Question

Explain how does the exchange of gases occur in plants across the surface of stem, roots and leaves.

Answer 1

In all the three plant parts the exchange of gases takes place through diffusion.

However the surface of a young stem will have stomata, while that of an older stem will have lenticels. The stomatal apparatus consists of a pore called the stoma, a pair of guard cells and subsidiary cells surrounding them. The exchange of gases through the stomatal pore is dependent upon the turgidity of the guard cells. Stomata are mainly present on the surface of the leaves apart from the epidermal surface of young stem. Lenticels are open pores. In roots stomatal pores as well as lenticels are absent, exchange of gases occurs through root hairs.