The heterochromatin is condensed in the following region of the chromosome :–

Options

A. Secondary constriction–I
B. Secondary constriction–II
C. Both the above
D. Telomere

Answer

**Step-by-Step Solution:**

1. **Understanding Heterochromatin**: Heterochromatin is a form of chromatin that is densely packed and typically transcriptionally inactive. It is found in specific regions of chromosomes.

2. **Identifying Chromosome Regions**: In a chromosome, there are specific regions known as constrictions. The two main types of constrictions are:
- **Primary Constriction (Centromere)**: This is the central region of the chromosome where the two sister chromatids are joined. Heterochromatin is usually found in a condensed form here.
- **Secondary Constriction**: These are additional constrictions that can occur on the chromosome, and heterochromatin can also be found in a condensed form in these regions.

3. **Evaluating the Options**:
- **Option 1: Secondary Constriction**: Heterochromatin can be condensed here.
- **Option 2: Primary Constriction**: Heterochromatin is also condensed here.
- **Option 3: Both the above**: This option includes both primary and secondary constrictions where heterochromatin is condensed.
- **Option 4: Telomere**: Telomeres are located at the ends of chromosomes and primarily serve to protect the chromosome ends, not where heterochromatin is condensed.

4. **Conclusion**: Since heterochromatin is condensed in both the primary and secondary constriction regions, the correct answer is **Option 3: Both the above**.

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