In photosystem-I the first electron acceptor is
(a) Plastocyanin
(b) An iron-sulfur protein
(c) Ferrodoxin
(d) Cytochorme

Options

A. Plastocyanin
B. An iron-sulfur protein
C. Ferrodoxin
D. Cytochorme

Answer

To solve the question regarding the first electron acceptor in Photosystem I (PSI), we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Role of Photosystem I (PSI)**:
- Photosystem I is a complex of proteins and pigments located in the thylakoid membranes of chloroplasts. Its primary function is to absorb light energy and facilitate the transfer of electrons.

2. **Identify the Components of PSI**:
- PSI contains various components, including chlorophyll, which absorbs light, and several proteins that assist in the electron transport chain.

3. **Determine the Process of Electron Transfer**:
- When PSI absorbs light, it excites electrons, which are then transferred through a series of proteins. The first electron acceptor in this process is critical for understanding the flow of energy.

4. **Evaluate the Given Options**:
- (a) Plastocyanin: This is a copper-containing protein that transfers electrons from the cytochrome b6f complex to PSI, but it is not the first acceptor.
- (b) An iron-sulfur protein: This refers to proteins that contain iron-sulfur clusters and are involved in electron transfer, but they are not the first acceptor in PSI.
- (c) Ferredoxin: This is a small iron-sulfur protein that receives electrons from PSI and is indeed the first electron acceptor.
- (d) Cytochrome: These are proteins that play a role in electron transport but are not the first acceptor in PSI.

5. **Conclude with the Correct Answer**:
- Based on the information, the first electron acceptor in Photosystem I is **(c) Ferredoxin**.

### Final Answer:
(c) Ferredoxin