Photosynthèse

Photosynthèse is the process used by plants, algae, and cyanobacteria to convert light energy into chemical energy, stored in the form of glucose. This process is fundamental to life on Earth as it produces the oxygen we breathe and the food that forms the base of most food webs.

The overall chemical equation for photosynthesis is 6CO2 + 6H2O + Light Energy → C6H12O6 + 6O2. This means that carbon dioxide from the atmosphere and water absorbed from the soil are used, along with light energy, to create glucose and oxygen.

Photosynthesis occurs in specialized organelles called chloroplasts, which contain chlorophyll, the pigment that absorbs sunlight. The process is typically divided into two main stages: the light-dependent reactions and the light-independent reactions (also known as the Calvin cycle).

In the light-dependent reactions, light energy is captured by chlorophyll and used to split water molecules. This process releases oxygen as a byproduct and generates energy-carrying molecules, ATP and NADPH.

The light-independent reactions then use the ATP and NADPH produced in the first stage to convert carbon dioxide into glucose. This glucose can then be used by the organism for energy or stored for later use.

Photosynthesis is influenced by various environmental factors, including light intensity, carbon dioxide concentration, and temperature. Variations in these factors can affect the rate at which photosynthesis occurs, impacting plant growth and overall ecosystem productivity.