blood vessels. Each lung contains 300-350 million alveoli, making it to a total of approximately 700 million in both the lungs. The alveolar surface when spread out covers about $80 m^{2}$ area. This large surface area makes the gaseous exchange more efficient.

Q.10. What would be the consequences of a deficiency of haemoglobin in our bodies?
Ans. Haemoglobin is the respiratory pigment that transports oxygen to the body cells for cellular respiration. Therefore, deficiency of haemoglobin in blood can affect the oxygen supplying capacity of blood. This can lead to deficiency of oxygen in the body cells. It can also lead to a disease called anaemia.

Q.11. Describe double circulation in human beings. Why is it necessary?
Ans. The human heart is divided into four chambers- the right atrium, the right ventricle, the left atrium, and the left ventricle.
Double Circulation : In humans, the blood flows twice in the heart before it completes one full round. It means, at first the blood flows in lungs (pulmonary circulation) and comes back to the heart. Then it flows to all the other parts of the body (systemic circulation). From all other parts of the body the blood is collected by veins back into the heart. For this reason the blood circulation in human body is called double circulation.

Importance of double circulation : As we know, warm-blooded animals such as humans have to maintain a constant body temperature by cooling themselves when they are in a hotter environment and by warming their bodies when they are in a cooler environment. Hence, they require more and more respiration so that they can produce more energy to maintain their body temperature. Thus, double circulation of blood in humans is more efficient.
Q.12. What are the differences between the transport of materials in xylem and phloem?

Q.13. Compare the functioning of alveoli in the lungs and nephrons in the kidneys with respect to their structure and functioning.