What are Bt crops? Explain how Bt cotton protects itself from bollworms.

1. 1 · Define in one line. Bt crops are transgenic plants that carry a toxin gene (cry) from Bacillus thuringiensis.
2. 2 · Name the genes. cryIAc and cryIIAb, whose proteins control cotton bollworms.
3. 3 · Explain the protoxin. The plant makes the toxin as an inactive protoxin.
4. 4 · Explain activation. In the bollworm's alkaline gut, the protoxin is converted into the active toxin.
5. 5 · Explain the killing. The toxin binds midgut epithelial cells, makes pores; the cells swell and lyse, and the insect dies.
6. 6 · Link to real life. Indian cotton farmers spray far less insecticide on Bt cotton.
7. 7 · Close in one line. So the crop carries its own insecticide, active only inside the pest.

Scoring tip: Use the words protoxin, alkaline, midgut epithelial cells and lysis: each is a marking point.