GATE 2025 Question Paper Ecology and Evolution (EY)

GATE
2025
Question Paper | Answer Key
Graduate Aptitude Test in Engineering
(GATE) is a prestigious national-level exam
that assesses candidates for
comprehensive understanding in various
undergraduate-level subjects in
Engineering, Technology, Science,
Architecture, and Humanities.

General Aptitude
Q.1 – Q.5 Carry ONE mark Each

Q.1 Here are two analogous groups, Group-I and Group-II, that list words in their
decreasing order of intensity. Identify the missing word in Group-II.

Group-I: Abuse → Insult → Ridicule

Group-II: ________ → Praise → Appreciate

(A) Extol

(B) Prize

(C) Appropriate

(D) Espouse

Q.2 Had I learnt acting as a child, I ________ a famous film star.

Select the most appropriate option to complete the above sentence.

(A) will be

(B) can be

(C) am going to be

(D) could have been

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Q.3 The 12 musical notes are given as 𝐶, 𝐶 # , 𝐷, 𝐷# , 𝐸, 𝐹, 𝐹 # , 𝐺, 𝐺 # , 𝐴, 𝐴# , and 𝐵.
12
Frequency of each note is √2 times the frequency of the previous note. If the
frequency of the note C is 130.8 Hz, then the ratio of frequencies of notes 𝐹 # and 𝐶
is:

(A) 6
√2

(B)
√2

(C) 4
√2

(D) 2

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Q.4 The following figures show three curves generated using an iterative algorithm. The
total length of the curve generated after ‘Iteration 𝑛’ is:

Note: The figures shown are representative.

1
Iteration 0:

1 1
Iteration 1: Length of each segment:
3 3

1
1
Iteration 2: 9 Length of each segment:
9

𝑛
(A) 5 2
( )
3

(B) 5 𝑛
( )
3

(C) 5 2𝑛
( )
3

(D) 5 𝑛(2𝑛−1)
( )
3

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Q.5 |𝑥|
Which one of the following plots represents 𝑓 (𝑥 ) = − , where 𝑥 is a non-
𝑥
zero real number?

Note: The figures shown are representative.

f(x)
(A)
(0,1)

x
(0, −1)

f(x)
(B)
(0,1)

x
(0, −1)

f(x)
(C)

(1,0)
x
(−1,0)

f(x)
(D)
(0,1)

x
(0, −1)

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Q.6 – Q.10 Carry TWO marks Each

Q.6 Identify the option that has the most appropriate sequence such that a coherent
paragraph is formed:

P. Over time, such adaptations lead to significant evolutionary changes with
the potential to shape the development of new species.

Q. In natural world, organisms constantly adapt to their environments in
response to challenges and opportunities.

R. This process of adaptation is driven by the principle of natural selection,
where favorable traits increase an organism’s chances of survival and
reproduction.

S. As environments change, organisms that can adapt their behavior, structure
and physiology to such changes are more likely to survive.

(A) P→Q→R→S

(B) Q→S→R→P

(C) R→S→Q→P

(D) S→P→R→Q

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Q.7 A stick of length one meter is broken at two locations at distances of 𝑏1 and 𝑏2 from
the origin (0), as shown in the figure. Note that 0 < 𝑏1 < 𝑏2 < 1. Which one of the
following is NOT a necessary condition for forming a triangle using the three
pieces?

Note: All lengths are in meter. The figure shown is representative.

(A) 𝑏1 < 0.5

(B) 𝑏2 > 0.5

(C) 𝑏2 < 𝑏1 + 0.5

(D) 𝑏1 + 𝑏2 < 1

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Q.8 Eight students (P, Q, R, S, T, U, V, and W) are playing musical chairs. The figure
indicates their order of position at the start of the game. They play the game by
moving forward in a circle in the clockwise direction.

After the 1st round, 4th student behind P leaves the game. After 2nd round, 5th student
behind Q leaves the game. After 3rd round, 3rd student behind V leaves the game.
After 4th round, 4th student behind U leaves the game. Who all are left in the game
after the 4th round?

Note: The figure shown is representative.

P

W R

U T

Q
V

S

(A) P; T; Q; S

(B) V; P; T; Q

(C) W; R; Q; V

(D) Q; T; V; W

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Q.9 The table lists the top 5 nations according to the number of gold medals won in a
tournament; also included are the number of silver and the bronze medals won by
them. Based only on the data provided in the table, which one of the following
statements is INCORRECT?

Nation Gold Silver Bronze

USA 40 44 41

Canada 39 27 24

Japan 20 12 13

Australia 17 19 16

France 16 26 22

(A) France will occupy the third place if the list were made on the basis of the total
number of medals won.

(B) The order of the top two nations will not change even if the list is made on the basis
of the total number of medals won.

(C) USA and Canada together have less than 50% of the medals awarded to the nations
in the above table.

(D) Canada has won twice as many total medals as Japan.

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Q.10 An organization allows its employees to work independently on consultancy
projects but charges an overhead on the consulting fee. The overhead is 20% of the
consulting fee, if the fee is up to ₹ 5,00,000. For higher fees, the overhead is
₹ 1,00,000 plus 10% of the amount by which the fee exceeds ₹ 5,00,000. The
government charges a Goods and Services Tax of 18% on the total amount (the
consulting fee plus the overhead). An employee of the organization charges this
entire amount, i.e., the consulting fee, overhead, and tax, to the client. If the client
cannot pay more than ₹ 10,00,000, what is the maximum consulting fee that the
employee can charge?

(A) ₹ 7,01,438

(B) ₹ 7,24,961

(C) ₹ 7,51,232

(D) ₹ 7,75,784

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Q.11 – Q.35 Carry ONE mark Each

Q. 11 In a linear regression, a line of best fit can be obtained by

(A) minimizing the sum of squares of the residuals

(B) minimizing the sum of the residuals

(C) minimizing the standard deviation from the mean

(D) minimizing the standard error of the mean

Q.12 Fly larvae of a species feed simultaneously on a shared rotting fruit. If the density
of fly larvae is high, then all the larvae grow up to be smaller sized adults than if
the larval density were low. Which one of the following processes best describes
this observation?

(A) Scramble competition

(B) Interspecific competition

(C) Competitive exclusion

(D) Apparent competition

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Q.13 In primates, males are often larger than females. If sexual dimorphism evolved to
enable males to compete for access to multiple females, in which mating system
would we expect to see the greatest sexual dimorphism?

(A) Monogamy

(B) Polygyny

(C) Polyandry

(D) Parthenogamy

Q.14 Hosts of parasites evolve effective immune responses to infection, which in turn
results in those parasites evolving increased infectiousness towards the hosts.
Which one of the following processes describes this type of interaction between
hosts and parasites?

(A) Co-evolution

(B) Quorum sensing

(C) Convergent evolution

(D) Character displacement

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Q.15 Male rhinoceros beetles have horns that they use to fight each other. Despite
the competitive advantage of having large horns, horn length never exceeds
two thirds of their body length. What form of selection explains why horn
length is constrained?

(A) Directional selection

(B) Disruptive selection

(C) Artificial selection

(D) Stabilizing selection

Q.16 Lizards that produce many eggs often have a shorter lifespan than those who
produce fewer eggs. Which one of the terms below describes the relationship
between the number of eggs and lifespan?

(A) Compensatory growth

(B) Frequency dependent selection

(C) Biomagnification

(D) Life-history tradeoff

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Q.17 A butterfly species in a homogenous forest patch starts exhibiting assortative
mating, such that spotted individuals always mate with each other and plain
individuals always mate with each other. This trait is heritable, and spotted
parents always produce spotted offspring and plain parents always produce
plain offspring. Which one of the following forms of speciation could this
prezygotic reproductive barrier most likely lead to?

(A) Sympatric speciation

(B) Cryptic speciation

(C) Allopatric speciation

(D) Peripatric speciation

Q.18 The hippocampus is a region of the brain whose size is positively correlated
with navigation and spatial mapping ability in birds and mammals. Which one
of the following observations would NOT be consistent with this statement?

(A) When the size of the hippocampus is surgically reduced in laboratory rats,
their ability to find food is reduced in a radial arm maze

(B) Bird species that hoard food in different parts of their territory have a larger
hippocampus than similarly-sized bird species that do not hoard food

(C) In domestic pigeons, non-homing varieties have a larger hippocampus than
homing varieties

(D) In voles, males have larger home ranges than females, and the hippocampus
of males is larger than that of females

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Q.19 A bird eats two types of worms, P and Q, picking them randomly. Which one
of the following describes the kind of probability distribution of the number of
worms of type P eaten by the bird in a day?

(A) Binomial

(B) Normal

(C) Log-normal

(D) Uniform

Q.20 Which one of the following is an example of a cell type found only in a single
phylum?

(A) Cnidocyte

(B) Erythrocyte

(C) Myocyte

(D) Neurocyte

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Q.21 Fossils of most of the modern animal phyla first appeared over a short period
of time. In which one of the following geological time periods did this occur?

(A) Cambrian

(B) Cretaceous

(C) Jurassic

(D) Permian

Q.22 Certain species of ibex and weevils depend on the same food source. A study
finds that the removal of ibex results in an increase in the number of weevils,
but the removal of weevils does not affect the ibex. Which one of the following
options best describes this interaction?

(A) Amensalism

(B) Commensalism

(C) Mutualism

(D) Parasitism

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Q. 23 Across trophic levels, energy flows from producers to primary consumers,
and from primary consumers to secondary consumers. Which one of the
following options best represents the percentage of energy that is transferred
from producers to secondary consumers?

(A) Between 0.01 and 0.02 %

(B) Between 0.5 and 1.5 %

(C) Between 7.5 and 12.5 %

(D) Between 72.5 and 77.5 %

Q.24 High water temperatures can cause coral bleaching, which often leads to coral
death. In coral reefs that experience repeated bleaching, there can be substantial
algal growth on dead coral, eventually leading to an algal dominated ecosystem.
Such a transformation is known as

(A) adaptive radiation

(B) coral transplantation

(C) coral recruitment

(D) phase shift

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Q. 25 The species richness of trees increases from North to South in the Western Ghats,
and from South to North in the Andes. Which one of the following can be an
explanation for these patterns?

(A) Greater incident solar radiation at lower latitudes

(B) Higher temperature at higher latitudes

(C) Greater distance from the coast at lower latitudes

(D) Stronger trade winds at higher latitudes

Q.26 Local communities are comprised of a subset of species from the regional
species pool. Which one of the following processes is LEAST likely to cause
species composition of local communities to differ from one another?

(A) Local interspecific competition

(B) Regionally stable climatic conditions

(C) Stochastic demographic variation

(D) Local predator-prey interactions

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Q.27 In this figure, the rectangle (P) depicts the range of temperature and rainfall in
which a plant species can survive and propagate. The circle (Q) demarcates the
range of temperature and rainfall in which this plant species is actually found.

Which one of the following statements about P and Q is accurate for this plant
species?

(A) P is the fundamental niche and Q is the realized niche

(B) P is the fundamental niche and Q is the habitat

(C) Q is the fundamental niche and P is the realized niche

(D) Q is the fundamental niche and P is the habitat

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Q.28 Match the following geographic regions to the mammals that are native to
those regions.

Geographic regions Mammals

(P) Western Ghats (i) Golden langur

(Q) Western Himalaya (ii) Malabar giant squirrel

(R) Northeast India (iii) Pika

(S) Andaman and Nicobar Islands (iv) Nilgai

(v) Long-tailed macaque

(A) P-iii; Q-ii; R-i; S-v

(B) P-ii; Q-iii; R-i; S-iv

(C) P-ii; Q-iii; R-i; S-v

(D) P-iii; Q-v; R-ii; S-iv

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Q.29 Mayflies lay eggs in water. Their nymphs (immature life stage) are aquatic
and adults are terrestrial. Some mayflies perceive dry, paved parking lots as
waterbodies and lay eggs there that do not survive. In this situation, which
one or more of these statements is/are correct?

(A) These parking lots are ecological sink habitats, whereas adjacent waterbodies
are source habitats

(B) This is an example of antagonistic coevolution between humans and insects

(C) Mayflies have an iteroparous life history strategy

(D) Laying eggs in these parking lots instead of waterbodies would reduce the
fitness of individual female mayflies

Q.30 Fish schools in coral reefs can comprise multiple species that swim and forage
together. Which one or more of the following options describe(s) potential fitness
benefit(s) to individuals in a mixed-species group?

(A) Individuals of some species draw the attention of predators away from the
school, thereby sacrificing themselves for the survival of the group

(B) Some species join mixed-species groups in order to hybridize

(C) Larger groups reduce the per capita risk of predation

(D) Individuals of some species feed on the substrate, while others feed on the
invertebrates that are flushed out by the substrate-feeder

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Q. 31 During migration, which one or more of the following do birds use for
long-distance navigation?

(A) Celestial cues

(B) Earth’s magnetic field

(C) Chemical cues

(D) Polarized light

Q.32 Which one or more of the following functions do insects directly perform
in ecosystems?

(A) Decomposition

(B) Pollination

(C) Photosynthesis

(D) Vernalization

Q.33 In a lake with a large population of fish, there are 4 blue fish for every red fish.
Every fish has an equal probability of being caught. If you dip a net into this
lake and pick up 4 individuals at random, the probability that you will get 2 fish
of each colour is _______

(Round off to three decimal places)

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Q.34 There are 9 different rock lizard species, each with a unique colour. Lizards of
2 different species sit on a rock at any given time. The number of possible colour
combinations of rock lizards seen together on a rock is ______

(Answer in integer)

Q.35 In a population of 534 blue sheep, there are two alleles, P and Q, at an autosomal
locus. Allele P has a frequency of 30%. The number of sheep with the QQ
genotype is 262. Assuming that this population is at Hardy-Weinberg equilibrium,
the expected percentage of sheep with the PQ genotype in the population is
______%

(Round off to two decimal places)

Q.36 – Q.65 Carry TWO marks Each

Q.36 Rotting leaves of mango are composed of 25% of compound P which decomposes
exponentially at a rate kP = 0.5 yr−1 and 75% of compound Q which decomposes
exponentially at a rate kQ = 0.1 yr−1.

What percentage of the initial amount of compound Q remains when half of the
initial amount of compound P has decomposed? Choose the closest numerical
value from the options provided.

(A) 87%

(B) 50%

(C) 75%

(D) 37%

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Q.37 The origin and proliferation of which one of the following organisms was
responsible for the ‘Great Oxidation Event’?

(A) Cyanobacteria

(B) Fungi

(C) Plants

(D) Virus

Q.38 Which one of the following mechanisms is expected to generate tightly linked
genes?

(A) Chromosomal inversion

(B) Deletion of an exon

(C) Gene duplication

(D) Insertion of an exon

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Q.39 Newts produce tetrodotoxin (TTX), a poison that targets sodium ion channels,
for defense against their predators, garter snakes. Several species of garter snakes
are resistant to newt TTX due to specific known amino acid substitutions in
garter snake sodium channels. Which one of the following is best-suited to
identify whether this adaptation in garter snakes has a single origin or multiple
independent origins?

(A) Building a gene phylogeny of sodium ion channel in garter snakes

(B) Building a species phylogeny of garter snakes

(C) Building a gene phylogeny of newt sodium ion channels and species phylogeny
of newts, and comparing them

(D) Building a gene phylogeny of garter snake sodium ion channels and a species
phylogeny of garter snakes, and comparing them

Q.40 Many insect species carry the endosymbiotic bacteria Wolbachia, which are
maternally inherited. Wolbachia persist over time in these insect hosts by
increasing the fitness of the infected host. This increased host fitness can lead
to the fixation of Wolbachia in the host population, wherein all individuals
carry it. Which one of the following statements describes a process that would
NOT allow Wolbachia to become fixed in the host population?

(A) Wolbachia induce cytoplasmic incompatibility and so, mating between
infected and uninfected host individuals produces no viable offspring

(B) Wolbachia increase the fecundity of the host by increasing its longevity

(C) Wolbachia increase the immune response of the host to other infections

(D) Wolbachia induce cytoplasmic compatibility and so, only mating between
infected and uninfected host individuals produces viable offspring

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Q.41 Figure F shows how predation rate changes with increasing prey density.

Which one of the figures represents the per capita death rate of prey under
the conditions of F?

(A) G

(B) H

(C) I

(D) J

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Q.42 Fungus S infects elm trees and fungus T infects chestnut trees, and both kill
their hosts within a year of infection. A forest with equal density of elm and
chestnut trees is colonized by both pathogenic fungi. A 100 years later, the
elm tree population has declined and the chestnut trees have become extinct.
Which one of the following mechanisms would NOT contribute to this outcome?

(A) Fungus S is dispersed by flightless beetles and fungus T disperses by wind

(B) Elm trees reproduce much more quickly than chestnut trees

(C) Elm seeds disperse far away from the parent, while chestnut seeds fall near
the parent

(D) Fungus S reproduces much more quickly than fungus T

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Q.43 The table below provides a list of study questions (P, Q, R) and statistical tests
(i, ii, iii).

Study question Statistical Test

(P) Does flower colour follow (i) Student’s t-test
Mendelian inheritance?

(Q) Does increased visitation by (ii) Chi-square test
pollinators increase the number of viable
fruits produced by an individual?

(R) Does the quantity of nectar (iii) Pearson’s correlation
production differ between flowers that analysis
were visited by pollinators compared to
those that had no pollinator visitation?

Which one of the following options correctly matches the study question to the
most appropriate statistical test?

(A) P-i; Q-ii; R-iii

(B) P-i; Q-iii; R-ii

(C) P-ii; Q-i; R-iii

(D) P-ii; Q-iii; R-i

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Q.44 A researcher wants to estimate the number of crickets in an isolated valley. They
captured 56 crickets in the first session, and then marked and released them. In
the second session, they captured 41 crickets of which 8 were already marked.

Assuming that there is no birth, death, immigration or emigration in the cricket
population during the study period, what is the estimated number of crickets in
this valley?

(A) 97

(B) 247

(C) 287

(D) 334

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Q.45 The table below lists potential environmental conditions in future climates,
related to atmospheric carbon dioxide concentrations (CO2) and mean annual
temperature (MAT).

The table also lists potential outcomes with respect to whether conditions will
favour grasses with C3 or C4 photosynthetic pathways.

Assuming no other changes in environmental conditions, match the options in
the two columns.

Environmental conditions Outcomes

(P) Increased CO2, no change in MAT (i) C3 performs better than C4

(Q) No change in CO2, increased MAT (ii) C4 performs better than C3

(iii) C3 and C4 perform equally

(A) P-i; Q-iii

(B) P-i; Q-ii

(C) P-ii; Q-iii

(D) P-iii; Q-ii

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Q.46 In a grassland (P), there are 8 plant species with a similar number of individuals
of each species. In another grassland (Q), there are 12 species with uneven
abundances. Which one of the following statements about the Shannon’s diversity
index of P and Q is correct?

(A) The diversity index of P is greater than Q

(B) The diversity index of P is less than Q

(C) The diversity index of P is equal to Q

(D) There is not enough information to draw a conclusion

Q.47 Which one of the following statements about genetic drift is accurate?

(A) Like mutation, drift increases genetic variation within a population

(B) Drift typically increases genetic differences between populations

(C) Drift typically reinforces the effects of natural selection in populations

(D) Drift increases with population size, leading to faster evolution

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Q.48 Mean global temperature since pre-industrial times has increased approximately
by

(A) 0 to 0.5 ℃

(B) 1 to 1.5 ℃

(C) 2 to 3 ℃

(D) 3 to 5 ℃

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Q.49 In a deer species that lives in groups, some individuals act as sentinels and are
vigilant for predators but there is a trade-off between foraging and vigilance. A
researcher collects data on the foraging rates of edge (black) and central (grey)
members of the group in two similar forests, one with and one without predators.
Which one of the following figures best supports the hypothesis that members at
the edge are acting as sentinels in this deer species?

(For comparisons within a forest, * denotes a statistically significant difference,
and NS denotes no difference. Comparisons between forests with versus without
predators are always statistically significantly different.)

(A) P

(B) Q

(C) R

(D) S

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Q.50 A patch of forest (I) has been declared as a protected area. Conservationists have
surveyed three other patches of forest (II, III and IV) and can only recommend
one of them for protection. In the figure below, each letter denotes a different
species of frog. The conservationists recommend that Patch IV should be
protected. Which one of the following metrics is this decision based on?

(A) Species richness

(B) Complementarity

(C) Alpha diversity

(D) Evenness

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Q.51 The numbers of rabbits (𝑅) and their predators, foxes (𝐹), in an ecosystem are
modelled by the Lotka-Volterra equations as follows:

𝑑𝑅
= 2𝑅 − 0.01 𝑅 𝐹
𝑑𝑡
𝑑𝐹
= −𝐹 + 0.005 𝑅 𝐹
𝑑𝑡
where the time is measured in months.

If there are currently 100 rabbits and 10 foxes, the number of rabbits is changing
at the rate of per month and the number of foxes is changing at the rate
of _______ foxes per month.

(A) +190 and -5

(B) +5 and -190

(C) -190 and +5

(D) -10 and +5

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Q.52 The number of species found on islands typically increases with the size of the
island. Which one or more of the following options explains this relationship
between island size and species richness?

(A) Large islands have more habitat types than small islands

(B) Large islands are colonized by more species than small islands

(C) Small islands have higher species extinction rates than large islands

(D) Small islands are closer to the mainland than large islands

Q.53 Decreasing surface area to volume ratio helps reduce heat loss in colder climates.
In which one or more of the following observations does this play a role?

(A) Related species of mammals are larger in size at higher latitudes

(B) Birds lay more clutches of eggs at higher latitudes

(C) Birds and mammals huddle tightly together at higher latitudes

(D) Mammals have longer limbs and larger ears at higher latitudes

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Q.54 The table below describes the number of tree species in a forest whose seeds
are dispersed by large or small animals, and whether they are insect or wind
pollinated.

In the past, seed dispersers and pollinators were abundant in this forest. Now,
there are very few large animal dispersers, but the number of small animal
dispersers has not changed. There are also very few insect pollinators in this
forest.

Which one or more of the following inferences about trees in the forest can
be drawn from these changes in seed dispersers and pollinators?

Insect pollinated Wind pollinated

Dispersed by large 85 tree species 19 tree species
animals

Dispersed by small 25 tree species 11 tree species
animals

(A) Mortality of all trees in this forest will decrease in the future

(B) Mortality of a large number of trees in this forest will increase in the future

(C) Regeneration of all tree species in this forest will increase in the future

(D) Regeneration of a large number of tree species will decrease in future

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Q.55 Which one or more of the following would make a plant community more
susceptible to invasion by exotic plants?

(A) Anthropogenic influx of nutrients

(B) Decline in density of a dominant species due to disease

(C) Arrival of a highly competitive exotic species

(D) Absence of suitable pollinators for an invading species

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Q.56 Aphids feed on both alfalfa and clover plants. A researcher collected and reared
different genotypes of aphids from separate alfalfa and clover fields. He then
measured the fecundity of both aphid groups when fed on each of the two host
plants. The figure summarizes the performance of aphid groups originating from
alfalfa (dashed) or clover (solid).

Which one or more of the following situations does the figure depict?

(A) Aphids demonstrate a genotype by environment interaction

(B) Aphids from clover fields are much less genetically variable than aphids
from alfalfa fields

(C) Aphids from clover fields are locally adapted to their original host

(D) Aphids from clover fields show high plasticity

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Q.57 Which one or more of the following processes has/have resulted in increased
greenhouse gases in the atmosphere over the last 100 years?

(A) Increasing levels of N2 in the atmosphere due to increased denitrification

(B) Increased release of CO2 into the atmosphere due to the burning of fossil fuels

(C) Increased release of methane into the atmosphere due to livestock

(D) Increased release of methane from wetlands soil

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Q.58 The figure below shows the reproductive success of two alternative mating
strategies, with respect to their frequency in the population. Territorial males
(solid line) defend territories to get mates, and Sneaker males (dashed line)
obtain mating opportunities without having territories.

Which one or more of the following conclusions can be drawn from this figure?

(A) The reproductive success of Territorial and Sneaker males can never be the
same in the population

(B) The reproductive success of Sneaker males is influenced by the proportion of
Territorial males in the population

(C) The highest possible reproductive success can be obtained by Sneaker males,
and not Territorial males

(D) Territorial males will always have a higher reproductive success than Sneaker
males

Organizing Institute: IIT Roorkee Page 40 of 45

Q.59 From the table below, choose one or more of the options that match(es) the
evolutionary biologists with the organisms they are well-known to have studied.

Evolutionary biologist Organism

(P) Charles Darwin (i) Mountain gorilla

(Q) Gregor Mendel (ii) Giant tortoise

(R) Dian Fossey (iii) Finches

(S) Frederick Griffith (iv) Pea plant

(v) Streptococcus pneumoniae

(A) P–ii; Q–iv; R–i; S–v

(B) P–ii; Q–iv; R–ii; S–iv

(C) P–iii; Q–iv; R–i; S–v

(D) P–v; Q–i; R–v; S–iii

Organizing Institute: IIT Roorkee Page 41 of 45

Q.60 Consider the following figure of sequence divergence over time. The dashed
and solid lines represent synonymous and non-synonymous substitutions,
respectively.

Which one or more of the following does the figure support?

(A) Adaptive evolution

(B) Molecular clock

(C) Neutral theory of evolution

(D) Positive selection

Organizing Institute: IIT Roorkee Page 42 of 45

Q.61 Modern humans of European descent have a much higher proportion of
Neanderthal DNA than modern humans of African descent. Which one or
more of the following statements is/are consistent with this information?

(A) Following the migration of Neanderthals out of Africa into Europe, modern
humans, who were already present in Europe, bred with them

(B) Following the migration of modern humans out of Africa into Europe,
Neanderthals, who were already present in Europe, bred with them

(C) Modern humans and Neanderthals bred in Africa and then migrated out of
Africa into Europe

(D) Modern humans and Neanderthals did not interbreed

Q.62 A phylogenetic tree representing the evolutionary relationship between various
vertebrates is shown below.

Given this tree topology, which one or more of the following statements is/are
correct?

(A) Crocodiles are more closely related to turtles than they are to dinosaurs

(B) Mammals represent the outgroup with respect to reptiles

(C) Dinosaurs are more closely related to crocodiles than they are to birds

(D) Reptiles are nested within mammals

Organizing Institute: IIT Roorkee Page 43 of 45

Q.63 The population of whirligig beetles in a lake grows or declines exponentially i.e.

𝑁(𝑡) = 𝑁(0)𝑒 𝑟𝑡

where 𝑁(𝑡) is the population size at time 𝑡, 𝑁(0) is the initial population size
and 𝑟 is the per capita rate of population change, occurring only due to birth
and death.

A researcher tracks population sizes for a year and finds the following:

Time interval Number of beetles Number of beetles
at start at end
January – March 1000 150
April – June 150 3013
July – September 3013 100
October – December 100 2009

Assuming that the individual birth rates remain constant throughout the year
and only death rates are affected, which one or more of the following statements
is/are true?

(In your calculations, round off the birth and date rates to two decimal places)

(A) The death rate during April–June is equal to that during October–December

(B) The death rate during July–September is lower than that during January–March

(C) The death rate during July–September is higher than that during January–March

(D) The death rate during April–June is higher than that during October–December

Organizing Institute: IIT Roorkee Page 44 of 45

Q.64 Which one or more of the following conditions is/are necessary for the evolution
of increased nectar production in an insect-pollinated plant via natural selection?

(A) Increased nectar production in individual plants results in greater fruit set and
number of offspring for these individuals

(B) The quantity of nectar produced by flowers varies across individuals in the
population

(C) The quantity of nectar produced by a flower increases when more pollinators
visit that same flower

(D) The quantity of nectar produced is heritable, i.e. passed on from parent to
offspring

Q.65 The following empirical relationship describes how the number of trees 𝑁(𝑡) in
a patch changes over time (𝑡)

𝑁(𝑡) = −2𝑡 2 + 12𝑡 + 24

where 𝑡 = 0 is when the number of trees were first counted.

Given this relationship, the maximum number of trees that occur in the patch is
______

(Round off to the nearest integer)

Organizing Institute: IIT Roorkee Page 45 of 45

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