A monosomic organism can best be represented

Options

A. 2n+1
B. 2n+2
C. n+1
D. 2n-1

Answer

To determine how a monosomic organism can be represented, we need to understand the concept of monosomy and how it relates to the karyotype of an organism.

### Step-by-Step Solution:

1. **Understanding Monosomy**:
- Monosomy refers to the condition where there is a missing chromosome from a pair. In other words, instead of having two copies of a chromosome, there is only one.

2. **Karyotype Representation**:
- The karyotype is a visual representation of an organism's complete set of chromosomes. It typically shows the number of chromosomes and their structure.

3. **Normal Chromosome Count**:
- In humans, the normal chromosome count is 46, which is organized into 23 pairs (2n = 46).

4. **Monosomic Condition**:
- If an organism is monosomic for a particular chromosome, it will have one less chromosome than the normal count. Therefore, the total number of chromosomes will be 45 (2n - 1).

5. **Example of Monosomy**:
- A well-known example of monosomy in humans is Turner’s syndrome, where females have only one X chromosome instead of two (X0). This results in a total of 45 chromosomes.

6. **Conclusion**:
- Thus, a monosomic organism can be represented by the karyotype notation of 2n - 1, indicating that there is one chromosome less than the diploid number.

### Final Answer:
A monosomic organism can best be represented by the karyotype notation **2n - 1**.

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