Consider the following statements : DNA Barcoding can be a tool to : 1. assess the age of a plant or animal. 2. distinguish among species that look alike. 3. identify undesirable animal or plant materials in processed foods. Which of the statements given above is/are correct ?
- (a) 1 only
- (b) 3 only
- (c) 1 and 2
- (d) 2 and 3 ✓ UPSC's answer
Why the answer is (d)
• DNA barcoding identifies species by sequencing a short standard gene region — the COI gene in animals, rbcL and matK in plants — and matching it against a reference library.
• Statement 2 is correct: it distinguishes species that look alike, including larvae, fragments and cryptic species.
• Statement 3 is correct: it detects adulteration and undeclared species in processed foods, herbal products and seafood (e.g. mislabelled fish).
• Statement 1 is wrong: a barcode identifies the species, not the age of an individual organism.
• Hence 2 and 3, option (d).
Why the other options are wrong
- (a) 1 only
- Statement 1 is wrong: barcoding does not determine age.
- (b) 3 only
- Statement 2 on distinguishing look-alike species is also correct.
- (c) 1 and 2
- Statement 1 is wrong; statement 2 is correct.
Asked in the GS Paper I of the UPSC Civil Services Preliminary Examination 2022, held on 5 June 2022. Question and answer key: Union Public Service Commission. Explanation: UPSC Answer Check.