UPSC Prelims 2001 Q130: Science & Technology – Biotechnology & Genetics
The American multinational company, Monsanto has produced an insect - resistant cotton
variety that is undergoing field - trials in India. A toxin gene
from which ONE of the following bacteria has been transferred to this transgenic cotton?
- (a) Bacillus subtilis
- (b) Bacillus thuringiensis
- (c) Bacillus amyloliquifanciens
- (d) Bacillus globli
Answer: (b) Bacillus thuringiensis
Explanation
Bacterium whose toxin gene was put into Monsanto's insect-resistant cotton
| Fact | Detail |
|---|---|
| Bacterium | Bacillus thuringiensis (Bt) — a soil bacterium |
| Gene | cry1Ac (Bollgard); codes for a crystal (Cry) protein |
| How it works | Protoxin becomes active in the alkaline gut of bollworm larvae and kills them |
| India | Field trials 1998-2001; Bt cotton approved in 2002 |
Monsanto's insect-resistant cotton carries a toxin gene from Bacillus thuringiensis, hence the name Bt cotton. The Cry protein kills bollworms but is harmless to humans because our gut is acidic. Bt cotton was approved in India in March 2002 by the GEAC.
Answer: (b) Bacillus thuringiensis.
Why each option is right or wrong
- (a) Incorrect. Bacillus subtilis is a common soil bacterium used in research, not the Bt source.
- (b) CORRECT. Bt cotton carries a toxin gene from Bacillus thuringiensis.
- (c) Incorrect. Bacillus amyloliquefaciens is not the source of the Cry toxin.
- (d) Incorrect. This is not the source of the Bt toxin.
Key point
Bt crops in India: only Bt cotton is approved for commercial cultivation; Bt brinjal is under a moratorium since 2010.
Remember
Bt cotton: cry gene from Bacillus thuringiensis.
Common mistakes
- Choosing Bacillus subtilis, the best-known Bacillus.
- Not linking the letters 'Bt' to thuringiensis.
- Thinking the Bt toxin harms humans directly.
Exam tip
Bt in any crop name = Bacillus thuringiensis.
Sources
- NCERT Class XII — Biology, chapter 'Biotechnology and its Applications' (Bt cotton)
- Genetic Engineering Appraisal Committee (MoEFCC) — approval of Bt cotton, 2002