Bt toxin is a

Options

A. crystalline, proteinaceous , insecticidal `beta` endotoxin
B. amorphous , proteinaceous , insecticidal `delta` endotoxin
C. crystalline, proteinaceous , insecticidal `delta` endotoxin
D. amorphous , proteinaceous , insecticidal `beta` endotoxin

Answer

To solve the question "Bt toxin is a", we need to analyze the options provided and understand the characteristics of Bt toxin. Here’s a step-by-step solution:

### Step 1: Understand what Bt toxin is
Bt toxin is derived from the bacterium Bacillus thuringiensis. This bacterium produces a protein that is toxic to certain insects.

**Hint:** Remember that Bt stands for Bacillus thuringiensis, which is crucial for understanding the origin of the toxin.

### Step 2: Identify the nature of Bt toxin
The toxin produced by Bacillus thuringiensis is known to be a crystalline protein. It forms crystals that are toxic to insects when ingested.

**Hint:** Focus on the term "crystalline" as it describes the physical form of the toxin.

### Step 3: Determine the type of endotoxin
The Bt toxin is classified as an insecticidal delta endotoxin. This means it is specifically designed to target and kill insects.

**Hint:** Recall that the term "endotoxin" refers to toxins that are part of the bacterial cell structure, and "delta" indicates the specific type produced by Bacillus thuringiensis.

### Step 4: Eliminate incorrect options
- **Amorphous proteinase**: This is incorrect because Bt toxin is crystalline, not amorphous.
- **Beta endotoxin**: This is also incorrect; the correct term is delta endotoxin.
- **Insecticidal beta endotoxin**: Again, this is incorrect for the same reason as above.

**Hint:** Cross-check the terms "beta" and "delta" with the information you have about the toxin.

### Step 5: Conclude the correct answer
Based on the analysis, the correct answer is that Bt toxin is a crystalline protein, insecticidal delta endotoxin.

**Final Answer:** Bt toxin is a crystalline protein, insecticidal delta endotoxin.