In human males all the chromosomes are paired perfectly except one. This/these unpaired chromosome is/are

Options

A. large
B. Y chromosome
C. small chromosome
D. X-chromosome

Answer

**Step-by-Step Solution:**

1. **Understanding Chromosomes in Humans:**
- Humans have a total of 46 chromosomes, which are organized into 23 pairs. These pairs consist of 22 pairs of autosomes and 1 pair of sex chromosomes.

2. **Identifying the Sex Chromosomes:**
- The 23rd pair of chromosomes are the sex chromosomes. In females, this pair consists of two X chromosomes (XX), while in males, it consists of one X chromosome and one Y chromosome (XY).

3. **Analyzing the Male Chromosome Pairing:**
- In males, the first 22 pairs of chromosomes (autosomes) are perfectly paired. However, the 23rd pair, which consists of the X and Y chromosomes, is not perfectly paired because the X chromosome is larger than the Y chromosome.

4. **Identifying the Unpaired Chromosome:**
- Since the X and Y chromosomes are not identical, the Y chromosome is the unpaired chromosome in human males. This is because it does not have a corresponding Y chromosome to pair with, unlike the X chromosome which has a matching X in females.

5. **Conclusion:**
- Therefore, the unpaired chromosome in human males is the Y chromosome.

**Final Answer:**
The unpaired chromosome in human males is the Y chromosome.

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