Work through the list without notes. If you cannot do a statement, follow its link, then come back. Guide = study guide; Practice = practice questions.
Understanding
- I can define gene, allele, genotype, phenotype, homozygous and heterozygous, and give an example of each. (Guide: “From chromosomes to traits”)
- I can explain the law of segregation by describing what happens to homologous chromosomes in meiosis I. (Guide: “The law of segregation”)
- I can explain independent assortment using the orientation of homologous pairs at metaphase I, and say why it does not apply to linked genes. (Guide: Figure 1; Practice Q6)
- I can explain why an allele for a non-functional enzyme is usually recessive, and predict when a mutant allele would be dominant instead. (Guide: “Why is one allele dominant?”; Practice Q7)
- I can explain how fertilization restores the diploid number and creates new combinations of alleles. (Guide: “The law of segregation”)
Calculation and skills
- I can draw a Punnett square and give both the genotypic and the phenotypic ratio, without confusing them. (Guide: Figure 2; Worked example 1)
- I can use the product rule and the sum rule to find the probability of an offspring genotype or phenotype for two or three genes. (Guide: “The rules of probability”; Practice Q2, Q7)
- I can find a conditional probability, such as the chance that an unaffected child of two carriers is a carrier. (Guide: “Reading pedigrees”; Practice Q5, Q7)
- I can calculate expected counts, χ² and degrees of freedom, and compare χ² with the critical value at p = 0.05. (Guide: Worked example 2; Practice Q4, Q6)
Reasoning
- I can use a test cross to work out the genotype of an individual with the dominant phenotype. (Guide: “Crosses as tools”; Practice Q1)
- I can read a pedigree, decide whether a trait is dominant or recessive and autosomal or X-linked, and justify each decision with evidence. (Guide: Figure 3; Practice Q3, Q5)
- I can write a null hypothesis that names the expected ratio, and conclude “reject” or “fail to reject” with a reason. (Guide: “The chi-square test”; Practice Q4, Q6)
- I can recognise when cross data point to linked genes rather than independent assortment. (Guide: Worked example 2; Practice Q6)
All ticked? Move on to Topic 5.4, Non-Mendelian Genetics, or return to the course roadmap.