AP BIOLOGY

Detailed explanation-1: -To reduce water loss the leaf is coated in a waxy cuticle to stop the water vapour escaping through the epidermis. Leaves usually have fewer stomata on their top surface to reduce this water loss.

Detailed explanation-2: -Decrease in the number of stomata: It is understood that the number of stomata is directly proportional to the transpiration rate. So, the reduction in the number of stomata reduces the transpiration rate. Waxy leaf cuticle: It is impermeable to water and thus prevents evaporation.

Detailed explanation-3: -Adaptation such as spines, thick cuticles, and sunken stomata helps the plant to reduce the rate of transpiration.

Detailed explanation-4: -Narrow leaves enable plants to shed heat through sensible heat loss during summer droughts, without the need for transpirational cooling. Additionally, small leaf dimensions confer a capac-ity for high transpiration when evaporative demand is low and water is abundant (i.e. winter).

Detailed explanation-5: -The leaves in hot or dry environments may be adapted to reduce transpiration . For example, their stomata may open at night and close at midday. This is the reverse of what usually happens, and it means that the stomata are closed when the rate of transpiration would be greatest.