An organism with two unlike genes of a trait is called :

Options

A. Homozygous
B. Heterozygous
C. Hemizygous
D. None of these.

Answer

To answer the question, "An organism with two unlike genes of a trait is called:", we can follow these steps:

### Step-by-Step Solution:

1. **Understanding Genes and Alleles**:
- Genes are segments of DNA that determine specific traits in an organism. Alleles are different forms of a gene that can exist for a particular trait. For example, for the trait of height, there can be alleles for tall (T) and dwarf (t).

2. **Identifying Types of Gene Combinations**:
- When an organism has two identical alleles for a trait (e.g., TT or tt), it is referred to as homozygous.
- Conversely, when an organism has two different alleles for a trait (e.g., Tt), it is referred to as heterozygous.

3. **Defining Heterozygous**:
- The term "heterozygous" specifically describes an organism that possesses two different alleles for a particular gene. This means the organism has one dominant allele and one recessive allele.

4. **Conclusion**:
- Therefore, an organism with two unlike genes (or alleles) of a trait is called **heterozygous**.

### Final Answer:
An organism with two unlike genes of a trait is called **heterozygous**.

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