B2 Genome, Cell Division and Genetics
DNA, genes, chromosomes, mitosis, meiosis, alleles, genetic crosses, sex determination and inherited disorders.
How to study for CCEA GCSE Double Award Science
Build each scientific explanation from a model or relationship, show quantitative working, and connect every practical claim to controlled evidence and evaluation.
Core concepts
Concept 1
Genes are DNA sequences on chromosomes, and alleles are alternative forms that contribute to inherited variation.
Exam cue: Identify the scientific model, relationship or practical evidence required by the command word.
Concept 2
Mitosis produces genetically identical diploid cells, whereas meiosis produces genetically varied haploid gametes.
Exam cue: Define symbols, show gametes and distinguish genotype probability from phenotype ratio.
Concept 3
Genetic diagrams connect parental genotypes, gametes and offspring probabilities without predicting an individual outcome.
Exam cue: Use the current CCEA specification formatting and entered tier to decide whether Higher-only detail applies.
Risk pitfalls and guardrails
Treating a dominant allele as common, stronger or guaranteed to spread through a population.
Guardrail: Do not import another board or science route, omit units from a calculation, or make a scientific claim beyond the stated evidence.
Giving a remembered fact without connecting it to the stated data, observation or scenario.
Guardrail: Do not import another board or science route, omit units from a calculation, or make a scientific claim beyond the stated evidence.
Importing content or paper structure from a separate-science or non-CCEA specification.
Guardrail: Do not import another board or science route, omit units from a calculation, or make a scientific claim beyond the stated evidence.
Memory anchors
Gene
Length of DNA carrying information for a characteristic or product.
Allele
Alternative form of a gene.
Genotype
Allele combination carried by an organism.
Phenotype
Observable feature produced by genotype and environment.
Mitosis
Cell division producing genetically identical diploid cells.
Meiosis
Cell division producing genetically varied haploid gametes.
Checkpoint rule
Do the check-up only after you can summarize each concept in one sentence and identify one dangerous pitfall from memory.
Knowledge Check (after reading)
Short check-up to confirm understanding of this module.
Check-up Questions
Which description best defines a gene?
At one gene locus, what is an allele?
Answer all questions to submit.
Next step personalized recommendations
Continue learning
Move forward only after this module is stable.
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