This free quiz has 9 real AQA A-level Biology exam questions on evolution and speciation (27 marks, about 35 minutes). It marks itself: for each answer you check your work against the real AQA mark scheme and tick the points you made.
What the quiz covers (AQA 3.7.3)
factors that cause phenotypic diversity within a species
how climate change can reduce survival by removing camouflage
why natural selection hasn't reduced the frequency of a late-onset disease allele
why an inherited condition can be more common in an isolated population
conclusions from a map of the expected and actual distributions of two species
how mate choice could lead to sympatric speciation
how variation in moulting time could help a population survive (4 marks)
explaining allopatric and sympatric speciation in fish and palm trees (4 and 5 marks)
How to use it
Write each answer in full before you open the mark scheme, then tick only the points you really made. For speciation answers, first decide whether the populations are geographically separated (allopatric) or in the same area (sympatric), then build the chain: mutation, reproductive isolation, different alleles selected, change in allele frequency, no fertile offspring. Use the details in the question rather than a stock answer.
Where students lose marks (from AQA examiners’ reports and mark schemes)
Each point below is followed by wording that gained marks.
Sympatric means same area. Many students described allopatric speciation when the question asked about sympatric speciation, and fewer than 2% gained full marks on one such question. Most missed the key idea that sympatric speciation happens without geographical isolation.
✔ Gains credit: sympatric speciation occurs in the same habitat, area or population, with no geographical isolation, e.g. a mutation causes different flowering times.
Name allopatric speciation. Students often said populations became geographically isolated but never named allopatric speciation, or gave different selection pressures without linking them to the separated areas. Some wrote “sympatric” by mistake.
✔ Gains credit: geographical isolation leads to allopatric speciation, and the separated populations face different environmental conditions or selection pressures.
Reproductive isolation comes first. Some students placed reproductive isolation at the end of speciation and lost the mark, and many gave two or three versions of the same idea for only one mark.
✔ Gains credit: reproductive isolation, no gene flow or separate gene pools at the start of the process, which allows different alleles to be selected in each population.
Variation from mutations. The mutation mark was lost when students wrote that organisms “mutate to adapt” or that the conditions or selection caused the mutations. Others mentioned mutation without linking it to variation.
✔ Gains credit: variation due to mutations in the different populations.
Disruptive selection. Few students referred to disruptive selection when explaining sympatric speciation.
✔ Gains credit: disruptive selection, where both extremes (e.g. both colours) are favoured, or selection against the middle.
Defining a new species. A significant number of students left out either “interbreed” or “fertile offspring” from the end of their answer. “Gene frequencies” and “inbreeding” were rejected.
✔ Gains credit: a change in allele frequencies, until the different species can no longer interbreed to produce fertile offspring.
Genetic drift and inbreeding. Genetic drift was rarely given, and students who used the term often didn't seem to understand it. Many just repeated that a population was small or isolated, confused inbreeding with interbreeding, or wrote “the mutation” instead of the allele.
✔ Gains credit: genetic drift means an allele's frequency is higher by chance, not by natural selection; or no interbreeding with other populations gives a small gene pool and a higher chance of inheriting the allele.
Keep practising
The other AQA 3.7 self-marking quizzes: Inheritance · Hardy–Weinberg · Populations in ecosystems
Next, topic 3.8: the gene expression quiz
The AQA topic index
weekly AQA group classes: Year 12 on Tuesdays at 5.15pm, Year 13 on Wednesdays or Thursdays at 6.30pm
Questions © AQA, from past A-level and AS Biology papers, with their mark schemes and examiners’ reports.