A : XO type sex determination is found in large number of insects.
R : ZW type sex determination is found in birds.

Options

A. If both Assertion & Reason are true and the reason is the correct explanation of the assertion, then mark (1)
B. If both Assertion & Reason are true and the reason is not the correct explanation of the assertion , then mark (2)
C. If Assertion is true statement but Reason is false, then mark (3)
D. If both Assertion and Reason are false statements, then mark (4)

Answer

To solve the assertion and reason question regarding sex determination in insects and birds, we can follow these steps:

### Step 1: Understand the Assertion
The assertion states that "XO type sex determination is found in a large number of insects."
- In XO sex determination, males have one sex chromosome (X) while females have two (XX). This means males are heterogametic (producing two types of gametes: X and no sex chromosome), while females are homogametic (producing only X gametes).

### Step 2: Understand the Reason
The reason states that "ZW type sex determination is found in birds."
- In ZW sex determination, females are heterogametic (ZW), producing two types of gametes (Z and W), while males are homogametic (ZZ), producing only Z gametes.

### Step 3: Analyze the Relationship
Both statements are true:
- The assertion about XO type sex determination in insects is correct.
- The reason about ZW type sex determination in birds is also correct.

However, the reason does not explain the assertion. The two statements describe different systems of sex determination in different groups of organisms and are not causally related.

### Step 4: Conclusion
Since both the assertion and reason are true but the reason does not explain the assertion, the correct answer is that both statements are true but the reason is not the correct explanation for the assertion.

### Final Answer
The answer is: Both A and R are true, but R is not the correct explanation of A.

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