Select an incorrect statement for noncyclic photophosphorylation

Options

A. it is a result of an interaction of photosystem I and photosystem II.
B. in it there is a continuous flow of electrons from water to photosystem I to photosystem II
C. electrons are finally transferred to NADP
D. electron flow from water to NADP is unidirectional

Answer

**Step-by-Step Solution:**

1. **Understanding Noncyclic Photophosphorylation**: Noncyclic photophosphorylation is a process that occurs in the light-dependent reactions of photosynthesis. It involves both Photosystem I (PSI) and Photosystem II (PSII) and results in the synthesis of ATP and NADPH.

2. **Flow of Electrons**: In noncyclic photophosphorylation, the flow of electrons begins with the splitting of water molecules (photolysis). This process releases electrons, protons, and oxygen. The electrons released from water are then transferred to Photosystem II.

3. **Role of Photosystems**: After the electrons are absorbed by Photosystem II, they are excited by light energy and passed through an electron transport chain. The electrons then move to Photosystem I, where they are re-excited and ultimately transferred to NADP+ to form NADPH.

4. **Directionality of Electron Flow**: The flow of electrons in noncyclic photophosphorylation is unidirectional. It starts from water, moves to Photosystem II, then to Photosystem I, and finally to NADP+. Therefore, the statement that suggests water is transferred directly to Photosystem I is incorrect.

5. **Identifying the Incorrect Statement**: The question asks for an incorrect statement regarding noncyclic photophosphorylation. The incorrect statement is that water is transferred to Photosystem I directly. In reality, water donates electrons to Photosystem II first.

**Final Answer**: The incorrect statement is that water is transferred to the first photosystem (Photosystem I) directly.

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