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Biology

Give biological reasons for the following statements:

(i) Some women have facial hair like beard and moustache.

(ii) Cutting of trees should be discouraged.

(iii) In some xerophytes leaves are modified into spines.

(iv) There is frequent urination in winter than in summer.

(v) The left ventricle of the heart has a thicker wall than the right ventricle.

Pollution

ICSE 2017

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Answer

(i) Due to Adrenal Virilism there is an overgrowth of Adrenal Cortex in some women. This causes the development of certain male characteristics like facial hair (beard and moustache) and deep male voice.

(ii) Cutting of trees results in an increase in the concentration of carbon dioxide in the atmosphere resulting in global warming. Hence cutting of trees should be discouraged.

(iii) In some xerophytes leaves are modified into spines. This modification helps plant prevent water loss by transpiration by minimizing the surface area. It also defends plants against herbivores animals.

(iv) During summer, the temperature is high. Hence, considerable part of water is lost from the body by means of perspiration. As a result, less water is flushed out from the body by the means of urination. During winter, there is less perspiration due to low temperature. Hence, maximum water is flushed out through urine. Thus, there is frequent urination in winter than in summer.

(v) The left ventricle pumps blood to the farthest points in the body such as the feet, the toes and the brain against the gravity while the right ventricle pumps the blood only up to the lungs. Therefore, the left ventricle has thicker walls than the right ventricle.

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