Keeping stomata closed during the day is an adaptation in desert plants that reduces which water-cycle process?

Correct answer: Transpiration

Correct answer: B, transpiration. Stomata are microscopic pores, usually in the epidermis of leaves, through which gases move and water vapour is lost. Desert air is often hot and dry, so an open stoma can cause rapid water loss. Closing stomata during the day reduces the diffusion of water vapour from the leaf to the atmosphere and therefore lowers transpiration. This adaptation can also restrict carbon-dioxide entry, so desert plants use additional strategies, such as opening stomata at cooler times in many plants. A is not the process being directly reduced in the question, although prolonged stomatal closure can affect photosynthesis. C is water uptake by roots or other surfaces, not water loss through leaves. D is cellular energy release and is not the main process controlled by stomata. Memory cue: stomata are gates; closing them saves water but may limit carbon dioxide.