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IB Biology SL A4.1 Evolution and Speciation Questions

Practise IB Biology SL A4.1 with questions on variation, natural selection, speciation, adaptation and changes in biodiversity.

Syllabus
First assessment 2025
Course
Biology SL
Level
SL

Exam points

  • Define evolution as cumulative change in heritable population characteristics, then explain how inherited variation and differential reproductive success change populations over generations.
  • Use DNA, RNA, amino-acid or protein sequence identity and differences to infer common ancestry, phylogeny and divergence.
  • Explain how selective breeding retains heritable variation to change inherited characteristics over generations, using dog, cattle or crop examples.
  • Distinguish homologous and analogous structures by origin, underlying structure and function, and use pentadactyl anatomy to infer common ancestry and divergent evolution.
  • Compare convergent and divergent evolution using ancestry, environments and selection pressures, identifying analogous wings, eyes or other independently evolved structures.
  • Explain how geographic or reproductive isolation, mutation, selection and time change gene pools toward formation of new species.
  • Identify prezygotic and postzygotic barriers that prevent gene flow between populations.
  • Evaluate breeding probabilities, population or allele-frequency data as evidence for reproductive isolation and speciation.

Covered syllabus points

A4.1.1—Evolution as change in heritable characteristicsA4.1.2—Evidence from sequencesA4.1.3—Evidence from selective breedingA4.1.4—Evidence from homologous structuresA4.1.5—Convergent evolutionA4.1.6—Speciation by splitting of pre-existing speciesA4.1.7—Reproductive isolation and differential selection

Question 1

[Maximum number: 8]

Explain how the process of evolution occurs.

Question 2

[Maximum number: 1]

What is a piece of evidence that all living organisms share a common ancestor?

A

They manufacture the same proteins.

B

They obtain energy from glucose.

C

DNA triplets code for the same amino acids.

D

Cells can synthesise all the amino acids.

Question 3

[Maximum number: 1]

Jersey (Bos taurus) is a breed of cattle. Cows of this breed produce higher milk yields than cows from other cattle breeds.

Figure for Question 3 — IB Biology SL

What has caused this breed to produce higher milk yields than other cattle breeds?

A

Natural selection

B

Selective breeding

C

Adaptive radiation

D

Random mutations

Question 4

[Maximum number: 1]

What term describes similar structures found in animals with a common ancestry?

A

Homologous

B

Inherent

C

Characteristic

D

Analogous

Question 5

[Maximum number: 4]

Convergent evolution increases similarities, despite differences in origins.

Explain how analogous structures can evolve.

Question 6

[Maximum number: 4]

Explain how divergent evolution may contribute to speciation.

Question 7

[Maximum number: 3]

Chimpanzees and bonobos are different species of primate. It is thought that neither species can swim. The map shows the relative locations of chimpanzees and bonobos in Africa.

Figure for Question 7 — IB Biology SL

Evidence suggests that the level of the Congo River was lower during one period in the past. At this time, chimpanzees could have migrated across.

Explain how bonobos could have evolved from chimpanzees by speciation.

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