In PS I, the reaction centre chl a has absorption maxima at____whereas in PS II, the reaction centre Chl a has absorption maxima at ___

Options

A. 700nm ,680nm
B. 680nm,700nm
C. 400nm,500nm
D. 700nm,800nm

Explanation

To answer the question regarding the absorption maxima of chlorophyll a in Photosystem I (PS I) and Photosystem II (PS II), we can follow these steps:

### Step-by-Step Solution:

1. **Identify Photosystem I (PS I)**:
- PS I is also known as P700. The "P" stands for pigment, and "700" refers to the wavelength of light (in nanometers) at which this pigment absorbs light most effectively.

2. **Determine the Absorption Maximum for PS I**:
- The absorption maximum for chlorophyll a in PS I (P700) is at **700 nanometers**. This means that chlorophyll a in PS I absorbs light most strongly at this wavelength.

3. **Identify Photosystem II (PS II)**:
- PS II is referred to as P680. Similar to PS I, "P" stands for pigment, and "680" indicates the wavelength of light at which this pigment absorbs light most effectively.

4. **Determine the Absorption Maximum for PS II**:
- The absorption maximum for chlorophyll a in PS II (P680) is at **680 nanometers**. This indicates that chlorophyll a in PS II absorbs light most effectively at this wavelength.

5. **Final Answer**:
- Therefore, the absorption maxima are:
- For PS I: **700 nanometers**
- For PS II: **680 nanometers**

### Summary:
- In PS I, the reaction centre chlorophyll a has absorption maxima at **700 nm**, whereas in PS II, the reaction centre chlorophyll a has absorption maxima at **680 nm**.

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