A human male how is hemizygous for a gene gives rise to

Options

A. brown eyes
B. phenylketonuria
C. colour-blindness
D. cystic fibrosis

Answer

To solve the question about what a human male who is hemizygous for a gene gives rise to, we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Hemizygosity**:
- Hemizygous refers to a condition where an individual has only one copy of a gene instead of the usual two. This is common in males for genes located on the X chromosome, as they have one X and one Y chromosome.

**Hint**: Remember that males are XY and females are XX; this is crucial for understanding hemizygosity.

2. **Identifying the Traits**:
- In the context of the question, we need to identify traits that can be expressed in a hemizygous male. Since males have only one X chromosome, any gene located on the X chromosome will be expressed if present.

**Hint**: Focus on traits that are linked to the X chromosome, as these will be the ones affected by hemizygosity.

3. **Examples of X-Linked Traits**:
- Common examples of X-linked traits include colorblindness and hemophilia. If a male inherits an allele for colorblindness on his X chromosome, he will express this trait because he lacks a second X chromosome that could carry a normal allele.

**Hint**: Think of conditions that are more prevalent in males due to their single X chromosome.

4. **Conclusion**:
- Therefore, if a human male is hemizygous for a gene, he is likely to express traits associated with that gene, particularly if it is an X-linked trait. In this case, colorblindness is a classic example of a condition that arises from hemizygosity in males.

**Hint**: Conclude by identifying that the hemizygous condition leads to the expression of any trait linked to the single copy of the gene present.

### Final Answer:
A human male who is hemizygous for a gene gives rise to traits associated with that gene, particularly if it is an X-linked trait, such as colorblindness.