The condition in which only one allele of a pair is present in a diploid organism is known as :-

Options

A. Homozygous
B. Heterozygous
C. Hemizygous
D. Incomplete dominance

Answer

To solve the question "The condition in which only one allele of a pair is present in a diploid organism is known as:", we can follow these steps:

### Step 1: Understand the Terminology
- **Allele**: Different forms of a gene that can exist at a specific locus on a chromosome.
- **Diploid Organism**: An organism that has two sets of chromosomes, one from each parent, which means it typically has two alleles for each gene.

### Step 2: Analyze the Options
The options provided are:
1. Homozygous
2. Heterozygous
3. Hemizygous
4. Incomplete dominance

### Step 3: Define Each Option
- **Homozygous**: This condition occurs when an organism has two identical alleles for a particular gene (e.g., AA or aa).
- **Heterozygous**: This condition occurs when an organism has two different alleles for a particular gene (e.g., Aa).
- **Hemizygous**: This condition occurs when only one allele of a gene is present. This is commonly seen in males for genes on the X chromosome, as they have only one X chromosome.
- **Incomplete Dominance**: This refers to a situation where one allele does not completely dominate another, resulting in a blended phenotype (e.g., red and white flowers producing pink flowers).

### Step 4: Identify the Correct Answer
From the definitions, we can see that:
- **Hemizygous** is the correct answer because it specifically refers to the condition where only one allele of a gene is present in a diploid organism.

### Conclusion
The correct answer to the question is **Hemizygous**.

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