If only one copy of a gene is present that condition is

Options

A. Hemizygous
B. Holozygous
C. Homozygous
D. Heterozygous

Answer

To determine the condition when only one copy of a gene is present, we can analyze the definitions of the terms related to gene presence:

1. **Understanding the Terms**:
- **Hemizygous**: This term refers to a condition where only one allele of a gene is present. This is commonly seen in males for genes located on the X chromosome, as they have only one X chromosome.
- **Holozygous**: This term is not commonly used in genetics. It seems to be a misinterpretation or confusion with other terms. It does not refer to a specific genetic condition.
- **Homozygous**: This condition occurs when an individual has two identical alleles for a particular gene (e.g., AA or aa).
- **Heterozygous**: This condition occurs when an individual has two different alleles for a particular gene (e.g., Aa).

2. **Identifying the Correct Answer**:
- Since the question specifically asks for a condition with only one copy of a gene, we look at the definitions. The only term that matches this description is **hemizygous**.

3. **Conclusion**:
- Therefore, the correct answer to the question "If only one copy of a gene is present, that condition is" is **hemizygous**.