Lyon's hypothesis is connected with

Options

A. Number of barr bodies
B. Genetic compatibility
C. Genetic incompatibility
D. Centromere position

Answer

**Step-by-Step Solution:**

1. **Understanding Lyon's Hypothesis**: Lyon's hypothesis, proposed by Mary Lyon, explains the phenomenon of X-chromosome inactivation in female mammals. This is a crucial concept in genetics, particularly in understanding dosage compensation.

2. **X-Chromosome Inactivation**: In female mammals, which have two X chromosomes (XX), one of the X chromosomes is randomly inactivated during early embryonic development. This process ensures that females do not have double the dosage of X-linked genes compared to males (who have one X and one Y chromosome).

3. **Formation of Barr Bodies**: The inactivated X chromosome condenses into a structure known as a Barr body. This is a visible manifestation of the inactivation process and is found in the nuclei of female cells.

4. **Connection to the Question**: The question asks what Lyon's hypothesis is connected with. The key term here is "Barr bodies," which are formed due to the inactivation of one X chromosome in females.

5. **Identifying the Correct Option**: Among the options provided:
- Number of Barr bodies
- Genetic compatibility
- Genetic incompatibility
- Centromere position

The correct answer is "number of Barr bodies" because Lyon's hypothesis directly relates to the inactivation of X chromosomes and the resulting formation of Barr bodies in female mammals.

**Final Answer**: Lyon's hypothesis is connected with the number of Barr bodies.

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