Question

(A) How is the movement of leaves of a sensitive plant different from the downward movement of the roots ?
OR
(B) There is a hormone which regulates carbohydrate, protein and fat metabolism in our body. Name the hormone and the gland which secretes it. Why is it important for us to have iodised salt in our diet?

Answer 1

(A). The movement of leaves in a sensitive plant is a nastic movement caused by changes in turgor pressure, and it is independent of the direction of the stimulus. The downward movement of roots is a tropic movement (geotropism), which occurs in response to gravity.

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(B). The hormone is Thyroxine, and it is secreted by the thyroid gland. Iodine is essential for the synthesis of thyroxine. A deficiency of iodine causes goitre, a disease resulting in the swelling of the thyroid gland.