Chromosome number 2n-1 is an example of

Options

A. trisomy
B. euploidy
C. polyploidy
D. monosomy

Answer

To solve the question "Chromosome number 2n-1 is an example of," we will follow these steps:

### Step-by-Step Solution:

1. **Understand the Chromosome Number Notation**:
- The notation "2n" refers to the diploid number of chromosomes, where "n" is the number of chromosomes in a haploid set. In humans, for example, "n" is 23, so "2n" is 46.

2. **Identify the Meaning of 2n-1**:
- The expression "2n-1" indicates that one chromosome is missing from the diploid set. This means there is a decrease in the total number of chromosomes.

3. **Define Monosomy**:
- When there is a loss of one chromosome from the diploid set, it is termed "monosomy." Therefore, "2n-1" represents a condition of monosomy.

4. **Provide an Example**:
- An example of monosomy in humans is Turner syndrome, which occurs when there is a missing X chromosome, resulting in a total of 45 chromosomes instead of the normal 46.

5. **Differentiate from Other Terms**:
- It is important to differentiate monosomy from other terms:
- **Trisomy** refers to the presence of an extra chromosome (2n+1).
- **Aneuploidy** is a broader term that includes both monosomy and trisomy, indicating an abnormal number of chromosomes.
- **Euploidy** refers to the normal set of chromosomes (2n).
- **Polyploidy** refers to having more than two sets of chromosomes (e.g., 4n).

### Final Answer:
Chromosome number 2n-1 is an example of **monosomy**.

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