The number of barr bodies in XXXXY is
(a) 1
(b) 2
(c) 3
(d) 4

Options

A. 1
B. 2
C. 3
D. 4

Answer

To determine the number of Barr bodies in an individual with the genotype XXXXY, we can follow these steps:

### Step-by-Step Solution:

1. **Understand Barr Bodies**: Barr bodies are inactivated X chromosomes in a cell. In females, typically one X chromosome is active while the others are inactivated.

2. **Identify the Number of X Chromosomes**: In the genotype XXXXY, there are a total of 4 X chromosomes (XXX) and 1 Y chromosome (Y).

3. **Apply the Barr Body Rule**: According to the rule established by M.F. Lyon, the number of Barr bodies is equal to the total number of X chromosomes minus one. This rule applies when there are two or more X chromosomes.

4. **Calculate the Number of Barr Bodies**:
- Total X chromosomes = 4 (from XXXX)
- Barr bodies = Total X chromosomes - 1 = 4 - 1 = 3

5. **Conclusion**: Therefore, the number of Barr bodies in an individual with the genotype XXXXY is 3.

### Final Answer:
(c) 3

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