Question

Cry II Ab and Cry I Ab produce toxins respectively that control

• A. Cotton bollworms and corn borer
• B. Corn borer and cotton bollworms
• C. Tobacco bud worms and nematodes
• D. Army worms and tobacco bud worms

Hint:

Remember: Cry IAb controls cotton bollworm, whereas Cry IIAb controls corn borer. Different Cry proteins target different insect groups.

Answer 1

The Correct Option is B

Concept: Bacillus thuringiensis (Bt) produces crystalline proteins known as Cry proteins. Different Cry genes produce toxins effective against different insect pests. These genes are transferred into crop plants to provide insect resistance.

Step 1: Understand Cry IAb. Cry IAb protein is highly effective against cotton bollworms and certain lepidopteran pests. Therefore Cry IAb is associated with protection against cotton bollworms.

Step 2: Understand Cry IIAb. Cry IIAb protein is effective against corn borer insects. Hence Cry IIAb provides protection against corn borers.

Step 3: Arrange in the order given in the question. The question asks: Cry IIAb $\rightarrow$ ? Cry IAb $\rightarrow$ ? Therefore, \[ \text{Cry IIAb} \rightarrow \text{Corn borer} \] \[ \text{Cry IAb} \rightarrow \text{Cotton bollworms} \] Hence option (B) is correct.