Question 41 from UPSC CSE 2022 - S&T

Question

Consider the following statements:
1. DNA Barcoding can be a tool to assess the age of a plant or animal.
2. DNA Barcoding can be a tool to distinguish among species that look alike.
3. DNA Barcoding can be a tool to identify undesirable animal or plant materials in processed foods.
Which of the statements given above is/are correct?

IASCODEX · Accepted Answer

Correct Option: D. 2 and 3

Strategy: - Identify the core functions of DNA barcoding: species differentiation (look-alikes) and detection of animal/plant material in food.
- Recognize what DNA barcoding does not do: it does not assess chronological age.
- Eliminate options that include age assessment, focusing only on validated applications.

Key Info: DNA barcoding is a molecular technique that sequences a short, standardized region of DNA for species identification. Commonly used markers include the mitochondrial cytochrome c oxidase I (COI) gene for animals and portions of the chloroplast genome for plants (e.g., rbcL, matK).

- **Species Identification**: Enables rapid, accurate identification of known species and detection of new or cryptic species, even when morphological features are inconclusive. It is used extensively in taxonomy, forensic science, ecology, and environmental monitoring.
- **Distinguishing Look-Alike Species**: Reliably separates species with similar or indistinguishable morphology (e.g., many butterflies and moths--Lepidoptera--or certain plant species) using barcode sequences. This aids in cataloging biodiversity and preventing fraudulent substitution in trade (e.g., timber, fish).
- **Food Authentication**: Detects undeclared or undesirable animal and plant content in processed foods by matching DNA fragments to reference databases. This uncovers food fraud, contamination, or adulteration, helping regulatory authorities ensure food safety and labeling compliance.
- **Not for Age Assessment**: While DNA reflects genetic identity, it does not directly provide chronological age information. Separate assays like telomere length or epigenetic clocks are used for age determination.
- **Applications**: Utilized by organizations such as the International Barcode of Life (iBOL), the Barcode of Life Data Systems (BOLD), and various national food safety agencies. It plays a significant role in conservation, customs enforcement, ecological studies, and global trade regulation.

IASCODEX · Answer

Option A: 1 only

IASCODEX · Answer

Option B: 3 only

IASCODEX · Answer

Option C: 1 and 2