Explain : (a) Blood goes only once through the heart in fishes. (b) Plants have low energy needs. (c) What are capillaries?

(a) Blood goes only once through the heart in fishes-

The fishes have only two-chambered heart. The blood is pumped to the gills and is oxygenated there. From the gills, this blood is transported to the rest of the body. Thus, the blood goes only ones through the heart in the fishes.

(b) Plants have low energy needs-

The maximum amount of energy is needed for movement. The plants cannot move from one place to another, which means there is no locomotion in the plants. The only movement that takes place in the plants is on a cellular level. Hence this movement does not require much energy. So that is why the plants have low energy needs.

(c) Capillaries-

Capillaries are the smallest blood vessels. They are thinly walled and connect arteries to veins. The exchange of material between blood and the surrounding cells takes place in the capillaries.