List and explain the two process involved in photosynthetic reaction

Answer 1

The two main processes involved in photosynthetic reactions are:

1. Light-dependent reactions: These reactions occur in the thylakoid membrane of the chloroplasts. They require light energy to take place. During light-dependent reactions, chlorophyll and other pigments in the thylakoid membrane capture sunlight. This energizes electrons and begins a series of complex chemical reactions. As a result, ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate) are produced. ATP is a molecule that stores and provides energy for cellular processes, and NADPH acts as a carrier molecule for high-energy electrons.

2. Light-independent reactions (Calvin cycle): After the light-dependent reactions, the light-independent reactions or Calvin cycle occur in the stroma of the chloroplasts. This cycle doesn't directly require light, but it relies on the products generated in the light-dependent reactions. During the Calvin cycle, carbon dioxide (CO2) is captured from the atmosphere and incorporated into an organic molecule called RuBP (ribulose-1,5-bisphosphate). This process is known as carbon fixation. The energy from ATP and the high-energy electrons from NADPH are then used to convert the CO2 into simple sugars, such as glucose. These sugars can be used as a source of energy or stored in the plant's cells. ATP and NADPH are regenerated within the cycle to be used again in the light-dependent reactions.

In summary, the light-dependent reactions capture light energy and convert it into chemical energy (ATP and NADPH), while the light-independent reactions utilize this energy to fix carbon dioxide and produce glucose. Both processes are essential for photosynthesis, allowing plants and other photosynthetic organisms to convert sunlight into usable energy.