UPSC Prelims 2013 · GS Paper I
Question 5: Science and Technology
Recombinant DNA technology (Genetic Engineering) allows genes to be transferred
- 1.across different species of plants
- 2.from animals to plants
- 3.from microorganisms to higher organisms
Select the correct answer using the codes given below.
AnswerUPSC’s answer is (d).
Recombinant DNA technology cuts a gene out of one organism and inserts it into another using a vector, so the source and the recipient need not be related. Bt cotton carries a gene from the bacterium Bacillus thuringiensis, which is microorganism to plant. Genes are routinely moved between plant species, and genes of animal origin can be made to work in plants. All three statements are therefore correct.
- 1. Genes can be moved between different plant species.
- 2. Animal genes can be inserted into plants and expressed there.
- 3. Bt cotton carries a bacterial gene, a microorganism-to-plant transfer.
How you could have got this
- If you were sure statement 1 is correct, (b) goes: it leaves 1 out.
What you needed to know: Genes can be moved between different plant species.
- Then, if you were sure statement 2 is correct, (a) and (c) go: each of them leaves 2 out.
What you needed to know: Animal genes can be inserted into plants and expressed there.
Only (d) is left. You didn’t need statement 3.
Which options go is worked out from UPSC’s key and the options, not by a model.
Why each option is right or wrong
- (a) Wrong. Transfer is not limited to plant-to-plant; statements 2 and 3 are also correct.
- (b) Wrong. Statement 1 is also correct, since genes can move across plant species.
- (c) Wrong. Statement 2 is also correct, since animal genes can be expressed in plants.
- (d) Correct. Genes can cross species, from animals to plants and from microbes to higher organisms.
Answer: UPSC’s key. Explanation: written by UPSC Grade, not by UPSC.
Source: UPSC, Civil Services (Preliminary) Examination 2013, General Studies Paper I, Series A. The paper on upsc.gov.in.