Question

Prefix of Bt cotton stands for
(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 from Bacillus thuringiensis

Answer 1

Bt cotton is a plant cotton variety that is genetically modified organism (GMO) or genetically modified pest-resistant, creating an insecticide to fight bollworm.

Complete answer:
-Over 200 different Bt toxins are produced by strains of the Bacillus thuringiensis bacterium, each harmful to various insects.
- Most importantly, the larvae of moths and butterflies, beetles, cotton bollworms, and ghtu flies are insecticidal to Bt toxins but are harmless to other life types.
-The Bt toxin coding gene has been incorporated as a transgene into cotton, causing it to develop this natural insecticide in its tissues. In several countries, lepidopteran larvae that are destroyed by the Bt protein in the genetically modified cotton they consume are the main pests of commercial cotton.
-By adding genes encoding toxin crystals in the endotoxin group of Cry, Bt cotton was created. The Cry toxins or crystal protein are dissolved due to the high pH level of the insect's stomach when insects attack and consume the cotton plant.
-On cells containing the brush border molecules, the dissolved and activated Cry molecules bind to cadherin-like proteins. The epithelium of the brush border membranes divides the body cavity from the gut thus allowing nutrient access.
-The Cry toxin molecules bind themselves to specific places on the cadherin-like proteins present on the midge's epithelial cells and ion channels are formed that enable potassium to flow. Potassium concentration control is important and causes cell death if left unchecked.
-Sufficient regulation of potassium ions is lost due to the development of cry ion channels and results in the death of epithelial cells.
- Gaps in the brush border membrane are formed by the death of such cells.
So, the correct answer is ‘carrying an endotoxin gene from Bacillus thuringiensis ’.

Note: -Bt cotton removes the need for vast quantities of broad-spectrum insecticides (some of which have developed pyrethroid resistance) to be used to destroy lepidopteran pests. In the farm area, this saves natural insect predators and also leads to the control of non-insecticide pests.