Monday, December 8, 2014



SCIENCE & TECHNOLOGY (Class-10) Chapter 6 : Life Process

1. What are the raw materials for photosynthesis? (1 mark)

Answer: The raw materials and other necessary items required for photosynthesis are Sunlight, Water, CO2and Chlorophyll.

2. Give the energy transformation that takes place in the process of photosynthesis. (1 mark)

Ans: Light energy converted into chemical energy

3. Write the equation of photosynthesis. (1 mark)

4. What is the respiratory organ of earthworm? (1 mark)

Ans: Gaseous exchange occurs through moist skin by diffusion

5. Give the function of xylem. (1 mark)
Ans:  Transport water and mineral to green leaves

6. Write any two functions of large intestine to man. (2 marks)

Ans(a)  Inner lining of colon has numbers of villi  that absorb water from undigested food and form solid waste
(b) Store solid secrete in rectum and spell out with anus

 7. How are lungs designed in human beings to maximize the area for exchange of gases (2 marks)

Ans:  The lungs get filled up with air during the process of inhalation as ribs are lifted up and diaphragm is flattened. The air that is rushed inside the lungs fills the numerous alveoli present in the lungs.
These numerous alveoli increase the surface area for gaseous exchange making the process of respiration more efficient.

8. Draw the human heart and label its parts. (2 marks)

Ans:  See NCERT Figure 6.10 -Sectional view of the human heart
9. Why is diffusion insufficient to meet the oxygen requirements of multicellular organisms like human? (2 marks)
Ans:  Diffusion is insufficient to meet the energy requirements of large multicellular organisms like humans because the volume of the human body is so big that oxygen the diffusion pressure alone cannot take care of oxygen delivery to all parts of the body. This is because oxygen has to travel large distances inside the body to reach each and every cell quickly but diffusion is a very slow process.

10. What is the role of the acid in our stomach? (2 marks)

Ans:  The hydrochloric acid creates an acidic medium which facilitates the action of the enzyme pepsin and also kills bacteria present in food.

11. Draw a diagram & describe the process by which excretion occurs in amoeba. (3 marks)
Ans:  Amoeba removes these wastes by simple diffusion from the body surface into the surrounding water.
[Amoeba is an ammonotelic organism since the principal excretory product is ammonia. Special excretory organelle in Amoeba is lacking. CO2 and ammonia are exerted by diffusing is solution through plasma membrane. The concentration of ammonia is always higher in Amoeba than in the surrounding water. The water enters through plasma membrane by “endosmosis”. Ammonia is formed in cytoplasm by metabolism. Surplus water enters contractile vacuole. This surplus water can rupture the animal’s body. Thus size of contractile vacuole increases, when the contractile vacuole is fully expanded with water, it moves towards the periphery. As it comes in close contact with the plasma membrane, the contractile vacuole bursts. Thus excess of water (surplus water) is discharged in the surrounding water, this phenomenon of controlling the amount of water in the body is called as “osmoregulation”. ]

12. How does blood circulate between lungs and heart in human beings? Give two functions of lymph in human body. (3 marks)

Ans: At first the impure blood from all the body parts reach the right auricle and then into right ventricle.From right ventricle it is carried to lungs through Pulmonary arteries .In lungs, it gets purified [alveoli do the purification] and then it is send  to left auricle through Pulmonary Vein. From left auricle it flows into left ventricle and then to all the body parts through systemic aorta.
Lymph carries digested and absorbed fat from intestine and drains excess fluid from extra cellular space back into the blood.

13. How do each of the following factors affect the productivity in the process of photosynthesis?
(i) Temperature   (ii) Water   (iii) Carbon dioxide.   (3 marks)

Ans:  (i) Temperature   : The higher the temperature then typically the greater the rate of photosynthesis, photosynthesis is a chemical reaction and the rate of most chemical reactions increases with temperature

(ii) Water   :  An increase in the amount of water leads to the increase in the amount of photosynthesis.
The amount of water available to the plant will affect the rate of photosynthesis. If the plant does not have enough water, the plant’s stomata will shut and the plant will be deprived of CO2, and thus lower photosynthesis rate .
(iii) Carbon dioxide. The concentration of carbon dioxide in the Earth’s atmosphere varies between 0.03% and 0.04%. An increase in the concentration of carbon dioxide gives an increase in the rate of photosynthesis.

14. Write necessary conditions for autotrophic nutrition and its by-products? (3 marks)
Ans: The necessary conditions for autotrophic nutrition are :

1. Sunlight   2.water 3.CO2     4.chlorophyll;   It’s by-products are  carbohydrates & oxygen

15. How are fats digested in our body? Where does this process take place? (3 marks)
Ans:  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.

16. (i) Draw a labeled diagram of the respiratory system of human beings with diaphragm at the end of expiration. (5 marks)
(ii) List four conditions required for efficient gas exchange in an organism
(ii) (a)A large surface area over which exchange can take place.
(b) A concentration gradient without which nothing will diffuse.
(c) A thin surface across which gases diffuse.

(d) Warm conditions


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