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Evolution — Free MYP4 Biology Practice Questions
1QuestionVariation within PopulationsConcept Practice
2 marks~3 minCriterion A
Five dogs were observed for the following traits: ear shape (pointed or floppy), coat colour (black, brown, white, or spotted), and body mass.
Body mass (kg): Dog A: 15 | Dog B: 22 | Dog C: 18 | Dog D: 31 | Dog E: 26
Body mass (kg): Dog A: 15 | Dog B: 22 | Dog C: 18 | Dog D: 31 | Dog E: 26
a
Identify one trait from the data that shows continuous variation and one trait that shows discontinuous variation. [1]
b
Explain why each identified trait belongs to its variation type, using specific values or categories from the data. [1]
Solutions
2QuestionMechanism of Natural SelectionConcept Practice
2 marks~3 minCriterion A
A population of beetles lives on a tree trunk. The beetles show variation in body colour: light brown, dark brown, and speckled. A bird preys on the beetles by sight.
a
Identify one way in which variation in beetle colour arises within the population. [1]
b
Using the terms selection pressure, differential survival, and adaptation, explain how the beetle population may change over successive generations. [1]
Solutions
3QuestionSelection Pressures in EcosystemsConcept Practice
2 marks~3 minCriterion A
The diagram shows a rocky shore ecosystem containing limpets, barnacles, crabs, and an oystercatcher — a bird that prises limpets from rocks and consumes them.
a
Identify the selection pressure acting on the limpet population in this ecosystem. [1]
b
Explain how this selection pressure could lead to a change in the limpet population over successive generations. [1]
Solutions
4QuestionDifferential Reproduction and FitnessConcept Practice
2 marks~3 minCriterion D
In a hospital ward, a patient with a bacterial infection is prescribed a ten-day course of antibiotics. After five days, the patient feels better and stops taking the medication. Some bacteria with a resistance mutation have survived.
a
Explain how differential reproduction will change the bacterial population in this patient after treatment stops. [1]
b
Identify one ethical issue that arises for the wider community if many patients behave in this way. [1]
Solutions
5QuestionBehavioral AdaptationsConcept Practice
2 marks~3 minCriterion C
The graph shows the change in migration timing for a bird species from 1960 to 2020. The y-axis represents the number of days earlier that migration occurs relative to 1960, and the x-axis represents the year. Describe the trend shown in the graph.
Solutions
6QuestionStructural Adaptations in OrganismsConcept Practice
2 marks~3 minCriterion A
The diagram below shows a cactus plant growing in a desert environment.
Explain how the spines of a cactus function as a structural adaptation that enhances survival in a desert environment. [2]
Explain how the spines of a cactus function as a structural adaptation that enhances survival in a desert environment. [2]
Solutions
7QuestionBehavioral AdaptationsConcept Practice
2 marks~3 minCriterion D
Many sea turtle hatchlings instinctively move towards light after hatching, which would naturally lead them to the ocean by following the moon's reflection on the water. However, artificial lights near nesting beaches now cause disorientation.
Outline ONE specific environmental impact of this disorientation, and briefly explain why the turtles' natural behavior is no longer effective.
Outline ONE specific environmental impact of this disorientation, and briefly explain why the turtles' natural behavior is no longer effective.
Solutions
8QuestionBiogeography and Species DistributionConcept Practice
2 marks~3 minCriterion A
Marsupials — mammals that raise young in a pouch — are found today on several continents, but one continent hosts by far the greatest diversity and concentration of marsupial species.
a
Identify the continent with the highest concentration of marsupials today. [1]
b
Using the theory of continental drift, explain one reason why marsupials are so highly concentrated on this continent. [1]
Solutions
9QuestionFossil Record and Evolutionary HistoryConcept Practice
2 marks~3 minCriterion D
The fossil record is incomplete: most organisms decompose before fossilisation can occur, and preservation strongly favours hard structures such as bones, shells, and teeth. As a result, soft-bodied organisms and transitional forms are rarely preserved, leaving gaps in evolutionary lineages.
a
Identify one specific reason why the fossil record is biased towards certain types of organisms. [1]
b
Explain how gaps in the fossil record could be misrepresented to undermine public confidence in evolutionary theory. [1]
Solutions
10QuestionDevelopment of the Theory of Evolution by Natural SelectionAssessment Practice
4 marks~6 minCriterion A
The diagram below shows two populations of the same beetle species: one living on light-coloured bark, the other on dark-coloured bark. Birds are the primary predators of these beetles. Both populations contain individuals with light and dark body colouration. This variation in colouration is heritable.
a
Identify which beetle colouration is more likely to survive in each environment and explain how camouflage provides this survival advantage. [2]
b
Discuss how the long-term outcome in each beetle population aligns with Darwin's theory of natural selection, referring to variation, selective pressure, and inheritance. [2]
Solutions
11QuestionVoyage of the HMS Beagle and ObservationsAssessment Practice
2 marks~3 minCriterion B
During his voyage on the HMS Beagle, Darwin observed finch species across the Galápagos Islands. The table below summarises his findings.
| Species | Beak shape | Primary food source |
|---|---|---|
| Ground Finch | blunt | seeds |
| Tree Finch | pointed | insects |
| Cactus Finch | curved | cactus nectar |
| Warbler Finch | thin | small insects |
| Woodpecker Finch | strong | larvae under bark |
a
Identify the pattern linking beak shape to food source in the data above. [1]
b
A new finch species is discovered on an island where the only food source is large, hard-shelled nuts. Deduce the most likely beak shape for this species, justifying your answer using evidence from the data. [1]
Solutions
12QuestionDevelopment of the Theory of Evolution by Natural SelectionAssessment Practice
8 marks~12 minCriterion D
A large urban hospital has used broad-spectrum antibiotics as a first-line treatment for bacterial infections for 20 years. Over this period, the proportion of infections caused by methicillin-resistant Staphylococcus aureus (MRSA) has risen from 2% to 35%. Scientists model this change as an example of natural selection acting on a bacterial population.
a
Explain how overuse of antibiotics has driven the increase in MRSA infections, using the theory of natural selection. [2]
b
Explain how the rise in MRSA infections could affect both patient mortality rates and hospital healthcare costs. [2]
c
Antibiotic residues from hospitals and farms enter soil and waterways. Evaluate the long-term consequences of this environmental antibiotic exposure for the evolution of bacterial populations in natural ecosystems. [4]
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Solutions
13QuestionDevelopment of the Theory of Evolution by Natural SelectionAssessment Practice
6 marks~9 minCriterion D
A conservation team proposes deploying a CRISPR-based gene drive to eliminate invasive rats from a remote island to protect native bird species. A gene drive is a genetic modification that spreads rapidly through a population, potentially causing local or global extinction of the target species. Rats reached the island via human shipping routes and have no natural predators there.
a
Explain how natural selection would act on the rat population in the absence of a gene drive. [2]
b
Discuss the ethical implications of humans deliberately using technology to drive a species to extinction. [2]
c
Analyse the ecological risks if the gene drive spreads beyond the target island to mainland rat populations. [2]
Solutions
14QuestionDevelopment of the Theory of Evolution by Natural SelectionAssessment Practice
5 marks~8 minCriterion C
Three fossil species document the fin-to-limb transition:
Eusthenopteron (fish): short humerus, radius, and ulna; fin rays extending from the bones.
Tiktaalik (transitional): longer humerus, radius, and ulna; shorter fin rays retained; wrist-like joint; robust ribs.
Acanthostega (early amphibian): distinct humerus, radius, ulna, and digits; no fin rays.
Eusthenopteron (fish): short humerus, radius, and ulna; fin rays extending from the bones.
Tiktaalik (transitional): longer humerus, radius, and ulna; shorter fin rays retained; wrist-like joint; robust ribs.
Acanthostega (early amphibian): distinct humerus, radius, ulna, and digits; no fin rays.
a
Identify one fish-like feature and one tetrapod-like feature present in Tiktaalik. [2]
b
Explain how the skeletal differences between Eusthenopteron and Acanthostega provide evidence for gradual evolutionary change. [2]
c
Evaluate the claim that "limbs evolved from fins suddenly, without intermediate forms." [1]
Solutions
15QuestionVoyage of the HMS Beagle and ObservationsAssessment Practice
3 marks~5 minCriterion C
During the HMS Beagle voyage (1831–1836), Charles Darwin visited the Galápagos Islands, where he collected finch specimens from several islands. He later noted that finches on islands with hard, tough seeds tended to have thick, crushing beaks, while finches on islands where insects were the primary food source tended to have slender, pointed beaks.
a
State what is meant by natural selection. [1]
b
Explain how the difference in finch beak shapes across the Galápagos Islands is an example of adaptation. [1]
c
Analyse how Darwin's finch observations from geographically isolated islands provided stronger evidence for natural selection than observations from a single island would have done. [1]
Solutions
16QuestionVariation within PopulationsAssessment Practice
6 marks~9 minCriterion A
During a severe drought on Daphne Major island, food became scarce and only large, hard seeds remained available. Beak depth measurements were recorded for a population of medium ground finches (Geospiza fortis) before and after the drought:
| Year | 1976 (before drought) | 1978 (after drought) |
|---|---|---|
| Mean beak depth (mm) | 9.2 | 10.1 |
| Range of beak depth (mm) | 7.0–11.5 | 8.5–11.5 |
| Sample size | 100 | 80 |
a
Describe the change in mean beak depth and the change in range of beak depths between 1976 and 1978. [2]
b
Analyse the data to identify which type of natural selection — directional, stabilising, or disruptive — is most likely occurring. [2]
c
Evaluate what would happen to the genetic variation for beak depth in this population if drought conditions persisted for several more generations. [2]
Solutions
17QuestionSurvival of the FittestAssessment Practice
2 marks~3 minCriterion D
In a hospital ward, doctors observe that a bacterial infection is no longer responding to a commonly prescribed antibiotic. Epidemiologists link this to widespread incomplete antibiotic courses in the local community over several years.
Explain how the concept of survival of the fittest accounts for the development of antibiotic resistance in this bacterial population. [1]
Identify one ethical issue arising from this situation and explain its implications for public health. [1]
Explain how the concept of survival of the fittest accounts for the development of antibiotic resistance in this bacterial population. [1]
Identify one ethical issue arising from this situation and explain its implications for public health. [1]
Solutions
18QuestionProcess of Natural Selection (Variation, Overproduction, Competition, Survival of the Fittest, Reproduction, Change Over Time)Assessment Practice
6 marks~9 minCriterion C
Farmers routinely administer antibiotics to healthy livestock at doses too low to treat infection — a practice linked to the global rise of antibiotic-resistant bacteria. Scientists warn that without intervention, resistant infections could cause more deaths annually than cancer by 2050.
a
Define subtherapeutic antibiotic use and explain how it acts as a selective pressure on bacterial populations. [2]
b
Using the steps of natural selection — overproduction, variation, survival of the fittest, and reproduction — explain how a resistant bacterial strain comes to dominate a livestock population over time. [2]
c
Evaluate the societal and environmental consequences of this practice, discussing the limitations of current regulatory approaches and the ethical trade-offs involved. [2]
Solutions
19QuestionMechanism of Natural SelectionAssessment Practice
4 marks~6 minCriterion A
The graph below shows the percentage of dark-coloured peppered moths (Biston betularia) in a polluted industrial forest and a clean rural forest over 50 years. In the polluted forest, the percentage of dark-coloured moths rose from approximately 10% to over 95%.
a
Describe the trend shown for the polluted forest. [1]
b
Identify the selective pressure acting on moth colour in the polluted forest and explain how it produced differential survival between light- and dark-coloured moths. [2]
c
Analyse how differential survival led to the change in allele frequency observed in the graph. [1]
Solutions
20QuestionDifferential Reproduction and FitnessAssessment Practice
7 marks~11 minCriterion B
A population of mice lives in a forest with dark soil. Fur colour is controlled by a single gene: allele (dark fur) is dominant over allele (light fur). Over 10 years, the habitat gradually transitions to grassland with light-coloured soil. Allele frequencies recorded across three generations are shown below.
| Generation | 1 | 2 | 3 |
|---|---|---|---|
| allele frequency | 0.90 | 0.75 | 0.55 |
a
Describe the trend in the frequency of the allele across the three generations. [2]
b
Deduce the approximate frequency of the allele in generation 4, justifying your reasoning with reference to the data. [2]
c
Explain how differential reproduction and fitness account for the observed change in allele frequency as the habitat shifts from forest to grassland. [3]
Solutions
21QuestionRole of Environmental Factors in SelectionAssessment Practice
6 marks~9 minCriterion C
A conservation organisation is evaluating two strategies to help a threatened coral species survive warmer ocean temperatures caused by climate change.
Approach 1 — Selective breeding: Corals with naturally higher heat tolerance are bred together across several generations to increase the prevalence of heat-tolerant traits.
Approach 2 — CRISPR gene editing: A heat-tolerance gene from a different coral species is inserted into the threatened species' genome, producing genetically modified corals for potential release into the wild.
Approach 1 — Selective breeding: Corals with naturally higher heat tolerance are bred together across several generations to increase the prevalence of heat-tolerant traits.
Approach 2 — CRISPR gene editing: A heat-tolerance gene from a different coral species is inserted into the threatened species' genome, producing genetically modified corals for potential release into the wild.
a
Explain how natural selection acts on a coral population as ocean temperatures rise. Your answer must use the terms variation, selection pressure, and allele frequency. [2]
b
Analyse how introducing selectively bred corals versus genetically modified corals would each affect the genetic diversity of the wild coral population. [2]
c
Evaluate whether the conservation benefits of using CRISPR to permanently modify a wild coral species justify the ecological risks and ethical concerns about interfering with natural evolutionary processes. [2]
Solutions
22QuestionBehavioral AdaptationsAssessment Practice
5 marks~8 minCriterion A
Figure 1 shows a peacock performing a courtship display: fanned tail feathers bearing iridescent eyespots, an upright posture, and an inflated vocal sac. Figure 2 shows a peahen's sensory anatomy, highlighting large laterally positioned eyes and auditory organs.
a
Using Figures 1 and 2, explain how specific features of the peacock's display are detected by the peahen's sensory receptors to produce a species-specific recognition signal. [3]
b
Explain how this behavioural adaptation reduces the likelihood of hybrid offspring being produced. [2]
Solutions
23QuestionAdaptation to Changing EnvironmentsAssessment Practice
6 marks~9 minCriterion D
The Tasmanian devil (Sarcophilus harrisii) population has declined severely due to Devil Facial Tumour Disease (DFTD), a contagious cancer that spreads more effectively through genetically uniform populations. Conservation biologists propose a genetic rescue: translocating individuals from a genetically diverse captive population into Tasmania to increase allelic diversity, particularly in immune-related genes, and improve disease resistance. The plan carries potential societal and environmental risks alongside its benefits.
a
Explain the biological basis for why low genetic diversity makes the Tasmanian devil population more susceptible to DFTD. [2]
b
Explain one societal impact and one environmental risk associated with the proposed genetic rescue plan. [2]
c
Evaluate whether the long-term benefits of this genetic rescue plan outweigh its risks, considering the limitations of the approach. [2]
Solutions
24QuestionAdaptation to Changing EnvironmentsAssessment Practice
2 marks~3 minCriterion A
Polar bears (Ursus maritimus) survive in Arctic environments where air temperatures regularly fall below −30 °C and sea ice provides the primary hunting ground.
a
Explain how the blubber layer helps a polar bear survive in its cold Arctic environment. [1]
b
A polar bear's large paws and its thick fur both contribute to survival on sea ice. Explain how each structure serves a different function, and suggest which adaptation is more critical for a bear actively hunting on ice. Justify your answer. [1]
Solutions
25QuestionBehavioral AdaptationsAssessment Practice
4 marks~6 minCriterion B
Pill bugs (woodlice) are small crustaceans that prefer dark and moist environments. An experiment was conducted to investigate their preference for different light intensities.
a
The diagram shows a simple Y-maze. Initially, 20 pill bugs are placed at the start. After 10 minutes, all pill bugs are found in the dark arm of the Y-maze. Explain why this happens.
b
A modified experiment uses a chamber divided into five sections connected in a line. Each section is lit with a different light intensity: 0 lux, 25 lux, 50 lux, 75 lux, and 100 lux. 20 pill bugs are placed in the 50 lux section. After 10 minutes, the number of pill bugs in each section is recorded. The results are as follows:
Light Intensity (lux): 0 25 50 75 100
Number of Pill Bugs: 11 6 2 1 0
Describe the pattern shown in the data.
Light Intensity (lux): 0 25 50 75 100
Number of Pill Bugs: 11 6 2 1 0
Describe the pattern shown in the data.
c
Predict what would happen to the distribution of pill bugs if the light gradient were reversed (i.e., 100 lux on the left, decreasing to 0 lux on the right). Justify your prediction based on the observed pattern of phototaxis.
Solutions
26QuestionAdaptation to Changing EnvironmentsAssessment Practice
3 marks~5 minCriterion C
The diagram shows a cross-section of a camel's nasal cavity. Scroll-like structures called turbinates line the nasal passage; arrows indicate airflow direction during both inhalation and exhalation.
a
Explain how the turbinates reduce respiratory water loss in camels during both inhalation and exhalation. [2]
b
A researcher proposes that a camel's kidneys contribute more to overall water conservation than its nasal turbinates. Evaluate this claim by identifying one structural feature of camel kidneys and explaining how it compares in effectiveness to the turbinate mechanism. [1]
Solutions
27QuestionBiogeography and Species DistributionAssessment Practice
8 marks~12 minCriterion D
The Wallace Line runs through a deep-water channel separating Bali and Lombok in Indonesia. Even when sea levels dropped 120 m during the last ice age, land bridges formed west of the line but the deep channel remained unbridged.
Native family counts per island:
Bali (west): Mammals 35 · Birds 120 · Reptiles 60
Lombok (east): Mammals 15 · Birds 110 · Reptiles 55
Native family counts per island:
Bali (west): Mammals 35 · Birds 120 · Reptiles 60
Lombok (east): Mammals 15 · Birds 110 · Reptiles 55
a
Identify the pattern in species distribution shown by the data above. [2]
b
A fossil marsupial is discovered on one of the islands. Deduce which side of the Wallace Line it most likely came from, using the ice-age sea-level data to support your reasoning. [3]
c
Justify why marsupials are found on one side of the Wallace Line and not the other, by analysing the roles of plate tectonic history and the deep-water channel as a dispersal barrier. [3]
Solutions
28QuestionFossil Record and Evolutionary HistoryAssessment Practice
6 marks~9 minCriterion B
Three transitional fossils document the fish-to-tetrapod transition:
Fossil A — Tiktaalik (~375 Ma): possesses wrist bones and neck vertebrae, but retains fin rays.
Fossil B — Acanthostega (~365 Ma): possesses distinct digits and neck vertebrae, but retains fin rays and limbs not fully adapted for weight-bearing.
Fossil C — Ichthyostega (~360 Ma): possesses well-developed, weight-bearing limbs and robust neck vertebrae, with greatly reduced fin rays.
Fossil A — Tiktaalik (~375 Ma): possesses wrist bones and neck vertebrae, but retains fin rays.
Fossil B — Acanthostega (~365 Ma): possesses distinct digits and neck vertebrae, but retains fin rays and limbs not fully adapted for weight-bearing.
Fossil C — Ichthyostega (~360 Ma): possesses well-developed, weight-bearing limbs and robust neck vertebrae, with greatly reduced fin rays.
a
For each fossil, identify one skeletal feature that supports the hypothesis that tetrapods evolved from lobe-finned fish. [3]
b
Tiktaalik and Acanthostega each retain fin rays despite possessing tetrapod features. Explain what this pattern of trait retention reveals about the nature of the fish-to-tetrapod transition. [1]
c
Evaluate whether this fossil sequence provides strong or weak support for the hypothesis that tetrapods evolved from lobe-finned fish. Justify your reasoning using evidence from all three fossils. [2]
Solutions
29QuestionBiogeography and Species DistributionAssessment Practice
5 marks~8 minCriterion C
Mesosaurus was a small freshwater reptile whose fossils are found exclusively in eastern South America and western Africa. These two regions align when the continents are repositioned together. Mesosaurus was physiologically incapable of surviving in saltwater and could not have crossed an ocean. The Atlantic Ocean currently separates the two fossil sites. Plate tectonics proposes that lithospheric plates move over geological time, driven by convection currents in the mantle.
a
Explain why the saltwater intolerance of Mesosaurus is significant when interpreting its fossil distribution across two continents. [1]
b
Explain how the fossil distribution of Mesosaurus, combined with the geographical alignment of the two continents, supports the theory of continental drift. [2]
c
Evaluate the strength of Mesosaurus fossil evidence for continental drift when compared with geological evidence such as matching rock formations or glacial deposits. [2]
Solutions
30QuestionMolecular Evidence and DNA AnalysisAssessment Practice
3 marks~5 minCriterion C
The graph below shows the relationship between the number of DNA sequence differences in a specific gene and estimated divergence time (millions of years ago) for six primate species compared to humans: chimpanzee, gorilla, orangutan, gibbon, rhesus monkey, and lemur.
a
Describe the trend shown in the graph. [1]
b
Explain what the trend suggests about the evolutionary relationship between chimpanzees and humans compared to lemurs and humans. [1]
c
Analyse one limitation of using DNA sequence differences in a single gene to determine evolutionary relationships among primates. [1]
Solutions
31QuestionFossil Record and Evolutionary HistoryAssessment Practice
4 marks~6 minCriterion A
The diagram shows three organisms arranged in chronological order: the lobe-finned fish Eusthenopteron, the transitional fossil Tiktaalik, and the early tetrapod Acanthostega.
a
Identify one characteristic that Tiktaalik shares with Eusthenopteron. [1]
b
Identify one characteristic that Tiktaalik shares with Acanthostega. [1]
c
Analyse how the combination of features present in Tiktaalik supports the hypothesis that tetrapods evolved from lobe-finned fish. [2]
Solutions
32QuestionMolecular Evidence and DNA AnalysisAssessment Practice
4 marks~6 minCriterion D
A wildlife forensics laboratory uses DNA barcoding to identify illegally traded ivory. Mitochondrial DNA sequences from seized samples are compared against a reference database of known African elephant populations, allowing conservation officers to pinpoint the geographic origin of each sample and direct anti-poaching operations accordingly.
a
Discuss one ethical implication of using genetic surveillance on endangered elephant populations. In your response, address both a potential conservation benefit and a specific concern about data privacy or misuse. [2]
b
Discuss one ecological limitation of relying on DNA barcoding for ivory identification. In your response, consider how poaching pressure may reduce the reliability of this forensic method over time. [2]
Solutions