Previous Year Questions

QUESTION ID:2

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?

QUESTION ID:3

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?

QUESTION ID:4

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

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

QUESTION ID:5

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?

QUESTION ID:6

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. 

QUESTION ID:7

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? 

QUESTION ID:8

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

QUESTION ID:9

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

QUESTION ID:10

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.)

QUESTION ID:11

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?

QUESTION ID:12

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

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. 

QUESTION ID:13

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?

QUESTION ID:14

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?

QUESTION ID:15

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?

QUESTION ID:16

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

QUESTION ID:17

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? 

QUESTION ID:18

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

QUESTION ID:19

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? 

QUESTION ID:20

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.

QUESTION ID:21

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?

QUESTION ID:22

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?

QUESTION ID:23

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?

QUESTION ID:24

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: 

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)

QUESTION ID:25

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?

QUESTION ID:26

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)