Cell structure is the first section of Module 2 and the foundation the rest of the course builds on. It covers the three types of microscope and how a slide is prepared and stained, magnification and resolution and the calculations behind them, the organelles of a eukaryotic cell and the route a secreted protein takes, and how prokaryotic cells differ.

• Microscopy, slide preparation and staining16
• Biological drawings, magnification and resolution15
• Eukaryotic cell ultrastructure17
• The secretory pathway and the cytoskeleton10
• Prokaryotic and eukaryotic cells compared7

Biological molecules is the second section of Module 2. It covers the properties that make water suitable for life, the structure and function of carbohydrates, lipids and proteins, the inorganic ions cells depend on, and the biochemical tests and separation techniques used to identify each group.

• The properties of water12
• Monomers, polymers and the elements of life8
• Monosaccharides and disaccharides12
• Polysaccharides and their functions11
• Lipids11
• Amino acids and protein structure15
• Globular and fibrous proteins8
• Inorganic ions10
• The biochemical tests16
• Colorimetry and chromatography10

Nucleotides and nucleic acids is the third section of Module 2. It covers what a nucleotide is made of, how nucleotides join into DNA and RNA, the structure of the double helix, how DNA copies itself semi-conservatively, and how a gene is read out into a polypeptide.

• Nucleotide structure and the bases14
• Polynucleotides, ADP and ATP11
• The structure of DNA7
• Semi-conservative DNA replication7
• The genetic code, transcription and translation13

Enzymes is the fourth section of Module 2. It covers what an enzyme does to the activation energy of a reaction, the lock and key and induced fit models of the active site, the conditions that raise and lower activity, and the cofactors, coenzymes and inhibitors that change how an enzyme works.

• Enzyme action: lock and key and induced fit13
• Factors affecting enzyme activity9
• Cofactors, coenzymes and enzyme inhibition12

Biological membranes is the fifth section of Module 2. It covers the fluid mosaic model and what each component of a membrane does, the conditions that make a membrane leak, the four ways substances cross it, and osmosis in animal and plant cells.

• Membrane structure and the fluid mosaic model21
• Factors affecting membrane permeability6
• Diffusion, active transport, endocytosis and exocytosis13
• Osmosis and water potential16

Cell division, cell diversity and cellular organisation closes Module 2. It covers the cell cycle and its checkpoints, the stages of mitosis and meiosis and what each one produces, how cells specialise for particular jobs, the tissues and organs they build, and stem cells.

• The cell cycle8
• Mitosis and observing it in root tips20
• Meiosis17
• Specialised cells16
• Tissues, organs and organ systems9
• Stem cells and differentiation10

Exchange surfaces is the first section of Module 3, examined on Biological Processes. It covers why surface area to volume ratio forces large organisms to develop exchange surfaces, the mammalian airways and how ventilation works, lung volumes measured on a spirometer, and gas exchange in fish and insects.

• Surface area to volume and the features of an exchange surface12
• The mammalian gas exchange system14
• Ventilation and lung volumes12
• Gas exchange in fish and insects12
• Dissecting and examining gas exchange tissue14

Transport in animals is the second section of Module 3. It covers single and double circulation, the structure of arteries, veins and capillaries, how tissue fluid forms and returns, the mammalian heart and the cardiac cycle, the electrocardiogram, and how blood carries oxygen and carbon dioxide.

• Why animals need transport systems12
• Arteries, veins and capillaries16
• Tissue fluid and lymph10
• The structure of the mammalian heart16
• The cardiac cycle and control of the heartbeat15
• The electrocardiogram11
• Transporting oxygen and carbon dioxide13
• Oxygen dissociation curves and the Bohr effect7

Transport in plants closes Module 3. It covers xylem and phloem and how they are arranged in root, stem and leaf, transpiration and the potometer, the pathways water takes from soil to leaf, the adaptations of xerophytes and hydrophytes, and translocation from source to sink.

• Xylem, phloem and vascular tissue17
• Transpiration and the potometer10
• Water uptake and movement up the xylem10
• Xerophytes and hydrophytes9
• Translocation10

Communicable diseases, disease prevention and the immune system opens Module 4, examined on Biological Diversity. It covers the four types of pathogen and how they spread, the defences of plants and animals, phagocytosis and the specific immune response, antibodies, the forms of immunity and vaccination, and antibiotic resistance.

• Pathogens and how disease is transmitted17
• Plant defences and non-specific animal defences12
• Phagocytes and phagocytosis8
• The specific immune response12
• Antibodies7
• Types of immunity10
• Vaccination8
• Medicines and antibiotic resistance11

Biodiversity is the second section of Module 4. It covers the three levels at which biodiversity is measured, the sampling methods used to estimate it, Simpson's Index of Diversity and the calculation behind it, what threatens biodiversity and why it is worth keeping, and conservation in situ and ex situ.

• The three levels of biodiversity15
• Sampling methods and equipment14
• Simpson's Index of Diversity12
• Measuring genetic biodiversity7
• Threats to biodiversity and reasons to maintain it8
• Conservation: in situ and ex situ11

Classification and evolution closes Module 4. It covers the taxonomic hierarchy and binomial naming, the five kingdoms and the three domains, phylogeny and the evidence that supports evolution, the sources of variation and the kinds of adaptation, and natural selection.

• The taxonomic hierarchy and binomial naming10
• The five kingdoms and the three domains14
• Phylogeny and the evidence for evolution6
• Variation and adaptation10
• Natural selection and resistance8

Communication and homeostasis opens Module 5, examined on Biological Processes. It covers why a multicellular organism needs a communication system, cell signalling, the receptors and effectors that make up a homeostatic loop, negative and positive feedback, and how endotherms and ectotherms hold body temperature steady.

• Cell signalling and communication systems8
• Homeostasis, negative and positive feedback7
• Thermoregulation in endotherms and ectotherms14

Excretion as an example of homeostatic control is the second section of Module 5. It covers why nitrogenous waste must become urea, the structure of the liver, the nephron and the stages of filtration and reabsorption, how ADH controls water balance, kidney failure and its treatments, and what a urine test can detect.

• Excretion and nitrogenous waste9
• The liver: structure and function18
• The structure of the kidney11
• The nephron17
• Ultrafiltration8
• Selective reabsorption and the loop of Henle13
• Osmoregulation and ADH9
• Kidney failure, dialysis and transplant15
• Urine testing and monoclonal antibodies6

Neuronal communication is the third section of Module 5. It covers how a sensory receptor turns a stimulus into a generator potential, the types of neurone and why myelination speeds transmission, the resting and action potentials, and how an impulse crosses a synapse.

• Sensory receptors and the Pacinian corpuscle8
• Types of neurone and myelination9
• Resting potential and the action potential17
• Transmission across a cholinergic synapse12
• Summation and inhibitory synapses7

Hormonal communication is the fourth section of Module 5. It covers how a hormone reaches its target and why only some cells respond, the adrenal glands and their hormones, the islets of Langerhans and the control of blood glucose by insulin and glucagon, and the two types of diabetes and how they are treated.

• Hormones and the adrenal glands13
• The pancreas and the islets of Langerhans6
• Controlling blood glucose13
• Diabetes and its treatment11

Plant and animal responses is the fifth section of Module 5. It covers tropisms and the hormones behind them and their commercial uses, the organisation of the nervous system, the reflex arc, fight or flight and the control of heart rate, and how a muscle contracts.

• Tropisms and plant responses to stress and herbivory11
• Plant hormones and their commercial uses16
• The nervous system and the brain10
• Reflex actions and the knee jerk reflex8
• Fight or flight and the control of heart rate12
• The structure of skeletal muscle7
• The neuromuscular junction and the sliding filament model13

Photosynthesis is the sixth section of Module 5. It covers the structure of the chloroplast and where each stage happens, the pigments and how chromatography separates them, the light-dependent reactions and photophosphorylation, the Calvin cycle, and the factors that limit the rate.

• Photosynthesis and chloroplast structure14
• Photosynthetic pigments and chromatography8
• The light-dependent stage10
• The Calvin cycle8
• Limiting factors14

Respiration closes Module 5. It covers the mitochondrion and the role of ATP, glycolysis, the link reaction and the Krebs cycle, oxidative phosphorylation and chemiosmosis, what happens when oxygen runs out, and how the respiratory quotient identifies the substrate being used.

• Respiration, ATP and the mitochondrion10
• Glycolysis8
• The link reaction and the Krebs cycle14
• Oxidative phosphorylation and chemiosmosis9
• Anaerobic respiration7
• Respiratory substrates and the respiratory quotient19

Cellular control opens Module 6, examined on Biological Diversity. It covers the three kinds of gene mutation and their effects, the lac operon as a model of gene regulation, transcription factors and splicing, the homeobox and Hox genes that lay out a body plan, apoptosis, and how mutation leads to cancer.

• Gene mutations and their effects10
• The lac operon10
• Transcription factors and post-transcriptional control11
• Homeobox and Hox genes9
• Mitosis and apoptosis9
• Oncogenes, tumour suppressor genes and cancer13

Patterns of inheritance is the second section of Module 6. It covers what makes a phenotype vary, monogenic and dihybrid crosses and the patterns that depart from them, the chi-squared test, the forms of selection and the drift acting on small populations, the Hardy-Weinberg equations, speciation, and artificial selection.

• Genetic and environmental variation9
• Monogenic and dihybrid inheritance, sex linkage and epistasis12
• The chi-squared test6
• Selection, genetic drift and the founder effect10
• The Hardy-Weinberg principle9
• Speciation and isolating mechanisms7
• Artificial selection13

Manipulating genomes is the third section of Module 6. It covers DNA sequencing and what bioinformatics does with the result, DNA profiling and the polymerase chain reaction, gel electrophoresis, the enzymes and vectors used to move a gene between organisms, and the ethics of doing so.

• DNA sequencing and bioinformatics11
• DNA profiling, PCR and gel electrophoresis13
• Genetic engineering: restriction enzymes and vectors8
• Genetic modification, its ethics, and gene therapy10

Cloning and biotechnology is the fourth section of Module 6. It covers natural and artificial plant cloning, micropropagation, embryo twinning and nuclear transfer in animals, the arguments for and against each, microorganisms in food and medicine, aseptic technique and fermentation, and immobilised enzymes.

• Natural plant cloning and taking cuttings15
• Micropropagation8
• Advantages and disadvantages of plant cloning10
• Animal cloning: embryo twinning and nuclear transfer11
• Advantages and disadvantages of animal cloning10
• Microorganisms in food production20
• Aseptic technique8
• Fermentation and its conditions7
• The microbial growth curve14
• Immobilised enzymes14

Ecosystems is the fifth section of Module 6. It covers the biotic and abiotic factors that shape an ecosystem, why so little biomass passes between trophic levels, the nitrogen and carbon cycles, succession from pioneer species to climax community, and how distribution and abundance are estimated.

• Ecosystems, biotic and abiotic factors9
• Biomass transfer between trophic levels13
• The nitrogen and carbon cycles16
• Succession, distribution and abundance14

Populations and sustainability closes Module 6. It covers what sets the size of a population and its carrying capacity, predator and prey cycles, competition within and between species, the difference between conservation and preservation, sustainable timber and fishing, and how human impacts are controlled.

• Population size and limiting factors16
• Predator-prey cycles and competition7
• Conservation and preservation9
• Sustainable timber production and fishing8
• Human impacts and how they are controlled9