Question

Why doesn't the stomata remain open during night?

Answer 1

CO₂ is taken up by the leaves, which are present on green stems through the stomata. Their stomata remain open at night but closed during day.

If the concentration of outside carbon di oxide increases than the normal 0.03%, the stomata get closed. This reduces the rate of transpiration.

It is a kind of adaptation in plants to carry out photosynthesis without much loss of water.