Chromosomes found in the salivary glands of Drosophila are

Options

A. Polytene
B. Supernumerary
C. Lampbrush
D. B -chromosome

Answer

To answer the question regarding the type of chromosomes found in the salivary glands of Drosophila, we can follow these steps:

### Step-by-Step Solution:

1. **Identify the Organism**:
- The question refers to Drosophila, commonly known as fruit flies. These are two-winged insects that are widely used in genetic research.

2. **Understand Chromosome Types**:
- There are different types of chromosomes, including polytene, supernumerary, lampbrush, and B chromosomes. Each type has distinct characteristics and functions.

3. **Focus on Salivary Glands**:
- In Drosophila, the salivary glands are known to contain a specific type of chromosome that is unique and important for genetic studies.

4. **Define Polytene Chromosomes**:
- Polytene chromosomes are formed by the replication of DNA without subsequent cell division, leading to many copies of the chromosome being aligned side by side. This results in a thick, banded appearance, which is characteristic of polytene chromosomes.

5. **Consider the Process of Endoreplication**:
- The formation of polytene chromosomes occurs through a process called endoreplication. In this process, DNA is replicated multiple times without cell division, allowing for the accumulation of chromatin material.

6. **Evaluate the Options**:
- Given the definitions:
- A) Polytene - Correct, as these are found in the salivary glands of Drosophila.
- B) Supernumerary - Incorrect, these are additional chromosomes not typically found in salivary glands.
- C) Lamp brush - Incorrect, these are found in oocytes of some organisms, not in Drosophila salivary glands.
- D) B chromosome - Incorrect, these are extra chromosomes that do not follow Mendelian inheritance.

7. **Conclusion**:
- The correct answer is A) Polytene chromosomes, as they are specifically found in the salivary glands of Drosophila.

### Final Answer:
The chromosomes found in the salivary glands of Drosophila are **polytene chromosomes**.

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