Consider the following statemetns
1. The thylakoids of blue-green algae are arranged singly in the stroma of chloroplasts.
2. In blue-green algae, the thylkoids are not only the sites for photosynthesis but also for respiration
Which of the statements given above is/are correct?

Options

A. (a) 1 only
B. (b) 2 only
C. (c) both 1 and 2
D. (d) Neither 1 nor 2

Answer

To solve the question, we need to evaluate the two statements regarding blue-green algae (cyanobacteria) and their thylakoids.

### Step-by-Step Solution:

1. **Evaluate the First Statement:**
- The first statement claims that "the thylakoids of blue-green algae are arranged singly in the stroma of chloroplasts."
- In blue-green algae, thylakoids are not arranged singly. Instead, they are organized in stacks or flattened sacs formed by the invagination and fusion of internal membranes. Therefore, this statement is **false**.

2. **Evaluate the Second Statement:**
- The second statement states that "in blue-green algae, the thylakoids are not only the sites for photosynthesis but also for respiration."
- This statement is **true**. In blue-green algae, thylakoids are indeed involved in photosynthesis, and they also play a role in the respiratory electron transfer chain. Thus, they are responsible for both photosynthesis and respiration.

3. **Conclusion:**
- Based on the evaluations, the first statement is false, and the second statement is true. Therefore, the correct answer is that only the second statement is correct.

### Final Answer:
The correct option is **B) 2 only**.