UPSC CSE Prelims 2022

Correct Option (d)

Explanation

Statements 2 and 3 are correct.

• DNA Barcoding: This technique utilizes a short, standardized genetic sequence (a 'barcode') from an organism's DNA to identify it to the species level. It is particularly effective where traditional morphological identification is challenging.
• Statement 2 is correct: DNA barcoding is highly effective in distinguishing among species that appear morphologically identical or very similar (cryptic species). By analyzing specific gene regions, it reveals genetic differences not apparent through visual inspection.
• Statement 3 is correct: DNA barcoding can be applied to identify the species origin of biological materials in processed foods. This is crucial for food authentication, detecting adulteration, ensuring compliance with labeling regulations, and identifying undesirable or undeclared animal or plant ingredients.
• Statement 1 is incorrect: DNA barcoding is not a tool for assessing the age of a plant or animal. Age determination typically involves methods such as radiocarbon dating for organic materials, dendrochronology (tree-ring dating) for trees, or analysis of growth rings in certain animals.

Incorrect Options

• Option (a) (1 only): Statement 1 is incorrect as DNA barcoding does not assess age.
• Option (b) (3 only): While statement 3 is correct, statement 2 is also correct, making this option incomplete.
• Option (c) (1 and 2): Statement 1 is incorrect, rendering this option invalid.