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IB Biology HL D4.1 Natural Selection Questions

Practise IB Biology HL D4.1 by interpreting selection evidence, tracing allele-frequency change and applying Hardy-Weinberg calculations to populations.

Syllabus
First assessment 2025
Course
Biology HL
Level
HL

Exam points

  • Explain how heritable variation and selection shift survival, reproduction and trait frequencies.
  • Explain how mutation creates new alleles, while meiosis and fertilisation create new combinations.
  • Interpret freezing-exposure data to evaluate selection for an inherited trait.
  • Explain how mate choice for courtship traits changes reproductive success.
  • Analyse Endler guppy data to distinguish predator and mate-choice effects on colour.
  • Define a gene pool and explain how isolation can drive allele-frequency divergence.
  • Explain how selection, mutation and recombination shift allele frequencies over generations.
  • Distinguish directional, stabilizing and disruptive selection from phenotype distributions.
  • Calculate allele, genotype or phenotype frequencies using p + q = 1 and p² + 2pq + q² = 1.
  • State Hardy-Weinberg assumptions and identify evolutionary forces that disrupt equilibrium.

Covered syllabus points

D4.1.1—Natural selection as mechanismD4.1.2—Roles of mutation and sexual reproductionD4.1.3—Overproduction and competitionD4.1.4—Abiotic factors as selection pressuresD4.1.5—Differences in adaptation, survival, reproductionD4.1.6—Traits must be heritableD4.1.7—Sexual selectionD4.1.8—Modelling selectionD4.1.9 (HL)—Gene pool conceptD4.1.10 (HL)—Allele frequenciesD4.1.11 (HL)—Changes in allele frequencyD4.1.12 (HL)—Types of selectionD4.1.13 (HL)—Hardy-Weinberg equationD4.1.14 (HL)—Hardy-Weinberg conditionsD4.1.15 (HL)—Artificial selection

Question 1

[Maximum number: 8]

Explain how evolution may happen in response to environmental change with evidence from examples.

Question 2

[Maximum number: 7]

Variation in genetically inherited characteristics is the basis for evolution.

Explain how genetic variation between the individuals in a species can be generated.

Question 3

[Maximum number: 1]

What promotes natural selection?

I. Overpopulation
II. Competition
III. Variation

A

I and II only

B

I and III only

C

II and III only

D

I, II and III

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