CASE STUDY
Some strains of Bacillus thuringiensis produce protein that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). Bacillus thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein. The Bt toxin proteins exists as inactive protoxins but once an insect ingests the inactive toxin, it is converted into an active form due to alkaline pH of the gut which solubilise the crystals.
Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as:
Answer & explanation
Correct answer: option 2
The correct answer is Option (2) → Lepidopterans, coleopterans and dipterans
Option (1) Grasshoppers and mosquitoes — Incorrect. Mosquitoes are dipterans, but grasshoppers are not named among the insects these proteins kill.
Option (2) Lepidopterans, coleopterans and dipterans — Correct. The passage names lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes).
Option (3) Coleopterans and nematodes — Incorrect. Nematodes are roundworms, not insects. Plants are protected against them by RNA interference, not by Bt toxin.
Option (4) Meloidogyne incognita — Incorrect. This is a nematode that infects the roots of tobacco plants. It is controlled by RNAi.
Note: This passage is taken from NCERT as it is. Most CUET (UG) questions come straight from NCERT, so study the book line by line, including figures and their titles.