Question

how does respiration occur in the stem of a plant

Answer 1

Respiration in stems of plants takes place through small pores on them called LENTICELS. They help the oxygen to enter the plant and carbon dioxide to go out. These pores are visible on barks of trees.

Answer 2

In the stem of herbaceous plants, stomatas are present. So, the exchange of gases takes place through stomata by the process of diffusion. In the woody and hard stems of big plants, the exchange of gases takes place through lenticels which are present on the bark of the stem.