Question

Why do the plants need less energy than animals?

Answer 1

Animals require more energy than plants.
This is due to various reasons. Some are :
1) Animals are motile organisms whereas plants are non-motile. Being motile requires more energy.
2) Plants have many dead tissues whereas this is not in the case of animals. Hence, again animals need more energy.

Plants being sessile stay at one place and lack the basic process of locomotion while animals move from one place to another in search of food, shelter and mates. The physical activity performed by the plants is also less when compared to animals.
Animals need more energy than plants as they eat complex food so more energy is needed to synthesise it whereas plants need simple food substances like water and carbon dioxide and in this less energy is needed for synthesis as compared to animals.