When the maternal and paternal chromosomes of a homologous pair carry identical alleles at the same locus, the organism is

Options

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

Answer

To solve the question, we need to understand the concepts of alleles, homologous chromosomes, and the terms homozygous and heterozygous.

### Step-by-Step Solution:

1. **Understanding Homologous Chromosomes**:
- Homologous chromosomes are pairs of chromosomes in a diploid organism, one inherited from the mother and one from the father. Each chromosome in the pair carries genes for the same traits.

**Hint**: Remember that homologous chromosomes come in pairs, one from each parent.

2. **Identifying Alleles**:
- Alleles are different forms of a gene that exist at a specific locus on a chromosome. For example, for a gene that determines flower color, one allele might be for red flowers (A) and another for white flowers (a).

**Hint**: Alleles can be identical (homozygous) or different (heterozygous).

3. **Identifying the Condition**:
- The question states that both the maternal and paternal chromosomes carry identical alleles at the same locus. This means that both chromosomes have the same version of the gene.

**Hint**: Look for the terms "identical alleles" in the question; they indicate a specific genetic condition.

4. **Defining Homozygous**:
- When an organism has two identical alleles for a particular gene, it is referred to as homozygous. For example, if both alleles are A (AA) or both are a (aa), the organism is homozygous.

**Hint**: The prefix "homo-" means same, which is key to identifying homozygous conditions.

5. **Defining Heterozygous**:
- If the alleles were different (e.g., one A and one a), the organism would be heterozygous. However, since the question specifies identical alleles, this condition does not apply.

**Hint**: The prefix "hetero-" means different, which is not applicable here.

6. **Conclusion**:
- Since the question specifies that the maternal and paternal chromosomes carry identical alleles at the same locus, we conclude that the organism is homozygous.

**Final Answer**: The organism is **homozygous**.