All life processes requires energy. Animals obtain energy through the food consumed by them. Green plants can prepare their own food, which is called photosynthesis.
2. Sun - A prime energy source:
The prime source of energy to our world is the Sun. All living organisms depend directly or indirectly on the sun for their energy needs. Oil, Coal, gas, solar power, wave power and wind power all derive energy from the sun - which has reached the earth either now or in the past.