Photosynthetic organisms are the main producers on Earth. Green plants, algae and some bacteria use light energy from the Sun to make glucose from carbon dioxide and water. Algae include the tiny floating phytoplankton that fill the surface of seas and lakes.
The glucose is used to make other organic compounds, such as starch, cellulose, proteins and fats. These compounds build the body of the producer, which is its biomass. Light energy is transferred into chemical energy stored in glucose and in the biomass made from it.
Consumers cannot photosynthesise. Animals eat producers, or eat other animals that have eaten producers, so the energy and biomass in nearly every food chain on Earth begin with photosynthesis. Photosynthesis also releases oxygen, which most living things need for respiration.