IGCSE Biology

State that continuous variation results in a range of phenotypes between two extremes; examples include body length and body mass

Use genetic diagrams to predict the results of monohybrid crosses involving codominance or sex linkage and calculate phenotypic ratios

Describe red-green colour blindness as an example of sex linkage

Describe a sex-linked characteristic as a feature in which the gene responsible is located on a sex chromosome and that this makes the characteristic more common in one sex than in the other

Explain the inheritance of ABO blood groups: phenotypes are A, B, AB and O blood groups and alleles are IA, IB and Io

Describe codominance as a situation in which both alleles in heterozygous organisms contribute to the phenotype

Explain how to use a test cross to identify an unknown genotype

Use Punnett squares in crosses which result in more than one genotype to work out and show the possible different genotypes

Use genetic diagrams to predict the results of monohybrid crosses and calculate phenotypic ratios, limited to 1:1 and 3:1 ratios

Interpret pedigree diagrams for the inheritance of a given characteristic