What does the genetics and cell division module cover?

This module covers Unit 2 sections 2.3 to 2.4: chromosomes, genes and DNA and the double helix, how genes code for proteins through transcription and translation, mitosis and meiosis, monohybrid inheritance with Punnett squares, and sex determination and the inheritance of genetic disorders such as cystic fibrosis.

Which exam assesses this module?

These topics are part of Unit 2 Body Systems, Genetics, Microorganisms and Health, a written paper worth 40 percent of the GCSE. Foundation tier lasts 1 hour 30 minutes and Higher tier lasts 1 hour 45 minutes, and a calculator is allowed for working out ratios and probabilities.

What is the difference between mitosis and meiosis?

Mitosis produces two genetically identical cells with the full chromosome number, used for growth and repair. Meiosis produces four genetically different gametes with half the chromosome number, used in sexual reproduction. Halving the number in meiosis means fertilisation restores the full number, and the shuffling of genes creates variation.

How do I do a genetic cross?

Write the parents' genotypes, work out the alleles in each parent's gametes, then draw a Punnett square with one parent's gametes along the top and the other's down the side. Fill in the boxes to get the offspring genotypes, then read off the genotype and phenotype ratios. Remember a ratio is an expected average, not a guarantee for each birth.

How should I revise this module?

Learn the nested relationship of nucleus, chromosome, gene and DNA, the base pairs, and the steps of protein synthesis. Memorise the contrasts between mitosis and meiosis. Drill Punnett squares for monohybrid crosses, sex determination and recessive disorders until they are automatic, then practise CCEA past-paper genetic-diagram questions.

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CCEA GCSE Biology: Genetics and cell division overview

An overview of the genetics and cell division module of CCEA GCSE Biology (Unit 2 sections 2.3 to 2.4), mapping chromosomes, genes and DNA, protein synthesis, mitosis and meiosis, monohybrid inheritance, and sex determination and genetic disorders, and how they are examined.

Generated by Claude Opus 4.87 min readCCEA 6568 Unit 2.3 to 2.4Updated 2026-06-14

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What this module covers
How it is examined
How to study it

This module is about how genetic information is stored, copied and passed on. It covers Unit 2 sections 2.3 to 2.4 and is examined on the Unit 2 written paper. This page maps the topics and links to a focused answer page for each.

What this module covers

Chromosomes, genes and DNA: How the nucleus, chromosomes, genes and DNA relate, the double helix and base pairing, the human chromosome number, and how genes control characteristics. Start with Chromosomes, genes and DNA.
Protein synthesis: How the base sequence of a gene codes for amino acids, transcription and translation, the roles of mRNA and ribosomes, and how mutations change proteins. See Protein synthesis.
Mitosis and meiosis: Mitosis for growth and repair, meiosis for gametes, and why meiosis creates variation. See Mitosis and meiosis.
Monohybrid inheritance: The key genetic terms, dominant and recessive alleles, genotype and phenotype, and Punnett squares. See Monohybrid inheritance.
Sex determination and genetic disorders: The X and Y chromosomes, the cross for boy or girl, and the inheritance of recessive disorders such as cystic fibrosis. See Sex determination and genetic disorders.

How it is examined

These topics appear on Unit 2, worth 40% of the GCSE. Expect structured questions on DNA structure and base pairing, the steps of protein synthesis, the contrasts between mitosis and meiosis, and Punnett-square crosses for inheritance, sex and disorders, often with a ratio or probability to calculate.

How to study it

Learn the nested structure from nucleus to DNA, the base pairs, and the steps of protein synthesis. Memorise the mitosis-versus-meiosis contrasts. The key skill is the Punnett square: practise it for monohybrid crosses, sex determination and recessive disorders until it is automatic. Then work through CCEA past papers and finish with the module quiz.

Sources & how we know this

CCEA GCSE Biology specification — CCEA (2017)