NEET regularly asks you to identify the correct line of evidence for evolution or match an example to its category. The high-frequency trap here is confusing the three pillars — paleontology, comparative embryology, and biogeography — or mis-classifying a specific example under the wrong heading.
Paleontological evidence relies on fossils preserved in sedimentary rock. Transitional fossils (e.g., Archaeopteryx with reptilian teeth + avian feathers) demonstrate intermediate forms. The fossil record allows relative dating by stratum position; radiometric dating gives absolute ages. NCERT Class 12 Biology Chapter 6 (page 132) explicitly notes that fossils represent "different forms of life that existed at different times."
Embryological evidence draws on the observation that vertebrate embryos pass through similar developmental stages (pharyngeal arches, post-anal tail, notochord). Karl Ernst von Baer's observation — not Haeckel's discredited "biogenetic law" — is the NCERT-accepted framing. NEET distractors often attribute embryological evidence to Haeckel alone; the correct anchor is comparative embryology showing shared ancestry, not recapitulation.
Biogeographical evidence explains why similar ecological niches on different continents are occupied by unrelated but morphologically similar species (convergent evolution) and why isolated landmasses (Australia, Madagascar) harbour unique fauna. Darwin's finches on the Galápagos illustrate adaptive radiation within a biogeographic context.
Watch-out for NEET: When a question says "Which is NOT an evidence of evolution?", expect distractors like "Mendel's laws" or "Hardy-Weinberg equilibrium" — these are mechanisms/models, not evidences. Keep the three categories (paleontology, embryology, biogeography) distinct from mechanisms of evolution.
Select an option to see the explanation. Wrong answers show why your choice was tempting — and name the exact trap it exploits.
Which of the following is considered a connecting link (transitional fossil) between reptiles and birds?
Biogeographical evidence of evolution is best illustrated by:
Which scientist's observations on vertebrate embryos are considered valid evidence for common ancestry in modern biology?
Darwin's finches on the Galápagos Islands show different beak shapes adapted to different food sources. This is an example of:
A paleontologist discovers a fossil with both amphibian and reptilian characters in a sedimentary stratum. This fossil provides:
Presence of flightless birds — rhea in South America, ostrich in Africa, and emu in Australia — best supports evolution through:
Which of the following is NOT an evidence of evolution?
An island far from the mainland has several species of lizards not found anywhere else, all apparently derived from a single colonising species. This observation combines which two lines of evolutionary evidence?
Given
An archipelago 1,000 km from the mainland contains 14 species of finches with different beak sizes/shapes. Genetic analysis confirms all 14 descend from a single mainland ancestor that colonised the islands approximately 2 million years ago.
Required
Identify the type of evolutionary evidence demonstrated. Classify the specific evolutionary phenomenon. Name one additional line of evidence that could strengthen this conclusion.
Concept
Biogeographical evidence explains species distribution in relation to geographic barriers. Adaptive radiation describes diversification from one ancestor into multiple species exploiting different ecological niches in a new environment (NCERT Class 12 Biology, Chapter 6).
Formula/Principle
No mathematical formula applies. The principle is: geographic isolation + available niches → adaptive radiation → multiple derived species from one ancestor.
Substitution/Application
- 14 species from 1 ancestor → diversification (adaptive radiation) - Archipelago isolated from mainland → geographic context (biogeography) - Different beak morphologies → different ecological niches exploited
Reasoning
The island setting explains WHY radiation occurred (new niches, no competitors). The morphological diversity of beaks is the OUTCOME of radiation. The genetic confirmation of single ancestry rules out convergent evolution (unrelated species becoming similar) — this is the opposite: related species becoming different.
Final answer
- Primary evidence: Biogeographical (island isolation + unique distribution) - Phenomenon: Adaptive radiation - Supporting evidence: Molecular evidence (genetic confirmation of monophyly) and comparative anatomy (homologous beak structures modified for different functions)
Common trap
Students confuse adaptive radiation with convergent evolution. Key distinction: adaptive radiation = one ancestor → many different forms (divergence). Convergent evolution = unrelated organisms → similar forms (e.g., wings in insects and birds). The direction of change is opposite.
Similar NEET-style question
"Australian marsupials show a variety of forms analogous to placental mammals on other continents. Which evolutionary phenomenon does this represent, and what type of evidence supports it?" Answer: Adaptive radiation of marsupials (one ancestor → diverse forms) supported by biogeographical evidence (isolation of Australian continent). The analogy with placental mammals is convergent evolution — a separate phenomenon. ---
Paleontology (fossils — Archaeopteryx, Glyptodon). Comparative anatomy — homologous (whale flipper, human arm — divergent), analogous (octopus eye, vertebrate eye — convergent). Embryology (gill slits in vertebrate embryos — Haeckel, since dismissed). Biogeography (Galapagos finches, Australian marsupials).
-- NCERT Class 12 Biology, Ch. 6, p. 132F2 ratio in monohybrid cross — products of independent assortment of two alleles per locus.
| Symbol | Quantity | SI Unit |
|---|---|---|
| ratio | F2 progeny ratio | - |
F2 ratio in dihybrid cross with two independently-segregating loci, complete dominance, no linkage.
| Symbol | Quantity | SI Unit |
|---|---|---|
| ratio | F2 phenotype ratio | - |
In an idealised population (no mutation, drift, selection, gene flow, random mating), allele and genotype frequencies remain constant.
| Symbol | Quantity | SI Unit |
|---|---|---|
| p | freq of dominant allele A | - |
| q | freq of recessive allele a | - |
Proportion of recombinant offspring measures genetic distance between linked loci. Capped at 50% (independent assortment).
| Symbol | Quantity | SI Unit |
|---|---|---|
| RF | recombination frequency | % |
These are the exact patterns that cause wrong answers in NEET. Each trap includes when it triggers and how to avoid it.
Category: Sign Convention
DNA polymerase synthesises only 5'→3'. Leading strand: continuous, same direction as fork. Lagging: discontinuous (Okazaki), opposite to fork.
Question on Okazaki, leading vs lagging, primer direction.
Reading template 3'→5'; synthesising 5'→3'. Lagging strand needs short fragments because it can't run continuously against fork direction.
Category: Negative Marking
Five forces disturb HW: mutation, gene flow, drift, selection, non-random mating. ANY of these violates equilibrium.
Question asks which factor maintains/disturbs HW.
Random mating + no other forces → equilibrium. ANY of mutation/migration/drift/selection/assortative mating → disequilibrium.
Category: Similar Terms
Monohybrid: genotype 1:2:1 (AA:Aa:aa); phenotype 3:1.
Question asks for one ratio while presenting cross details.
Always note dominance: phenotype merges Aa + AA; genotype keeps them separate.
Category: Similar Terms
X-linked recessive (haemophilia, colour-blindness): affects males predominantly; carrier mother → 50% sons affected; affected father → all daughters carriers but not affected.
Pedigree question; carrier vs affected.
Sex chromosomes: XX vs XY. Recessive on X needs both copies (XaXa) in female, only one (XaY) in male.
Category: Similar Terms
Allopatric: geographic isolation. Sympatric: same area, no physical barrier (e.g. polyploidy in plants, host-shift).
Question gives speciation scenario and asks which type.
If geographic barrier mentioned → allopatric. If population overlaps → sympatric.
Root cause: formula misuse
Genotype frequencies: p² (AA) + 2pq (Aa) + q² (aa) = 1. Allele frequencies: p + q = 1. Don't drop 2pq.
Root cause: concept gap
ALL DNA pol synthesises 5'→3'. Lagging strand uses Okazaki fragments to APPEAR to extend toward fork while each fragment grows 5'→3'.
Root cause: concept gap
Frameshift = ANY indel NOT divisible by 3 (since codons are triplets). Indels of 3, 6, 9... preserve reading frame.
Root cause: term confusion
Start codon: AUG (Met / fMet). Stop codons: UAA (ochre), UAG (amber), UGA (opal/umber).
51 questions from NEET 2020, 2021, 2022, 2023, 2024, 2025. Answers verified against NTA official keys.
Identify the statement that is NOT correct.
Which factor is important for termination of transcription?
What is the pattern of inheritance for polygenic trait?
Which of the following statement is correct regarding the process of replication in E.coli?
Which one of the following factors will not affect the Hardy-Weinberg equilibrium?
The phenomenon of pleiotropism refers to
What is the role of RNA polymerase III in the process of transcription in Eukaryotes?
Among eukaryotes, replication of DNA takes place in :
Expressed Sequence Tags (ESTs) refers to
Unequivocal proof that DNA is the genetic material was first proposed by
Broad palm with single palm crease is visible in a person suffering from-
Select the correct group/set of Australian Marsupials exhibiting adaptive radiation.
XO type of sex determination can be found in :
The process of translation of mRNA to proteins begins as soon as :
Which of the following occurs due to the presence of autosome linked dominant trait ?
Detritivores breakdown detritus into smaller particles. This process is called:
If the length of a DNA molecule is 1.1 metres, what will be the approximate number of base pairs?
Which of the following is not a desirable feature of a cloning vector?
Mutations in plant cells can be induced by: 130. Match List-I with List-II.
Which of the following RNAs is not required for the synthesis of protein?
•ŸÈ‹ πŸ ∑ § ‚◊ÿ «UË.∞Ÿ.∞. ∑§Ë ∑È §«U‹Ë ∑§Ê πÊ ‹Ÿ ◊ ∑§ÊÒŸ‚Ê
Recurring question shapes from past papers. Each pattern shows why wrong options look tempting.
similar term confusion
Biology relies on precise terminology; close terms tempt selection.
Test yourself on this topic with real past-paper questions:
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