Every Evolution and Behaviour question CSIR-NET Life Sciences has set in its last 11 papers, sorted by topic, with 16 of them solved step by step. Answers follow NTA’s final answer keys.
Unit 11 of the CSIR-NET Life Sciences syllabus, Evolution and Behavior, runs from the origin of cells and the fossil record to population genetics, speciation, molecular phylogenetics and animal behaviour. We went through all 11 papers from February 2022 to June 2025 and pulled out every question from this unit. It is one of the three biggest units in Parts B and C.
How much of the paper is Evolution and Behaviour?
Across the 11 papers, 127 of the 1,375 Part B and Part C questions (9.2%) came from Unit 11. That ranks it third of the 13 units. 71 of the 127 were 4-mark Part C questions.
| Paper | Part B | Part C | Total |
|---|---|---|---|
| June 2025 | 7 | 7 | 14 |
| December 2024, Shift 1 | 7 | 6 | 13 |
| December 2024, Shift 2 | 6 | 6 | 12 |
| June 2024, Shift 1 | 6 | 5 | 11 |
| June 2024, Shift 2 | 6 | 6 | 12 |
| December 2023, Shift 1 | 3 | 8 | 11 |
| December 2023, Shift 2 | 3 | 4 | 7 |
| June 2023, Shift 1 | 7 | 7 | 14 |
| June 2023, Shift 2 | 3 | 9 | 12 |
| February 2022, Shift 1 | 4 | 3 | 7 |
| February 2022, Shift 2 | 4 | 10 | 14 |
| All 11 papers | 56 | 71 | 127 |
Which Evolution and Behaviour topics come up most
Brain, Behaviour & Evolution and Mechanisms of Evolution – Selection, Speciation & Population Genetics together account for 68% of the unit’s questions.
16 solved Evolution and Behaviour PYQs
One or two from each major subtopic, from different papers. Try each one before you open the solution.
In a paper wasp, a worker helps to raise 4 full-sisters instead of producing 4 offspring of her own. According to Hamilton’s rule, will selection favour this altruistic behaviour in terms of genetic units?
- 1Yes, because 3.0 genetic units are gained and 2.0 genetic units are lost.
- 2Yes, because 2.0 genetic units are gained and 1.0 genetic unit is lost.
- 3No, because 2.0 genetic units are gained and 3.0 genetic units are lost.
- 4No, because 2.0 genetic units are gained and 4.0 genetic units are lost.
Show answer and solution
Paper wasps are haplodiploid. Full sisters share their father’s whole haploid genome, so their relatedness is r = 0.75. A mother’s relatedness to her own offspring is 0.5. Raising 4 sisters gives 4 × 0.75 = 3.0 genetic units, while giving up 4 offspring costs 4 × 0.5 = 2.0. Since rB > C, Hamilton’s rule predicts that selection favours helping.
Consider alleles ‘A’ and ‘a’ in a population. The frequency of heterozygotes will be highest when:
- 1Frequency of ‘A’ is more than frequency of ‘a’
- 2Frequency of ‘A’ is less than frequency of ‘a’
- 3Frequency of ‘A’ is equal to frequency of ‘a’
- 4Frequency of ‘A’ and ‘a’ affects the frequency of homozygotes, not heterozygotes
Show answer and solution
Heterozygote frequency is 2pq = 2p(1 − p). It reaches its maximum at p = q = 0.5, where 2pq = 0.5, and falls as either allele becomes more common. So heterozygotes are most frequent when the two alleles are equally frequent.
Colour blindness affects approximately 1 in 12 men (8%). In a population that is in Hardy-Weinberg Equilibrium (HWE) where 8% of men are colour-blind due to a sex-linked recessive gene. What proportion of women are expected to be carriers?
- 10.92
- 20.85
- 30.78
- 40.15
Show answer and solution
Answer: (4) 0.15
Men have one X, so the share of colour-blind men equals the frequency of the recessive allele: q = 0.08 and p = 0.92. Women have two X chromosomes, so carriers occur at 2pq = 2 × 0.92 × 0.08 = 0.147, about 0.15. (Colour-blind women would be q2 = 0.0064.)
Recessive lethal alleles are never completely eliminated from the population because:
- 1lethal alleles are always conditional in nature.
- 2lethal alleles have selective advantage.
- 3lethal alleles protect organisms from other deleterious mutations.
- 4they are maintained in the population as heterozygotes.
Show answer and solution
Answer: (4) they are maintained in the population as heterozygotes.
When a lethal allele is rare, almost every copy sits in a heterozygote, where it is hidden from selection. Only the rare homozygotes (q2) die, so each generation removes very few copies, and q falls ever more slowly (qn = q0/(1 + nq0)). New mutations then keep it at a low equilibrium.
Which one of the following is an example of character displacement?
- 1Two sympatric lizards with similar morphologies consume the same insects.
- 2Two sympatric birds evolve distinct beak shapes to consume seeds of different plants.
- 3A predator evolves higher visual acuity to catch camouflaged prey.
- 4Two plant species have similar flower shapes to attract the same pollinators.
Show answer and solution
Answer: (2) Two sympatric birds evolve distinct beak shapes to consume seeds of different plants.
Character displacement (Brown and Wilson, 1956) is the divergence of traits between competing species where they occur together, which reduces competition. Two sympatric birds evolving different beak shapes to eat different seeds is the textbook case, as in Darwin’s ground finches. Option 4 describes convergence, not displacement.
Within a broadly distributed taxonomic clade, populations and species of larger size are generally found in colder environments, while populations and species of smaller size are typically found in warmer regions. This observation is commonly referred to as:
- 1Allen’s rule
- 2Bergman’s rule
- 3Gause’s rule
- 4Gloger’s rule
Show answer and solution
Answer: (2) Bergman’s rule
Bergmann’s rule: within a widespread clade of endotherms, larger forms live in colder places, because a larger body has less surface area per unit volume and loses heat more slowly. Allen’s rule concerns shorter extremities in the cold. Gloger’s rule links darker pigmentation to humid climates, and Gause’s principle is competitive exclusion.
Runaway selection was proposed by R. A. Fisher to explain the evolution of extravagant secondary sexual characters. The model is based on the exaggeration of characters in male, and female choice for these exaggerated characters. Which one of the following statements is considered an assumption of this model?
- 1Exaggeration of characters in males, and female choosiness for exaggeration are both heritable.
- 2Neither exaggeration of characters in males, nor female choosiness for exaggeration are heritable.
- 3Exaggeration of characters in males is heritable but female choosiness for exaggeration is not heritable.
- 4Exaggeration of characters in males is not heritable but female choosiness for exaggeration is heritable.
Show answer and solution
Answer: (1) Exaggeration of characters in males, and female choosiness for exaggeration are both heritable.
Fisher’s runaway works because both the male trait and the female preference are heritable and become genetically correlated. Females that choose exaggerated males have sons that carry the trait and daughters that carry the preference. Each therefore drags the other along, and the trait keeps growing until survival costs halt it.
Based on the theory of kin selection, choose the correct statement:
- 1A gene for altruism will spread in the population if the act of altruism increases the actor’s gene in the next gene pool only through direct fitness.
- 2A gene for altruism will spread in the population if the act of altruism increases the actor’s gene in the next gene pool only through indirect fitness.
- 3A gene for altruism will spread in the population if the act of altruism increases the actor’s gene in the next gene pool through direct or indirect fitness.
- 4Altruistic behaviour reduces the fitness of the trait bearer so a gene responsible for altruism cannot spread in a population and will be maintained at a very low frequency.
Show answer and solution
Answer: (3) A gene for altruism will spread in the population if the act of altruism increases the actor’s gene in the next gene pool through direct or indirect fitness.
Hamilton’s idea of inclusive fitness counts both direct fitness (one’s own offspring) and indirect fitness (extra offspring of relatives, weighted by relatedness). A gene for altruism spreads whenever it raises its total representation by either route, that is, when rB > C. Options 1 and 2 each leave out one route.
Eusocial societies are NOT characterised by which of the following?
- 1Altruism
- 2Kin selection
- 3Guarding against intruders
- 4Equal reproductive opportunities
Show answer and solution
Answer: (4) Equal reproductive opportunities
Eusociality is defined by a reproductive division of labour: a few queens (and kings) breed and sterile or nearly sterile workers do not. Equal reproductive opportunity is therefore the opposite of eusociality. Altruism, kin selection and cooperative defence of the colony are all typical features.
Which one of the following is NOT an example of learning?
- 1Imprinting
- 2Fixed action pattern
- 3Operant conditioning
- 4Habituation
Show answer and solution
Answer: (2) Fixed action pattern
A fixed action pattern, such as a goose rolling an egg back into its nest, is an innate, stereotyped sequence. Once a sign stimulus releases it, it runs to completion without needing experience. Imprinting, operant conditioning and habituation all change behaviour through experience, so they are forms of learning.
Which one of the following statements defines a monophyletic group?
- 1A group of organisms that share a common ancestor and all of its descendants.
- 2A group of organisms that includes species from unrelated lineages.
- 3A group of organisms that lack a common ancestor.
- 4A group of organisms that always lack apomorphic characters.
Show answer and solution
Answer: (1) A group of organisms that share a common ancestor and all of its descendants.
A monophyletic group (clade) contains an ancestor and all of its descendants, and is defined by shared derived characters (synapomorphies). A group that leaves out some descendants is paraphyletic, for example reptiles without birds. One built from unrelated lineages is polyphyletic, for example “warm-blooded animals”.
Which one of the following phenomena describes the evolution of wings in bats, birds, and insects?
- 1Homoplasy
- 2Common ancestry
- 3Pleiomorphy
- 4Symplesiomorphy
Show answer and solution
Answer: (1) Homoplasy
Bats, birds and insects evolved wings independently. Their common ancestor had no wings. A similarity that does not come from common ancestry is homoplasy, produced by convergence, parallelism or reversal. Symplesiomorphy is a shared ancestral character, the opposite case.
Which one of the following statements about the molecular clock hypothesis as proposed by Zuckerkandl and Pauling 1962 is CORRECT?
- 1DNA and protein sequences evolve at a relatively constant rate.
- 2DNA sequences evolve at a relatively slow rate when compared to proteins.
- 3Amino acid sequences evolve stochastically.
- 4Protein sequences do not evolve even when DNA evolves at a constant rate.
Show answer and solution
Answer: (1) DNA and protein sequences evolve at a relatively constant rate.
Zuckerkandl and Pauling compared haemoglobin sequences across species and saw that the number of amino acid differences rose roughly in proportion to the time since the lineages split. They proposed that macromolecules evolve at a relatively constant rate, so sequence divergence can be used as a molecular clock to date branching events.
Who experimentally demonstrated “Mutations occur randomly”?
- 1Alfred Hershey and Martha Chase
- 2Matthew Meselson and Franklin Stahl
- 3Salvador Luria and Max Delbrück
- 4François Jacob and Jacques Monod
Show answer and solution
Answer: (3) Salvador Luria and Max Delbrück
Luria and Delbrück’s fluctuation test (1943) counted phage-resistant E. coli in many parallel cultures. The counts varied far more than the Poisson spread expected if phage exposure had induced the resistance. So resistance mutations arise at random, before selection, and selection only reveals them.
The Burgess Shale in the Canadian Rocky Mountains is known for its Cambrian fossils. This site is abundant in which one of the following fossil assemblages?
- 1Arthropods
- 2Dinosaurs
- 3Woody plants
- 4Fishes
Show answer and solution
Answer: (1) Arthropods
The Burgess Shale (about 508 million years old, British Columbia) preserves soft-bodied Cambrian animals in fine detail. Most of its species are arthropods and their relatives: trilobites, Marrella, Anomalocaris and others. Dinosaurs (Mesozoic), woody plants (from the Devonian) and true fishes all come much later.
Consider the following four geological periods.
- A. Quaternary
- B. Cretaceous
- C. Jurassic
- D. Cambrian
Which one of the following options represents the correct arrangement of these geological periods from earliest to recent:
- 1A-B-D-C
- 2D-C-B-A
- 3C-B-D-A
- 4B-A-C-D
Show answer and solution
Answer: (2) D-C-B-A
The Cambrian (about 539–485 million years ago) is the first period of the Paleozoic. The Jurassic (about 201–145) and Cretaceous (about 145–66) are Mesozoic periods. The Quaternary (2.58 million years ago to today) is the youngest. Earliest to most recent: D–C–B–A.
All 127 Evolution and Behaviour questions, by subtopic
Each link opens the question on its full paper page. Press Show answer and solution there to see NTA’s final key and a worked solution.
Brain, Behaviour & Evolution (45 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q31 | B | In a study on honey bee foraging, researchers investigated how dopamine release in the mushroom bodies affects the bee’s ability to learn… |
| Jun 2025, Q98 | C | Which one of the following statements best describes the function of magnetite in animal migration? |
| Jun 2025, Q110 | C | Male crickets call at dusk when the light intensity falls below a certain level. A researcher kept these insects in the laboratory under… |
| Jun 2025, Q126 | C | The table below lists insect sensory structures (Column X) with their function (Column Y). Which one of the following options correctly… |
| Jun 2025, Q133 | C | Caterpillars produce defensive vibrations that travel through plant stems to deter its predators. The table below summarises data collected… |
| Jun 2025, Q138 | C | The Hawk-Dove game serves as a model for conflict resolution in evolutionary game theory, wherein players 1 and 2 have the option of… |
| Dec 2024 S1, Q32 | B | Many marine mammals communicate over several kilometres in the ocean. This is due to |
| Dec 2024 S1, Q38 | B | Cleaner fish remove parasites from larger fish. Which evolutionary mechanism most likely maintains this interaction? |
| Dec 2024 S1, Q81 | C | Match the animal in Column X with its characteristic in Column Y. Which one of the following options represents all correct matches between… |
| Dec 2024 S1, Q102 | C | The following statements are about parental care and variance in reproductive success in a bird species. Select the option that identifies… |
| Dec 2024 S1, Q141 | C | The Marginal Value Theorem describes the behaviour of an animal foraging in a habitat where resources occur in patches. A major prediction… |
| Dec 2024 S2, Q31 | B | Which one of the following options suggests indirect selection in a population? |
| Dec 2024 S2, Q100 | C | In a paper wasp, a worker helps to raise 4 full-sisters instead of producing 4 offspring of her own. According to Hamilton’s rule, will… |
| Dec 2024 S2, Q117 | C | A researcher studying the mating systems in birds (operational sex ratio 1:1) uses the number of successful matings as a measure of male… |
| Dec 2024 S2, Q139 | C | Consider a predator that can forage on two prey types, where Prey1 is the more profitable prey and Prey2 is the less profitable prey. While… |
| Jun 2024 S1, Q28 | B | Which one of the following is an example of dishonest signaling? |
| Jun 2024 S1, Q111 | C | The statements below are about possible genetic relatedness between individuals of a monogamous, haplodiploid insect. Which one of the… |
| Jun 2024 S2, Q27 | B | Ian Pavlov conducted experiments to demonstrate that a dog that associates the sound of a bell with food, would salivate on hearing the… |
| Jun 2024 S2, Q56 | B | Runaway selection was proposed by R. A. Fisher to explain the evolution of extravagant secondary sexual characters. The model is based on… |
| Jun 2024 S2, Q78 | C | Male mating systems have evolved in response to female mating strategies and ecological factors that determine spatial distribution of… |
| Jun 2024 S2, Q112 | C | Consider a species of group-living bird in which individuals produce alarm calls to alert group members of the presence of a predator. The… |
| Dec 2023 S1, Q62 | B | Monogamy in sexually reproducing animals is seemingly paradoxical given that males must maximise their number of matings for higher… |
| Dec 2023 S1, Q131 | C | The graph given below is based on the optimal foraging theory. If the Y axis represents “Cumulative Resource Intake” following the law of… |
| Dec 2023 S1, Q132 | C | Defending a territory is energetically expensive and animals should invest in this only if it is profitable. A sunbird species is dependent… |
| Dec 2023 S2, Q60 | B | Which one of the following is NOT an example of learning? |
| Dec 2023 S2, Q134 | C | Certain animal species use infrasound for acoustic signaling. In this context, consider the statements below: Which one of the following… |
| Dec 2023 S2, Q135 | C | The following table lists selected concepts (Column X) in behavioral biology and their descriptions (Column Y): Which one of the following… |
| Jun 2023 S1, Q48 | B | Which one of the following is correct regarding zeitgebers? |
| Jun 2023 S1, Q56 | B | Which one of the following species of birds is known to migrate across the Himalayas? |
| Jun 2023 S1, Q63 | B | Given that Asian Koel is a brood parasite, which one of the following statements is TRUE for this species? |
| Jun 2023 S1, Q134 | C | In many sexually reproducing organisms, females make mate choice decisions based on male display traits. Several models have been proposed… |
| Jun 2023 S1, Q135 | C | Based on the theory of kin selection, choose the correct statement: |
| Jun 2023 S2, Q61 | B | In a cooperatively breeding species, under which condition is a helper more likely to exhibit philopatry? |
| Jun 2023 S2, Q134 | C | Males of a species of grasshopper produce loud calls to attract females. Most energy of these calls lie in the species-specific frequency… |
| Jun 2023 S2, Q135 | C | Behavioral and cognitive responses in organisms are finely tuned to environmental cues. Given below is a list of specific hormone/chemical… |
| Jun 2023 S2, Q136 | C | Many species of birds call at dawn in temperate regions. The phenomenon is referred to as “Dawn Chorus”. Several explanations have been… |
| Feb 2022 S1, Q60 | B | Mimicry where deceptiveness of the mimic’s signal is high and fitness consequences signaled to the receiver by the mimic is also high (and… |
| Feb 2022 S1, Q128 | C | In the Table below, Column I describes movements of organisms and Column II describes the type of movement. Which one of the following… |
| Feb 2022 S1, Q131 | C | A researcher is interested in investigating if parental investment (PI, panel A) by male seahorses and pipefishes is correlated with their… |
| Feb 2022 S2, Q60 | B | Select the correct statement that best describes animal territories |
| Feb 2022 S2, Q63 | B | Eusocial societies are NOT characterised by which of the following? |
| Feb 2022 S2, Q128 | C | Consider predators with a choice between two prey types: a big prey 1 which has energy value E1, handling time h1, and search time S1 and… |
| Feb 2022 S2, Q129 | C | Which of the following is NOT the function of dispersal behaviour in which organisms move away from their natal homes? |
| Feb 2022 S2, Q131 | C | Which of the following pairs of traits is most likely in a species when maternal investment is very high? |
| Feb 2022 S2, Q135 | C | When species express a suite of correlated traits (e.g., behavior, morphology, function), within a given context or across contexts, it is… |
Mechanisms of Evolution – Selection, Speciation & Population Genetics (41 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q52 | B | Why might a plant species evolve cleistogamous flowers in addition to chasmogamous ones? |
| Dec 2024 S1, Q21 | B | Which one of the following is the most significant factor that explains the evolution of iteroparity in animals? |
| Dec 2024 S1, Q35 | B | Within a broadly distributed taxonomic clade, populations and species of larger size are generally found in colder environments, while… |
| Dec 2024 S1, Q60 | B | Which one of the following is an example of character displacement? |
| Dec 2024 S1, Q70 | B | Tectonic uplift can alter the drainage patterns of rivers, thereby isolating populations of many species. Population isolation of this kind… |
| Dec 2024 S1, Q86 | C | The following statements describe change in allele frequencies over time. Which one of the following options represents the combination of… |
| Dec 2024 S1, Q92 | C | Two closely related sympatric ladybird beetle species in a rainforest have evolved to specialise on different insect prey. Which one of the… |
| Dec 2024 S2, Q43 | B | In life history theory, the concept of ‘cost of reproduction’ refers to: |
| Dec 2024 S2, Q48 | B | A grassland has five sympatric species of grasshoppers. Males sing species-specific songs to attract conspecific females. The song… |
| Dec 2024 S2, Q57 | B | Which one of the following statements is INCORRECT regarding seasonality and sex in aphids? |
| Dec 2024 S2, Q134 | C | Evolution by natural selection may produce organisms that are adapted to their environment. Given below are four statements regarding… |
| Jun 2024 S1, Q44 | B | Which one of the following concepts can explain host-parasite co-evolution? |
| Jun 2024 S1, Q49 | B | Select the statement that describes guild coevolution, also known as diffuse coevolution. |
| Jun 2024 S1, Q105 | C | In a frog species, foot webbing is controlled by a single gene where the allele for nonwebbed feet (W) is dominant and webbed feet (w) is… |
| Jun 2024 S2, Q60 | B | Natural selection can maintain genetic polymorphisms. Which one of the following CAN NOT contribute to the maintenance of polymorphisms? |
| Jun 2024 S2, Q99 | C | The mutation rate refers to the frequency at which new mutations arise in the genome of an organism and is typically expressed as: Mutation… |
| Jun 2024 S2, Q105 | C | The following graphs represent the effect of two environmental conditions (E1 and E2) resulting in two optimal phenotypes (OE1 and OE2) for… |
| Dec 2023 S1, Q63 | B | Sometimes similar traits or characteristics evolve in two distinct lineages independently, such as venoms in scorpions and snakes. This… |
| Dec 2023 S1, Q119 | C | Consider a highly diverse community of closely related species of lizards which has evolved in a short period of time and that occupies… |
| Dec 2023 S1, Q122 | C | Given below are species concepts (Column X) and their descriptions (Column Y): Which one of the following options represents all the correct matches? |
| Dec 2023 S1, Q129 | C | Based on theoretical concepts of mating systems in plants, pollen : ovule ratios are likely to be most skewed in which one of the following cases? |
| Dec 2023 S1, Q133 | C | Given below are statements related to different types of natural selection models. Select the correct option that represents the… |
| Dec 2023 S2, Q131 | C | Consider a disease caused by a recessive allele. In a study population, one out of every 500 individuals (0.20%) has the disease. Based on… |
| Jun 2023 S1, Q51 | B | Consider alleles ‘A’ and ‘a’ in a population. The frequency of heterozygotes will be highest when: |
| Jun 2023 S1, Q52 | B | Recessive lethal alleles are never completely eliminated from the population because: |
| Jun 2023 S1, Q62 | B | Directional Selection for a particular trait will lead to the frequency of the trait: |
| Jun 2023 S1, Q124 | C | It has been observed that within a flowering season, a plant may produce more male flowers which may be correlated with the longevity of… |
| Jun 2023 S1, Q131 | C | The following trees represent different evolutionary mechanisms. Select the tree that best represents punctuated equilibrium. |
| Jun 2023 S1, Q132 | C | The following list represents two types of reproductive isolation (Column P) that can lead to speciation. Column Q represents the processes… |
| Jun 2023 S1, Q133 | C | A scientist is using the Hardy-Weinberg equation to assess if a population is in equilibrium or is evolving. She recorded the following… |
| Jun 2023 S2, Q50 | B | Reduction in the frequency of heterozygous genotype with a concomitant increase in the frequency of homozygous genotype, in context of… |
| Jun 2023 S2, Q62 | B | Which one of the following options best represents the sequence of events leading to the phenomenon of introgression? |
| Jun 2023 S2, Q116 | C | A founder population has an Aa heterozygous genotype with a frequency of 1, and no individual with either AA or aa genotypes. With repeated… |
| Jun 2023 S2, Q127 | C | The theory of island biogeography has synthesized into theory the following concepts, except: |
| Jun 2023 S2, Q132 | C | The following statements are potential explanations for the continued existence of genes that control eye development in eyeless cavefish… |
| Feb 2022 S1, Q130 | C | In a population that is in Hardy-Weinberg equilibrium, the frequency of the recessive homozygote genotype of trait q is 0.04. The… |
| Feb 2022 S2, Q61 | B | Convergent evolution creates: |
| Feb 2022 S2, Q62 | B | Select the correct option that describes the above graph regarding length of bird’s bill: |
| Feb 2022 S2, Q113 | C | Sampling of 200 persons for their ABO blood group was done from an urban area. The types of blood group observed in the given population… |
| Feb 2022 S2, Q130 | C | Colour blindness affects approximately 1 in 12 men (8%). In a population that is in Hardy-Weinberg Equilibrium (HWE) where 8% of men are… |
| Feb 2022 S2, Q132 | C | A researcher studying a cricket species finds that individuals on either side of a large river have different call frequencies on average… |
Molecular Evolution & Phylogenetics (23 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q24 | B | A 16S rRNA gene-based maximum-likelihood tree of soil isolates shows a long branch at the node connecting a clade of Actinobacteria to a… |
| Jun 2025, Q70 | B | In the circular synteny maps of Poaceae family, providing insights into the origin and evolution of grass genomes, which one of the… |
| Dec 2024 S1, Q144 | C | Synonymous mutations (solid black circle) and non-synonymous mutations (different symbols) are plotted on two hypothetical phylogenies (A… |
| Dec 2024 S2, Q23 | B | Which one of the following statements defines a monophyletic group? |
| Dec 2024 S2, Q25 | B | Which one of the following phenomena describes the evolution of wings in bats, birds, and insects? |
| Jun 2024 S1, Q80 | C | Phylogenetic trees are used to examine From the above statements, select the correct combination of statements that best represent the… |
| Jun 2024 S1, Q103 | C | The following statements describe different patterns of sequence evolution. Which one of the options is NOT true about sequence evolution… |
| Jun 2024 S1, Q104 | C | Molecular phylogeny indicates that whales are closely related to the artiodactyls. Given this information, select the phylogenetic tree… |
| Jun 2024 S2, Q47 | B | Which one of the following molecular phylogenetic trees depicts the correct relationship among invertebrates? |
| Jun 2024 S2, Q48 | B | Which one of the statements about homoplasy is NOT true? |
| Jun 2024 S2, Q106 | C | The phylogenetic tree given below shows single nucleotide polymorphisms observed among four individuals of the scorpion species… |
| Jun 2024 S2, Q143 | C | The following tree shows phylogenetic relationships between species A to D. Which of the following molecular mechanisms would be… |
| Dec 2023 S1, Q134 | C | Which one of the following Newick trees represents the correct relationship between apes. |
| Dec 2023 S1, Q135 | C | The table below lists phylogenetic reconstruction methods and the description of these methods, which includes both algorithmic and… |
| Dec 2023 S2, Q61 | B | Which one of the following statements about the molecular clock hypothesis as proposed by Zuckerkandl and Pauling 1962 is CORRECT? |
| Dec 2023 S2, Q132 | C | An ancestral sequence (TTAG) has diverged into two sequences and has since accumulated nucleotide substitutions along two lineages (1 and… |
| Jun 2023 S1, Q64 | B | The following terms represent different methods in phylogenetic tree constructions. Select the option that represents all distance-based methods? |
| Jun 2023 S1, Q136 | C | In four taxa (A, B, C and D), two characters (shape and color) were scored to infer their phylogenetic relationship. The two character… |
| Jun 2023 S2, Q120 | C | The figure below depicts the evolutionary tree of organisms based on characteristics that are depicted as numbers (i-iv). Choose the option… |
| Jun 2023 S2, Q131 | C | The two phylogenetic trees given below represent evolutionary patterns in species or population. The differently colored or dashed lines… |
| Feb 2022 S1, Q62 | B | Select the correct statement related to phylogeny of primates. |
| Feb 2022 S2, Q133 | C | Biased gene conversion (BGC) has been proposed to cause changes in allele frequencies in a population. Select the statement that is NOT… |
| Feb 2022 S2, Q134 | C | The following statements were made describing the properties of a UPGMA tree (Unweighted Pair Group Method with Arithmetic Mean): Which one… |
Paleontology & Evolutionary History (12 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q27 | B | Which one of the following is the correct chronological order of major eras from oldest to youngest? |
| Jun 2025, Q107 | C | The Satpura Hypothesis suggests that the Satpura Range in central India acted as a bridge for the migration of Malayan taxa into peninsular… |
| Jun 2025, Q124 | C | Which one of the following options correctly represents mass extinction events in increasing order of percentage loss of species? |
| Dec 2024 S1, Q65 | B | What type of invertebrate fossils, commonly found in the Spiti Valley of India, are characteristic of the Cambrian era? |
| Dec 2024 S2, Q91 | C | Consider the following statements on patterns in global biogeography. Which one of the options given below contains the correct set of… |
| Jun 2024 S1, Q64 | B | Select the geological time where some of the major events, like an increase in marine diversity, dominance of gymnosperms, diversification… |
| Jun 2024 S1, Q69 | B | In 2007, scientists reported the fossil of a deer-like animal in Kashmir, India which is considered the most recent terrestrial ancestor of… |
| Jun 2024 S2, Q34 | B | The Burgess Shale in the Canadian Rocky Mountains is known for its Cambrian fossils. This site is abundant in which one of the following… |
| Dec 2023 S1, Q61 | B | Which one of the following geological events in the Cretaceous had a massive impact on the climate and biodiversity of India? |
| Dec 2023 S2, Q63 | B | Absence of dormant buds and absence of annual growth rings in a fossilized trunk specimen of a coal swamp plant indicates: |
| Feb 2022 S1, Q59 | B | Given below are statements on ‘living fossils’. Select the correct statements. |
| Feb 2022 S1, Q61 | B | Consider the following four geological periods. Which one of the following options represents the correct arrangement of these geological… |
Origin of Cells & Unicellular Evolution (3 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2025, Q45 | B | Which of the following features establishes stromatolites as a source of early evidence for life on earth? |
| Jun 2025, Q54 | B | According to the Oparin-Haldane hypothesis, which one of the following statements best describes the Earth’s early atmosphere? |
| Dec 2024 S2, Q131 | C | With reference to the origin of multicellularity in different life forms, which one of the following statements is INCORRECT? |
Emergence of Evolutionary Thoughts (3 questions)
| Paper and question | Part | Question |
|---|---|---|
| Jun 2024 S1, Q26 | B | Who experimentally demonstrated “Mutations occur randomly”? |
| Jun 2023 S2, Q133 | C | Column X lists evolutionary ideas and scientists who proposed them, and Column Y lists the description of these ideas. Which one of the… |
| Feb 2022 S2, Q122 | C | The table below enlists name of scientists and different areas of scientific contribution Which one of the following options represents a… |
PYQs for every CSIR-NET unit
How to revise Evolution and Behaviour with these questions
- Start with the two biggest subtopicsBrain, Behaviour & Evolution and Mechanisms of Evolution – Selection, Speciation & Population Genetics are where most of the marks have been. Revise them first.
- Attempt before you readWork through a subtopic’s questions on paper, then check them against the answer keys.
- Find the repeatsThe same ideas keep coming back in new wording. When you get one wrong, look for its earlier version in the list above.
- Finish with a full paperTake a whole paper in live exam mode to practise choosing which Part C questions to attempt.
Keep going
<
p class=”lbq-src”>Source: CSIR-NET Life Sciences question papers and final answer keys, National Testing Agency, February 2022 to June 2025. Subtopic tags, difficulty ratings and solutions: Lesson Basket.
