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Previous year question hub

Interactions - Evolution - Ecology and Evolution Previous Year Questions

Practice Interactions - Evolution - Ecology and Evolution previous year questions organised from real papers, with year-wise coverage and clear topic navigation.

8Papers
8Years
15Questions
1Topics

Interactions question pattern

Every graph below is calculated only from this selection.

Questions by year

Compare question counts across years.

Difficulty distribution

How the classified questions are distributed by difficulty.

Easy 9 60%
Medium 6 40%

Question type distribution

MCQ, numerical, multiple-select and other formats found in these papers.

MCQ 13 86.7%
Numerical Answer Type (NAT) 1 6.7%
MSQ 1 6.7%

Subject weightage

Top subjects by unique question coverage.

Ecology and Evolution
15 Qs

Most asked topics

Top topics across the included previous year papers.

Evolution
15 Qs

Subtopic coverage

Top subtopics inside this exact selection.

Interactions
15 Qs

Paper coverage

Question coverage for the most populated papers. Every active PYP paper remains listed below.

Ecology and Evolution (EY) 2026
2 Qs
Ecology and Evolution (EY) 2025
3 Qs
Ecology and Evolution (EY) 2024
1 Qs
Ecology and Evolution (EY) 2022
3 Qs
Ecology and Evolution (EY) 2020
1 Qs
Ecology and Evolution (EY) 2019
1 Qs
Ecology and Evolution (EY) 2018
2 Qs
Ecology and Evolution (EY) 2016
2 Qs

Included previous year papers

Newest papers appear first. Search these papers or sort by year and name.

Paper nameYearPDFAttempt
Ecology and Evolution (EY) 20262026
2 questions in this view
2026
Ecology and Evolution (EY) 20252025
3 questions in this view
2025
Ecology and Evolution (EY) 20242024
1 questions in this view
2024
Ecology and Evolution (EY) 20222022
3 questions in this view
2022
Ecology and Evolution (EY) 20202020
1 questions in this view
2020
Ecology and Evolution (EY) 20192019
1 questions in this view
2019
Ecology and Evolution (EY) 20182018
2 questions in this view
2018
Ecology and Evolution (EY) 20162016
2 questions in this view
2016

All Interactions previous year questions

Practice every matching question in batches of 20, with every available option.

1
2018 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2018

Which of the following is an example of complete intrinsic post-zygotic reproductive isolation between two species P and Q?

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2
2018 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2018

An altruist provides help worth 10 units of fitness to a recipient, at a personal cost of 1 unit of fitness. As per kin-selection theory, the minimum value of genetic relatedness between the actors and the recipients that is necessary to maintain altruism in the population is ____ (answer up to 1 decimal place).

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3
2019 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2019

Under which of the following conditions is rapid pollen tubes growth most likely to evolve?

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4
2020 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2020
In plants with bisexual flowers (hermaphrodites), mate-choice by females is expected to be important under which of the following cases?
i) Seed set is pollen-limited rather than resource-limited.
ii) Obligate self-pollination is present.
iii) Seed set is resource-limited rather than pollen-limited.
iv) Obligate cross-pollination is present.
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5
2024 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2024

Which one of the following is a result of antagonistic coevolution?

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6
2025 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2025

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?

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7
2025 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2025

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?

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8
2025 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2025

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?

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9
2016 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2016
According to Hamilton’s Rule, an altruistic act will spread in a population due to kin selection, when B/C > 1/r, where B is the benefit to the recipient, C is the cost to the actor and r is the genetic relatedness of the recipient to the actor. Given this relationship, a human may forego producing one of her own offspring to help her full sibling raise offspring, only if it results in at least ______ or more extra offspring produced by her sibling.
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10
2016 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2016
Which of the following is NOT an example of an evolutionary arms race?
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11
2022 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2022
Which one of the following organisms is a cytoplasmically inherited symbiotic bacterium that can cause extreme female-biased sex ratios in many insects?
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12
2022 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2022
Certain plants and animals rely on toxins such as cardiac glycosides for self-defense. Digitoxin and bufalin, structurally similar toxins produced by foxglove plants and bufonid toads, respectively, are one such example. Which one of the following statements about these toxins is correct?
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13
2022 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2022
Which one or more of the following options represent(s) an evolutionary arms race?
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14
2026 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2026
Which one of the following concepts describes a co-evolutionary arms race between a pathogen and its host?
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15
2026 · Ecology and Evolution · Evolution · Interactions
Ecology and Evolution (EY) 2026
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 ______.
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