NCERT Solutions Class 10 Science Chapter 6 Life Process
1. The kidneys in human beings are a part of the system for
(a) nutrition.
(b) respiration.
(c) excretion.
(d) transportation.
Answer:
(c) In human beings, the kidneys are a part of the system for 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) In a plant, the xylem is responsible for 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) The autotrophic mode of nutrition requires carbon dioxide, water, chlorophyll and sunlight.
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) The breakdown of pyruvate to give carbon dioxide, water and energy takes place in mitochondria.
5. How are fats digested in our bodies? Where does this process take place?
Answer:
Fats are present in the form of large globules in the small intestine. The small intestine gets the secretions in the form of bile juice and pancreatic juice respectively from the liver and the pancreas. The bile salts (from the liver) break down 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.
6. What is the role of saliva in the digestion of food?
Answer:
Saliva is secreted by the salivary glands, located under the tongue. It makes the food soft for easy swallowing. It contains a digestive enzyme called salivary amylase, which breaks down starch into sugar.
7. What are the necessary conditions for autotrophic nutrition and what are its byproducts?
Answer:
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 byproducts of photosynthesis. 6CO2 + 6H2O ℎℎ ℎ → C6H12O6 + 6O2
8. What are the differences between aerobic and anaerobic respiration? Name some organisms that use the anaerobic mode of respiration.
Answer:
Difference between Aerobic respiration and Anaerobic respiration:

Anaerobic respiration occurs in the roots of some waterlogged plants, some parasitic worms, animal muscles and some micro-organisms such as yeasts.
9. How are the alveoli designed to maximise the exchange of gases?
Answer:
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 a total of approximately 700 million in both the lungs. The alveolar surface when spread out covers about 80 m2 area. This large surface area makes the gaseous exchange more efficient.

10. What would be the consequences of a deficiency of haemoglobin in our bodies?
Answer:
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.
11. Describe double circulation in human beings. Why is it necessary?
Answer:
Because both oxygen and carbon dioxide have to be transported by the blood, the heart has different chambers to prevent the oxygen-rich blood from mixing with the blood containing carbon dioxide. The human heart is divided into four chambers − the right atrium, the right ventricle, the left atrium and the left ventricle. Oxygen-rich blood from the lungs comes to the thin-walled upper chamber of the heart on the left, the left atrium. The left atrium relaxes when it is collecting this blood. It then contracts, while the next chamber, the left ventricle, expands, so that the blood is transferred to it. When the muscular left ventricle contracts in its turn, the blood is pumped out to the body.

De-oxygenated blood comes from the body to the upper chamber on the right, the right atrium, as it expands. As the right atrium contracts, the corresponding lower chamber, the right ventricle, dilates. This transfers blood to the right ventricle, which in turn pumps it to the lungs for oxygenation. During this process blood goes twice through the heart. That’s why it is known as double circulation.
Double Circulation is necessary:
The separation of oxygenated and de-oxygenated blood allows a more efficient supply of oxygen to the body cells. This efficient system of oxygen supply is very useful in warm-blooded animals such as human beings. As we know, warm blooded animals 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 O2 for more respiration so that they can produce more energy to maintain their body temperature.
Thus, the circulatory system of humans is more efficient because of the double circulatory heart.
12. What are the differences between the transport of materials in xylem and phloem?
Answer:
Difference between Xylem and Phloem:

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

14. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like humans?
Answer:
In multi-cellular organisms, all the cells may not be in direct contact with the surrounding environment. Thus, simple diffusion will not meet the requirements of all the cells.
15. What criteria do we use to decide whether something is alive?
Answer:
Any visible movement such as walking, breathing, or growing is generally used to decide whether something is alive or not. However, a living organism can also have movements, which are not visible to the naked eye. Therefore, the presence of molecular movement inside the organisms used to decide whether something is alive or not.
16. What are outside raw materials used for by an organism?
Answer:
An organism uses outside raw materials mostly in the form of food (Since life on earth depends on carbon based molecules, most of these food sources are also carbon-based) and oxygen. The raw materials required by an organism can be quite varied depending on the complexity of the organism and its environment.
17. What processes would you consider essential for maintaining life?
Answer:
Life processes such as nutrition, respiration, transportation, excretion, etc. are essential for maintaining life.
18. What are the differences between autotrophic nutrition and heterotrophic nutrition?
Answer:
