Identify the statement which is not true for Bt. toxin?

Options

A. It is the product of cry - gene of Bacillus thuringienis
B. It is secreted I crystalline state called protoxin
C. It creates pores in the midgut of insect larvae
D. The toxin causes cell wall damage to Bacillus thuringiensis

Answer

To identify the statement that is not true for Bt toxin, we can follow these steps:

### Step-by-Step Solution:

1. **Understand the Context**: Bt toxin refers to the toxin produced by the bacterium Bacillus thuringiensis, which is widely used in agriculture as a biological pesticide.

2. **Evaluate Each Statement**:
- **Statement 1**: "The product of cry gene of Bacillus thuringiensis."
- This statement is true. The Cry proteins are indeed produced by Bacillus thuringiensis and are responsible for its insecticidal properties.

- **Statement 2**: "It is secreted by a crystalline state called a pro toxin."
- This statement is also true. Bt toxin is initially produced as a crystalline protein (pro toxin) that is activated in the gut of insects.

- **Statement 3**: "It creates pores in the mid gut of insect larvae."
- This statement is true as well. The activated Bt toxin binds to the gut cells of insects and creates pores, leading to cell lysis and death of the larvae.

- **Statement 4**: "The toxin causes cell wall damage to Bacillus thuringiensis."
- This statement is not true. The Bt toxin does not cause damage to the cell wall of Bacillus thuringiensis itself; rather, it acts on the gut cells of insects.

3. **Conclusion**: The statement that is not true for Bt toxin is the fourth one: "The toxin causes cell wall damage to Bacillus thuringiensis."

### Final Answer:
The statement which is not true for Bt toxin is: "The toxin causes cell wall damage to Bacillus thuringiensis."

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