Given below are two statements: Statement I: Bt toxins are insect group specific and coded by a gene cry 1Ac. Statement II: Bt toxin exists as inactive protoxin in B. thuringiensis. However, after ingestion by the insect the inactive protoxin gets converted into active form due to acidic pH of the insect gut. In the light of the above statements, choose the correct answer from the options given below: (NEET 2024)
Answer: (B) Statement I is true but Statement II is false. Answer: (b) Statement I is true but Statement II is false Solution: Statement I is true — most Bt toxins are insect-group specific and the toxin is coded by a gene named cry (e.g.
- A.Both Statement I and Statement II are false
- B.Statement I is true but Statement II is false✓
- C.Statement I is false but Statement II is true
- D.Both Statement I and Statement II are true
Correct Answer
(B) Statement I is true but Statement II is false
Solution & Explanation
Answer: (b) Statement I is true but Statement II is false Solution: Statement I is true — most Bt toxins are insect-group specific and the toxin is coded by a gene named cry (e.g. cryIAc). Statement II is false — the inactive protoxin is converted to active toxin due to the ALKALINE pH of the insect gut, not acidic pH. Hence Statement I true, Statement II false. NCERT Reference: Ch 10, p.179, line 45 — "once an insect ingest the inactive toxin, it is converted into an active form"; p.179, line 46 — "of toxin due to the alkaline pH of the gut which solubilise the crystals."