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CAIE A Level Biology 9700

Selection and evolution questions

Exam-style questions on Selection and evolution, ordered from foundation to challenge. Pick one, write your answer the way you would in the exam, and it comes back marked against the mark scheme, point by point.

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Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.

  1. Describe4 marksStandardIn a study of two different taxa, researchers observed two distinct speciation events. Event A: A population of lizards on either side of a newly formed river canyon shows genetic divergence over generations, leading…
  2. Explain5 marksStandardA biologist studies a population of wildflowers. Two traits are recorded: flower colour (red or white) and leaf length (measured in cm). The following data were obtained: Flower colour: 120 red, 80 white. Leaf length…
  3. Compare4 marksStandardIn the alpine plant Gentiana verna, the number of petals per flower is either 4 or 5; there are no intermediate numbers. In the garden rose Rosa × hybrida, the number of petals per flower varies continuously from 6 to…
  4. Describe5 marksStandardA population of a single bird species lives on an isolated island. Over time, two distinct groups emerge that do not interbreed. One group has a different mating song and feeds on a different type of seed than the…
  5. Outline5 marksStandardOutline the process by which the formation of a mountain range can lead to allopatric speciation. Also outline how analysis of DNA sequence data could provide evidence that two populations have become separate species.
  6. Explain5 marksStandardA researcher studies a population of speckled beetles (Diaperis maculata) in two habitats: woodland and grassland. The elytra (wing case) pattern in this species is either spotted or striped; this characteristic is…
  7. Explain5 marksStandardA mainland population of a bird species has two alleles for feather colour: B (brown) and b (white). The frequency of the B allele is 0.7 and the frequency of the b allele is 0.3. A small group of 10 birds from this…
  8. Describe4 marksStandardA population of a plant species was studied over 20 generations. During this period, the environment became increasingly drier. The table shows the mean seed mass and standard deviation of seed mass in the population…
  9. Outline5 marksStandardOutline how selective breeding can be used to improve milk yield in dairy cattle over several generations.
  10. Explain5 marksStandardA species of finch (Fringilla montana) is found in a large, continuous forest. A mountain range formed, splitting the forest into two separate regions: a northern region with cooler, wetter conditions and a southern…
  11. Describe5 marksStandardA biologist studying a population of snails notices two traits: shell colour pattern (which occurs in three distinct forms: solid brown, striped, or banded) and shell width (which ranges continuously from 2.0 mm to 4.5…
  12. Outline4 marksStandardA dairy farmer aims to improve the average milk yield of her herd over several generations. Outline the process of selective breeding she would use to achieve this.
  13. Describe5 marksStandardIn a population of birds on an island, a mutation causes some males to produce higher-pitched courtship songs than the ancestral lower-pitched song. Females are known to prefer the song type they heard from their…
  14. Explain4 marksStandardA population of birds on a mainland has a wide range of beak lengths. A small flock of 20 birds colonises a distant island. The allele frequencies for beak length in the island population are different from those in…
  15. Outline4 marksStandardThe table below shows the percentage similarity in DNA sequence between three species of flowering plants, A, B, and C. Species A Species B Species C Species A 100% 92% 78% Species B 100% 81% Species C 100% Outline how…
  16. Compare4 marksStandardIn a plant species, leaf length varies continuously from 5 cm to 20 cm, while flower petal number shows only two distinct values: 4 or 5, with no intermediates. Compare the genetic basis of continuous variation (leaf…
  17. Outline4 marksStandardA small group of birds from a large mainland population colonises a remote island. The mainland population has a wide range of allele frequencies for a gene controlling beak size. Outline how the founder effect may…
  18. Describe4 marksStandardA population of freshwater cichlid fish lives in a large lake. A river from the lake was diverted by a landslide, creating a new isolated lake. Meanwhile, within the original lake, some cichlids began breeding in the…
  19. Describe5 marksStandardA biologist studied shell colour in two populations of the snail Cepaea nemoralis. Shell colour is controlled by a single gene with multiple alleles. In Population A, the snails live in woodland with mixed leaf litter…
  20. Outline5 marksStandardA population of a butterfly species (Erebia tyndarus) originally lived in a continuous alpine meadow. Over millions of years, tectonic uplift created a mountain range that split the habitat into two separate valleys…
  21. Compare5 marksStandardA student investigated the length of petals (in mm) in two populations of the same wildflower species. Population A grew in a shaded woodland, while Population B grew in an open meadow. The student measured 10 flowers…
  22. Describe5 marksStandardA dairy farmer has a herd of 100 cows with an average milk yield of 25 litres per day. He aims to increase the average milk yield to 35 litres per day over 10 generations. Describe the steps involved in a selective…
  23. Explain4 marksStandardA population of a beetle species has two alleles, A and a, for a gene controlling wing colour. The table shows the frequencies of these alleles before and after a severe flood that killed most of the population. Time…
  24. Explain4 marksStandardThe table shows the number of base differences in a mitochondrial gene sequenced from four species of bird belonging to the genus Avifuga. Species pair Number of base differences A. rubra and A. caerulea 8 A. rubra and…
  25. Outline5 marksStandardOutline the sequence of events by which a bacterial population becomes resistant to an antibiotic, as an example of natural selection.
  26. Explain4 marksStandardIn a study of flower petal length, samples were taken from a wild population and a cultivated population of the same plant species. The data are shown below. Population Sample size Mean petal length (cm) Standard…
  27. Explain5 marksStandardA species of lizard, Anolis carolinensis, is found on the mainland of a continent. A small number of individuals are swept out to sea on a floating log and eventually reach a distant island, where they establish a new…
  28. Describe4 marksStandardIn a population of riverbank sunflowers, researchers studied two traits: the number of petals per flower (either 5 or 6) and the height of plants measured in centimetres (range 30–120 cm). The petal number is…
  29. Describe5 marksStandardA biologist studies two traits in a population of wild roses. Trait A is flower colour: individual plants produce either red or white flowers, with no intermediate shades. Trait B is leaf length, measured in…
  30. Explain4 marksStandardTable 1 shows the number of DNA base differences in a homologous gene (1000 base pairs) among five species of a genus of beetles found on different islands in an archipelago. The islands are: Island 1 (lowland forest…
  31. Explain4 marksStandardA student measured the heights (cm) of two groups of tomato seedlings. Group A was grown in full sunlight, Group B in shade. The results are shown. Group n Mean height (cm) SD A 20 15.2 2.3 B 20 11.8 2.1 The t-test…
  32. Compare5 marksStandardA botanist compares the number of petals in two species of wild rose. Table 1 shows the petal counts for 10 flowers from each species. Flower Species A Species B 1 5 4 2 5 5 3 5 6 4 5 7 5 5 5 6 5 8 7 5 4 8 5 6 9 5 5 10…
  33. Outline7 marksChallengeThe table shows the distribution of beak depth in a finch population before and after a severe drought. Before drought: mean beak depth = 8.2 mm, range = 6–10 mm. After drought: mean beak depth = 9.1 mm, range = 7–11…
  34. Describe6 marksChallengeIn a study of a species of deer, researchers measured body mass (kg) and recorded coat colour (either light brown or dark brown) in two populations: one from a lowland area and one from a highland area. (a) Describe…
  35. Describe6 marksChallengeThe original mainland population of a bird species has an allele frequency of 0.5 for a particular beak size allele, L. A small flock of birds, containing only 10 individuals, is blown off course and establishes a new…
  36. Outline7 marksChallengeIn a population of wildflowers (Centaurea cyanus), there is variation in petal length. Due to a change in pollinator behaviour, bees now show a strong preference for flowers with longer petals. The table below shows…
  37. Explain5 marksChallengeA biologist studies three populations of a butterfly species (Populations A, B, and C). Population A and B are separated by a mountain range, while Population B and C occur in the same valley but use different host…
  38. Compare7 marksChallengeIn a study of dairy cattle, researchers recorded two traits: milk yield (litres per day) for 50 cows from each of two different farms, and coat colour type (either black-and-white or red-and-white) for the same cows…
  39. Outline6 marksChallengeThe table shows the percentage similarity of a 500-base-pair region of mitochondrial DNA from three species of birds (A, B, C) from different islands. Species pair DNA sequence similarity (%) A and B 98.0 A and C 92.5…
  40. Outline6 marksChallengeThe table shows the percentage similarity in a mitochondrial DNA sequence among three species of a genus of rodents found on different islands. Species pair DNA sequence similarity (%) A and B 98.2 A and C 96.5 B and C…
  41. Describe6 marksChallengeA population of wildflowers (species Lupinus texensis) growing in a prairie was studied for two alleles at a single gene locus: allele A and allele a. In 2015, the population consisted of 10 000 individuals, and the…
  42. Outline6 marksChallengeA population of a beetle species is divided by the formation of a mountain range. Outline how this event could lead to the formation of two new beetle species over time, and explain how DNA sequence data could be used…
  43. Compare7 marksChallengeIn a species of sunflower, the number of ray florets on the flower head shows discontinuous variation: individuals have either 8 or 13 florets, with no intermediate numbers. The seed mass, however, shows continuous…
  44. Describe7 marksChallengeA group of pelagic fish species in a deep lake is thought to have evolved from a single ancestral species. DNA sequence analysis of a conserved gene shows that species A and B are 99.8% identical, while species A and C…
  45. Describe6 marksChallengeA biologist studied leaf length in two populations of the same plant species. Population A grows in shaded woodland and Population B in open grassland. The biologist measured leaf length (cm) in 40 plants from each…
  46. Explain5 marksChallengeA dairy farmer has been selectively breeding her herd of cows to increase milk yield over many generations. Initially, the average milk yield was 20 litres per day. After 50 years of selective breeding, the average…
  47. Explain5 marksChallengeIn a population of snails, shell banding pattern is a discontinuous character: shells are either banded or unbanded. A survey recorded 320 banded and 80 unbanded individuals. A student also measured shell width (a…
  48. Explain5 marksChallengeA new antibiotic, novamycin, is introduced to treat infections caused by the bacterium Staphylococcillus fictilis. Initially, novamycin is very effective, but after several years, some infections no longer respond to…
  49. Describe7 marksChallengeTwo closely related species of frog (A and B) inhabit the same region. Species A is found in fast-flowing streams on the eastern side of a mountain range, while species B lives in stagnant ponds on the western side…
  50. Explain5 marksChallengeFour species of finch (A, B, C, D) are found across an archipelago. Species A is found on the mainland, species B and C on adjacent islands with a narrow channel between them, and species D on a remote island far from…
  51. Outline6 marksChallengeA species of ground beetle (Carabus sp.) is widely distributed across a lowland region. A mountain range rises in the middle of its range, splitting the population into two separate groups (eastern and western). After…
  52. Describe7 marksChallengeA population of the warbler species Phylloscopus trochiloides inhabits a forest in Southeast Asia. Within this forest, two types of fig trees, Ficus benghalensis and Ficus religiosa, fruit at different times of the…
  53. Explain5 marksChallengeA researcher measured the stem heights (cm) of two varieties of sunflower grown in two different fields. She wanted to investigate whether the difference in mean height is due to genetic factors, environmental factors…
  54. Describe6 marksChallengeA botanist is studying two populations of a wild plant species. In both populations, flower colour is either red or white, with no intermediate shades. However, leaf length shows a wide range of values from 2 cm to 12…
  55. Describe6 marksChallengeA researcher studying a species of wild flower (Bidens tripartita) counts the number of spines on the leaves of 100 plants from a dry, open habitat and 100 plants from a shaded, moist habitat. The number of spines per…
  56. Compare7 marksChallengeA researcher investigates variation in leaf width (mm) in a species of alpine plant, Lobelia gibberosa. Two populations were sampled: Population A from a lowland valley (altitude 500 m) and Population B from a…
  57. Outline7 marksChallengeThe table below shows the distribution of petal length in two populations (A and B) of the same plant species. Each population was sampled from a different habitat. Petal length (mm) Number of individuals in Population…