Arm ratio in metacentric condition is :-

Options

A. `1 : 1`
B. `1 : 2`
C. `1 : 3`
D. `2 : 3`

Answer

### Step-by-Step Solution:

1. **Understanding Chromosome Structure**:
- Chromosomes are made up of two sister chromatids joined at a point called the centromere. The centromere divides the chromosome into two arms: the shorter arm (P arm) and the longer arm (Q arm).

2. **Identifying Metacentric Chromosomes**:
- A metacentric chromosome is characterized by its centromere being located in the middle. This results in two arms of equal length.

3. **Arm Ratio in Metacentric Chromosomes**:
- Since both arms (P and Q) are equal in length in a metacentric chromosome, the arm ratio is expressed as 1:1.

4. **Comparison with Other Chromosome Types**:
- In contrast, telocentric chromosomes have only one arm (the other arm is absent), and acrocentric chromosomes have one short arm and one long arm, leading to an arm ratio that is not equal (for example, approximately 1:1.73 for submetacentric chromosomes).

5. **Conclusion**:
- Therefore, in metacentric chromosomes, the arm ratio is definitively 1:1.

### Final Answer:
The arm ratio in metacentric condition is 1:1.

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