Question

What plant structures control the passage of `H_2O` out of the plant and `CO_2` into the plant?

Answer 1

There are three; stomata, lenticles and cuticle.

Explanation:

Stomata are the structures mostly used for removal of water(transpiration) and absorption of Carbon dioxide. They are specialized cells present on the lower surface of leaves.

Lenticels are specialized pores present in stem of some higher plants. These are also used for gaseous exchange.

Cuticle is also used for transpiration and absorption of carbon dioxide.