`H_(2)` donor during photosynthesis is

Options

A. `NADH`
B. `ATP`
C. `NADP`
D. `NADPH`.

Answer

To determine the hydrogen donor during photosynthesis, we need to analyze the provided options one by one:

1. **NADH**: This molecule is primarily involved in cellular respiration, not photosynthesis. It plays a role in transferring electrons in metabolic processes but does not donate hydrogen in the context of photosynthesis. Therefore, this option is incorrect.

2. **ATP**: ATP (adenosine triphosphate) is known as the energy currency of the cell. While it provides energy for various cellular processes, it does not serve as a hydrogen donor in photosynthesis. Thus, this option is also incorrect.

3. **NADP**: NADP (nicotinamide adenine dinucleotide phosphate) is an electron acceptor in photosynthesis. It accepts electrons and hydrogen ions during the light-dependent reactions but does not donate them. Therefore, this option is incorrect as well.

4. **NADPH**: NADPH (nicotinamide adenine dinucleotide phosphate in its reduced form) is the molecule that donates electrons and hydrogen during the process of photosynthesis. It is produced in the light-dependent reactions and is used in the Calvin cycle to reduce carbon compounds. Thus, this option is correct.

**Final Answer**: The hydrogen donor during photosynthesis is **NADPH**.

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