Question

What are stomata and lenticels ?what is their role in respiration?

Answer 1

Stomata (plural stoma) are tiny openings or pores in the epidermis of leaves and they are mostly found on the under surface plant leaves . Each stoma are guarded by a pair of specilised sclerenchyma cells known as Guard cells which is of bean shaped that controls the opening and closing of stomata.
Respiration in plants can takes place in roots,stem or leaves. Stomata helps in respiration of plants through leaves.It happens as folows , Oxygen in atmosphere enters in to leaf through stomata and reaches the cells through a process called diffusion. This oxygen is used in respiration in cells of the leaf and the carbon dioxide produced(during respiration) diffuses out from the cells of leaves to atmosphere through stomata.

Lenticels are porous tissue consisting of cells with large intercellular spaces in the periderm(outermost layers of stems and roots of woody plants).It functions as a pore and a pathway for gas exchange (respiration). It is similar to stomata but stomata usually works at day time whereas lenticels works at night.