Previous Year Questions

QUESTION ID:2

During the process of succession in a community, species that are good colonisers are gradually replaced by species that are good competitors. Which one or more of the following statements is/are consistent with this pattern?

QUESTION ID:3

An ornamental shrub species was brought from Japan in the early 1800s to India, where it was planted frequently in gardens and parks. The species persisted for many decades without spreading, and then began to spread invasively fifty years ago. Which one or more of the following processes could have led to it becoming invasive?

QUESTION ID:4

Male voles pair with either a single female (monogamous) or with two females (polygynous) during a given breeding season. The probability of a male being polygynous in a breeding season is 0.2. The reproductive success (number of offspring) of monogamous males is 2, and of polygynous males is 3. A male’s expected reproductive success in a breeding season is ____________________. (Round off to one decimal place)

QUESTION ID:5

Consider a randomly breeding population of squirrels with two morphs – white striped and brown striped. In a population, 16% are white striped individuals, while the rest are all brown striped. The trait for stripes is governed by one gene where the allele for brown stripes is dominant. Assuming Hardy–Weinberg equilibrium, the frequency of the allele for white stripes would be ______. (Round off to two decimal places)

QUESTION ID:6

Observations of algal species showed that their diversity was higher in pools where there were grazing snails compared to pools without snails. Which one of the following statements best explains this result?

QUESTION ID:7

QUESTION ID:8

Given below is a table with ecological observations and processes

Select the option that best matches each ecological observation with its corresponding process.

QUESTION ID:9

An ecologist must determine whether

(i) the means of two independent samples differ, and

(ii) there is an association between two continuous variables

Assuming that all samples are normally distributed, which one of the following options represents the most appropriate statistical tests for (i) and (ii), respectively?

QUESTION ID:10

Males of the swordtail fish Xiphophorus helleri possess long tails, while those of X. maculatus do not. Females of X. helleri prefer males with longer tails. Interestingly, experimental studies show that females of X. maculatus prefer X. maculatus males with attached artificial long tails over those without.If the long-tailed Xiphophorus species evolved from ancestors that lacked a long tail, which one of the following processes best explains the evolution of the observed preference among X. maculatus females?

QUESTION ID:11

Which one of the options given best matches vector to disease?

QUESTION ID:12

Optimal foraging theory predicts whether a foraging animal will be risk-prone, risk-averse or risk-insensitive depending on a utility function that describes the value of each additional food item to the animal. Risk-prone foraging is expected when the utility increases disproportionately with each additional food item encountered. Which one of the graphs shown depicts a scenario where risk-prone foraging would be expected?

QUESTION ID:13

There are two species, X and Y, with abundances 𝑥 and 𝑦, respectively. Species X has growth rate 𝛼, and species Y has growth rate 𝛽. Assume that the sum of the species abundances is constant over time, i.e., 𝑥+𝑦=1. Let 𝑥 and 𝑦 follow the rate equations:

where 𝜑 is the average species fitness.

Which one of the following options correctly represents the expression for 𝜑?

QUESTION ID:14

The graphs shown represent the relationship between population size (𝑁) and population growth rate  . Which one of the following growth curves represents a density-dependent population that experiences a strong Allee effect?

QUESTION ID:15

The abundance (X) of a plant species with respect to the anthropogenic stressor habitat destruction (h) is shown. The solid and the dashed curves represent stable and unstable population equilibrium abundances, respectively

In the absence of any stochasticity, and with increasing values of h, what is the value of h at which a sudden population collapse would occur?

QUESTION ID:16

Consider the graph shown, where S is species richness and A is area. S and A are log-transformed and the slope is not equal to 1.

The relationship between untransformed S and A follows a/an

QUESTION ID:17

The graph shows the rank-abundance relationships for species in three communities, P, Q and R.

Which one of the following statements is true with respect to the evenness of the three communities?

QUESTION ID:18

The graph shows bird species richness in a large contiguous forest patch and a small adjacent forest fragment, before and soon after the large contiguous forest patch was replaced by an oil palm plantation.

Which one of the following options best explains the pattern shown?

QUESTION ID:19

Honey bees are haplodiploid, which means that the relatedness is, on average, expected to be 0.75 between

QUESTION ID:20

Match the mollusc taxa to their respective orders

QUESTION ID:21

A terrestrial species P is found in both India and West Africa and nowhere else, while a marine species Q is found in the Arabian Sea and the Bay of Bengal. The two species have similar generation times. An ecologist builds haplotype networks based on DNA sequences from these species, where each circle represents one haplotype and each dash (−) represents a mutation. Which one of the following inferences is best supported by the haplotype networks shown?

QUESTION ID:22

Grey langurs found in the southern Western Ghats (SWG) and grey langurs in Sri Lanka (SL) look very similar. Nilgiri langurs (found in SWG) and purple faced langurs (found in SL) also look similar. If allopatry played a role in the early diversification of this group (at point x in the tree), which one of the phylogenetic trees is most likely to be correct?

QUESTION ID:23

Two bird species, A and B, are found on a single mountainside. A is a low-elevation species, found between 500 m and 1500 m Above Sea Level (ASL), while B is a high-elevation species, found between 1000 m and 2000 m ASL. At 1250 m ASL, species A and B have very different bill morphologies, but the bill morphology of species A at 500 m is very similar to the bill morphology of species B at 2000 m ASL. Which one or more of the following explain(s) the difference in bill morphology at 1250 m ASL?

QUESTION ID:24

Which one or more of the following is/are greenhouse gas(es)?

QUESTION ID:25

QUESTION ID:26

Female Anopheles mosquitoes bite humans to get blood. Researchers performed an experiment to study whether females use temperature or scent cues, or both, when locating human hosts. They presented female mosquitoes with membranes kept at different temperatures. Some membranes also had human scent applied to them. The response to each treatment was measured as the percentage of females that landed on the membrane (50 females for each treatment). The table shows the treatments and the corresponding responses

Which one or more of the following inferences is/are supported by these results?

QUESTION ID:27

A phylogenetic tree for the evolution of two pigmentation traits in species of fish is shown for clades X, Y and Z. Genes A and/or B, if mutated, can cause dark pigmentation in the body

Which one or more of the following statements is/are correct?

QUESTION ID:28

In conservation biology, which one or more of the following is/are used to calculate the effective population size, Ne ?

QUESTION ID:29

In the foodweb diagrams shown, R represents the primary producer, C1 and C2 represent intermediate consumers, and P represents the top predator. Which one or more of these diagrams show(s) intraguild predation?

QUESTION ID:30

You are a plant ecologist studying a plant in the genus Veronica. You notice that, at open rocky sites, Veronica grows as a creeper spreading low to the ground, whereas in grasslands, the stem stands upright. You collect seeds from multiple populations in each habitat type and grow them under uniform conditions in a greenhouse. You find that all the plants grown in the greenhouse have stems that stand upright. Which one or more of the following explanations best support(s) your observations?

QUESTION ID:31

One hypothesis for why the tropics have far greater species richness than higher latitudes is that the tropics are relatively aseasonal. Low seasonality can encourage high species richness through which one or more of the following mechanisms?

QUESTION ID:32

The figure illustrates the soil zinc tolerance of the grass species Anthoxanthum along a transect from inside a mine to the middle of a pasture outside the mine

Which one or more of the following processes explain(s) the observed pattern of zinc tolerance in this grass species?

QUESTION ID:33

In a forest, there are tigers, hare, and deer. On a given day, the probability of a tiger hunting a hare is 0.35, a deer is 0.25, and either a hare or a deer is 0.55. The probability of a tiger hunting both a hare and a deer on a given day is __________. (Round off to two decimal places).

QUESTION ID:34

Consider a discrete random variable X that takes values from the set S = {0, 1, 2, 3}, being the number of individuals of a species within a habitat. Consider the probability distribution of X with Pr(X = 0) = 0.15, Pr(X = 1) = 0.25 and Pr(X = 3) = 0.5, where Pr denotes probability. The value of Pr(X = 2) is _______. (Round off to two decimal places)

QUESTION ID:35

There are nine species of Impatiens (balsams) found in laterite plateaus of the northern Western Ghats, each with a distinct colour. If a plateau has exactly 6 species, then the number of possible colour combinations in the plateau is __________. (Answer in integer)