In photosystem I (PS I), chlorophyll a with maximum absorption at __ and in Photosystem II (PS II), chlorophyll a with peak absorption at _____ acts as reaction centres.

Options

A. 680 nm, 690 nm
B. 700 nm, 680 nm
C. 680 nm, 700 nm
D. 700 nm, 670 nm

Answer

**Step-by-Step Solution:**

1. **Understanding Photosystems**: Photosystems are complexes in plants that play a crucial role in photosynthesis. They consist of chlorophyll and other pigments that capture light energy.

2. **Identifying Photosystem I (PS I)**: In Photosystem I, the primary pigment is chlorophyll a, which has a maximum absorption peak at a specific wavelength. This wavelength is crucial for the photosynthetic process.

3. **Finding the Absorption Peak for PS I**: The maximum absorption peak for chlorophyll a in Photosystem I is at 700 nm. This is often referred to as P700.

4. **Identifying Photosystem II (PS II)**: Similarly, Photosystem II also contains chlorophyll a, but it has a different absorption peak.

5. **Finding the Absorption Peak for PS II**: The peak absorption for chlorophyll a in Photosystem II is at 680 nm, known as P680.

6. **Final Answer**: Therefore, in Photosystem I (PS I), chlorophyll a has a maximum absorption at **700 nm**, and in Photosystem II (PS II), chlorophyll a has a peak absorption at **680 nm**.

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