Previous Year Questions

QUESTION ID:2

A black square PQRS has been cut into two parts. One part of it is shown in Panel I. Which one of the shapes in Panel II is the other part?

QUESTION ID:3

A day can only be cloudy or sunny. The probability of a day being cloudy is 0.5, independent of the condition on other days. What is the probability that in any given four days, there will be three cloudy days and one sunny day? 

QUESTION ID:4

The values of Stock A and Stock B on a particular day are Rs. 50 and Rs. 80, respectively. An investor invests Rs. 100 in Stock A and Rs. 80 in Stock B. He sells all the stocks the next day when the value of Stock A is Rs. 55 and Stock B is Rs. 70. The profit made by the investor is Rs. ________

QUESTION ID:5

‘When it is raining, peacocks dance.’

Based only on this sentence, which one of the following options is necessarily true? 

QUESTION ID:6

Water : P :: Food : Q

Choose the P and Q combination from the options below to form a meaningful analogy. 

QUESTION ID:7

Two tiles are missing in Panel I. Which one of the options in Panel II is the appropriate choice for the missing tiles?

QUESTION ID:8

Figures (i) and (ii) represent intercity highway systems. The black dots represent cities and the line segments between them represent intercity highways. A salesperson needs to make a trip. She needs to start from a city, visit each of the remaining cities exactly once, and finally return to the same city from which she started.

Which one of the following options is then true?

QUESTION ID:9

The figure in Panel I below is a grid of cells with four rows and four columns. The numbers on the top and on the left represent the number of cells that are to be shaded in that column and row, respectively. Which one of the options shown in Panel II below represents the grid shaded correctly?

QUESTION ID:10

An unbiased six-faced dice whose faces are marked with numbers 1, 2, 3, 4, 5, and 6 is rolled twice in succession and the number on the top face is recorded each time. The probability that the sum of the two recorded numbers is a prime number is ________

QUESTION ID:11

Two sister species, A and B, are distributed along a continuous elevational gradient in the Himalayas. Species A is distributed from the foothills to 1800 metres above sea level and species B is distributed from 1800 to 3500 metres above sea level. Which one of the following modes of speciation best explains their distribution? 

QUESTION ID:12

Which one of the following is an invasive plant species in India? 

QUESTION ID:13

Phytoecdysone is a defensive secondary chemical that __________. 

QUESTION ID:14

The physiologist Ivan Pavlov conducted an experiment on dogs, in which a bell was sounded every time food was provided. In this experiment, dogs eventually showed the salivary reflex (a response to food) when the bell was sounded, even if food was not provided. This is an example of ________. 

QUESTION ID:15

Ecologists have studied the distributions of birds on archipelagos. Some studies found an interesting ‘checkerboard’ pattern within island groups. Sister species were never present on the same island, even when the islands were very close to each other. Which one of the following processes best explains this checkerboard pattern? 

QUESTION ID:16

Which one of the following phylogenetic trees illustrates the relationship between Archaea, Bacteria and Eukarya?

QUESTION ID:17

The Biological Species Concept was proposed by _________. 

QUESTION ID:18

In a diploid population of N individuals, the probability of fixation of a new neutral mutation (assuming no other mutation occurs) is _________. 

QUESTION ID:19

Species that co-occur in space and time tend to be similar to each other in traits such as tolerance to heat or to drought. This is most likely because of _________. 

QUESTION ID:20

Which one of the following statements is true for most ants and bees? 

QUESTION ID:21

Which one of the following concepts describes a co-evolutionary arms race between a pathogen and its host? 

QUESTION ID:22

A flask containing nutrient-rich media is seeded with 100 isogenic bacteria. Assuming that no bacteria die in the flask, after approximately how many generations will the population reach a size of 105 ? 

QUESTION ID:23

The field of allometry assesses how species traits scale with each other. Given the relationship between metabolic rate and body mass, which one of the following statements is true? 

QUESTION ID:24

According to life history theory, when parents can only provide limited nutrients and care to their offspring, the number and size of the offspring are expected to be ___________. 

QUESTION ID:25

Which one of the following elements cycles the LEAST (mass per year) through the atmosphere? 

QUESTION ID:26

The colour and markings of the eggs of the common cuckoo (Cuculus canorus) are similar to those of the eggs of the great reed warbler (Acrocephalus arundinaceus). Which one or more of the following options explain(s) this similarity? 

QUESTION ID:27

Which one or more of the following is/are NOT essential for evolution by natural selection to take place in a population? 

QUESTION ID:28

In a null hypothesis significance test, the significance level α was set to 0.01. For which one or more of the following p values would the null hypothesis be rejected? 

QUESTION ID:29

Which one or more of the following benefits can explain the evolution of dispersal of animals from their natal area?

QUESTION ID:30

Which one or more of the following is/are signalling mechanism(s) that birds are known to use to beg their parent for food? 

QUESTION ID:31

Which one or more of the following diseases is/are zoonotic? 

QUESTION ID:32

Which one or more of the following phenomena make(s) small populations vulnerable to extinction? 

QUESTION ID:33

In a population of birds, the proportion of blue individuals is 0.4 and the proportion of males is 0.3. Assuming that colour and sex are independent of each other, the probability that a randomly sampled individual from this population is a blue male is ______ (Round off to two decimal places)

QUESTION ID:34

Assume that the human haploid genome is 3 × 10⁹ base pairs long. The mutation rate, when DNA is copied, is 5 × 10⁻¹¹ per base pair per replication. Based on these numbers, the expected number of mutations that take place per replication of the human haploid genome is _______ (Round off to two decimal places) 

QUESTION ID:35

The coefficient of relatedness r is the probability that a gene in one individual is identical by descent with a gene in another individual. In a large, diploid, sexually reproducing population with outbreeding, the value of r for two offspring with the same mother but different fathers is __________ (Round off to two decimal places)

QUESTION ID:36

Living in groups confers benefits but also imposes costs. The figure below depicts how per capita benefits (solid line) and costs (dashed line), both measured in the same units, vary as a function of group size. Given these patterns in benefits and costs, which one of the group sizes P, Q, R, S best represents the optimal group size?

QUESTION ID:37

The table below provides the abundances of species 1 to 10 for communities P, Q, and R, with a total of 100 individuals in each community. The Simpson’s diversity index D for each of these communities can be calculated using the formula: D = 1 − Σ_𝑖 𝑝_𝑖 ² , where 𝑝𝑖 is the proportion of individuals in the community that belong to the i ^th species. 

Which one of the following statements is true about the comparison of Simpson’s index between these communities? 

QUESTION ID:38

Many species of reef fish change sex once during the course of their lives. In these fish, big body size increases competitive ability. When high male-male competition results in high variance in fitness among males, which one of the following scenarios is most likely?  

QUESTION ID:39

When comparing life-history traits across animal species, which one of the following relationships is LEAST expected under r- and K-selection theory? 

QUESTION ID:40

Two isolated populations M and N have population sizes of 100 and 1000 individuals, respectively. The starting allele frequencies p and q are 0.5 in both populations. Assuming no selection, which one of the following is expected after 100 generations? 

QUESTION ID:41

Two bacterial variants are growing together in the same flask. At any relative frequency of the two variants, the population growth rate of the rarer variant is higher. The above is an example of ________. 

QUESTION ID:42

The graph below shows a plot of annual rainfall on the X axis and number of plant species on the Y axis. Based on the pattern in the graph, which one of the following statistical methods would be most appropriate to model the relationship between annual rainfall and the number of plant species?

QUESTION ID:43

The phylogeny of six species of birds is illustrated below, where the horizontal branch lengths correspond to genetic distance. These six species are distributed in three islands X, Y, and Z. Island X harbours species 1, 4, 6; Island Y harbours species 1, 2, 4; and Island Z harbours species 3, 4, 5. Which one of the following is true about the phylogenetic diversity of these islands?

QUESTION ID:44

Terrestrial biomes such as tundra, taiga, temperate forests, and tropical forests are distributed in different parts of the world. Which one of the following options best represents the environmental factors that determine the distribution of these biomes? 

QUESTION ID:45

In a population, the frequency of an allele changes with time as given in the table:

Which one of the following describes how allele frequency changes with year? 

QUESTION ID:46

Despite their striking morphological similarity to each other, Old World and New World vultures are not phylogenetically related. Old World vultures are most closely related to eagles, while New World vultures are most closely related to storks. The morphological similarity between Old World and New World vultures is an example of ____________. 

QUESTION ID:47

The distributions of beak size in a bird population at two different times are shown below. In going from time t = 0 to t = t1, the variance of the distribution in beak size in the population has _________.

QUESTION ID:48

Percent sequence divergences between two sister species were calculated for an exon (E), intron (I), and the flanking neutral (N) region of a gene under purifying selection. Which one of the following options best describes the expected divergence in E, I, and N between the sister species? 

QUESTION ID:49

Islands typically have higher species extinction rates and are more isolated than the mainland. In the figures below (P, Q, R, S), the solid line denotes the relationship between species richness and increasing area within a mainland; the dashed line denotes the relationship between species richness and islands of different sizes.

Which one of the figures above represents the most likely relationships? 

QUESTION ID:50

A bacterium can be approximated as a cylinder with a hemisphere at each end, as shown in the figure. The cylinder has a height of 1 µm and diameter of 1 µm. Assuming that the density of the bacterium is equal to that of water, what is the approximate mass of this bacterium?

Given: density of water = 10³ kg/m³ ; 1 µm = 10^-6 m

Volume of a cylinder = 𝜋𝑟²ℎ, where r is the radius and h is the height of the cylinder

Volume of a sphere = 4/3 𝜋𝑟³ , where r is the radius of the sphere

QUESTION ID:51

Students M and N sampled body lengths of two populations of a fish species using the same study design. A summary of their data (mean ± standard error) is shown below.

Given that the data are normally distributed, when comparing the means of the populations using a t-test, which student will find a lower p-value? 

QUESTION ID:52

Forest patches are embedded within a landscape dominated by crop fields. The crop fields around fragmented forest patches are thought to affect the abundance of different butterfly species to different extents. The graph below shows the pattern of butterfly abundance (means, and error bars representing 95% confidence intervals) of three species, M, N, and O between the forest patches and the crop fields.

Which one of the following options best describes the impact of fragmentation on the three different butterfly species? 

QUESTION ID:53

Many species in mountain ranges are shifting their ranges to higher, cooler elevations in response to warming temperatures because of climate change. The graph below shows how the midpoint of elevational range in the year 2025 is related to the midpoint of the elevational range in the year 2000 for species in temperate (open circle) and tropical (solid circle) mountain ranges. Each point represents a species, and the dashed line is the 1:1 or the identity line (with intercept = 0 and slope = 1).

Which one of the following statements is consistent with the above graph?

QUESTION ID:54

Two species of butterflies are equally toxic to their main potential predator. Their morphological similarity helps to reduce predation rates on both species. This phenomenon is known as _________. 

QUESTION ID:55

The phylogeny below shows the relationship between six species based on whole genome data. The sequence of a part of a particular gene from each species is provided at the tips of the tree. Based on the principle of parsimony, which one of the following is the expected sequence for the ancestor X?

QUESTION ID:56

Consider a predator encountering two prey types P₁ and P₂. Assume the energy value of P₁ is greater than that of P₂. Assume also that the search time to find each prey type is inversely proportional to its abundance in the habitat. The prey-choice model in optimal foraging theory evaluates whether the predator should specialise on P₁ or generalise to feed on both P₁ and P₂. This model predicts specialising on P₁ when: 

where 𝐸₁ is the energy value of P₁; ℎ₁ is handling time for P₁; 𝐸₂ is the energy value of P₂; ℎ₂ is handling time for P₂; 𝑆₁ is the search time for P₁. According to the condition given above, which one or more of the following options does the decision to specialise on P₁ depend on? 

QUESTION ID:57

In some insect species, males are much larger than females. Which one or more of the following evolutionary hypotheses can explain such male-biased size dimorphism? 

QUESTION ID:58

A researcher is interested in understanding whether multi-species sociality (in which species form cohesive groups with other species) plays a role in helping species cope with habitat disturbance. She estimates the survival rates of social species and solitary species in undisturbed and disturbed habitats, and these are plotted in the graph below. Circles represent mean survival rates and error bars represent 95% confidence intervals.

Based on the means and confidence intervals presented in the graph (α = 0.05), which one or more of the following can be reasonably concluded? 

QUESTION ID:59

A research group studied the timing of Arctic ground squirrel emergence from hibernation. They collected data over a 25-year period and found that female and male ground squirrels differed in how variable their emergence times were. Across years, no matter what the above-ground temperatures were, male ground squirrels emerged in the same week in April. Females usually emerged during the same week as the males if it coincided with snowmelt; but in colder years, they re-entered hibernation and emerged later after snowmelt. Which one or more of the following statements is/are possible proximate cause(s) for this phenological pattern? 

QUESTION ID:60

A native species of butterfly at one site in North America used to feed on plant species P. In the 1960s, an exotic plant species Q was introduced at this site. The butterfly switched to feeding on Q, so much so that it was no longer found feeding on P. When the plant species Q was removed from the site in the 1990s, the butterfly species went locally extinct. Later, a population of the same butterfly species from elsewhere, that still fed on plant P, came and occupied the same site. Which one or more of the processes listed below has/have occurred here? 

QUESTION ID:61

Species 1 and 2 belong to the same genus and co-occur at the same site. Which one or more of the following strategies would facilitate their coexistence at the site?

QUESTION ID:62

A researcher carried out an experiment to study how daylength and temperature influence diapause in a moth species. He placed larvae in one of four treatment conditions for 2 weeks, with 30 larvae in each condition. The treatments involved two temperatures (18 °C or 27 °C) and two lighting conditions (12h:12h Light:Dark (LD) or complete darkness (DD)). At the end of the experiment, he counted the number of larvae that had entered diapause and those that had not. The data are shown below.

Which one or more of the following conclusions can he reasonably make from these findings?

QUESTION ID:63

Population growth of a species can be modelled as

where 𝑁(𝑡) is the population size at time 𝑡; 𝑟 is the growth rate; and 𝐾 is the carrying capacity of the environment.

For is maximized at 𝑁 = _____ (Answer in integer)

QUESTION ID:64

The genome of a diploid species has 10 genes. In a population of this species, if each gene has two unique alleles, then the number of possible unique genotypes in this population is ______ (Answer in integer)

QUESTION ID:65

Bob is studying the effect of coral and sponge species on reef ecosystems using experiments in artificial square tanks. In each tank, he places 3 species of corals and 2 species of sponges. If there are 6 species of corals and 5 species of sponges to choose from, the minimum number of tanks required to test all combinations of 3 coral and 2 sponge species is _______ (Answer in integer)