Question

Describe the exchange of gases which takes place in the leaves of a plant

(a) during daytime, and (b) at night.

Answer 1

(a) During the daytime, the leaves use some of the oxygen produced through photosynthesis for respiration. For photosynthesis, the leaves not only use the carbon dioxide produced through respiration but some carbon dioxide is also taken in from the air. Thus, during the daytime, oxygen diffuses out and carbon dioxide diffuses in.

(b) At night, as photosynthesis does not takes place, oxygen is not produced. Thus, oxygen from the air diffuses into the leaves to carry out respiration. And carbon dioxide produced by respiration diffuses out into the air. So, at night, oxygen diffuses in and carbon dioxide diffuses out.