One of the main sources of energy comes from the energy of the sun.

Photosynthesis is the main way energy is obtained.

The energy from the sun is made into sugars, which will be the energy need for the living systems.

Plants and microorganisms use this process to combine inorganic molecules CO2 + H20 = energy rich organic compounds (glucose, sugar). Oxygen will be released at the end.

Equation for Photosynthesis:
carbon dioxide + water = glucose + oxygen
(sunlight) (enzymes)chloroplast's: organelles that carry on photosynthesis in green plant cells