Question

stomata of desert plant remains closed during daytime. how do they take up carbon dioxide and perform photosynthesis

Answer 1

Good question.
Stomata of desert plants remains closed most of the time during the day ( to reduce the amount of transpiration ) but for some time it remains open and photosynthesis takes place during that time and it stores the energy

Answer 2

Desert plants take up carbon dioxide at night and prepare an intermediate compound.

This intermediate compound is acted upon by the energy absorbed during the day by the chlorophyll.