AQA A-Level Biology Syllabus

• • 31 min read
Make us preferred on Google
Summarise with AI:

AQA A-Level Biology Syllabus (7402) – Topics and Lessons

The AQA A-Level Biology Syllabus (7402) covers the main biological concepts, processes and practical skills that students need to study for the AQA A-Level Biology examination. The syllabus contains eight main topics, including Biological Molecules, Cells, Exchange of Substances, Genetic Information and Variation, Energy Transfers, Responses to the Environment, Genetics and Evolution, and the Control of Gene Expression.

The first four topics are studied in both AS Biology (7401) and A-Level Biology (7402). The remaining four topics are studied only at A-Level. The syllabus also includes 12 required practical activities, mathematical skills, scientific investigations and the analysis of biological data.

This page provides the AQA A-Level Biology syllabus in a topic-wise and lesson-wise format. Each lesson includes a short description of the main concepts students need to study. The required practical activities are included under their relevant topics. The content is organised according to the AQA Biology specification, Version 1.6, July 2026.

1. Biological Molecules

1.1 Monomers and Polymers

  • Monomers and Polymers – Study monomers as small molecular units and polymers as large molecules formed from repeated monomers. Learn about monosaccharides, amino acids and nucleotides as biological monomers.
  • Condensation and Hydrolysis Reactions – Learn how condensation reactions join molecules by forming chemical bonds with the removal of water. Study how hydrolysis reactions break these bonds using water molecules.

1.2 Carbohydrates

  • Monosaccharides – Study the structure and functions of simple sugars, including glucose, fructose and galactose. Learn about the structural differences between alpha-glucose and beta-glucose.
  • Disaccharides – Learn how two monosaccharides combine through condensation to form a glycosidic bond. Study the formation of maltose, sucrose and lactose and the monosaccharides present in each.
  • Polysaccharides – Study the structure and functions of starch, glycogen and cellulose. Understand how their glycosidic bonds, branching and molecular arrangements relate to energy storage and structural support.
  • Biochemical Tests for Carbohydrates – Learn how Benedict’s reagent is used to test for reducing and non-reducing sugars. Study the iodine test for starch and the interpretation of positive and negative results.

1.3 Lipids

  • Triglycerides – Study the structure of triglycerides formed from glycerol and three fatty acids. Learn how ester bonds are formed and how triglycerides function as energy stores.
  • Phospholipids – Learn the structure of phospholipids and their role in cell membranes. Study the properties of hydrophilic phosphate-containing groups and hydrophobic fatty acid tails.
  • Saturated and Unsaturated Fatty Acids – Study the structural differences between saturated and unsaturated fatty acids. Learn how these differences influence the properties of lipids.
  • Emulsion Test for Lipids – Learn how the ethanol emulsion test is used to detect lipids in biological samples.

1.4 Proteins

  • Amino Acids and Peptide Bonds – Study the general structure of amino acids, including the amino group, carboxyl group and variable R group. Learn how condensation reactions form peptide bonds, dipeptides and polypeptides.
  • Protein Structure – Study the primary, secondary, tertiary and quaternary structures of proteins. Understand the roles of hydrogen bonds, ionic bonds and disulfide bridges in maintaining protein structure.
  • Protein Structure and Function – Learn how the three-dimensional structure of a protein determines its biological function. Study the structural properties of proteins found in different biological systems.
  • Biuret Test for Proteins – Study the use of Biuret reagent to identify proteins in biological samples and interpret the resulting colour change.

1.5 Enzymes

  • Enzyme Structure and Function – Study enzymes as biological catalysts that reduce the activation energy of reactions. Learn about active sites, substrate specificity and the formation of enzyme-substrate complexes.
  • Mechanism of Enzyme Action – Learn the induced-fit model of enzyme action and how enzyme and substrate interactions allow reactions to occur.
  • Factors Affecting Enzyme Activity – Study the effects of temperature, pH, enzyme concentration and substrate concentration on enzyme-controlled reactions. Learn how these factors affect reaction rates.
  • Enzyme Inhibition – Study competitive and non-competitive inhibition. Understand how inhibitor concentration affects enzyme activity and the formation of enzyme-substrate complexes.
  • Required Practical 1: Enzyme Activity – Investigate how a selected variable affects the rate of an enzyme-controlled reaction. Measure reaction rates, control variables and analyse the experimental results.

1.6 Nucleic Acids

  • Structure of DNA and RNA – Study DNA and RNA as polymers of nucleotides. Learn the components of DNA and RNA nucleotides, including pentose sugars, phosphate groups and nitrogenous bases.
  • DNA Double Helix Structure – Learn how two polynucleotide strands form the DNA double helix. Study complementary base pairing, hydrogen bonds and phosphodiester bonds.
  • Differences Between DNA and RNA – Compare DNA and RNA in terms of sugar, nitrogenous bases, number of polynucleotide strands and biological functions.
  • Semi-Conservative DNA Replication – Study DNA replication involving DNA helicase, complementary base pairing and DNA polymerase. Understand how each new DNA molecule contains one original strand and one newly synthesised strand.
  • Experimental Evidence for DNA Replication – Learn how scientific evidence was used to support the semi-conservative model of DNA replication.

1.7 ATP

  • Structure of ATP – Study adenosine triphosphate as a nucleotide derivative containing adenine, ribose and three phosphate groups.
  • ATP Hydrolysis and Energy Transfer – Learn how ATP hydrolysis produces ADP and inorganic phosphate. Study the role of ATP in energy-requiring reactions and phosphorylation of molecules.
  • ATP Synthesis – Study the formation of ATP from ADP and inorganic phosphate, including the role of ATP synthase during photosynthesis and respiration.

1.8 Water and Inorganic Ions

  • Biological Importance of Water – Study water as a solvent and metabolite. Learn about its high heat capacity, latent heat of vaporisation, cohesion and role in biological transport.
  • Inorganic Ions in Living Organisms – Study the roles of hydrogen ions, iron ions, sodium ions and phosphate ions. Understand their importance in pH, haemoglobin, co-transport, DNA and ATP.

2. Cells

2.1 Cell Structure

2.2 Cell Division

  • Cell Cycle – Study interphase and mitosis as parts of the eukaryotic cell cycle. Learn when DNA replication occurs and how cells prepare for division.
  • Stages of Mitosis – Study prophase, metaphase, anaphase and telophase. Learn about chromosome behaviour, spindle fibres and the separation of sister chromatids.
  • Cytokinesis – Learn how the cytoplasm divides following nuclear division to produce two daughter cells.
  • Regulation of Cell Division and Cancer – Study the control of mitosis and how uncontrolled cell division can lead to tumours and cancers. Understand how some cancer treatments target cell division.
  • Binary Fission in Prokaryotes – Study bacterial reproduction by binary fission, including DNA replication and division of the cytoplasm.
  • Viral Replication – Learn how viruses use host cells to produce new viral particles instead of dividing independently.
  • Required Practical 2: Mitosis in Root Tips – Prepare stained root tip squashes and observe mitotic stages using a light microscope. Calculate the mitotic index and determine actual cell sizes.

2.3 Transport Across Cell Membranes

  • Fluid Mosaic Model of Cell Membranes – Study the arrangement of phospholipids, proteins, glycoproteins and glycolipids in biological membranes. Learn about membrane fluidity and the role of cholesterol.
  • Simple Diffusion – Study the passive movement of substances down concentration gradients. Learn how the phospholipid bilayer affects the movement of different molecules.
  • Facilitated Diffusion – Learn how channel proteins and carrier proteins transport substances across membranes without ATP.
  • Osmosis and Water Potential – Study the movement of water across partially permeable membranes in relation to water potential gradients.
  • Active Transport – Learn how carrier proteins use energy from ATP hydrolysis to move substances against concentration gradients.
  • Co-Transport – Study the absorption of glucose and sodium ions by epithelial cells lining the mammalian ileum.
  • Adaptations for Membrane Transport – Learn how membrane surface area, transport proteins and concentration gradients affect transport rates.
  • Required Practical 3: Water Potential of Plant Tissue – Prepare a dilution series of a solute and use experimental measurements to produce a calibration curve for determining the water potential of plant tissue.
  • Required Practical 4: Cell Membrane Permeability – Investigate how a selected variable affects the permeability of cell-surface membranes.

2.4 Cell Recognition and the Immune System

  • Cell Recognition and Antigens – Study cell-surface molecules involved in recognising self and foreign material. Learn the definition of antigens and how antigen variation affects disease prevention.
  • Phagocytosis – Learn how phagocytes engulf pathogens and destroy them using hydrolytic enzymes.
  • T Lymphocytes and Cellular Immunity – Study antigen-presenting cells and the role of helper T cells in activating cytotoxic T cells, B cells and phagocytes.
  • B Lymphocytes and Humoral Immunity – Learn about clonal selection, antibody production and the development of plasma cells and memory cells.
  • Antibody Structure and Function – Study antibody structure and antigen-antibody complexes. Learn how antibodies contribute to agglutination and the phagocytosis of bacterial cells.
  • Primary and Secondary Immune Responses – Compare immune responses during the first and subsequent exposure to an antigen. Study the role of memory cells.
  • Vaccination and Herd Immunity – Learn how vaccines stimulate immunity and provide protection against infectious diseases. Study the concept of herd immunity and ethical issues associated with vaccination.
  • Active and Passive Immunity – Compare immunity produced through an individual’s immune response with immunity provided by transferred antibodies.
  • HIV and AIDS – Study the structure of human immunodeficiency virus and its replication in helper T cells. Learn how HIV damages the immune system and causes AIDS.
  • Monoclonal Antibodies – Study the use of monoclonal antibodies in medical diagnosis and targeted treatment. Learn about their benefits, limitations and ethical considerations.
  • ELISA Test – Learn how enzyme-linked immunosorbent assay uses antibodies to detect specific antigens or antibodies in biological samples.

3. Organisms Exchange Substances with Their Environment

3.1 Surface Area to Volume Ratio

  • Surface Area to Volume Ratio – Study how the relationship between surface area and volume changes as the size of an organism increases. Learn how to calculate surface area-to-volume ratios.
  • Adaptations for Efficient Exchange – Learn how body shape, exchange surfaces and mass transport systems help organisms maintain efficient exchange of substances.
  • Surface Area, Diffusion and Metabolic Rate – Study the relationship between surface area-to-volume ratio, diffusion and the metabolic requirements of organisms.

3.2 Gas Exchange

  • Gas Exchange in Single-Celled Organisms – Learn how small unicellular organisms exchange gases directly across their body surfaces.
  • Gas Exchange in Insects – Study the tracheal system, including spiracles, tracheae and tracheoles. Learn how insects exchange gases while limiting water loss.
  • Gas Exchange in Fish – Study gill filaments and lamellae. Learn how counter-current flow maintains diffusion gradients for oxygen absorption.
  • Gas Exchange in Plants – Study the roles of stomata and mesophyll tissues in gas exchange. Learn about adaptations of xerophytic plants that reduce water loss.
  • Human Gas Exchange System – Study the structure of the lungs, trachea, bronchi, bronchioles and alveoli. Learn how alveoli are adapted for efficient gas exchange.
  • Mechanism of Breathing – Learn how the diaphragm and intercostal muscles produce pressure changes during inspiration and expiration.
  • Lung Disease and Gas Exchange – Study how lung diseases, smoking and air pollution affect ventilation and gas exchange. Learn to interpret data involving risk factors and disease incidence.

3.3 Digestion and Absorption

3.4 Mass Transport in Animals

  • Haemoglobin Structure and Function – Study haemoglobin as a protein with quaternary structure. Learn about its role in oxygen transport.
  • Oxygen Dissociation Curve – Study oxygen loading and unloading by haemoglobin. Learn about cooperative oxygen binding and the shape of the oxyhaemoglobin dissociation curve.
  • Bohr Effect – Learn how changes in carbon dioxide concentration affect the affinity of haemoglobin for oxygen.
  • Adaptations of Haemoglobin – Study how haemoglobins from different organisms show different oxygen transport properties.
  • Human Circulatory System – Study the general pattern of blood circulation in mammals, including the major vessels associated with the heart, lungs and kidneys.
  • Structure of the Human Heart – Learn the main structures of the heart and their functions in maintaining unidirectional blood flow.
  • Cardiac Cycle – Study changes in pressure and volume during atrial and ventricular contraction and relaxation. Learn how heart valves control blood flow.
  • Blood Vessels – Compare the structure and functions of arteries, arterioles, veins and capillaries.
  • Tissue Fluid Formation – Learn how fluid moves out of capillaries to form tissue fluid and how it returns to the circulatory system.
  • Cardiovascular Disease – Study risk factors associated with cardiovascular disease and the interpretation of epidemiological evidence.
  • Required Practical 5: Dissection of an Exchange or Transport System – Dissect an animal or plant gas exchange system, mass transport system or an organ within such a system. Observe and identify structures related to their functions.

3.5 Mass Transport in Plants

  • Xylem and Water Transport – Study the structure and function of xylem tissue. Learn the cohesion-tension theory explaining water transport through plants.
  • Phloem and Translocation – Study the transport of organic substances through phloem. Learn the mass flow hypothesis and the movement of assimilates between sources and sinks.
  • Evidence for Translocation – Learn how tracer experiments and ringing experiments provide evidence for the movement of substances in phloem.
  • Transpiration and Water Movement – Study how water loss from leaves contributes to water movement through plants and how environmental conditions influence transpiration.

4. Genetic Information, Variation and Relationships Between Organisms

4.1 DNA, Genes and Chromosomes

  • DNA Organisation in Prokaryotes and Eukaryotes – Compare circular DNA in prokaryotic cells with linear DNA associated with histones in eukaryotic chromosomes.
  • Genes and Loci – Study genes as DNA sequences that code for polypeptides or functional RNA molecules. Learn how each gene occupies a particular locus on a DNA molecule.
  • Genetic Code – Study DNA base triplets and their relationship with amino acid sequences. Learn why the genetic code is described as universal, non-overlapping and degenerate.
  • Coding and Non-Coding DNA – Learn about exons, introns and non-coding repetitive DNA sequences in eukaryotic genomes.

4.2 DNA and Protein Synthesis

4.3 Genetic Diversity Through Mutation and Meiosis

  • Gene Mutations – Study changes in DNA base sequences, including base substitution and deletion. Learn how mutations may affect the amino acid sequence of proteins.
  • Chromosome Mutations – Study chromosome non-disjunction during meiosis and how it can alter chromosome numbers.
  • Meiosis – Learn how two successive nuclear divisions produce haploid daughter cells from a diploid parent cell.
  • Independent Segregation of Chromosomes – Study how the random separation of homologous chromosomes produces genetically different gametes.
  • Crossing Over – Learn how the exchange of genetic material between homologous chromosomes increases genetic variation.
  • Random Fertilisation – Study how the random fusion of genetically different gametes increases variation among offspring.
  • Mitosis and Meiosis Comparison – Compare the number of divisions, chromosome numbers and genetic composition of cells produced by mitosis and meiosis.

4.4 Genetic Diversity and Adaptation

  • Genetic Diversity – Study genetic diversity as the number of different alleles within a population. Learn why genetic diversity is important for natural selection.
  • Natural Selection – Learn how mutations produce new alleles and how advantageous alleles may increase in frequency through differential reproductive success.
  • Directional and Stabilising Selection – Study directional selection using antibiotic resistance in bacteria and stabilising selection using human birth weight.
  • Adaptations – Learn how anatomical, physiological and behavioural adaptations improve the survival and reproductive success of organisms.
  • Antibiotic Resistance – Study the development of antibiotic-resistant bacteria through mutation and natural selection.
  • Required Practical 6: Antimicrobial Substances – Use aseptic techniques to investigate how antimicrobial substances affect microbial growth.

4.5 Species and Taxonomy

  • Species Concept – Study species identification based on the ability of organisms to interbreed and produce fertile offspring.
  • Courtship Behaviour and Species Recognition – Learn how courtship behaviour contributes to mate recognition and successful reproduction.
  • Biological Classification – Study hierarchical classification using domain, kingdom, phylum, class, order, family, genus and species.
  • Binomial Nomenclature – Learn how organisms are named using a two-part scientific naming system.
  • Phylogenetic Classification – Study how evolutionary relationships are used to classify organisms. Learn how DNA sequencing and immunological evidence help determine relationships.

4.6 Biodiversity Within a Community

  • Biodiversity – Study biological diversity at different geographical scales and its importance in communities.
  • Species Richness – Learn how the number of different species is used to describe biodiversity.
  • Index of Diversity – Study how species abundance and richness are combined in an index of diversity. Learn to calculate and interpret diversity indices.
  • Farming and Biodiversity – Study how intensive agricultural practices can reduce biodiversity and the need to balance food production with conservation.

4.7 Investigating Diversity

  • Measuring Genetic Diversity – Study how genetic diversity is investigated using observable characteristics, DNA base sequences, mRNA sequences and amino acid sequences.
  • Molecular Evidence of Evolutionary Relationships – Learn how differences in DNA and protein sequences provide evidence of relationships between organisms.
  • Sampling and Statistical Analysis – Study random sampling, mean values and standard deviation as methods of analysing variation within a species.

5. Energy Transfers in and Between Organisms (A-Level Only)

5.1 Photosynthesis

  • Photosynthesis Overview – Study how chlorophyll absorbs light energy and how photosynthesis produces organic compounds from carbon dioxide and water.
  • Light-Dependent Reaction – Learn about photoionisation of chlorophyll, electron transfer and the formation of ATP and reduced NADP.
  • Photolysis of Water – Study how water is split during the light-dependent reaction to produce electrons, protons and oxygen.
  • Chemiosmosis in Photosynthesis – Learn how electron transport and proton gradients across chloroplast membranes are involved in ATP synthesis.
  • Light-Independent Reaction (Calvin Cycle) – Study carbon fixation involving ribulose bisphosphate (RuBP), glycerate 3-phosphate (GP), triose phosphate and the enzyme rubisco.
  • Regeneration of RuBP – Learn how ATP and reduced NADP are used in the Calvin cycle and how triose phosphate contributes to RuBP regeneration and the synthesis of organic substances.
  • Limiting Factors of Photosynthesis – Study the effects of light intensity, carbon dioxide concentration and temperature on photosynthesis. Learn how limiting factors influence agricultural productivity.
  • Required Practical 7: Photosynthetic Pigment Chromatography – Separate and investigate pigments extracted from leaves using chromatography.
  • Required Practical 8: Chloroplast Dehydrogenase Activity – Investigate how a selected factor affects the rate of dehydrogenase activity in chloroplast extracts.

5.2 Respiration

  • Cellular Respiration and ATP Production – Study how respiratory substrates are broken down and how respiration provides ATP for cellular activities.
  • Glycolysis – Learn how glucose is phosphorylated and converted to pyruvate. Study the production of ATP and reduced NAD during glycolysis.
  • Anaerobic Respiration – Study the conversion of pyruvate to lactate or ethanol and how NAD is regenerated to maintain glycolysis.
  • Link Reaction – Learn how pyruvate is converted to acetylcoenzyme A before entering the Krebs cycle.
  • Krebs Cycle – Study the oxidation reactions of the Krebs cycle and the production of reduced coenzymes, ATP and carbon dioxide.
  • Electron Transport Chain and Oxidative Phosphorylation – Learn how electrons pass along the electron transport chain and how proton gradients drive ATP synthesis in mitochondria.
  • Chemiosmotic Theory of ATP Synthesis – Study the role of mitochondrial membranes, proton movement and ATP synthase in ATP formation.
  • Alternative Respiratory Substrates – Learn how the breakdown products of lipids and amino acids can be used in aerobic respiration.
  • Required Practical 9: Rate of Respiration – Investigate how a selected variable affects the respiration rate of cultures of single-celled organisms.

5.3 Energy and Ecosystems

  • Biomass and Energy Storage – Study biomass as biological material containing stored chemical energy. Learn how dry mass and calorimetry can be used to estimate energy content.
  • Gross Primary Production (GPP) – Study the total chemical energy stored by producers through photosynthesis.
  • Net Primary Production (NPP) – Learn how respiratory losses affect the energy available for plant growth and other trophic levels. Use the relationship NPP = GPP − R.
  • Secondary Production – Study energy transfer to consumers and how ingestion, waste production and respiration affect net production.
  • Productivity and Energy Transfer – Learn how primary and secondary productivity are measured and how energy passes between trophic levels.
  • Improving Energy Transfer Efficiency – Study farming practices that reduce energy losses and increase the efficiency of food production.

5.4 Nutrient Cycles

  • Nutrient Recycling in Ecosystems – Study how nutrients are recycled between organisms and their environment.
  • Nitrogen Cycle – Learn about nitrogen fixation, ammonification, nitrification and denitrification. Study the role of microorganisms in these processes.
  • Phosphorus Cycle – Study the movement and recycling of phosphorus within ecosystems.
  • Decomposition and Saprobionts – Learn how saprobiotic microorganisms break down dead organic material and release nutrients.
  • Mycorrhizal Associations – Study how mycorrhizal fungi help plants absorb water and inorganic ions.
  • Fertilisers and Eutrophication – Learn why natural and artificial fertilisers are applied to agricultural land. Study nutrient leaching and eutrophication as environmental consequences.

6. Organisms Respond to Changes in Their Internal and External Environments (A-Level Only)

6.1 Survival and Response

  • Stimuli and Responses – Study how organisms detect and respond to changes in their internal and external environments.
  • Plant Growth Responses – Learn how indoleacetic acid (IAA) influences cell elongation in plant roots and shoots. Study phototropism and gravitropism.
  • Taxes and Kineses – Compare directional movement towards or away from stimuli with changes in the rate of movement in response to environmental conditions.
  • Reflex Actions – Study the structure and function of a simple three-neurone reflex arc. Learn how reflexes provide rapid protective responses.
  • Required Practical 10: Animal Movement – Investigate how an environmental variable affects animal movement using a choice chamber or maze.

6.2 Receptors

  • Sensory Receptors – Study receptor specificity and how stimuli produce generator potentials.
  • Pacinian Corpuscles – Learn the basic structure of Pacinian corpuscles and how mechanical deformation affects sodium ion channels to produce a generator potential.
  • Structure of the Retina – Study rod and cone cells in the human retina. Learn about their differences in light sensitivity, colour vision and visual acuity.

6.3 Control of Heart Rate

6.4 Nervous Coordination

  • Structure of a Myelinated Neurone – Study the structure of myelinated motor neurones and the relationship between their components and functions.
  • Resting Potential – Learn how ion distribution, membrane permeability and electrochemical gradients produce the resting membrane potential.
  • Action Potential – Study depolarisation and the generation of action potentials. Learn the all-or-nothing principle.
  • Propagation of Nerve Impulses – Study how action potentials travel along myelinated and non-myelinated axons.
  • Saltatory Conduction – Learn how myelin increases the speed of nerve impulse transmission.
  • Refractory Period – Study how the refractory period limits the frequency of action potentials and ensures discrete impulses.
  • Factors Affecting Nerve Impulse Speed – Learn how axon diameter, myelination and temperature influence conduction velocity.

6.5 Synaptic Transmission

  • Structure of a Synapse – Study the presynaptic neurone, synaptic cleft, neurotransmitter-containing vesicles and postsynaptic membrane.
  • Cholinergic Synaptic Transmission – Learn the sequence of events involved in neurotransmitter release, receptor binding and generation of postsynaptic responses.
  • Temporal and Spatial Summation – Study how multiple synaptic inputs combine to influence the generation of action potentials.
  • Inhibitory Synapses – Learn how inhibitory synaptic inputs reduce the likelihood of an action potential.
  • Neuromuscular Junction – Study the structure and function of neuromuscular junctions and compare them with cholinergic synapses.
  • Effects of Drugs on Synapses – Learn how substances that interfere with neurotransmitter release, receptor binding or breakdown can alter synaptic transmission.

6.6 Skeletal Muscle Contraction

  • Structure of Skeletal Muscle – Study skeletal muscle fibres, myofibrils and their arrangement within muscles.
  • Actin and Myosin Filaments – Learn the ultrastructure of myofibrils and the roles of actin and myosin in muscle contraction.
  • Sliding Filament Mechanism – Study how actin and myosin interact to produce muscle contraction.
  • Calcium Ions and Muscle Contraction – Learn how calcium ions and tropomyosin regulate actin-myosin interactions.
  • ATP and Phosphocreatine – Study the roles of ATP and phosphocreatine in providing energy for muscle contraction.
  • Slow and Fast Muscle Fibres – Compare the structure, location and functional properties of slow and fast skeletal muscle fibres.
  • Antagonistic Muscle Action – Learn how skeletal muscles work in antagonistic pairs to produce movement.

6.7 Homeostasis and Negative Feedback

  • Homeostasis – Study homeostasis as the maintenance of a stable internal environment. Learn the importance of regulating body temperature, blood pH and blood glucose.
  • Negative Feedback – Learn how negative feedback mechanisms detect deviations from normal conditions and activate corrective responses.
  • Positive and Negative Feedback – Compare feedback mechanisms and interpret examples of biological control systems.

6.8 Control of Blood Glucose Concentration

  • Blood Glucose Regulation – Study the factors that influence blood glucose concentration and the role of the liver in maintaining glucose levels.
  • Glycogenesis, Glycogenolysis and Gluconeogenesis – Learn how glucose is stored as glycogen, released from glycogen and synthesised from non-carbohydrate substances.
  • Role of Insulin – Study how insulin promotes glucose uptake and glycogen synthesis by acting on target cells.
  • Role of Glucagon – Learn how glucagon stimulates glycogen breakdown and gluconeogenesis.
  • Role of Adrenaline – Study how adrenaline influences blood glucose concentration through its action on target cells.
  • Second Messenger Mechanism – Learn how adenylate cyclase, cyclic AMP and protein kinase participate in the actions of glucagon and adrenaline.
  • Type 1 and Type 2 Diabetes – Compare the causes of Type 1 and Type 2 diabetes and their management through insulin or dietary control.
  • Required Practical 11: Glucose Concentration by Colorimetry – Prepare glucose solutions of known concentration and construct a calibration curve. Use colorimetry to determine the glucose concentration of an unknown simulated urine sample.

6.9 Control of Blood Water Potential

  • Osmoregulation – Study how mammals maintain the water potential of their blood within suitable limits.
  • Structure of the Nephron – Learn the structure and functions of the glomerulus, Bowman’s capsule, proximal convoluted tubule, loop of Henle, distal convoluted tubule and collecting duct.
  • Ultrafiltration and Selective Reabsorption – Study how glomerular filtrate is formed and how useful substances are reabsorbed into the blood.
  • Loop of Henle and Water Conservation – Learn how ion transport in the loop of Henle establishes a concentration gradient in the kidney medulla.
  • Antidiuretic Hormone (ADH) – Study the roles of the hypothalamus, posterior pituitary and ADH in regulating water reabsorption and blood water potential.

7. Genetics, Populations, Evolution and Ecosystems (A-Level Only)

7.1 Inheritance

  • Genotype and Phenotype – Study genotype as the genetic constitution of an organism and phenotype as the expression of genetic and environmental influences.
  • Alleles and Patterns of Dominance – Learn about dominant, recessive and codominant alleles. Study homozygous and heterozygous genotypes.
  • Monohybrid Inheritance – Study genetic crosses involving one gene and predict genotypic and phenotypic ratios.
  • Dihybrid Inheritance – Learn how to predict inheritance patterns involving two genes using genetic diagrams.
  • Codominance and Multiple Alleles – Study inheritance involving codominant alleles and genes with more than two possible alleles.
  • Sex-Linked Inheritance – Learn how genes carried on sex chromosomes produce particular inheritance patterns.
  • Autosomal Linkage – Study genes located on the same autosome and how linkage affects inheritance.
  • Epistasis – Learn how one gene can influence or mask the phenotypic expression of another gene.
  • Chi-Squared Test in Genetics – Study the use of the chi-squared test to compare observed phenotypic ratios with expected genetic ratios.

7.2 Populations

7.3 Evolution and Speciation

  • Variation Within Populations – Study how mutations, meiosis, random fertilisation and environmental conditions produce differences between individuals.
  • Natural Selection and Evolution – Learn how differential survival and reproductive success change allele frequencies across generations.
  • Types of Selection – Study stabilising, directional and disruptive selection and their effects on population characteristics.
  • Genetic Drift – Learn how random events can change allele frequencies, particularly in small populations.
  • Reproductive Isolation – Study how separation of populations can allow genetic differences to accumulate.
  • Allopatric Speciation – Learn how geographical isolation can contribute to the formation of new species.
  • Sympatric Speciation – Study how new species can develop without geographical separation.
  • Evolutionary Change and Biodiversity – Learn how long-term evolutionary processes contribute to the diversity of living organisms.

7.4 Populations in Ecosystems

  • Communities and Ecosystems – Study how populations of different species form communities and interact with abiotic components of the environment.
  • Ecological Niches – Learn how organisms occupy particular niches determined by their adaptations and environmental conditions.
  • Carrying Capacity – Study the maximum population size that an ecosystem can support and the factors affecting it.
  • Abiotic Factors Affecting Populations – Learn how physical and chemical conditions influence population size.
  • Biotic Factors Affecting Populations – Study competition and predation as factors influencing population growth and survival.
  • Intraspecific and Interspecific Competition – Compare competition within a species and competition between different species.
  • Population Sampling Using Quadrats and Transects – Study how randomly placed quadrats and belt transects are used to estimate population size and distribution.
  • Mark-Release-Recapture Method – Learn how marked organisms can be used to estimate the abundance of mobile species. Study the assumptions and calculations associated with the method.
  • Ecological Succession – Study primary succession from pioneer species to climax communities. Learn how species gradually alter the environment during succession.
  • Conservation and Ecosystem Management – Learn about the conservation of habitats, management of succession and the conflict between human resource use and biodiversity protection.
  • Required Practical 12: Species Distribution – Investigate how a selected environmental factor affects the distribution of a species using appropriate ecological sampling methods.

8. The Control of Gene Expression (A-Level Only)

8.1 Gene Mutations

  • Types of Gene Mutations – Study addition, deletion, substitution, inversion, duplication and translocation of DNA bases.
  • Effects of Mutations on Proteins – Learn how changes in DNA base sequences can alter the amino acid sequence and structure of a protein.
  • Frameshift Mutations – Study how the addition or deletion of bases can change the reading frame and alter downstream codons.
  • Silent Mutations and the Degenerate Genetic Code – Learn why some base substitutions do not change the amino acid encoded by a codon.
  • Spontaneous Mutations and Mutagens – Study mutations arising during DNA replication and how mutagenic agents increase mutation rates.

8.2 Stem Cells and Cell Specialisation

8.3 Regulation of Gene Expression

  • Transcription Factors – Study how transcription factors regulate the transcription of target genes in eukaryotic cells.
  • Oestrogen and Gene Transcription – Learn how oestrogen acts through intracellular receptors to influence transcription.
  • Epigenetic Control of Gene Expression – Study heritable changes in gene activity that occur without altering the DNA base sequence.
  • DNA Methylation – Learn how changes in DNA methylation can influence gene transcription.
  • Histone Acetylation – Study how histone acetylation affects chromatin organisation and gene expression.
  • RNA Interference (RNAi) – Learn how RNA interference can reduce gene expression by inhibiting translation of target mRNA.
  • Environmental Influences on Gene Expression – Study how environmental factors can alter patterns of gene activity and contribute to phenotypic differences.

8.4 Gene Expression and Cancer

  • Benign and Malignant Tumours – Compare the characteristics of benign and malignant tumours.
  • Oncogenes – Study how abnormal activity of oncogenes contributes to uncontrolled cell growth.
  • Tumour Suppressor Genes – Learn how tumour suppressor genes help regulate cell division and how changes in their activity can contribute to cancer.
  • Epigenetics and Cancer – Study the relationship between abnormal DNA methylation and cancer development.
  • Hormonal Influences on Cancer – Learn how increased oestrogen concentrations may contribute to the development of some breast cancers.
  • Cancer Prevention and Treatment – Study how knowledge of oncogenes, tumour suppressor genes and gene regulation can be applied to cancer research and treatment.

8.5 Genome Projects

  • Genome Sequencing – Study how genome sequencing projects determine DNA base sequences in different organisms.
  • Human Genome Project – Learn about genome sequencing in humans and its importance in biological and medical research.
  • Genome and Proteome Relationships – Study how genome information may be used to investigate protein production. Learn why non-coding DNA and regulatory genes make this more difficult in complex organisms.
  • Applications of Genome Sequencing – Learn how genome information can support the identification of potential antigens and the development of vaccines.

8.6 Recombinant DNA Technology

  • Recombinant DNA Technology – Study the transfer of DNA fragments between organisms and the production of genetically modified organisms.
  • DNA Isolation and Gene Production – Learn how desired DNA fragments are obtained using restriction enzymes, reverse transcriptase or artificial gene synthesis.
  • Complementary DNA (cDNA) – Study how reverse transcriptase is used to produce DNA from an mRNA template.
  • Restriction Endonucleases and DNA Ligase – Learn how restriction enzymes cut DNA and DNA ligase joins DNA fragments.
  • Polymerase Chain Reaction (PCR) – Study PCR as a method of amplifying DNA fragments in vitro.
  • In Vivo DNA Amplification – Learn how transformed host cells are cultured to produce multiple copies of inserted DNA.
  • Gene Vectors and Transformation – Study the insertion of DNA fragments into vectors and their transfer into recipient cells.
  • Promoters, Terminators and Marker Genes – Learn how these DNA sequences and markers are used in recombinant DNA technology.
  • Genetically Modified Organisms – Study applications of recombinant DNA technology in agriculture, medicine and industry.
  • Gene Therapy – Learn how recombinant DNA technology can be applied to the treatment of genetic disorders.
  • Ethical and Social Issues of Genetic Engineering – Study the possible benefits, risks, ownership issues and social implications of recombinant DNA technology.

8.7 DNA Probes and Genetic Screening

  • DNA Probes – Study labelled DNA probes and how they are used to identify specific DNA sequences.
  • DNA Hybridisation – Learn how complementary DNA strands bind and how hybridisation can be used to locate particular alleles.
  • Genetic Screening – Study the use of DNA probes to identify inherited conditions and genetic risk factors.
  • Personalised Medicine – Learn how genetic information can help predict drug responses and guide medical treatment.
  • Genetic Counselling – Study the use of genetic screening results in assessing inherited disease risks and supporting medical decisions.

8.8 Genetic Fingerprinting

  • Variable Number Tandem Repeats (VNTRs) – Study repeated DNA sequences that vary between individuals and their importance in genetic identification.
  • Principle of Genetic Fingerprinting – Learn how differences in DNA fragment patterns can be used to distinguish between individuals.
  • PCR in Genetic Fingerprinting – Study how DNA fragments are amplified before analysis.
  • Gel Electrophoresis – Learn how DNA fragments are separated and how banding patterns are interpreted.
  • Forensic Applications of Genetic Fingerprinting – Study the use of DNA profiles in forensic identification.
  • Medical Applications of Genetic Fingerprinting – Learn how genetic fingerprinting can be used to investigate genetic relationships and support diagnosis.
  • Applications in Animal and Plant Breeding – Study the use of DNA fingerprinting to investigate genetic variation and relationships in breeding programmes.

Disclaimer: The AQA A-Level Biology Syllabus (7402) information on this page is provided for educational and reference purposes. Biology Notes Online is an independent educational website and is not affiliated with, endorsed by, sponsored by or officially associated with AQA (Assessment and Qualifications Alliance).

The syllabus has been independently organised into main topics, subtopics and individual lessons to help students and teachers locate the required subject content. The lesson descriptions are summaries and should not be treated as a replacement for the complete official specification. Students and teachers should consult the official AQA Biology specification for examination requirements, assessment arrangements, practical activities and syllabus updates. AQA retains the copyright to its official specification and examination materials.

For copyright concerns or content-related enquiries, contact biologynotesonlinecontact@gmail.com.

References

  1. AQA. (2026). AS and A-level Biology (7401, 7402): Specification (Version 1.6). https://cdn.sanity.io/files/p28bar15/green/912f1f616159ee1ae4911d7179c566b98604ca3f.pdf
  2. AQA. (n.d.). A-level Biology (7402): Specification. https://www.aqa.org.uk/subjects/biology/a-level/biology-7402/specification

Make us preferred on Google

Start Asking Questions