- The sun is the main source of energy on Earth.
- The energy from the sun is changed into many different forms.
- Some of it is used by green plants to make food by photosynthesis.
- When plants are eaten the energy they contain passes on to other organisms.
- Plants and animals release energy from food by respiration.
- Respiration converts chemical energy from food into other forms.
- In animals the chemical energy in food may be converted into heat, motion, chemical and sound energy.
- This energy is lost from the ecosystem.