Pigment molecule present at reaction centre of PS-I and PS-II respectively are

Options

A. Chl-a and chl-a
B. chl-a and chl-b
C. chl-b and chl-a
D. chl-b and chl-b

Answer

To solve the question regarding the pigment molecules present at the reaction centers of Photosystem I (PS-I) and Photosystem II (PS-II), we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Photosynthesis**:
- Photosynthesis occurs in plants, where light energy is absorbed and converted into chemical energy to produce food. This process takes place in chloroplasts, which contain structures called photosystems.

**Hint**: Remember that photosystems are essential for capturing light energy during photosynthesis.

2. **Identifying Reaction Centers**:
- Each photosystem has a reaction center, which is the site where pigment molecules are located. These pigments absorb light and convert it into energy.

**Hint**: Focus on what the reaction center does and the role of pigment molecules in energy conversion.

3. **Main Pigment in Photosystems**:
- The primary pigment molecule present in both PS-I and PS-II is chlorophyll A. This pigment is crucial for capturing light energy.

**Hint**: Chlorophyll A is the key pigment in both photosystems; think about its role in absorbing specific wavelengths of light.

4. **Accessory Pigments**:
- In addition to chlorophyll A, there are accessory pigments in both photosystems that help absorb light at different wavelengths and transfer that energy to chlorophyll A.

**Hint**: Accessory pigments assist chlorophyll A by broadening the spectrum of light that can be utilized for photosynthesis.

5. **Conclusion**:
- Since the question asks for the pigment molecules at the reaction centers of PS-I and PS-II, we conclude that the answer is chlorophyll A for both.

**Hint**: When answering questions about specific components in biological systems, always reference the primary and accessory roles of molecules involved.

### Final Answer:
The pigment molecules present at the reaction center of Photosystem I and Photosystem II respectively are **Chlorophyll A** for both.