Which of the following is a mismatch regarding the transgenic organism and its application :-

Options

A. Oncomouse `hArr` study of cancer
B. transgenic tobacco `rArr` herbicide resistance
C. Bt-cotton `rArr` nematode resistance
D. Knockout mice `rArr` study of gene expression

Answer

To determine the mismatch regarding transgenic organisms and their applications, we will analyze each option provided in the question step by step.

### Step-by-Step Solution:

1. **Analyze Oncomouse**:
- Oncomouse is a genetically modified mouse designed specifically for cancer research. It has been engineered to develop tumors, making it a valuable model for studying cancer.
- **Conclusion**: This option is correctly matched.

2. **Evaluate Transgenic Tobacco**:
- Transgenic tobacco plants have been modified to be resistant to herbicides, specifically bromozyanil. A gene that detoxifies this harmful compound was inserted into the tobacco plant using Agrobacterium tumefaciens.
- **Conclusion**: This option is correctly matched.

3. **Examine Bt Cotton**:
- Bt cotton is genetically modified to express the Bt gene, which provides resistance against bollworms, a significant pest for cotton crops. The Bt gene produces a toxin that is harmful to these insects.
- However, the statement claims that Bt cotton is nematode resistant, which is incorrect. Bt cotton is specifically designed for bollworm resistance, not nematode resistance.
- **Conclusion**: This option is mismatched.

4. **Review Knockout Mice**:
- Knockout mice are genetically engineered to have specific genes deleted (knocked out) to study the effects of those genes on gene expression and protein production.
- **Conclusion**: This option is correctly matched.

### Final Answer:
The mismatch regarding the transgenic organism and its application is **Option 3: Bt cotton and nematode resistance**.

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