Biology›Year 11›Module 3›Checkpoint 2

Checkpoint Quiz 2 — Evidence for Evolution and Natural Selection

Covers Lessons 05–09: fossil evidence, anatomical evidence, biogeography, molecular evidence and the mechanism of natural selection.

Covers L05–L09 12 MC · 3 Short Answer 24 marks total

Lesson Summaries

L05 Fossil Evidence

The fossil record preserves evidence of past life across geological time. Stratigraphy shows that older layers lie below younger ones in undisturbed rock, transitional fossils link major groups with mixed ancestral and derived traits, and radiometric dating provides qualitative age estimates using predictable isotope decay. The record is incomplete and biased, but still strongly supports evolution.

stratigraphytransitional fossilsradiometric datinghalf-life

L06 Anatomical Evidence

Homologous structures share the same underlying anatomy and origin despite different functions, supporting common ancestry and divergent evolution. Analogous structures share function but not origin, reflecting convergent evolution. Vestigial structures and comparative embryology both support the idea that evolution modifies existing body plans and that vertebrates share deep ancestry.

homologousanalogousvestigialembryology

L07 Biogeography

Biogeography studies how species are distributed across Earth and how those patterns reflect evolutionary history. Geographic isolation reduces gene flow and drives divergence, island systems can produce adaptive radiation and high endemism, and major distribution patterns such as marsupials across Gondwanan landmasses or faunal shifts across Wallace's Line support common ancestry and isolation-driven evolution.

geographic isolationadaptive radiationendemismWallace's Line

L08 Molecular Evidence

DNA and protein sequence similarity provide quantitative evidence for relatedness: more similar sequences usually mean a more recent common ancestor. Cytochrome c can be compared across aerobic organisms, mtDNA helps trace maternal lineages, and DNA barcoding identifies species from short standardised sequences when morphology is missing or misleading.

sequence similaritycytochrome cmtDNADNA barcoding

L09 Darwin, Wallace and Natural Selection

Natural selection explains how evolution occurs. It requires variation, heritability, differential survival and reproduction, and a selection pressure. Over generations, favoured alleles increase in frequency. Antibiotic resistance in MRSA is a model example because resistant variants already existed before treatment and were selected by antibiotic use. This mechanism differs from Lamarck's incorrect idea of inherited acquired characteristics.

natural selectionselection pressureallele frequencyMRSA
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Answer the multiple choice first, then use the short answers to check whether you can explain and evaluate the whole evidence-for-evolution sequence.

Multiple Choice — 12 questions

Choose the best answer, then read the feedback. Questions are grouped by lesson focus.

Lesson 05 — Fossil Evidence

1. What does stratigraphy tell scientists most directly?

A The exact age in years of every fossil
B Which rock layers and fossils are older or younger relative to one another
C The DNA sequence of extinct organisms
D The exact habitat preference of every organism in a layer

2. Why are transitional fossils such as Tiktaalik important?

A They must be the direct ancestor of a modern species to matter
B They show a mixture of traits expected between earlier and later lineages
C They prove evolution occurred in one sudden jump
D They matter only because they are rare museum specimens
Lesson 06 — Anatomical Evidence

3. Which pair is the best example of homologous structures?

A Human arm and whale flipper
B Bird wing and insect wing
C Shark body and dolphin body
D Any two structures with the same function

4. Why can convergent evolution mislead classification?

A It makes all species equally related
B It can make unrelated organisms look similar in function or form
C It turns homologous structures into vestigial ones
D It means classification can never be scientifically valid
Lesson 07 — Biogeography

5. Which statement best explains why island species often show high endemism?

A Islands always contain more species than continents
B Isolation limits gene flow and allows locally evolved species to persist
C Island climates force every species to become unrelated
D All nearby islands must contain identical organisms

6. Wallace's Line is most useful as evidence for evolution because it:

A Separates warm and cold climates across the tropics
B Marks a sharp faunal boundary that reflects deep historical isolation
C Represents a political border drawn by colonial powers
D Proves all nearby islands share identical species
Lesson 08 — Molecular Evidence

7. If two species share a very high proportion of DNA sequence similarity, the best inference is that they:

A Share a more recent common ancestor
B Must live in the same environment today
C No longer experience mutation
D Evolved independently but happened to produce the same sequences

8. What is the main advantage of DNA barcoding?

A It always makes morphology unnecessary
B It can identify species when morphology is incomplete or misleading
C It only works on complete fossil material
D It predicts future climate change from DNA alone
Lesson 09 — Natural Selection

9. Which is one of the required conditions for natural selection?

A Organisms must need a trait strongly enough
B Some variation must be heritable
C All members of the population must face identical outcomes
D Individuals must acquire the trait during their lifetime

10. Which statement best explains MRSA antibiotic resistance?

A Bacteria intentionally mutate because the antibiotic forces them to adapt
B Resistant variants already existed and were favoured by antibiotic use
C The antibiotic inserted a resistance allele into every surviving cell
D Bacteria passed on a learned behaviour of resistance

11. Which statement correctly distinguishes Darwinian natural selection from Lamarckian inheritance?

A Darwin argued species never change, while Lamarck said they do
B Lamarck proposed inheritance of acquired traits, whereas Darwinian selection acts on existing heritable variation
C Darwin used fossils while Lamarck only used embryos
D Lamarck thought the environment mattered but Darwin did not

12. What is the overall outcome of natural selection over many generations?

A Individual organisms rewrite their DNA to suit the environment
B Favoured alleles become more common in the population over time
C All alternative alleles disappear immediately
D Populations change only through random need-based events

Short Answer — 12 marks

Use these to check whether you can explain, compare and evaluate across the whole IQ2 evidence sequence.

13. Explain how two different lines of evidence from Lessons 05–08 support the theory of evolution. 4 MARKS

1 mark: first evidence line | 1 mark: how it supports evolution | 1 mark: second evidence line | 1 mark: explanation

14. Explain how natural selection accounts for antibiotic resistance in bacteria. In your answer, refer to variation, heritability and selection pressure. 4 MARKS

1 mark: variation | 1 mark: heritability | 1 mark: selection pressure/differential survival | 1 mark: frequency change over generations

15. Assess whether molecular evidence is always superior to morphological evidence in evolutionary studies. 4 MARKS

1 mark: judgement | 1 mark: molecular strength | 1 mark: morphological role/strength | 1 mark: evaluative conclusion

  • 1. B — Stratigraphy gives the relative order of layers and fossils.
  • 2. B — Transitional fossils show predicted mixes of ancestral and derived traits.
  • 3. A — Human arms and whale flippers are homologous structures.
  • 4. B — Convergent evolution can make unrelated organisms look similar.
  • 5. B — Isolation promotes local divergence and high endemism on islands.
  • 6. B — Wallace's Line is a sharp faunal boundary reflecting deep isolation.
  • 7. A — High DNA similarity supports a more recent common ancestor.
  • 8. B — DNA barcoding helps identify species when morphology is ambiguous or missing.
  • 9. B — Heritable variation is one of the required conditions for natural selection.
  • 10. B — Resistant variants already existed and were selected by antibiotic use.
  • 11. B — Lamarck proposed acquired-trait inheritance; Darwinian selection acts on existing heritable variation.
  • 12. B — Natural selection changes allele frequencies in populations over generations.

13. One line of evidence is the fossil record. Stratigraphy shows older and younger forms in a time-ordered sequence, and transitional fossils such as Tiktaalik show mixtures of traits expected near major evolutionary transitions. Another line of evidence is molecular evidence. Species with more similar DNA or protein sequences are inferred to share a more recent common ancestor, which supports evolution through descent with modification.

14. Antibiotic resistance in bacteria is explained by natural selection because variation already exists in the population, including rare resistant variants created by mutation. Resistance is heritable because the genetic basis can be passed to offspring when those bacteria reproduce. The antibiotic acts as a selection pressure by killing more susceptible bacteria, while resistant bacteria survive and reproduce more successfully. Over generations, the resistance allele becomes more common in the population.

15. Molecular evidence is often extremely powerful because it compares relatedness directly through DNA or protein sequences and can resolve misleading morphology caused by convergent evolution or incomplete specimens. However, it is not always superior in every context. Morphological evidence remains useful for field identification, whole-organism comparison and ecological interpretation. The strongest evolutionary studies usually combine both, using molecular evidence to test or refine relationships suggested by morphology.

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