Which of the following is NOT true for Bt toxin?
(A) It is produced by Bacillus thuringiensis
(B) It is produced in active form
(C) It exist as inactive protoxin
(D) It is used to produce nematode-resistant plants
Choose the correct answer from the options given below:
Answer & explanation
Correct answer: option 4
The correct answer is Option (4) → (B) and (D)
(A) It is produced by Bacillus thuringiensis — True.
(B) It is produced in active form — Not true. It exists as an inactive protoxin.
(C) It exist as inactive protoxin — True.
(D) It is used to produce nematode-resistant plants — Not true. Nematode resistance uses RNA interference.
NCERT Extract:
Biotechnological Applications in Agriculture – “… Bt Cotton: Some strains of Bacillus thuringiensis produce proteins that kill certain insects such as lepidopterans (tobacco budworm, armyworm), coleopterans (beetles) and dipterans (flies, mosquitoes). B. thuringiensis forms protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein. … Actually, the Bt toxin protein exist as inactive protoxins but once an insect ingest the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which solubilise the crystals. The activated toxin binds to the surface of midgut epithelial cells and create pores that cause cell swelling and lysis and eventually cause death of the insect.”