A-level Biology

This topic considers the ultrastructure of prokaryotes, eukaryotes and viruses. Details of the types of nuclear division are included and how these are involved in animal and plant reproduction. Microscopy and observational skills are developed through the preparation of stained plant tissue.

This topic considers the evidence used in developing models for the classification of organisms. It also considers the limitations of these models. The topic includes the principles underlying natural selection and how this can lead to speciation.

This topic considers the requirements for cell transport mechanisms and mass flow systems in organisms. The roles of the components of the mammalian circulatory system and the vascular system in plants are studied. Practical skills are developed by investigating factors that affect membrane permeability and water potential of plant tissues.

This topic builds on knowledge of carbohydrates and enzymes. It considers the energy sources in living organisms and how energy transfers occur. Details of the stages in respiration and photosynthesis, the roles of co-enzymes and electrons along with the uses of intermediates are included. Practical skills are developed in the investigations of photosynthetic pigments and the factors that affect respiration rates and photosynthesis.

This topic builds on knowledge of prokaryotes, eukaryotes, viruses and transport systems. It considers how some microorganisms act as pathogens. Details of how the human body responds to infection are included. The social, economic and ethical implications of the methods of treatment and control of the spread of infection are discussed. Microbial techniques are used in the isolation of bacteria and the investigation of the factors that affect their rate of growth.

This topic builds on the knowledge of nucleic acids and proteins and how they are involved in gene expression. It also considers epigenetics, the use of stem cells, and how these are contributing to medical advances. Finally, it discusses the ethical implications of the use of gene technology in scientific developments.

This topic builds on the knowledge of meiosis and natural selection. It considers the dihybrid inheritance of alleles and genes, studying the inheritance of unlinked and linked genes. The effect of selection pressures on the allele frequencies in gene pools and their impact on speciation are discussed.

This topic builds on knowledge of transport mechanisms and considers the processes of chemical and nervous coordination. Details of the role of plant growth substances and hormonal control in mammals are included. Osmoregulation in mammals adapted to dry environments is considered. Details of the effect of drugs on the transmission of nerve impulses are studied. Practical skills are developed in the investigation of the effect of gibberellin on germination.

This topic considers the interactions between the organisms and the environment within an ecosystem. It includes details of how biotic and abiotic factors are involved in the development of ecosystems over time. Human influences on ecosystems and the need for conservation are also discussed.