AP BIOLOGY

Detailed explanation-1: -Their stomata only open at night, when humidity tends to be higher and temperatures are cooler, both factors that reduce water loss from leaves. CAM plants are typically dominant in very hot, dry areas, like deserts.

Detailed explanation-2: -Leaves and stems of many desert plants have a thick, waxy covering, keeping the plants cooler and reducing evaporative loss. Some plants, such as Ephedra (Mormon tea) and cacti, carry out most or all of their photosynthesis in their green stems.

Detailed explanation-3: -The opening of stomata through night time is a physiological alteration to prevent loss of water through transpiration.-Sedum, Kalanchoe, Pineapple, Opuntia are some examples of CAM plants. These plants also carry out double carbon dioxide fixation.

Detailed explanation-4: -In desert plants, the stomata is open during night. During night, desert plants absorb carbon dioxide and form an intermediate. Then during day time when the stomata is closed to prevent loss of water, they use this stored carbon dioxide to perform photosynthesis.

Detailed explanation-5: -The stomatal openings remain closed at night as photosynthesis is not conducted without sunlight. They are closed to prevent water loss via the stomatal pores. The gaseous exchange required at night doesn’t occur via stomatal openings and is conducted by diffusion.