Select the mismatch

Options

A. cry I Ac – Helicoverpa
B. cry I Ab – Com borer
C. cry II Ab – Corn borer
D. cry I Ab – Ostrinia

Answer

To solve the question "Select the mismatch," we need to analyze the options provided and determine which one does not correctly match the Bt toxin (Cry gene) with the corresponding pest.

### Step-by-Step Solution:

1. **Understand the Cry Genes**:
- Cry genes are derived from the bacterium *Bacillus thuringiensis* (Bt) and encode for proteins that are toxic to specific insects.
- The main Cry genes mentioned are Cry1AC, Cry1AB, and Cry2AB.

2. **Identify the Insects**:
- **Cry1AC**: This gene is effective against the cotton bollworm, scientifically known as *Helicoverpa*.
- **Cry1AB**: This gene is also effective against the cotton bollworm.
- **Cry2AB**: This gene is effective against the corn borer.

3. **Analyze Each Option**:
- **Option 1**: Cry1AC - Helicoverpa: This is correct because Cry1AC targets the cotton bollworm (*Helicoverpa*).
- **Option 2**: Cry1AB - Corn borer: This is incorrect. Cry1AB targets the cotton bollworm, not the corn borer.
- **Option 3**: Cry2AB - Corn borer: This is correct as Cry2AB is effective against the corn borer.
- **Option 4**: Cry1AB - Australia: This option is misleading as it does not specify an insect but refers to a geographical location. However, it is still correct since Cry1AB is known to be effective against the cotton bollworm.

4. **Conclusion**:
- The mismatch is found in **Option 2**: Cry1AB - Corn borer. Cry1AB does not target the corn borer; it targets the cotton bollworm instead.

### Final Answer:
The mismatch is **Cry1AB - Corn borer**.