Cultivation of Bt cotton has been much in the news. The prefix Bt means

Options

A. "Barium-treated" cotton seeds
B. "Bigger thread"Variety of cotton with better tensile strength.
C. Produced by"Biotechnology"using restriction enzymes and ligases.
D. Carrying an endotoxin gene Bacillus thuringienesis.

Answer

B

Explanation

Cotton and other monocultured crops require an inrenstive use of pesticides as various types of pests attack these crops causing extensive damage.So far,the only successful approach to engineering crops for insect tolerence has benn the addition of Bt toxin,a family of toxins originally derived from soil bacteria.The Bt toxin contained by the Bt crops is no different from other chemical pesticides,but causes much less damage to the environment.THese toxins are effective against a variety of economically important crops pests but pose no hazard to non-target oranisms like mammls and fish.The Bt gene was isolated and tranferred from a bacterium bacillus thuringiensis to American cotton.The American cotton was subsequently crossed with Indian cotton to intoduce the gene into native varieties.Bt toxin protects the cotton plants from ballworm (A.lepidoptera),a major pest of cotton.The worm feeding on the leaves of a Bt cotton plant becomes lethargic and sleepy,thereby causing less damage to the plant.