If a wavelength of above 680 nm is available for excitement, the product of the reaction will be

Options

A. `O_(2)`
B. ATP and `NADPH_(2)`
C. ATP
D. `NADPH_(2)`

Answer

To solve the question regarding the products of the reaction when a wavelength of above 680 nm is available for excitation, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Context**: The question pertains to the light reactions of photosynthesis, specifically focusing on the photosystems involved (PSI and PSII).

2. **Understand the Role of Wavelengths**:
- Photosystem II (PSII) primarily absorbs light at a wavelength of around 680 nm.
- Photosystem I (PSI) absorbs light at a wavelength of around 700 nm.

3. **Determine the Reaction in PSII**:
- When light at or above 680 nm is absorbed by PSII, it excites electrons.
- These excited electrons are transferred to the primary electron acceptor.

4. **Electron Transport Chain**:
- The excited electrons move through the electron transport chain, leading to the production of ATP through photophosphorylation.
- The process involves the splitting of water molecules (photolysis) to replace the lost electrons in PSII, producing oxygen and protons (H+).

5. **Identify the Reaction in PSI**:
- The electrons that reach PSI after passing through the electron transport chain are further excited by light (at around 700 nm).
- This process ultimately leads to the reduction of NADP+ to NADPH.

6. **Final Products**:
- From the light reactions involving PSII and PSI, the main products formed are ATP and NADPH.
- Therefore, when a wavelength of above 680 nm is available, the products of the reaction will be ATP and NADPH.

### Final Answer:
The products of the reaction will be **ATP and NADPH**.

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