A gene is said to be dominant if

Options

A. It expresses its effect only in homozygous state
B. It expresses its effect only in heterozygous condition
C. It expresses it effect both in homozygous and heterozygous condition
D. It never expresses it's effect in any condition

Answer

**Step-by-Step Solution:**

1. **Understanding Dominant Genes**: A gene is termed dominant if it can express its trait in both homozygous and heterozygous conditions. This means that the dominant gene will show its effect even when only one copy is present.

2. **Alleles and Their Representation**: In genetics, alleles are different forms of a gene. Dominant alleles are usually represented by capital letters (e.g., 'A'), while recessive alleles are represented by lowercase letters (e.g., 'a').

3. **Homozygous vs. Heterozygous Conditions**:
- **Homozygous Condition**: This occurs when both alleles in the allelomorphic pair are the same (e.g., 'AA' or 'aa'). In this case, if the alleles are both dominant (AA), the dominant trait will be expressed.
- **Heterozygous Condition**: This occurs when the alleles in the pair are different (e.g., 'Aa'). Here, the presence of the dominant allele ('A') will mask the effect of the recessive allele ('a'), resulting in the expression of the dominant trait.

4. **Conclusion**: Therefore, a gene is said to be dominant if it expresses itself in both homozygous (AA) and heterozygous (Aa) conditions.

**Final Answer**: A gene is said to be dominant if it expresses itself in both homozygous and heterozygous conditions.

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