Which of the following stimulates balbiani ring formation in polytene chromosomes :-

Options

A. Dynien
B. Juvenile harmone
C. Ecdyson
D. Histone

Answer

To solve the question about which substance stimulates Balbiani ring formation in polytene chromosomes, we can follow these steps:

### Step 1: Understand Polytene Chromosomes
Polytene chromosomes are large chromosomes that consist of many DNA strands (thousands of DNA strands). They are typically found in the salivary glands of certain insects, such as Drosophila and Chironomus. These chromosomes are known for their high level of transcriptional activity.

**Hint:** Polytene chromosomes are characterized by their size and the presence of many DNA strands.

### Step 2: Learn About Balbiani Rings
Balbiani rings are specific structures observed in polytene chromosomes, named after the scientist E.G. Balbiani who first described them in 1881. These rings appear as large puffs on the chromosomes and are sites of high RNA production.

**Hint:** Balbiani rings are associated with high levels of RNA synthesis and are named after the scientist who discovered them.

### Step 3: Identify the Stimulus for Balbiani Ring Formation
The question asks which substance stimulates the formation of Balbiani rings. The key substance that induces this formation is Ecdysone, a hormone that plays a crucial role in the molting and metamorphosis of insects. Ecdysone stimulates the development of imaginal discs and the apoptosis of larval tissues, leading to the formation of Balbiani rings in polytene chromosomes.

**Hint:** Look for a hormone associated with insect development that stimulates the formation of Balbiani rings.

### Step 4: Eliminate Incorrect Options
The other options provided, such as Juvenile Hormone, Dynein, and Histone, do not stimulate Balbiani ring formation. Juvenile Hormone is involved in maintaining larval characteristics, Dynein is a motor protein, and Histone is a protein that helps package DNA but does not stimulate Balbiani rings.

**Hint:** Consider the roles of the other options and how they relate to the formation of Balbiani rings.

### Conclusion
Based on the information gathered, the correct answer to the question is **Ecdysone**, as it is the substance that stimulates Balbiani ring formation in polytene chromosomes.

**Final Answer:** Ecdysone (Option 3).