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Topic 3: Genetics

4 dot points across 4 inquiry questions. Click any dot point for a focused answer with worked past exam questions where available.

What is the structure of DNA, and how does it code for proteins?

Describe DNA as a polymer, the genome and a gene, how DNA is extracted from fruit, and how the order of bases controls protein synthesis through transcription and translation.
A focused answer to Edexcel GCSE Biology 3.4 to 3.10B, covering DNA as a double helix polymer, the genome and genes, DNA extraction, and how the base sequence controls protein synthesis by transcription and translation.
10 min answer →

How are characteristics inherited, and how do we predict the offspring of a cross?

Explain the key genetic terms, use genetic diagrams, Punnett squares and pedigrees for monohybrid inheritance and sex determination, and calculate outcomes as ratios, percentages and probabilities.
A focused answer to Edexcel GCSE Biology 3.11B to 3.18B, covering the genetic terms, monohybrid crosses with Punnett squares and pedigrees, sex determination, probability calculations, and codominance in the ABO blood groups.
11 min answer →

How do sexual and asexual reproduction differ, and what does meiosis do?

Explain the advantages and disadvantages of asexual and sexual reproduction, and the role of meiotic cell division in producing four genetically different haploid daughter cells.
A focused answer to Edexcel GCSE Biology 3.1B to 3.3, covering the advantages and disadvantages of asexual and sexual reproduction and the role of meiosis in producing four genetically different haploid gametes.
9 min answer →

What causes variation between organisms, and what effect do mutations have?

Describe how most phenotypes result from multiple genes, the genetic and environmental causes of variation, the outcomes of the Human Genome Project, and that variation arises through mutations.
A focused answer to Edexcel GCSE Biology 3.19 to 3.23, covering polygenic inheritance, the genetic and environmental causes of variation, the outcomes of the Human Genome Project, and how mutations create variation.
9 min answer →