What are dark reactions in photosynthesis?

Dark reactions in photosynthesis, also known as the Calvin cycle, are part of the process that occurs in the stroma of chloroplasts. These reactions do not require light directly; instead, they utilize the products generated by the light-dependent reactions (such as ATP and NADPH) to fix carbon dioxide into organic molecules.

During dark reactions, carbon dioxide enters the cycle and is incorporated into an existing 5-carbon sugar molecule, ribulose bisphosphate (RuBP), eventually leading to the production of glucose and other carbohydrates that plants can use for energy and growth. This process highlights the importance of these reactions in converting inorganic carbon into organic matter, which forms the basis for the food chain.

Understanding that dark reactions do not necessitate light energy for their occurrence is crucial. They are capable of taking place at any time of day as long as the necessary substrates and energy carriers, produced during the light-dependent reactions, are available. This ensures that plants can continue to synthesize organic compounds even when light is not present.