UPSC Prelims 2020 CSAT Paper II · Q64 of 80 Comprehension medium

Passage

Passage—3 Genome editing is different from genome modification. Genome editing typically involves finding the part of a plant genome that could be changed to render it less vulnerable to disease, or resistant to certain herbicides, or to increase yields. Researchers use 'molecular scissors' to dissect the genome and repair it, which is a process that occurs naturally when plants are under attack from diseases and can throw up new mutations that enable the plant to survive future attacks. This evolutionary process can effectively be speeded up now that it is possible to examine plant genomes in detail in laboratories, and create mechanisms through which the relevant genes can be altered very precisely.

With reference to the above passage, the following assumptions have been made : 1. Genome editing does not require the transfer of genes from one plant to another. 2. Through genome editing, the chosen genes can be altered precisely in a manner akin to the natural process that helps plants to adapt to the environmental factors. Which of the above assumptions is/are valid?

  1. (a) 1 only
  2. (b) 2 only
  3. (c) Both 1 and 2 ✓ UPSC's answer
  4. (d) Neither 1 nor 2

Why the answer is (c)

• Assumption 1 is valid because the passage describes genome editing as dissecting and repairing the existing plant genome using 'molecular scissors' to alter relevant genes, without mentioning the introduction of foreign genes from other plants.

• Assumption 2 is valid because the text states that the editing process mimics natural mechanisms where plants throw up new mutations to survive diseases, effectively speeding up this evolutionary adaptation.

• The passage explicitly links the precision of gene alteration in the lab to the natural process of plants adapting to environmental attacks like diseases.

• Since both assumptions are directly supported by the text's description of the mechanism and its similarity to natural evolution, both are valid.

• Therefore, the correct option is (c) Both 1 and 2.

Why the other options are wrong

(a) 1 only
This option is incorrect because Assumption 2 is also valid, as the passage explicitly compares the editing process to natural mutation mechanisms for adaptation.
(b) 2 only
This option is incorrect because Assumption 1 is also valid, as the passage describes altering existing genes rather than transferring genes from one plant to another.
(d) Neither 1 nor 2
This option is incorrect because both assumptions are supported by the passage, making the claim that neither is valid false.

Asked in the CSAT Paper II of the UPSC Civil Services Preliminary Examination 2020, held on 4 October 2020. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.

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