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
Full viewThis 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).
- Defines DNA barcoding as sequencing a short, standardized gene region to identify species.
- Explains identification by comparing individual sequences to a reference database, a method that distinguishes taxa based on genetic differences.
- Describes intent to deploy DNA barcoding at large scale and to construct a 'library of life' preserving DNA extracts for all species.
- Emphasizes building the informatics and reference resources required to use barcodes for inventorying and describing biodiversity.
- States that species differ markedly in their genetic makeup even when closely related species share many hereditary characteristics.
- Provides the genetic-difference rationale that underlies using DNA sequences to separate closely related or similar-looking species.
- Defines DNA barcoding as a method for rapidly and accurately identifying species by sequencing standardized gene regions.
- Describes comparison of individual sequences to a reference database — the technical basis for detecting specific animal or plant species.
- Lists goals to build a large DNA barcode reference library and informatics platforms needed for identification at scale.
- Shows infrastructure intent that enables matching unknown samples to known species, supporting detection of undesirable taxa.
- States processed foods originate from agricultural, animal husbandry and fisheries raw materials, establishing that processed products contain animal/plant inputs.
- Links food processing to transformation of biological raw materials, implying the relevance of species-level identification in processed goods.
- [THE VERDICT]: Logical Trap. Statements 2 & 3 are direct from Shankar IAS (Ch 16). Statement 1 requires basic biological common sense to eliminate.
- [THE CONCEPTUAL TRIGGER]: Conservation Technology > Modern methods of Species Identification (DNA Barcoding vs DNA Fingerprinting).
- [THE HORIZONTAL EXPANSION]: Memorize the 'Identity vs Age' toolkit: DNA Barcoding (Species ID); DNA Fingerprinting (Individual ID); Dendrochronology (Tree Age via rings); Carbon-14 Dating (Fossil Age); e-DNA (Presence without capture).
- [THE STRATEGIC METACOGNITION]: When studying a scientific tool, apply the 'Mechanism Test'. Ask: 'Does the underlying variable (DNA) change with the target variable (Age)?' Since germline DNA doesn't change as you grow older, it cannot measure age. This logic kills Statement 1 instantly.
DNA barcoding is a sequencing method that uses short standardized gene regions to rapidly and accurately identify species.
High-yield for questions on biodiversity, conservation policy and biosurveillance; links molecular techniques to species inventories and building reference libraries (useful for essays and ethics/implementation questions). Enables answering comparative questions about when molecular identification is appropriate versus other methods.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 16: Conservation Efforts > 16.17. DNA BARCODING > p. 248
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 16: Conservation Efforts > Goals: > p. 249
Tree growth rings provide a direct, countable record used to determine the chronological age of trees.
Important for questions on methods of age determination, paleo-climatology and forest ecology; offers a clear non-molecular age-assessment technique to contrast with molecular approaches, aiding balanced answers.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 13: Plant Diversity of India > Annual rings > p. 204
Plants produced by vegetative propagation are genetically similar to the parent and can reach reproductive maturity earlier than seed-grown individuals, complicating simple age assessments.
Useful for questions on plant breeding, agriculture and conservation where 'age' and 'maturity' diverge; helps distinguish chronological age from physiological or developmental state when evaluating methods for age assessment.
- Science , class X (NCERT 2025 ed.) > Chapter 7: How do Organisms Reproduce? > 7.2.5 Vegetative Propagation > p. 117
DNA barcoding identifies species by sequencing a short, standardized gene region and comparing sequences to a reference database.
High-yield for biodiversity and conservation questions: explains a modern molecular tool for species identification, links molecular biology with taxonomy and conservation policy, and helps answer questions on species inventorying and forensic identification.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 16: Conservation Efforts > 16.17. DNA BARCODING > p. 248
Effective DNA-based identification requires a curated reference library and informatics platforms to compare query sequences.
Important for policy and implementation topics: shows the infrastructure (databases, sequencing core facilities) needed to scale molecular identification, connects to international collaborations and conservation programs.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 16: Conservation Efforts > Goals: > p. 249
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 16: Conservation Efforts > 16.17. DNA BARCODING > p. 248
Species can be genetically distinct even when they are morphologically similar, providing the basis for molecular discrimination.
Fundamental for questions on species concepts and cryptic species: helps explain why morphology may fail and genetics succeeds, links to evolution, speciation, and conservation prioritization.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 8: Biodiversity > b) Species diversity: > p. 143
DNA barcoding uses short standardized genetic markers and sequence comparison to determine species identity, which is the core mechanism for detecting unwanted animal or plant material.
High-yield for questions on biotechnology, conservation, and food safety; connects molecular methods to practical applications like species authentication and forensic identification. Mastery enables answering questions on diagnostic techniques and policy implications for biosurveillance.
- Environment, Shankar IAS Acedemy .(ed 10th) > Chapter 16: Conservation Efforts > 16.17. DNA BARCODING > p. 248
e-DNA (Environmental DNA). Since Barcoding is for organism samples, the next logical question is on e-DNA, which detects species from water/soil samples without physical capture. Also, the specific marker gene usually used for animals is 'COI' (Cytochrome c oxidase I).
The 'Static Blueprint' Logic. DNA is an organism's permanent blueprint. Does a building's blueprint change 10 years after construction? No. Therefore, reading the blueprint (DNA) cannot tell you the age of the building (Animal). Statement 1 is illogical. Eliminate A and C.
Link this to GS-3 Internal Security & Economy: The Wildlife Crime Control Bureau (WCCB) uses DNA Barcoding to identify poached items (tiger bones sold as medicine) and FSSAI uses it to detect food adulteration (beef in mutton exports).