Light-independent reactions occur after which event?

Light-independent reactions, commonly referred to as the Calvin cycle, occur after an electron has been liberated from chlorophyll during the light-dependent reactions of photosynthesis. During these light-dependent reactions, sunlight is absorbed by chlorophyll, leading to the excitation of electrons. These liberated electrons are then transported through the electron transport chain, which ultimately results in the production of ATP and NADPH.

The importance of the liberation of an electron lies in its role in generating the energy carriers (ATP and NADPH) that are essential for driving the light-independent reactions. These energy carriers provide the necessary energy and reducing power for carbon fixation, where carbon dioxide is incorporated into organic molecules. The light-independent reactions do not occur until after this initial step, as they rely on the products generated from the light-dependent phase.

In contrast, chlorophyll production, while essential for the overall process of photosynthesis, takes place before the electrons are liberated and is not directly relevant to the timing of the light-independent reactions. Similarly, while ATP synthesis occurs during the light-dependent reactions, it is the liberation of the electron that specifically marks the transition to the light-independent phase.