The respiratory organ of fish is called:

Give an example of small organism in which the ratio of surface area to volume is high.

The water proof layer that protects human skin.

Carbon dioxide and oxygen diffuse in and out of leaves through small openings called:

Guard cells become turgid by actively transporting which of the following ions?

The most numerous cells in the epithelium of the bronchus and bronchioles are called:

Percentage of oxygen present in the atmosphere.

The respiratory system of insects is called:

Fish gills are covered by a bony flap called:

Write the name of the process of stomatal opening and closure.