NCERT Solutions for Class 10 Science Chapter 6 Life Processes

1. The kidneys in human beings are a part of the system for

(a) nutrition. (b) respiration. (c) excretion. (d) transportation.

Answer: (c) excretion.

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.

Answer: (a) transport of water.

3. The autotrophic mode of nutrition requires

(a) carbon dioxide and water. (b) chlorophyll. (c) sunlight. (d) all of the above.

Answer: (d) all of the above

4. The breakdown of pyruvate to give carbon dioxide, water and energy takes place in

(a) cytoplasm. (b) mitochondria. (c) chloroplast. (d) nucleus.

Answer: (b) mitochondria.

5. How are fats digested in our bodies? Where does this process take place?

Answer: Small intestine receives bile juices and pancreatic juices from liver and pancreas respectively during the process of digestion. Fats are present in small intestine in large globules. In intestine bile juices break fat into small globules on which pancreatic enzymes acts on. This process is called emulsification of fats. Process takes place in small intestine.

6. What is the role of saliva in the digestion of food?

Answer: Saliva is released from salivary glands present in the mouth. While chewing and swallowing food it moistens the food material. Saliva contains salivary amylase that breaks starch in food into sugar.

7. What are the necessary conditions for autotrophic nutrition and what are its byproducts?

Answer: Photosynthesis is responsible for autotrophic nutrition. For autotrophic nutrition carbon dioxide, water, chlorophyll and sunlight are required conditions. Carbohydrates and oxygen are the byproducts obtained during this process. Following reaction shows process of photosynthesis

                               Sunlight

6CO₂ + 6H₂O ⟶ C₆H₁₂O₆ + 6O₂

                             Chlorophyll

8. What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.

Answer:

Aerobic respiration	Anaerobic respiration
It is carried out in presence of oxygen	It is carried out in absence of oxygen
Gases are exchanged between organism and it surrounding	No exchange of gases
It always releases CO2 and H2O	End products of anaerobic respiration vary
Complete oxidation of glucose occurs	Incomplete oxidation of glucose occurs

9. How are the alveoli designed to maximise the exchange of gases?

Answer: Lungs contains small balloon like structures known as alveoli. Each lung contains millions of alveoli having huge network of blood vessels. When alveoli is spread it covers large surface area which makes exchange of gases efficient.

10. What would be the consequences of a deficiency of haemoglobin in our bodies?

Answer: Haemoglobin is responsible for carrying oxygen to each and every cell in the body. Thus, its deficiency will affect oxygen supplying capacity of blood, which in turn causes deficiency of oxygen in blood cells. It causes diseases anemia.

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

Answer: Heart is responsible for pumping the blood throughout the body with the circulatory system. To prevent mixing of oxygenated and deoxygenated blood heart has four chambers left atrium, left ventricle, right atrium and right ventricle. Due to pumping action deoxygenated blood from heart is passed to lungs and oxygenated blood received from lungs is passed to rest body parts. During each cycle, blood is collected twice in heart, therefore, this type of circulation is called double circulation.

Process of Double Circulation:

• Left atrium relaxes, thus oxygen rich blood from lungs is collected.
• Left atrium contracts and left ventricle relaxes, thus, blood is transferred to left ventricle.
• Left ventricle contracts forcing the blood to pass in all parts of the body.
• Right atrium relaxes so as to collect deoxygenated blood from all parts of the body.
• Right atrium contracts and right ventricle relaxes, thus deoxygenated blood is transferred to right ventricle.
• Right ventricle contracts forcing the blood to be transferred to lungs.
• Valves are present at the junction of atrium and ventricles. These valves prevents backflow of blood.

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

Answer:

Xylem	Phloem
Xylem transfers water and minerals in plants	Phloem transports food material in plants
Water is transported from roots to all parts of the plants, only in upward direction	Food is transferred to all parts of the plants in both upward and downward direction

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

Answer:

Alveoli	Nephrons
Structure: Are balloon like structure present inside the lungs Walls are one cell thick containing huge network of blood vessels	Structure: Tubular structures present inside the kidneys Contains thin walled blood vessels Made of bowman’s capsules, glomerulus, renal tube, etc
Functions: Location for exchange of gases Gases are exchanged between network of blood vessels and alveoli.	Functions: Are basic unit of filtration Blood enters kidney through renal arteries. Blood and nitrogenous waste are collected in collecting duct

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