Question

Bt-cotton is resistant for

• A. Round-worm
• B. Fluke-worm
• C. Boll-worm
• D. Pin-worm

Answer 1

Answer: (C)

Boll-worm

Bacillus thuringiensis (Bt) is a Gram-positive bacterium that produces crystals during sporulation. These crystals comprise ~130 kDa protoxins called crystal proteins which are potent and highly specific insecticides. Once ingested by the specific host, these crystals dissolve in the alkaline conditions of the gut thereby activating the protoxins. The active toxins then bind to receptors on midgut epithelial cells, become inserted into the plasma membrane where they form pores leading to cell death through osmotic lysis. This special feature of Bt toxin was explored in genetic engineering to produce a genetically modified variety of cotton known as "Bt cotton" which produce the insecticide. This transgenic variety of cotton is resistant to bollworm.