Highest arm ratio occur in which chromosome :-

Options

A. Telocentric
B. Metacentric
C. Submetacentric
D. Acrocentric

Answer

To determine which chromosome has the highest arm ratio, we need to analyze the characteristics of different types of chromosomes based on their centromere positions. Here’s a step-by-step breakdown of the solution:

### Step-by-Step Solution:

1. **Understand Chromosome Types**:
- Chromosomes can be classified based on the position of their centromeres into four types:
- **Metacentric**: Centromere is located at the center, resulting in two equal arms (P and Q).
- **Submetacentric**: Centromere is slightly off-center, resulting in one arm being longer than the other.
- **Acrocentric**: Centromere is located closer to one end, resulting in one very short arm (P) and one long arm (Q).
- **Telocentric**: Centromere is located at the end of the chromosome, resulting in only one arm (Q) and no P arm.

2. **Calculate Arm Ratio**:
- The arm ratio is calculated as the length of the longer arm (Q) divided by the length of the shorter arm (P).
- For **Metacentric** chromosomes, the arm ratio is 1:1 (P = Q).
- For **Submetacentric** chromosomes, the arm ratio is greater than 1 but not the highest.
- For **Telocentric** chromosomes, since there is no P arm, the arm ratio is undefined (0).
- For **Acrocentric** chromosomes, the P arm is very short compared to the Q arm, leading to a significantly high arm ratio.

3. **Identify the Highest Arm Ratio**:
- Among the types discussed, the **Acrocentric** chromosomes have the highest arm ratio because the P arm is minimal compared to the long Q arm.

4. **Conclusion**:
- Therefore, the chromosome type that exhibits the highest arm ratio is the **Acrocentric** chromosome.

### Final Answer:
The highest arm ratio occurs in **Acrocentric chromosomes**.