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Assertion (A) According to "genic balal...

Assertion (A) According to "genic balalnce therory" the karyotype with AA-XO in Drosophila is sterile female .
Reason (R ) Y- chromosome in Drosophila lacks male determining factor

A

Both A and R are true . R ois correct explanation of A

B

Both A and R are true ,R is not correct explanation of A

C

A is true but R is false

D

A is false but R is true

Text Solution

AI Generated Solution

The correct Answer is:
### Step-by-Step Solution: 1. **Understanding the Assertion (A)**: The assertion states that according to the "genic balance theory," the karyotype with AA-XO in Drosophila is a sterile female. - **Explanation**: In Drosophila, the genic balance theory posits that sex determination is based on the ratio of X chromosomes to the number of sets of autosomes. In this case, the AA-XO karyotype indicates that there are two sets of autosomes (AA) and only one X chromosome (X), with no Y chromosome present. This results in a sterile female because the balance is skewed. 2. **Understanding the Reason (R)**: The reason states that the Y chromosome in Drosophila lacks a male determining factor. - **Explanation**: In Drosophila, male characteristics are not solely determined by the Y chromosome. Instead, the male determining factors are located on the autosomes. The Y chromosome does not carry these factors, which means that its presence alone does not guarantee male development. 3. **Evaluating the Truth of Both Statements**: - The assertion is true because, according to the genic balance theory, the AA-XO configuration leads to a sterile female. - The reason is also true because the Y chromosome does not contain the male determining factors; these are found on the autosomes. 4. **Determining the Relationship**: The reason provided explains why the assertion is true. The absence of a Y chromosome (and thus the male determining factors) is what leads to the AA-XO karyotype being a sterile female. 5. **Conclusion**: Both the assertion (A) and the reason (R) are true, and R is the correct explanation of A. Therefore, the correct answer is that both A and R are true, and R is the correct explanation of A. ### Final Answer: Both A and R are true, and R is the correct explanation of A. ---
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