Question

C. Short Answer Questions:
11. What is peristalsis?
12.What are the characteristics of silk fibres?
13.Dark colours are good absorbers of heat. Explain.
14.What is the role of stomata in plant cells?
15. Why are forest called the green lungs of nature?
D
Long Answer Questions:​

Answer 1

Answer:

11.Peristalsis is a radially symmetrical contraction and relaxation of muscles that propagates in a wave down a tube, in an anterograde direction

12.Good insulator

Lightweight

Smooth

Soft

13.Dark colors absorb a lot more heat than lighter ones because they absorb more light energy. In fact, the closer to black a color is, the more heat it absorbs from light sources. The key is that colors do not absorb different amounts of heat, only heat from light.

14.Stomata are composed of a pair of specialized epidermal cells referred to as guard cells (Figure 3). Stomata regulate gas exchange between the plant and environment and control of water loss by changing the size of the stomatal pore

15.Forest is called as the green lung because they fix the carbon dioxide in the presence of sunlight and convert them into glucose by the process of photosynthesis. ... Thus forest replenishes oxygen in turn of carbon dioxide.

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Answer 2

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Question 11. What is peristalsis?

Question 12. What are the characteristics of silk fibres?

Question 13. Dark colours are good absorbers of heat. Explain.

Question 14. What is the role of stomata in plant cells?

Question 15. Why are forest called the green lungs of nature?

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Answer 11. When certain muscles in the digestive and urinary tracts contract, it is called peristalsis .

Answer 12. It has mny characteristics some are given below –

• It has good tensile strength, which allows it to withstand great pulling pressure.
• Silk is the strongest natural fibre and has moderate abrasion resistance.
• The strength of the thrown yarns is mainly due to the continuous length of the fibre.

Answer 13. The amount of energy absorbed and radiated is decided by the colour. White is a good reflector while black is a good absorber of heat. Dark colors absorb a lot more heat than lighter ones because they absorb more light energy.

Answer 14. Roles of stomata are given below –

• Stomata regulate gas exchange between the plant and environment and control of water loss by changing the size of the stomatal pore.

Answer 15. Forest is called as the green lung because they fix the carbon dioxide in the presence of sunlight and convert them into glucose by the process of photosynthesis.

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