Cultivation of Bt. Cotton has been much in the news. The prefix Bt. Means :

Options

A. " Barium treated" cotton seeds
B. "Bigger thread " variety cotton with better tensile strength
C. Produced by " biotechnology " using restriction enzymes and ligases
D. Carrying an endotoxin gene from Bacillus thuringiensls

Answer

**Step-by-Step Solution:**

1. **Understanding the Prefix "Bt":** The prefix "Bt" in Bt cotton stands for "Bacillus thuringiensis," which is a type of bacterium.

2. **Identifying the Role of Bacillus thuringiensis:** Bacillus thuringiensis (Bt) is a gram-positive bacterium that produces a toxin harmful to certain insects. This bacterium is utilized in biotechnology to create genetically modified organisms (GMOs).

3. **Genetic Modification Process:** In the case of Bt cotton, scientists isolate the gene responsible for producing the insecticidal toxin from Bacillus thuringiensis and insert it into the genome of the cotton plant. This process results in the cotton plant being able to produce the toxin itself.

4. **Function of Bt Cotton:** The Bt cotton plant produces a toxin that is harmful to specific insects. When these insects consume the cotton leaves, the toxin affects their digestive system, causing them to swell and eventually die. This helps protect the cotton crop from insect damage.

5. **Conclusion:** Therefore, the prefix "Bt" in Bt cotton specifically refers to the bacterium Bacillus thuringiensis, which is responsible for the production of the endotoxin that protects the cotton plant from pests.

**Final Answer:** The prefix "Bt" means "Bacillus thuringiensis."

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