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IBBiologySLExam QuestionsContinuity & ChangeNatural Selection

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First teaching 2023

First exams 2025

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Natural Selection (SL IB Biology)

Exam Questions

2 hours27 questions

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Natural Selection

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Natural Selection

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1
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Which process does not generate heritable variation in a population?

  • Mutation

  • Mitosis

  • Metaphase I of meiosis

  • Fertilisation

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2
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Which of the following statements correctly explains the process of natural selection?

I. Some species produce small numbers of young and provide higher levels of parental care

II. Advantageous alleles increase an individual's chance of surviving and reproducing

III. Individuals that change to suit their environment pass their alleles on to offspring

IV. Advantageous alleles increase in frequency in the population

  • I and II only

  • I, II, III, and IV

  • II, III, and IV only

  • II and IV only

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11 mark

Which of the following applies to the process of evolution by natural selection?

  1. Changes in the phenotype of organisms in a population
  2. Selection pressures favouring certain alleles within a population
  3. Individuals with a certain genetic makeup will not pass on their genes
  4. Changes in the allele frequencies within a population over time

  • II only

  • I, II and III

  • II and IV only

  • I, II, III and IV

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21 mark

Which of the following processes generate genetic variation?

  1. Random assortment
  2. Mitosis
  3. DNA replication
  4. Random fertilisation

  • I and III only

  • I and IV only

  • I, III, and IV only

  • I, II, III, and IV

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31 mark

Which of the following must occur for natural selection to take place?

  • Sexual reproduction.

  • Genetic variation.

  • The presence of predators.

  • Advantageous characteristics.

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41 mark

Research was carried out on beak size in the island-living finch species Geospiza fortis. G. fortis feeds on seeds, which are plentiful, small, and soft in the years when the weather is normal, but which become larger and tougher in drought years. Some of the research results are shown in the graph below.

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Which of the following statements explains the results in the graph?

  • Finches adapt to drought years by developing larger beaks, passing on the characteristic to their offspring, and leading to an increase in average beak size.

  • Average finch beak size increases during years of drought and decreases during wet years.

  • Average beak size increased from 9.5 mm in 1976 to 9.9 mm in 1977, before slowly decreasing to 9.7 mm by 1979.

  • Finches with larger beaks have an advantage when competing for food in drought years, and are therefore more likely to survive and pass on their alleles, leading to an increase in average beak size.

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11 mark

Which of the following does not describe the process of natural selection? 

  • A species of antelope where the population has stronger muscles after the individuals with weak muscles are eaten by predators

  • When a bacteria is exposed to a new type of antibiotic the exposure causes the bacteria to become resistant

  • Sharks adapting to store more oxygen in their blood because the sharks with less oxygen were more likely to die

  • Dark peppered moths increasing in number during the industrial revolution in response to increased predation of the light colour moths

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2
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In adult humans, the ability to digest the lactose sugar in milk depends on the presence of an allele known as -13910*T. Individuals with this allele continue to produce the enzyme lactase into adulthood; this is known as lactase persistence. Individuals without this allele are not able to produce lactase after infancy and cannot digest lactose as adults. The table below shows the frequency of the -13910*T allele in European Neolithic hunter-gatherers who lived around 5 000 years ago and in modern Europeans.

  European Neolithic hunter-gatherers  Modern Europeans
Frequency of -13910*T allele 0.03 (+/- 0.11) 0.74 (+/- 0.06)

Which of the following can be concluded from the table?

  • There is no significant difference in the frequency of the -13910*T allele between Neolithic hunter-gatherers and modern day humans in Europe

  • Lactase persistence gave a survival advantage to humans at some stage between Neolithic and modern-day times

  • Lactase persistence gave a survival advantage to European Neolithic hunter-gatherers

  • Adult European Neolithic hunter-gatherers did not consume milk

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