What is light an dark reaction in photosynthesis?

Question

Answer

basically three steps are involved in photosynthesis 1) chlorophyll pigment absorbs sunlight and becomes excited and loses electrons.2) photolysis of water3) and last is reduction of carbon dioxide to carbohydrate with the help of a reducing agent NADPH2 ( nicotinamide adenine dinucleotude phosphate)

Answer

the portion of photosynthesis in which light is involved is light reaction . it takes place in grana and the portion of photosynthesis in which light is not involved is called dark reaction and it take a place in stroma

Answer

Light Reactions
The light reactions of photosynthesis occur in the thylakoid membranes of chloroplasts. They convert solar energy into chemical energy in the form of ATP and NADPH.

Photon Absorption: Light energy is absorbed by chlorophyll pigments, exciting electrons.
Water Splitting: Photolysis of water molecules generates oxygen, protons, and electrons.
Electron Transport Chain: Excited electrons move through a series of proteins, releasing energy to pump protons into the thylakoid lumen.
ATP Formation: Protons flow back into the stroma via ATP synthase, driving the conversion of ADP and inorganic phosphate into ATP.
NADPH Production: Electrons reduce NADP+ to form NADPH, a crucial electron carrier.

Dark Reactions (Calvin Cycle)
The dark reactions, or Calvin Cycle, occur in the stroma of chloroplasts and do not require light directly. They utilize ATP and NADPH produced in the light reactions to fix carbon dioxide into organic molecules.

Carbon Fixation: CO2 is attached to ribulose bisphosphate (RuBP) by the enzyme RuBisCO, forming 3-phosphoglycerate (3-PGA).
Reduction Phase: ATP and NADPH convert 3-PGA into glyceraldehyde-3-phosphate (G3P), a three-carbon sugar.
Regeneration Phase: Some G3P molecules are used to regenerate RuBP, allowing the cycle to continue, while others contribute to glucose and other carbohydrates.

In summary, the light reactions capture energy, while the dark reactions use that energy for carbon fixation, contributing to the overall process of photosynthesis.

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