OCR A Level Biology A
OCR A Level Biology A Module 6: Genetics, Evolution and Ecosystems Exam Questions
Free OCR A Level Biology A exam questions for Module 6: Genetics, Evolution and Ecosystems, with a mark scheme for every pack. Covers gene expression, mutations, inheritance and statistics, Evolution and speciation, DNA technology, cloning, biotechnology, ecosystems and population sustainability.
Module 6: Genetics, Evolution and Ecosystems exam questions
6 question packs of real past exam questions, each with its mark scheme. Do not stop after a few: answer as many as you can without notes, then mark every answer with the mark scheme. The more questions you do, the more quickly you will spot how examiners ask about each idea.
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A-Level Biology Flashcards for 2027 Onwards
Every answer is written in mark scheme wording, so you learn exactly what examiners give marks for. Then test yourself with the questions on this page.
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About OCR A Level Biology A Module 6: Genetics, Evolution and Ecosystems
Module 6 of OCR A Level Biology A, Genetics, Evolution and Ecosystems, explores how genes are controlled and inherited, how populations evolve, how DNA can be manipulated, and how ecosystems and populations function. It covers the lac operon and homeobox genes, mutations, crosses with the chi-squared test, Hardy-Weinberg, speciation, PCR and genetic engineering, cloning and biotechnology, energy flow, nutrient cycles, succession and conservation. It extends DNA and protein synthesis from Module 2 and biodiversity from Module 4. Examiners love genetic cross problems, chi-squared, epistasis ratios, gel electrophoresis interpretation and capture-recapture calculations.
What you need to know
- 6.1.1 Types of gene mutation and their effects, regulation of gene expression at transcriptional, post-transcriptional and post-translational levels including the lac operon, homeobox genes, and apoptosis and mitosis in development.
- 6.1.2 Continuous and discontinuous variation, monohybrid and dihybrid crosses, codominance, multiple alleles, sex linkage, autosomal linkage, epistasis, the chi-squared test, genetic drift, the Hardy-Weinberg principle, artificial selection and speciation.
- 6.1.3 DNA sequencing, bioinformatics, PCR, gel electrophoresis, DNA profiling, genetic engineering with restriction enzymes, ligase and vectors, and gene therapy.
- 6.2.1 Natural clones in plants, artificial cloning by tissue culture and in animals by embryo twinning and SCNT, the use of microorganisms in biotechnology, culturing and the growth curve, and immobilised enzymes.
- 6.3.1 Ecosystems as dynamic, biomass transfer and efficiency, the nitrogen and carbon cycles, succession, and measuring distribution and abundance.
- 6.3.2 Population size limiting factors, predator-prey relationships, conservation and preservation, sustainable management of resources, and balancing human needs with conservation in named ecosystems.
Common mistakes in Module 6: Genetics, Evolution and Ecosystems
- Saying all mutations change the protein. Silent mutations change a codon to one coding for the same amino acid, because the code is degenerate.
- Describing the lac repressor as binding to lactose to switch genes on. The repressor binds to the operator; lactose binds to the repressor, changing its shape so it leaves the operator and transcription can occur.
- Choosing the wrong degrees of freedom in chi-squared. Degrees of freedom equal the number of categories minus one.
- Saying DNA fragments move to the negative electrode in gel electrophoresis. DNA is negatively charged so it moves towards the positive electrode, with shorter fragments moving further.
- Ignoring the assumptions of capture-recapture. It assumes no migration, births or deaths between samples and that marking does not affect survival.
Try three Module 6: Genetics, Evolution and Ecosystems exam-style questions
1. 40 snails are marked and released. A second sample of 50 contains 10 marked snails. Estimate the population size. (2 marks)
Show the mark scheme answer
Population = (40 x 50) / 10; = 200.
2. Explain how PCR amplifies a DNA sample. (4 marks)
Show the mark scheme answer
Heated to about 95 degrees C to separate strands; cooled to about 55 degrees C so primers anneal; heated to about 72 degrees C so Taq polymerase adds complementary nucleotides; cycle repeated, doubling DNA each cycle.
3. Explain how allopatric speciation occurs. (4 marks)
Show the mark scheme answer
Population separated by a geographical barrier; no gene flow between the groups; different selection pressures and mutations change allele frequencies; eventually the groups cannot interbreed to produce fertile offspring.
Module 6: Genetics, Evolution and Ecosystems FAQs
What does OCR A Level Biology A Module 6: Genetics, Evolution and Ecosystems cover?
Cellular control, patterns of inheritance, manipulating genomes, cloning and biotechnology, ecosystems, and populations and sustainability.
Which papers is Module 6 examined in?
It is assessed in Paper 2 (Biological diversity) and Paper 3 (Unified biology).
How do I get confident with genetics questions in Module 6?
Practise full genetic diagrams with parental genotypes, gametes, a Punnett square and ratios, then test results with chi-squared, including dihybrid, sex linkage and epistasis examples.
