UPSC Prelims 2014 · Question 52 of 100
UPSC Prelims 2014 question on Techniques for Transgenic Crops
- ExamUPSC CSE
- Year2014
- PaperGeneral Studies Paper I
- SubjectScience and Technology
- TopicBiotechnology
- DifficultyHard
- TypeStatement
Consider the following techniques/phenomena:
1. Budding and grafting in fruit plants
2. Cytoplasmic male sterility
3. Gene silencing
Which of the above is/are used to create transgenic crops?
Show answer
Answer: B. 2 and 3 only
Verdict
The answer is 2 and 3 only. Cytoplasmic male sterility and gene silencing belong to modern crop biotechnology, while budding and grafting do not.
Analysis
Statement 1 is INCORRECT. Budding and grafting are conventional horticultural techniques that join tissues of existing plants and introduce no foreign gene, so they cannot produce a transgenic crop. Statement 2 is CORRECT in the sense the examiner intends. Cytoplasmic male sterility is used to control pollination in hybrid and engineered seed development. Statement 3 is CORRECT. Gene silencing, including RNA interference approaches, is a recognised genetic engineering tool in transgenic crop development.
Source
Annals of Botany and National Center for Biotechnology Information material.
How to crack it
Split the list into conventional breeding and molecular technique, because that boundary is what UPSC is testing. Grafting is old horticulture and predates genetics entirely, so it goes out immediately, and that one rejection removes three of the four options. The remaining judgement is uncomfortable, since cytoplasmic male sterility is not itself transgenesis, but with grafting excluded the option structure leaves only one survivor. Use structure to close a question you cannot close on biology alone.
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