9 The timing of gene expression is important in the developmental process
9.1 Identify the role of genes in embryonic development
9.2 Summarise the role of gene cascades in determining limb formation in birds and mammals.
9.3 Describe the evidence which indicates the presence of ancestral vertebrate gene homologues in lower animal classes
9.4 Discuss the evidence available from current research about the evolution of genes and their actions
9.5 Identify data sources, gather, process and analyse information from secondary sources and use available evidence to assess the evidence that analysis of genes provides for evolutionary relationships