Question

Give a brief account of Bt-cotton.

Answer 1

Hint: Bt-cotton. is a genetically modified organism (GMO), which is created to develop resistance against a pest known as bollworm. Bollworm is a worm which damages normal cotton crops and Bt-cotton. produces insecticide to its pest bollworm.

Complete answer:
Cotton is a very important crop with respect to the textile industry. Cotton is used to make a variety of clothes and is produced in large amounts in India as well as other countries. But this crop is affected by a pest named as bollworm.

A bacterial strain Bacillus thuringiensis produces Bt-toxins , which is harmful for many insects such as larvae of moths, butterflies, beetles, bollworm, flies, etc. By using genetic engineering the gene which is responsible for the production of the toxins, is inserted into the genome of the cotton to make it naturally produce those Bt-toxins and fight with pests which affects the crop yield, crop productivity, etc.

Protein which is responsible for the toxicity in the Bt-cotton. is known as cry protein or cry endotoxins. So, whenever a pest eats the plant tissues having these cry toxins, cry protein gets dissolved inside the gut of the insect due to its high pH in the gut. This leads to activation of the cry protein and Activated protein gets absorbed by the epithelial layer of the gut of the insect which leads to the formation of pores in the plasma membrane of the epithelial cells.

Presence of pores in the epithelial layer leads to death of the insect and hence, crop can be saved from the harmful effect of the pests.

Hence, the correct answer is option (B).

Note: Bt-toxins are not harmful for humans. Because to activate cry protein, pH should be higher and the pH of the human gut is on the acidic side which means pH is not sufficient in the human gut to activate the cry protein. So, it cannot be harmful for humans. Bt-cotton. is accepted and grown at large scale in India and many other countries.