Cambridge AS & A Level Biology
16.2The roles of genes in determining the phenotype
The roles of genes in determining the phenotype in Cambridge AS & A Level Biology: what the syllabus expects you to know, the learning objectives and how to practise.
Subtopic122 practice questions6 lessons
Learning objectives
What the syllabus expects you to be able to do.
- 16.2.1Explain gene, locus, allele, dominant, recessive, codominant, linkage, test cross, F1, F2, phenotype, genotype, homozygous and heterozygous.
- 16.2.2Use genetic diagrams and Punnett squares for monohybrid and dihybrid crosses with dominance, codominance, multiple alleles and sex linkage.
- 16.2.3Use genetic diagrams for dihybrid crosses with autosomal linkage and epistasis.
- 16.2.4Use genetic diagrams to explain and predict test crosses.
- 16.2.5Use the chi-squared test (formula provided) to test the significance of differences between observed and expected results.
- 16.2.6Explain how genes, proteins and phenotype are related for TYR (albinism), HBB (sickle cell anaemia), F8 (haemophilia) and HTT (Huntington's disease).
- 16.2.7Explain how the Le and le alleles affect gibberellin synthesis and stem elongation.
Lessons
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Autosomal linkage and epistasis
40 min
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Dihybrid inheritance
40 min
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Genes, proteins and phenotype
30 min
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Monohybrid inheritance and genetic diagrams
40 min
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Sex determination and sex linkage
35 min
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The chi-squared test in genetics
40 min
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Sample question
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