AS and A Level Biology

Explain what is meant by discontinuous variation and continuous variation

Explain, with examples, that phenotypic variation is due to genetic factors or environmental factors or a combination of genetic and environmental factors

Explain how gibberellin activates genes by causing the breakdown of DELLA protein repressors, which normally inhibit factors that promote transcription

State that transcription factors are proteins that bind to DNA and are involved in the control of gene expression in eukaryotes by decreasing or increasing the rate of transcription

Explain genetic control of protein production in a prokaryote using the lac operon (knowledge of the role of cAMP is not expected)

Describe the differences between structural genes and regulatory genes and the differences between repressible enzymes and inducible enzymes

Explain the role of gibberellin in stem elongation including the role of the dominant allele, Le, that codes for a functional enzyme in the gibberellin synthesis pathway, and the recessive allele, le, that codes for a non-functional enzyme

Explain the relationship between genes, proteins and phenotype with respect to the: • TYR gene, tyrosinase and albinism • HBB gene, haemoglobin and sickle cell anaemia • F8 gene, factor VIII and haemophilia • HTT gene, huntingtin and Huntington’s disease

Use the chi-squared test to test the significance of differences between observed and expected results (the formula for the chi-squared test will be provided, as shown in the Mathematical requirements)

Interpret and construct genetic diagrams, including Punnett squares, to explain and predict the results of test crosses