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?

The correct answer is D, 2 and 3. DNA barcoding tells us which species a sample belongs to, not how old the organism is. The method reads a short, standard stretch of DNA, such as the mitochondrial COI gene in animals or the rbcL and matK genes in plants, and matches it against a reference library of known species. Because this sequence differs between species but varies little within one species, it can separate look-alike and cryptic species, and even identify eggs, larvae or damaged specimens that cannot be named by eye. The same test can detect the species present in powders, meat products, herbal mixtures and processed foods, so it is used to catch adulteration, mislabelled fish and banned animal or plant material. Statement 1 is wrong because a barcode shows identity, not age. Option A is wrong because it keeps only statement 1, the incorrect one. Option B is wrong because it leaves out statement 2. Option C is wrong because it includes statement 1. Exam tip: DNA barcoding answers 'which species is this?', never 'how old is it?'.