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The genetically modified brinjal in India has been developed for insect resistance. Bt brinjal is a transgenic brinjal that is developed by inserting a crystal gene from the Bacillus thuringiensis into the brinjal’s genome. This process of insertion is accomplished using Agrobacterium mediated recombination.

1. Bt toxin genes were isolated from Bacillus thuringiensis which incorporated into cotton plant to form a genetically modified crop called Bt cotton. Bt cotton has high yield and resistance to bollworms.
2. About Bt toxin, it is true, that the inactive protoxin gets converted into active form in the insect gut. There are several advantages in expressing Bt toxins in transgenic Bt crops. The level of toxin expression can be very high, thus delivering sufficient dosage to the pest.
3. The toxin expression is contained within the plant system and hence only those insects that feed on the crop perish. The toxin expression promotes and replaces the use of synthetic pesticides in the environment.
4. The bacterium Bacillus thuringiensis is widely used in contemporary biology as insecticide. Bacillus thuringiensis (also known as Bt) is a Gram-positive, soil dwelling bacterium of the genus Bacillus. Bacillus thuringiensis produces a parasporal insecticidal crystal protein.

Correct answer: About Bt toxin, it is true, that the inactive protoxin gets converted into active form in the insect gut. There are several advantages in expressing Bt toxins in transgenic Bt crops. The level of toxin expression can be very high, thus delivering sufficient dosage to the pest.

Solution

Bt toxin is produced as an inactive protoxin and becomes active only in the alkaline gut of susceptible insects. Transgenic Bt crops can express the toxin at high levels, so the pest receives a lethal dose when feeding on the plant.

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