Question map
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 ?
Explanation
The correct answer is Option 4 (2 and 3) because DNA barcoding is a molecular method used for species identification based on specific genetic markers.
- Statement 1 is incorrect: DNA barcoding identifies the taxonomic identity of an organism, not its chronological age. Age is typically determined through methods like carbon dating, dendrochronology (tree rings), or physiological markers, which DNA sequencing cannot provide.
- Statement 2 is correct: This is the primary purpose of barcoding. It uses short, standardized gene sequences (like COI in animals) to distinguish between morphologically similar or "cryptic" species that are otherwise difficult to tell apart by sight.
- Statement 3 is correct: Since DNA persists even after processing, barcoding can detect food fraud or contamination by identifying the specific species present in processed products, such as verifying fish species in fillets or detecting adulterants in herbal supplements.
Therefore, while barcoding is excellent for species differentiation and forensic analysis, it lacks the mechanism to assess age, making statements 2 and 3 the only correct applications.
PROVENANCE & STUDY PATTERN
Guest previewThis is a classic 'Definition Boundary' question. While Statements 2 and 3 are standard textbook applications found in Shankar IAS, Statement 1 is a 'Mechanism Trap'. You must know not just what a technology does, but fundamentally how it works (DNA sequence = static identity, not a clock) to eliminate the wrong option.
This question can be broken into the following sub-statements. Tap a statement sentence to jump into its detailed analysis.
- Explicitly describes use of the COI barcoding gene to identify species and infer maternal origin of hybrids.
- Frames barcoding as a tool for identification and lineage (maternal) assignment rather than for measuring age.
- Study aims focus on species identification, maternal lineage, and correct labelling — no mention of age assessment.
Defines DNA barcoding as sequencing a short standardized gene region to identify species by comparing to a reference database.
A student could infer that a method built to distinguish species-level identity is not designed to measure chronological age and could test whether barcode regions vary predictably with age.
Describes goals of DNA barcoding including building a 'library of life' and using standardized barcodes for species census and biosurveillance.
One can extend this to reason that barcoding aims at taxonomic/inventory tasks rather than temporal (age) estimates, so you'd ask if reference libraries include age-annotated sequences.
Explains dendrochronology: tree annual rings are used to determine a tree's age (non-genetic method for age estimation).
Compare a physical ageing method (rings) with genetic methods to explore whether DNA-based markers are necessary or sufficient for age determination in plants.
States vegetative propagation produces genetically similar plants that can flower earlier than seed-grown ones.
This implies genetic identity does not equal chronological age — a propagated plant may be genetically like the parent but younger in years, so barcoding (which captures genetic identity) would not indicate age.
Notes UV radiation can cause damage/mutations to DNA in plants and animals.
A student might extend this to ask whether age-related accumulation of DNA damage/mutations is measurable in barcode regions (and whether barcodes are sensitive or standardized enough to reflect such accumulation).
This statement analysis shows book citations, web sources and indirect clues. The first statement (S1) is open for preview.
Login with Google to unlock all statements.
This statement analysis shows book citations, web sources and indirect clues. The first statement (S1) is open for preview.
Login with Google to unlock all statements.
This tab shows concrete study steps: what to underline in books, how to map current affairs, and how to prepare for similar questions.
Login with Google to unlock study guidance.
Discover the small, exam-centric ideas hidden in this question and where they appear in your books and notes.
Login with Google to unlock micro-concepts.
Access hidden traps, elimination shortcuts, and Mains connections that give you an edge on every question.
Login with Google to unlock The Vault.