Question

What is the primary function of Bt toxin in genetically modified crops like Bt Cotton?

• A. Enhancing nutrient content.
• B. Providing resistance to fungal infections.
• C. Acting as a natural insecticide.
• D. Increasing drought tolerance.

Hint:

Remember the name: \textbf{Bt} stands for {\textbf{B}acillus \textbf{t}huringiensis}. This bacterium produces a protein toxic to insects. So, Bt crops are insect-resistant. The 't' in Bt can remind you of 'toxin'.

Answer 1

The Correct Option is C

Step 1: Understanding the Concept:
The question asks for the main purpose of incorporating the Bt toxin gene into crops such as cotton. "Bt" stands for {Bacillus thuringiensis}, a soil bacterium.
Step 2: Detailed Explanation:


The bacterium {Bacillus thuringiensis} naturally produces a class of proteins called Cry proteins, commonly known as Bt toxins.
These proteins are harmless to humans, mammals, and most beneficial insects, but they are highly toxic to the larvae of certain insect pests, such as the cotton bollworm.
The mechanism of action involves the insect larva ingesting the protein. In the alkaline environment of the insect's midgut, the inactive protoxin is cleaved into its active form. This active toxin then binds to specific receptors on the gut wall, creating pores that lead to cell lysis, gut paralysis, and ultimately, the death of the insect.
Genetic engineering has allowed scientists to isolate the gene (Cry gene) that codes for this toxin from the bacterium and insert it into the genome of plants like cotton, corn, and brinjal.
The resulting genetically modified (GM) crop, such as Bt Cotton, can produce its own Bt toxin. When a susceptible insect pest tries to feed on the plant, it ingests the toxin and is killed. Therefore, the primary function of the Bt toxin is to make the plant resistant to certain insect pests, effectively making it act as a natural insecticide.
Step 3: Final Answer:
The primary function of Bt toxin in GM crops is to act as a built-in, natural insecticide, protecting the plant from specific insect pests.