Practise 38 exam-style questions on Fossils for AQA GCSE Biology. Write your answer as you would in the exam and get it marked in seconds against the mark scheme, point by point, with an AI tutor on hand if you get stuck.
38 questions
2–4 marks each
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20 questions, marked as you go
Sample questions with model answers
Here are 4 of the questions in this topic, each with a model answer, an explanation of why it earns the marks and the mark scheme an examiner would use.
Question 1
3 marks
What is an index fossil and how is it used to date sedimentary rock layers?
Model answer
An index fossil is a fossil of a species that was widespread but existed for a relatively short geologic time. It is used for relative dating: if the index fossil is found in a rock layer, the layer can be correlated to the known age range of that species.
Explanation
Index fossils help geologists match rock layers of the same age in different places. Because the species lived for only a short period, its presence indicates the layer formed during that specific time interval.
Mark scheme
1 mark
definition: species widespread and existed for short time (index fossil)
2 marks
use: correlates rock layers by matching index fossil to known time range (relative dating)
Award if idea of using known age range to date layers is given.
Question 2
3 marks
Give two ways scientists can determine whether two similar-looking fossils are from the same species or different species.
Model answer
Compare detailed morphology (measurements of diagnostic features), examine stratigraphic position/age, and if possible compare molecular data (if DNA preserved) or compare tooth/bone microstructure and consider reproductive isolation evidence where available.
Explanation
Species determination uses multiple lines of evidence including morphology, stratigraphy, and molecular data when available; a combination helps determine species identity.
Mark scheme
1 mark
compare morphology/measurements of diagnostic features
1 mark
compare age/stratigraphic position or look for molecular evidence if available
1 mark
look for distinctive features indicating reproductive isolation (where possible) or compare microstructure
Any other valid scientific method may be credited.
Question 3
4 marks
Explain how comparative anatomy (homologous structures) and molecular (DNA) evidence support the idea of common ancestry.
Model answer
Homologous structures (similar bone arrangements) in different species indicate descent from a common ancestor with modification. DNA sequences that are similar between species show shared genetic heritage; more similar DNA indicates a more recent common ancestor.
Explanation
Both anatomical similarities and genetic similarities reflect inheritance from a common ancestor. Anatomical features can show modification for different functions, while DNA comparisons provide quantifiable measures of relatedness.
Mark scheme
2 marks
comparative anatomy: homologous structures indicate common ancestry with divergent evolution
Accept examples such as pentadactyl limb in mammals, birds, reptiles.
2 marks
molecular evidence: similarity in DNA/protein sequences indicates relatedness; greater similarity implies more recent common ancestor
Award mention of DNA or amino acid sequence comparisons.
Question 4
4 marks
Some critics say the fossil record contradicts Darwin’s gradualism. Using scientific reasoning, explain how the fossil record can be reconciled with evolutionary theory.
Model answer
Apparent sudden appearances can result from rare fossilisation, incomplete record, or rapid evolution in small isolated populations (punctuated equilibrium). Darwinian evolution includes both gradual change and mechanisms (selection, drift, isolation) that can produce rapid speciation.
Explanation
Gaps in the fossil record are expected due to preservation biases. Mechanisms such as rapid adaptive change in isolated populations can produce patterns that match the fossil data without contradicting evolution by natural selection.
Mark scheme
2 marks
explain limits: incomplete fossil record and rarity of preservation can make gradual change look sudden
2 marks
explain biological reasons: rapid evolution in small isolated populations (speciation) or punctuated patterns are compatible with evolutionary mechanisms
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