The variant of cry genes used to control corn borers is

Options

A. crylAc
B. crylAb
C. cryllAb
D. Both (a) and (b)

Answer

To determine the variant of cry genes used to control corn borers, we can follow these steps:

### Step 1: Understand the Source of Cry Genes
The cry genes are derived from the bacterium **Bacillus thuringiensis** (Bt). This bacterium produces proteins that are toxic to certain insects.

**Hint:** Look for the origin of the cry genes and their function in pest control.

### Step 2: Identify the Function of Cry Proteins
The proteins encoded by cry genes are specifically designed to target the midgut of insects. When insects feed on plants that express these proteins, the proteins become active and form pores in the insect's gut, leading to lysis (cell breakdown) and ultimately the death of the insect.

**Hint:** Focus on how these proteins interact with insect physiology.

### Step 3: Recognize the Specific Cry Variants
Different cry genes target different pests. For corn borers, the relevant cry gene variants are:
- **Cry1AB**: Specifically effective against corn borers.
- **Cry1AC**: Targets other pests, not specifically corn borers.
- **Cry2AB**: Primarily targets cotton bollworms.

**Hint:** Compare the specific cry gene variants and their target pests.

### Step 4: Analyze the Options Given
The options provided are:
1. Cry1AC
2. Cry1AB
3. Cry2AB
4. Both A and B

From our understanding, **Cry1AB** is the variant that is specifically used to control corn borers.

**Hint:** Eliminate options that do not directly relate to corn borers.

### Step 5: Select the Correct Answer
Based on the analysis, the correct answer is **Cry1AB**, as it is the variant of cry genes used to control corn borers.

**Final Answer:** **Cry1AB**