AQA · A-Level
Your journey to excellence inBiology
By Revision Genie
I want to study…
Start learning
Start with the first Biology lesson.
Monomers and Polymers
1Monomers and PolymersRead next2Condensation and Hydrolysis ReactionsRead next3Monosaccharides: Structure and TypesRead next4Formation of DisaccharidesRead next5Structure of α-Glucose and β-GlucoseRead next6Polysaccharides: Glycogen and StarchRead next7Cellulose: Structure and FunctionRead next8Biochemical Tests for Reducing SugarsRead next9Biochemical Tests for Non-Reducing SugarsRead next10Biochemical Tests for StarchRead next11Triglycerides: Structure and FormationRead next12Saturated vs Unsaturated Fatty AcidsRead next13Phospholipids: Structure and PropertiesRead next14Emulsion Test for LipidsRead next15Amino Acids: General StructureRead next16Peptide Bonds and PolypeptidesRead next17Protein Structures: Primary to QuaternaryRead next18Hydrogen, Ionic, and Disulfide Bonds in ProteinsRead next19Biuret Test for ProteinsRead next20Enzymes: Induced Fit ModelRead next21Factors Affecting Enzyme ActivityRead next22Competitive and Non-Competitive InhibitionRead next23Required Practical: Enzyme Rate InvestigationRead next24DNA Structure: Nucleotides and Base PairingRead next25RNA Structure and FunctionRead next26DNA Replication: Semi-Conservative ProcessRead next27Role of DNA Helicase and PolymeraseRead next28ATP Structure and HydrolysisRead next29ATP Resynthesis and Energy CouplingRead next30Properties of Water in BiologyRead next31Water as a Metabolite and SolventRead next32Heat Capacity and Latent Heat of VaporisationRead next33Cohesion and Surface Tension in WaterRead next34Inorganic Ions: Roles in Biological ProcessesRead next35Hydrogen Ions and pHRead next36Iron Ions in HaemoglobinRead next37Sodium Ions and Co-TransportRead next38Phosphate Ions in DNA and ATPRead next
Overview of Cell Theory
1Overview of Cell TheoryRead next2Structure of Eukaryotic CellsRead next3Functions of Eukaryotic OrganellesRead next4Specialisation in Eukaryotic CellsRead next5Structure of Prokaryotic CellsRead next6Features of Prokaryotic CellsRead next7Structure of VirusesRead next8Principles of Optical MicroscopyRead next9Principles of Electron MicroscopyRead next10Magnification vs ResolutionRead next11Measuring Objects in MicroscopyRead next12Cell Fractionation TechniquesRead next13Ultracentrifugation ProcessRead next14Stages of the Cell CycleRead next15DNA Replication in InterphaseRead next16Chromosome Behaviour in MitosisRead next17Role of Spindle Fibres in MitosisRead next18Cytokinesis in Eukaryotic CellsRead next19Uncontrolled Cell Division and CancerRead next20Binary Fission in ProkaryotesRead next21Viral Replication MechanismsRead next22Fluid-Mosaic Model of MembranesRead next23Role of Cholesterol in MembranesRead next24Simple Diffusion Across MembranesRead next25Facilitated Diffusion MechanismRead next26Osmosis and Water PotentialRead next27Active Transport Across MembranesRead next28Co-Transport MechanismRead next29Adaptations for Rapid TransportRead next30Antigens and Cell RecognitionRead next31Immune System Identification of PathogensRead next32Phagocytosis of PathogensRead next33Cellular Response of T LymphocytesRead next34Role of B Lymphocytes in ImmunityRead next35Structure and Function of AntibodiesRead next36Primary and Secondary Immune ResponsesRead next37Vaccines and Herd ImmunityRead next38Active vs Passive ImmunityRead next39Structure of HIV VirusRead next40Replication of HIV in Helper T CellsRead next41Symptoms of AIDS and HIV MechanismRead next42Why Antibiotics Fail Against VirusesRead next43Monoclonal Antibodies in MedicineRead next44Ethical Issues in Vaccine UseRead next45ELISA Test for AntibodiesRead next
Surface Area to Volume Ratio
1Surface Area to Volume RatioRead next2Adaptations for Gas Exchange in Single-Celled OrganismsRead next3Gas Exchange in InsectsRead next4Gas Exchange in Fish and Counter-Current FlowRead next5Gas Exchange in Dicotyledonous PlantsRead next6Human Gas Exchange System StructureRead next7Alveolar Epithelium and Gas ExchangeRead next8Mechanism of BreathingRead next9Effect of Lung Disease on Gas ExchangeRead next10Digestion of Carbohydrates by AmylaseRead next11Digestion of Lipids by Lipase and Bile SaltsRead next12Digestion of Proteins by PeptidasesRead next13Co-Transport Mechanisms for Absorption in the IleumRead next14Role of Micelles in Lipid AbsorptionRead next15Haemoglobin Structure and FunctionRead next16Oxyhaemoglobin Dissociation CurveRead next17The Bohr Effect and Carbon DioxideRead next18Adaptations of Haemoglobin in Different AnimalsRead next19Structure of the Human HeartRead next20Pressure and Volume Changes in the Cardiac CycleRead next21Structure and Function of Arteries, Veins, and CapillariesRead next22Formation and Return of Tissue FluidRead next23Xylem and Cohesion-Tension TheoryRead next24Phloem and Mass Flow HypothesisRead next25Tracers and Ringing Experiments in PlantsRead next
Structure of DNA
1Structure of DNARead next2Structure of RNARead next3Nucleotides and Their ComponentsRead next4Complementary Base PairingRead next5DNA as a Double HelixRead next6RNA as a Single StrandRead next7DNA Replication ProcessRead next8Role of DNA HelicaseRead next9Role of DNA PolymeraseRead next10Semi-Conservative ReplicationRead next11Evidence for DNA Carrying Genetic InformationRead next12The Genetic Code: Universal, Non-Overlapping, DegenerateRead next13Genes and Their LocusRead next14Coding vs Non-Coding DNARead next15Exons and IntronsRead next16Transcription ProcessRead next17Role of RNA Polymerase in TranscriptionRead next18Splicing of Pre-mRNARead next19Structure of mRNARead next20Structure of tRNARead next21Translation ProcessRead next22Role of Ribosomes in TranslationRead next23Role of tRNA in TranslationRead next24Role of ATP in Protein SynthesisRead next25Gene Mutations: Substitution and DeletionRead next26Degenerate Nature of the Genetic CodeRead next27Mutagenic AgentsRead next28Chromosome Non-DisjunctionRead next29Meiosis: Two Nuclear DivisionsRead next30Independent Segregation in MeiosisRead next31Crossing Over in MeiosisRead next32Genetic Variation Through MeiosisRead next33Random Fertilisation and Genetic DiversityRead next34Calculating Genetic Combinations in MeiosisRead next35Genetic Diversity and Natural SelectionRead next36Random Mutation and EvolutionRead next37Directional Selection Example: Antibiotic ResistanceRead next38Stabilising Selection Example: Human Birth WeightRead next39Adaptations: Anatomical, Physiological, BehaviouralRead next40Species Definition: Fertile OffspringRead next41Courtship Behaviour in Species RecognitionRead next42Taxonomy: Hierarchical ClassificationRead next43Binomial Naming SystemRead next44Phylogenetic ClassificationRead next45Species Richness and BiodiversityRead next46Index of Diversity CalculationRead next47Impact of Farming on BiodiversityRead next48Measuring Genetic DiversityRead next49DNA Base Sequence ComparisonsRead next50Amino Acid Sequence ComparisonsRead next51Quantitative Sampling MethodsRead next52Standard Deviation in Variation StudiesRead next
Overview of Energy Transfers in Organisms
1Overview of Energy Transfers in OrganismsRead next2The Process of PhotosynthesisRead next3The Light-Dependent ReactionRead next4Photoionisation of ChlorophyllRead next5Electron Transfer Chain in PhotosynthesisRead next6Photolysis of WaterRead next7ATP Production in PhotosynthesisRead next8Reduced NADP in PhotosynthesisRead next9The Light-Independent ReactionRead next10Role of Rubisco in PhotosynthesisRead next11The Calvin CycleRead next12Triose Phosphate and Organic SubstancesRead next13Limiting Factors in PhotosynthesisRead next14Chromatography of Plant PigmentsRead next15Dehydrogenase Activity in ChloroplastsRead next16Introduction to RespirationRead next17Glycolysis ProcessRead next18Anaerobic Respiration and PyruvateRead next19Aerobic Respiration OverviewRead next20The Link ReactionRead next21The Krebs CycleRead next22Oxidative PhosphorylationRead next23Chemiosmotic Theory in RespirationRead next24Alternative Respiratory SubstratesRead next25Investigating Respiration RatesRead next26Energy Flow in EcosystemsRead next27Gross Primary Production (GPP)Read next28Net Primary Production (NPP)Read next29Calculating Net Production in ConsumersRead next30Efficiency of Energy TransfersRead next31Farming Practices and Energy TransferRead next32Measuring BiomassRead next33Calorimetry for Energy ContentRead next34Nutrient Cycles OverviewRead next35The Nitrogen CycleRead next36Role of Saprobionts in DecompositionRead next37Ammonification and NitrificationRead next38Nitrogen Fixation and DenitrificationRead next39The Phosphorus CycleRead next40Role of Mycorrhizae in Nutrient UptakeRead next41Artificial and Natural FertilisersRead next42Environmental Impact of FertilisersRead next43Leaching and EutrophicationRead next
Definition of Stimulus and Response
1Definition of Stimulus and ResponseRead next2Role of Receptors in DetectionRead next3Role of Coordinators in ResponseRead next4Role of Effectors in ResponseRead next5Comparison of Nervous and Hormonal ResponsesRead next6Plant Growth Factors and ResponsesRead next7Effect of IAA on Cell ElongationRead next8Phototropism in PlantsRead next9Gravitropism in PlantsRead next10Simple Reflexes and SurvivalRead next11Taxes and Kineses in OrganismsRead next12Structure of Pacinian CorpuscleRead next13Function of Stretch-Mediated Sodium ChannelsRead next14Sensitivity of Rods and Cones in RetinaRead next15Visual Acuity and Optical PigmentsRead next16Myogenic Stimulation of the HeartRead next17Role of SAN, AVN, and Purkyne TissueRead next18Chemoreceptors and Pressure ReceptorsRead next19Autonomic Nervous System and Heart RateRead next20Structure of Myelinated Motor NeuroneRead next21Resting Potential in NeuronesRead next22Generation of Action PotentialRead next23All-or-Nothing Principle in NeuronesRead next24Transmission Along Non-Myelinated AxonsRead next25Saltatory Conduction in Myelinated AxonsRead next26Refractory Period and Impulse FrequencyRead next27Factors Affecting Speed of ConductionRead next28Structure of Synapse and Neuromuscular JunctionRead next29Transmission Across Cholinergic SynapseRead next30Unidirectionality of Synaptic TransmissionRead next31Temporal and Spatial SummationRead next32Inhibitory Synapses and Their RoleRead next33Comparison of Synapse and Neuromuscular JunctionRead next34Structure of Skeletal MuscleRead next35Microscopic Structure of MyofibrilsRead next36Role of Actin and Myosin in ContractionRead next37Role of Calcium Ions in Muscle ContractionRead next38ATP and Phosphocreatine in Muscle ContractionRead next39Slow and Fast Skeletal Muscle FibresRead next40Principles of HomeostasisRead next41Importance of Stable Temperature and pHRead next42Importance of Stable Blood Glucose LevelsRead next43Negative Feedback in HomeostasisRead next44Role of Liver in Glucose RegulationRead next45Insulin Action on Target CellsRead next46Glucagon Action on Target CellsRead next47Adrenaline and Second Messenger ModelRead next48Causes and Management of DiabetesRead next49Structure of NephronRead next50Formation of Glomerular FiltrateRead next51Reabsorption in Proximal Convoluted TubuleRead next52Role of Loop of Henle in Sodium GradientRead next53Reabsorption in Collecting DuctsRead next54Role of ADH in OsmoregulationRead next
Genotype and Phenotype
1Genotype and PhenotypeRead next2Alleles: Dominant, Recessive, CodominantRead next3Homozygous and Heterozygous AllelesRead next4Monohybrid CrossesRead next5Dihybrid CrossesRead next6Sex-Linkage in Genetic DiagramsRead next7Autosomal LinkageRead next8Multiple Alleles in InheritanceRead next9Epistasis in Genetic CrossesRead next10Chi-Squared Test in GeneticsRead next11Population and Gene PoolRead next12Allele Frequency in PopulationsRead next13Hardy-Weinberg PrincipleRead next14Using Hardy-Weinberg EquationRead next15Sources of Genetic VariationRead next16Natural Selection and Allele FrequencyRead next17Directional SelectionRead next18Stabilising SelectionRead next19Disruptive SelectionRead next20Allopatric SpeciationRead next21Sympatric SpeciationRead next22Genetic Drift in Small PopulationsRead next23Reproductive Isolation and SpeciationRead next24Ecosystems: Biotic and Abiotic FactorsRead next25Competition Within and Between PopulationsRead next26Energy Transfer in EcosystemsRead next27Trophic Levels and Energy FlowRead next28Calculating Efficiency of Energy TransferRead next29Gross and Net Primary ProductionRead next30Measuring Biomass and Energy in EcosystemsRead next31Nitrogen Cycle ProcessesRead next32Phosphorus Cycle ProcessesRead next33Role of Saprobionts in DecompositionRead next34Mycorrhizae and Nutrient UptakeRead next35Natural and Artificial FertilisersRead next36Environmental Impact of FertilisersRead next37Leaching and EutrophicationRead next38Examining Population DynamicsRead next39Sampling Techniques for BiodiversityRead next40Species Richness and Index of DiversityRead next41Calculating Index of DiversityRead next42Conservation vs Farming PracticesRead next43Genetic Diversity Assessment MethodsRead next44DNA Base Sequences in Diversity StudiesRead next45Amino Acid Sequences in Diversity StudiesRead next46Random Sampling in Population StudiesRead next47Standard Deviation in Biological DataRead next48Phylogenetic Classification SystemsRead next49Courtship Behaviour and Species RecognitionRead next50Binomial Naming SystemRead next
Gene Expression Overview
1Gene Expression OverviewRead next2Regulation of TranscriptionRead next3Role of Transcription FactorsRead next4RNA Interference MechanismRead next5Epigenetics and Gene ExpressionRead next6DNA Methylation and Gene SilencingRead next7Histone Modification and Gene ActivationRead next8Acetylation vs. Methylation of HistonesRead next9Epigenetic InheritanceRead next10Mutations and Their Effects on GenesRead next11Base Substitution MutationsRead next12Base Deletion MutationsRead next13Frameshift Mutations ExplainedRead next14Degenerate Nature of Genetic CodeRead next15Mutagenic Agents and Their ImpactRead next16Cancer and Uncontrolled Cell DivisionRead next17Oncogenes and Tumor Suppressor GenesRead next18Role of p53 in Cell Cycle RegulationRead next19Stem Cells and Gene ExpressionRead next20Totipotent vs. Pluripotent CellsRead next21Induced Pluripotent Stem Cells (iPSCs)Read next22Applications of Stem Cell TherapyRead next23Control of Gene Expression in ProkaryotesRead next24The Lac Operon ModelRead next25Inducible vs. Repressible OperonsRead next26Post-Transcriptional RegulationRead next27Alternative Splicing MechanismRead next28Post-Translational ModificationsRead next29Protein Activation by PhosphorylationRead next30Exam Trap: Misinterpreting Epigenetic DataRead next31Exam Trap: Mutation Effects on Protein FunctionRead next32Exam Trap: Confusing Operon ModelsRead next33Worked Example: Predicting Mutation OutcomesRead next34Worked Example: Interpreting Epigenetic ChangesRead next35Worked Example: Lac Operon RegulationRead next36Practical: Investigating Gene Expression in Stem CellsRead next37Practical: Effects of Mutagens on DNARead next38Practical: Chromatin Structure AnalysisRead next
Monomers, polymers, condensation and hydrolysis
1Monomers, polymers, condensation and hydrolysisRead next2Eukaryotic cells and organellesRead next3Surface area to volume ratio and exchange surfacesRead next4DNA, genes, chromosomes and the genetic codeRead next5Photosynthesis overview and limiting factorsRead next6Stimuli, receptors and effectorsRead next7Monohybrid and dihybrid inheritanceRead next8Control of transcription and translationRead next9Carbohydrates: structure, roles and testsRead next10Prokaryotic cells, viruses and virus replicationRead next11Gas exchange in insects (tracheal system)Read next12Transcription (including RNA processing)Read next13Required practical 7: chromatography of photosynthetic pigmentsRead next14Plant responses: tropisms and IAA (auxin)Read next15Codominance, multiple alleles and sex linkageRead next16Gene regulation, mutations and cancerRead next17Lipids: triglycerides, phospholipids and testsRead next18Microscopes: magnification, resolution and measuring cellsRead next19Gas exchange in fish (gills and countercurrent flow)Read next20Translation and protein synthesisRead next21Light-dependent reactions and photophosphorylationRead next22Animal movement: taxis and kinesisRead next23Linkage and interpreting genetic crossesRead next24Cell differentiation and developmentRead next25Proteins: structure (primary–quaternary) and functionsRead next26Cell fractionation and ultracentrifugationRead next27Gas exchange in plants (leaf structure and stomata)Read next28Mutations and their effectsRead next29Light-independent reactions (Calvin cycle)Read next30Required practical 10: investigating animal responses (choice chambers/mazes)Read next31Chi-squared test for genetic ratiosRead next32Stem cells and ethical considerationsRead next33Enzymes: induced fit, factors affecting rate and inhibitionRead next34The cell cycle and mitosisRead next35Gas exchange in mammals (lungs and ventilation)Read next36Meiosis and how variation is generatedRead next37Respiration: glycolysis and anaerobic pathwaysRead next38Neurones and the nervous systemRead next39Populations, gene pools and allele frequenciesRead next40Epigenetics (methylation and histone modification)Read next41Required practical 1: enzyme-controlled reaction ratesRead next42Required practical 2: root tip squashes and mitotic indexRead next43Digestion and absorption (enzymes, ileum, co-transport)Read next44Genetic diversity and natural selectionRead next45Respiration: link reaction, Krebs cycle and oxidative phosphorylationRead next46Action potentials and transmission speedRead next47Hardy–Weinberg calculations and assumptionsRead next48RNA interference and post-transcriptional controlRead next49DNA and RNA structureRead next50Cell membranes and transport (diffusion, osmosis, active transport)Read next51Mass transport in mammals (heart, vessels, tissue fluid and lymph)Read next52Investigating antimicrobial substances (aseptic technique)Read next53Required practical 8: dehydrogenase activity in chloroplast extractsRead next54Synapses and neuromuscular junctionsRead next55Natural selection, genetic drift and speciationRead next56Genome projects, sequencing and bioinformaticsRead next57DNA replication (semi-conservative)Read next58Required practical 3: water potential in plant tissue (calibration curve)Read next59Haemoglobin and oxygen dissociation curvesRead next60Required practical 6: antimicrobials and microbial growthRead next61Required practical 9: respiration rate in single-celled organismsRead next62Muscle contraction and the sliding filament modelRead next63Ecosystems: populations, communities and successionRead next64Recombinant DNA: enzymes, vectors and transformationRead next65ATP and energy transferRead next66Required practical 4: investigating membrane permeabilityRead next67Mass transport in plants (xylem, transpiration, phloem translocation)Read next68Classification and phylogenetic relationshipsRead next69Energy transfer in ecosystems (trophic levels, pyramids, efficiency)Read next70Homeostasis and negative feedbackRead next71Conservation and maintaining biodiversityRead next72PCR, electrophoresis and DNA probesRead next73Water and inorganic ions (including pH and buffers)Read next74Cell recognition and the immune system (including HIV and monoclonal antibodies)Read next75Required practical 5: dissection of a gas exchange or mass transport system/organRead next76Biodiversity sampling and using data to compare habitatsRead next77Nutrient cycles and fertiliser impacts (nitrogen/phosphorus, eutrophication)Read next78Blood glucose control (insulin, glucagon and diabetes)Read next79Required practical 12: distribution of organisms in a habitat (fieldwork)Read next80Genetic fingerprinting: methods, uses and ethicsRead next81Required practical 11: glucose calibration curve (colorimetry)Read next82Osmoregulation: kidney, nephron and ADHRead next
Previews load for the first 60 in this unit.