Question

14 8. Plants must have special adaptations to dissuade water loss in arid environments. The figure above has several important coping mechanisms indicated. Identify each number.

Answer 1

1 – Cuticle : A thick waxy cuticle above the epidermis makes the surface impermeable to water, and hence reduces the transpiration rate.

2- Upper Epidermis - Epidermis is packed densely together and is covered by a cuticle, a waxy layer secreted by the cells. This helps in preventing water loss

3 – Mesophyll - Presence of palisade and spongy mesophyll cells help in preventing water loss

4 – Lower Epidermis - Covered by cuticle to prevent water loss.

5 – Sunken stomata in crypts(pits) - to reduce air movements thus creating a environment of moist air. This reduces the water potential gradient between the leaf air spaces and the external environment, and therefore decreases the rate of transpiration.

6 – Hairs – The cells in the epidermis may differentiate into hair-like structures called trichomes. These hair arise from epidermal cells, they reduce the heating effect of sunlight and further reduce transpiration