Birds and mammals need more energy than other class of animals like reptiles because
They move faster.
They breath faster.
They have to keep their body warm.
They eat more complex food which needs more energy to break down.
Animals have a requirement of temperature regulation, unlike plants, which needs energy.
Why do birds and mammals need more energy?
Digestion needs the help of two or more systems in the body to provide energy from food.which are these systems and how do they help?