Source: https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-3-2-sliding-filament-theory [Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [A Level](https://senecalearning.com/en-gb/revision-notes/a-level.md) › [Biology](https://senecalearning.com/en-gb/revision-notes/a-level/biology.md) › [AQA](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa.md) › Sliding Filament Theory # Sliding Filament Theory Biology: AQA A Level, topic 6.3.2 ## Sliding Filament Theory The sliding filament theory explains how muscle contraction is coordinated in myofibrils. An overview of the steps involved are: ### Depolarisation of the sarcolemma ![Depolarisation of the sarcolemma](https://image-v2.cdn.app.senecalearning.com/2018-08/588f7a21-b682-4536-b67e-defd50d6d98b/Sarcomere.jpg) - Muscle contraction is initiated when an action potential arrives at the muscle cells. - The action potential depolarises the sarcolemma. ### Contraction of the sarcomeres ![Contraction of the sarcomeres](https://image-v2.cdn.app.senecalearning.com/2018-08/588f7a21-b682-4536-b67e-defd50d6d98b/Sarcomere.jpg) - Depolarisation of the sarcolemma causes the myosin and actin filaments to slide over each other. - The sliding movement causes the sarcomeres to contract. ### Muscle contraction ![Muscle contraction](https://image-v2.cdn.app.senecalearning.com/2018-08/588f7a21-b682-4536-b67e-defd50d6d98b/Sarcomere.jpg) - There are multiple sarcomeres along the length of myofibrils. - As many sarcomeres contract simultaneously, the muscle fibres contract. - Contraction of the muscle fibres causes the whole muscle to contract. ### Muscle relaxation ![Muscle relaxation](https://image-v2.cdn.app.senecalearning.com/2018-08/588f7a21-b682-4536-b67e-defd50d6d98b/Sarcomere.jpg) - After the muscle has contracted, the sarcomeres relax. - The filaments slide back over each other and the muscle relaxes. ## Myosin Heads The Sliding Filament Theory takes place due to globular heads on myosin filaments. The globular heads allow myosin and actin filaments to bind together and slide past each other. ### Globular head ![Globular head](https://image-v2.cdn.app.senecalearning.com/2018-10/f0478aff-49c4-41d9-b6d6-ef87d085e9bd/Muscle-Contraction-1-one-myosin-sliding-filament-.png) - Myosin filaments have globular heads. - Globular heads can move back and forth. - The movement of the globular heads is what allows actin and myosin filaments to slide past each other in muscle contraction. ### Binding sites ![Binding sites](https://image-v2.cdn.app.senecalearning.com/2018-10/a2058661-f552-47b3-a0e4-a934407f124f/Muscle-Contraction-two-2-sliding-filament-myosin-.png) - There are two binding sites on every myosin head: - One site can bind to actin. - One site can bind to ATP. - There is also a binding site for the myosin heads on actin filaments. This is called the actin-myosin binding site. ### Tropomyosin ![Tropomyosin](https://image-v2.cdn.app.senecalearning.com/2018-10/ec818c5a-9f9d-4a71-931d-c15fdb2d8ee8/Muscle-Contraction-three-3-sliding-filament-myosin-tropomyosin-.png) - Tropomyosin is a protein that is located on actin filaments. - Tropomyosin plays an important role in muscle contraction because it blocks the actin-myosin binding site when muscle fibres are at rest. - When muscle fibres are stimulated, the tropomyosin protein is moved so that myosin heads can bind to the actin-myosin binding site. - When actin and myosin bind, they can slide past each other to cause muscle contraction. ## ATP and Phosphocreatine Muscle contraction is a very energetically demanding process so ATP needs to be made rapidly. This is done in the following ways: ### Aerobic respiration ![Aerobic respiration](https://image-v2.cdn.app.senecalearning.com/2018-03/435cf69a-b849-4e56-8ea3-40c940a430fd/shutterstock_569531539.jpg) - Aerobic respiration makes ATP through oxidative phosphorylation. - Aerobic respiration requires oxygen. It is mainly used for extended periods of low-intensity muscle use (e.g. jogging 5km). ### Anaerobic respiration ![Anaerobic respiration](https://image-v2.cdn.app.senecalearning.com/2018-03/f722a55c-dd13-4471-af9d-7ec1e4af5945/shutterstock_288632147.jpg) - Anaerobic respiration makes ATP by glycolysis and lactate fermentation. - Lactate is produced by lactate fermentation. - The build-up of lactate in the muscles can cause fatigue. - Anaerobic respiration is mainly used short periods of high-intensity muscle use (e.g. sprinting 100m). ### Phosphocreatine ![Phosphocreatine](https://image-v2.cdn.app.senecalearning.com/2018-10/f064474e-6edb-4b3b-88e9-4c282d516c9d/ATP-adenosine-triphosphate-energy-.png) - Phosphocreatine is a molecule that can supply ATP for muscle contraction. - During intense muscular effort, phosphocreatine donates phosphate to ADP to produce ATP. The ATP produced is used to sustain muscle contraction. - During low periods of muscle activity, ATP can be used to phosphorylate creatine back to phosphocreatine. - This process is anaerobic and produces no lactate but phosphocreatine is in short supply. ## Test yourself on Sliding Filament Theory - Stages in Sliding Filament Theory - What causes the myosin and actin filaments to slide over each other? - Which of these do NOT bind to myosin heads? - Which of the following statements about myosin heads are true? - Which of these are NOT used to produce ATP for muscle contraction? [Practise this topic for free](https://app.senecalearning.com/classroom/course/d0ce0c30-6417-11e8-8edc-d9cd1c890408/section/3a4a3f4f-a2fd-4017-a7b8-f6f992b5a50d/session) - Previous topic: [6.3.1 Skeletal Muscle](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-3-1-skeletal-muscle.md) - Next topic: [6.3.3 Contraction](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-3-3-contraction.md) ## Biology: AQA A Level contents ### 1 Biological Molecules - 1.1 Monomers & Polymers - [1.1.1 Monomers & Polymers](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-1-1-monomers-and-polymers.md) - [1.1.2 Condensation & Hydrolysis Reactions](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-1-2-condensation-and-hydrolysis-reactions.md) - 1.2 Carbohydrates - [1.2.1 Structure of Carbohydrates](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-2-1-structure-of-carbohydrates.md) - [1.2.2 Types of Polysaccharides](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-2-2-types-of-polysaccharides.md) - [1.2.3 End of Topic Test - Monomers, Polymers and Carbs](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-2-3-end-of-topic-test-monomers-polymers-and-carbs.md) - [1.2.4 Exam-Style Question - Carbohydrates](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-2-4-exam-style-question-carbohydrates.md) - [1.2.5 A-A* (AO3/4) - Carbohydrates](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-2-5-a-a-ao34-carbohydrates.md) - 1.3 Lipids - [1.3.1 Triglycerides & Phospholipids](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-3-1-triglycerides-and-phospholipids.md) - [1.3.2 Types of Fatty Acids](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-3-2-types-of-fatty-acids.md) - [1.3.3 Testing for Lipids](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-3-3-testing-for-lipids.md) - [1.3.4 Exam-Style Question - Fats](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-3-4-exam-style-question-fats.md) - [1.3.5 A-A* (AO3/4) - Lipids](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-3-5-a-a-ao34-lipids.md) - 1.4 Proteins - [1.4.1 The Peptide Chain](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-4-1-the-peptide-chain.md) - [1.4.2 Investigating Proteins](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-4-2-investigating-proteins.md) - [1.4.3 Primary & Secondary Protein Structure](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-4-3-primary-and-secondary-protein-structure.md) - [1.4.4 Tertiary & Quaternary Protein Structure](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-4-4-tertiary-and-quaternary-protein-structure.md) - [1.4.5 Enzymes](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-4-5-enzymes.md) - [1.4.6 Factors Affecting Enzyme Activity](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-4-6-factors-affecting-enzyme-activity.md) - [1.4.7 Enzyme-Controlled Reactions](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-4-7-enzyme-controlled-reactions.md) - [1.4.8 End of Topic Test - Lipids & Proteins](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-4-8-end-of-topic-test-lipids-and-proteins.md) - [1.4.9 A-A* (AO3/4) - Enzymes](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-4-9-a-a-ao34-enzymes.md) - [1.4.10 A-A* (AO3/4) - Proteins](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-4-10-a-a-ao34-proteins.md) - [1.4.11 Diagnostic Misconceptions - Enzyme Inhibitors](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-4-11-diagnostic-misconceptions-enzyme-inhibitors.md) - 1.5 Nucleic Acids - [1.5.1 DNA & RNA](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-5-1-dna-and-rna.md) - [1.5.2 Nucleotides](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-5-2-nucleotides.md) - [1.5.3 Polynucleotides](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-5-3-polynucleotides.md) - [1.5.4 DNA Replication](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-5-4-dna-replication.md) - [1.5.5 Exam-Style Question - Nucleic Acids](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-5-5-exam-style-question-nucleic-acids.md) - [1.5.6 A-A* (AO3/4) - Nucleic Acids](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-5-6-a-a-ao34-nucleic-acids.md) - 1.6 ATP - [1.6.1 Structure of ATP](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-6-1-structure-of-atp.md) - [1.6.2 Hydrolysis of ATP](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-6-2-hydrolysis-of-atp.md) - [1.6.3 Resynthesis of ATP](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-6-3-resynthesis-of-atp.md) - [1.6.4 End of Topic Test - Nucleic Acids & ATP](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-6-4-end-of-topic-test-nucleic-acids-and-atp.md) - 1.7 Water - [1.7.1 Importance of Water](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-7-1-importance-of-water.md) - [1.7.2 Structure of Water](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-7-2-structure-of-water.md) - [1.7.3 Properties of Water](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-7-3-properties-of-water.md) - [1.7.4 A-A* (AO3/4) - Water](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-7-4-a-a-ao34-water.md) - 1.8 Inorganic Ions - [1.8.1 Inorganic Ions](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-8-1-inorganic-ions.md) - [1.8.2 End of Topic Test - Water & Inorganic Ions](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/1-8-2-end-of-topic-test-water-and-inorganic-ions.md) ### 2 Cells - 2.1 Cell Structure - [2.1.1 Introduction to Cells](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-1-1-introduction-to-cells.md) - [2.1.2 Eukaryotic Cells & Organelles](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-1-2-eukaryotic-cells-and-organelles.md) - [2.1.3 Eukaryotic Cells & Organelles 2](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-1-3-eukaryotic-cells-and-organelles-2.md) - [2.1.4 Prokaryotes](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-1-4-prokaryotes.md) - [2.1.5 A-A* (AO3/4) - Organelles](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-1-5-a-a-ao34-organelles.md) - [2.1.6 Methods of Studying Cells](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-1-6-methods-of-studying-cells.md) - [2.1.7 Microscopes](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-1-7-microscopes.md) - [2.1.8 End of Topic Test - Cell Structure](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-1-8-end-of-topic-test-cell-structure.md) - [2.1.9 Exam-Style Question - Cells](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-1-9-exam-style-question-cells.md) - [2.1.10 A-A* (AO3/4) - Cells](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-1-10-a-a-ao34-cells.md) - 2.2 Mitosis & Cancer - [2.2.1 Mitosis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-2-1-mitosis.md) - [2.2.2 Stages of Mitosis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-2-2-stages-of-mitosis.md) - [2.2.3 Investigating Mitosis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-2-3-investigating-mitosis.md) - [2.2.4 Cancer](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-2-4-cancer.md) - [2.2.5 A-A* (AO3/4) - The Cell Cycle](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-2-5-a-a-ao34-the-cell-cycle.md) - 2.3 Transport Across Cell Membrane - [2.3.1 Cell Membrane Structure](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-3-1-cell-membrane-structure.md) - [2.3.2 A-A* (AO3/4) - Membrane Structure](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-3-2-a-a-ao34-membrane-structure.md) - [2.3.3 Diffusion](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-3-3-diffusion.md) - [2.3.4 Osmosis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-3-4-osmosis.md) - [2.3.5 Active Transport](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-3-5-active-transport.md) - [2.3.6 End of Topic Test - Mitosis, Cancer & Transport](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-3-6-end-of-topic-test-mitosis-cancer-and-transport.md) - [2.3.7 Exam-Style Question - Membranes](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-3-7-exam-style-question-membranes.md) - [2.3.8 A-A* (AO3/4) - Membranes & Transport](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-3-8-a-a-ao34-membranes-and-transport.md) - [2.3.9 A-A*- Mitosis, Cancer & Transport](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-3-9-a-a-mitosis-cancer-and-transport.md) - 2.4 Cell Recognition & the Immune System - [2.4.1 Immune System](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-1-immune-system.md) - [2.4.2 Phagocytosis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-2-phagocytosis.md) - [2.4.3 T Lymphocytes](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-3-t-lymphocytes.md) - [2.4.4 B Lymphocytes](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-4-b-lymphocytes.md) - [2.4.5 Antibodies](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-5-antibodies.md) - [2.4.6 Primary & Secondary Response](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-6-primary-and-secondary-response.md) - [2.4.7 Vaccines](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-7-vaccines.md) - [2.4.8 HIV](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-8-hiv.md) - [2.4.9 Ethical Issues](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-9-ethical-issues.md) - [2.4.10 End of Topic Test - Immune System](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-10-end-of-topic-test-immune-system.md) - [2.4.11 Exam-Style Question - Immune System](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-11-exam-style-question-immune-system.md) - [2.4.12 A-A* (AO3/4) - Immune System](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-12-a-a-ao34-immune-system.md) - [2.4.13 Diagnostic Misconceptions - Humoral vs Cellular](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/2-4-13-diagnostic-misconceptions-humoral-vs-cellular.md) ### 3 Substance Exchange - 3.1 Surface Area to Volume Ratio - [3.1.1 Size & Surface Area](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-1-1-size-and-surface-area.md) - [3.1.2 A-A* (AO3/4) - Cell Size](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-1-2-a-a-ao34-cell-size.md) - 3.2 Gas Exchange - [3.2.1 Single-Celled Organisms](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-2-1-single-celled-organisms.md) - [3.2.2 Multicellular Organisms](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-2-2-multicellular-organisms.md) - [3.2.3 Control of Water Loss](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-2-3-control-of-water-loss.md) - [3.2.4 Human Gas Exchange](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-2-4-human-gas-exchange.md) - [3.2.5 Ventilation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-2-5-ventilation.md) - [3.2.6 Dissection](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-2-6-dissection.md) - [3.2.7 Measuring Gas Exchange](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-2-7-measuring-gas-exchange.md) - [3.2.8 Lung Disease](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-2-8-lung-disease.md) - [3.2.9 Lung Disease Data](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-2-9-lung-disease-data.md) - [3.2.10 End of Topic Test - Gas Exchange](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-2-10-end-of-topic-test-gas-exchange.md) - [3.2.11 A-A* (AO3/4) - Gas Exchange](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-2-11-a-a-ao34-gas-exchange.md) - 3.3 Digestion & Absorption - [3.3.1 Overview of Digestion](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-3-1-overview-of-digestion.md) - [3.3.2 Digestion in Mammals](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-3-2-digestion-in-mammals.md) - [3.3.3 Absorption](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-3-3-absorption.md) - [3.3.4 End of Topic Test - Substance Exchange & Digestion](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-3-4-end-of-topic-test-substance-exchange-and-digestion.md) - [3.3.5 A-A* (AO3/4) - Substance Ex & Digestion](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-3-5-a-a-ao34-substance-ex-and-digestion.md) - 3.4 Mass Transport - [3.4.1 Haemoglobin](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-1-haemoglobin.md) - [3.4.2 Oxygen Transport](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-2-oxygen-transport.md) - [3.4.3 The Circulatory System](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-3-the-circulatory-system.md) - [3.4.4 The Heart](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-4-the-heart.md) - [3.4.5 Blood Vessels](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-5-blood-vessels.md) - [3.4.6 Cardiovascular Disease](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-6-cardiovascular-disease.md) - [3.4.7 Heart Dissection](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-7-heart-dissection.md) - [3.4.8 Xylem](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-8-xylem.md) - [3.4.9 Phloem](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-9-phloem.md) - [3.4.10 Investigating Plant Transport](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-10-investigating-plant-transport.md) - [3.4.11 End of Topic Test - Mass Transport](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-11-end-of-topic-test-mass-transport.md) - [3.4.12 A-A* (AO3/4) - Mass Transport](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-12-a-a-ao34-mass-transport.md) - [3.4.13 Diagnostic Misconceptions - Concentration Gradient](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-13-diagnostic-misconceptions-concentration-gradient.md) - [3.4.14 Diagnostic Misconceptions - Cardiac Cycle](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-14-diagnostic-misconceptions-cardiac-cycle.md) - [3.4.15 Diagnostic Misconceptions - Carrying Capacity](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-15-diagnostic-misconceptions-carrying-capacity.md) - [3.4.16 Diagnostic Misconceptions - Translocation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/3-4-16-diagnostic-misconceptions-translocation.md) ### 4 Genetic Information & Variation - 4.1 DNA, Genes & Chromosomes - [4.1.1 DNA](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-1-1-dna.md) - [4.1.2 Genes](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-1-2-genes.md) - [4.1.3 Non-Coding Genes](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-1-3-non-coding-genes.md) - [4.1.4 The Genetic Code](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-1-4-the-genetic-code.md) - [4.1.5 A-A* (AO3/4) - DNA](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-1-5-a-a-ao34-dna.md) - 4.2 DNA & Protein Synthesis - [4.2.1 Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-2-1-protein-synthesis.md) - [4.2.2 Transcription & Translation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-2-2-transcription-and-translation.md) - [4.2.3 End of Topic Test - DNA, Genes & Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-2-3-end-of-topic-test-dna-genes-and-protein-synthesis.md) - [4.2.4 Exam-Style Question - Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-2-4-exam-style-question-protein-synthesis.md) - [4.2.5 A-A* (AO3/4) - Coronavirus Translation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-2-5-a-a-ao34-coronavirus-translation.md) - [4.2.6 A-A* (AO3/4) - Transcription](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-2-6-a-a-ao34-transcription.md) - [4.2.7 A-A* (AO3/4) - Translation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-2-7-a-a-ao34-translation.md) - 4.3 Mutations & Meiosis - [4.3.1 Mutations](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-3-1-mutations.md) - [4.3.2 Meiosis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-3-2-meiosis.md) - [4.3.3 A-A* (AO3/4) - Meiosis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-3-3-a-a-ao34-meiosis.md) - [4.3.4 Meiosis vs Mitosis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-3-4-meiosis-vs-mitosis.md) - [4.3.5 End of Topic Test - Mutations, Meiosis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-3-5-end-of-topic-test-mutations-meiosis.md) - [4.3.6 A-A* (AO3/4) - DNA,Genes, CellDiv & ProtSynth](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-3-6-a-a-ao34-dnagenes-celldiv-and-protsynth.md) - [4.3.7 Diagnostic Misconceptions - Meiosis vs Mitosis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-3-7-diagnostic-misconceptions-meiosis-vs-mitosis.md) - 4.4 Genetic Diversity & Adaptation - [4.4.1 Genetic Diversity](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-4-1-genetic-diversity.md) - [4.4.2 Natural Selection](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-4-2-natural-selection.md) - [4.4.3 A-A* (AO3/4) - Natural Selection](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-4-3-a-a-ao34-natural-selection.md) - [4.4.4 Adaptations](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-4-4-adaptations.md) - [4.4.5 Investigating Natural Selection](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-4-5-investigating-natural-selection.md) - [4.4.6 End of Topic Test - Genetic Diversity & Adaptation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-4-6-end-of-topic-test-genetic-diversity-and-adaptation.md) - [4.4.7 A-A* (AO3/4) - Genetic Diversity & Adaptation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-4-7-a-a-ao34-genetic-diversity-and-adaptation.md) - 4.5 Species & Taxonomy - [4.5.1 Courtship Behaviour](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-5-1-courtship-behaviour.md) - [4.5.2 Phylogeny](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-5-2-phylogeny.md) - [4.5.3 Classification](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-5-3-classification.md) - [4.5.4 DNA Technology](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-5-4-dna-technology.md) - [4.5.5 A-A* (AO3/4) - Species & Taxonomy](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-5-5-a-a-ao34-species-and-taxonomy.md) - 4.6 Biodiversity Within a Community - [4.6.1 Biodiversity](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-6-1-biodiversity.md) - [4.6.2 Index of diversity](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-6-2-index-of-diversity.md) - [4.6.3 Agriculture](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-6-3-agriculture.md) - [4.6.4 End of Topic Test - Species,Taxonomy& Biodiversity](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-6-4-end-of-topic-test-speciestaxonomyand-biodiversity.md) - [4.6.5 A-A* (AO3/4) - Species,Taxon&Biodiversity](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-6-5-a-a-ao34-speciestaxonandbiodiversity.md) - 4.7 Investigating Diversity - [4.7.1 Genetic Diversity](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-7-1-genetic-diversity.md) - [4.7.2 Quantitative Investigation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/4-7-2-quantitative-investigation.md) ### 5 Energy Transfers (A2 only) - 5.1 Photosynthesis - [5.1.1 Overview of Photosynthesis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-1-1-overview-of-photosynthesis.md) - [5.1.2 Photoionisation of Chlorophyll](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-1-2-photoionisation-of-chlorophyll.md) - [5.1.3 Production of ATP & Reduced NADP](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-1-3-production-of-atp-and-reduced-nadp.md) - [5.1.4 Cyclic Photophosphorylation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-1-4-cyclic-photophosphorylation.md) - [5.1.5 Light-Independent Reaction](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-1-5-light-independent-reaction.md) - [5.1.6 A-A* (AO3/4) - Photosynthesis Reactions](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-1-6-a-a-ao34-photosynthesis-reactions.md) - [5.1.7 Limiting Factors](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-1-7-limiting-factors.md) - [5.1.8 Photosynthesis Experiments](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-1-8-photosynthesis-experiments.md) - [5.1.9 End of Topic Test - Photosynthesis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-1-9-end-of-topic-test-photosynthesis.md) - [5.1.10 A-A* (AO3/4) - Photosynthesis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-1-10-a-a-ao34-photosynthesis.md) - 5.2 Respiration - [5.2.1 Overview of Respiration](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-2-1-overview-of-respiration.md) - [5.2.2 Anaerobic Respiration](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-2-2-anaerobic-respiration.md) - [5.2.3 A-A* (AO3/4) - Anaerobic Respiration](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-2-3-a-a-ao34-anaerobic-respiration.md) - [5.2.4 The Link Reaction](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-2-4-the-link-reaction.md) - [5.2.5 The Krebs Cycle](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-2-5-the-krebs-cycle.md) - [5.2.6 Oxidative Phosphorylation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-2-6-oxidative-phosphorylation.md) - [5.2.7 Respiration Experiments](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-2-7-respiration-experiments.md) - [5.2.8 End of Topic Test - Respiration](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-2-8-end-of-topic-test-respiration.md) - [5.2.9 A-A* (AO3/4) - Respiration](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-2-9-a-a-ao34-respiration.md) - [5.2.10 Diagnostic Misconceptions - Aerobic vs Anaerobic](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-2-10-diagnostic-misconceptions-aerobic-vs-anaerobic.md) - 5.3 Energy & Ecosystems - [5.3.1 Biomass](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-3-1-biomass.md) - [5.3.2 Production & Productivity](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-3-2-production-and-productivity.md) - [5.3.3 Agricultural Practices](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-3-3-agricultural-practices.md) - 5.4 Nutrient Cycles - [5.4.1 Nitrogen Cycle](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-4-1-nitrogen-cycle.md) - [5.4.2 Phosphorous Cycle](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-4-2-phosphorous-cycle.md) - [5.4.3 Fertilisers & Eutrophication](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-4-3-fertilisers-and-eutrophication.md) - [5.4.4 End of Topic Test - Nutrient Cycles](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-4-4-end-of-topic-test-nutrient-cycles.md) - [5.4.5 A-A* (AO3/4) - Energy,Ecosystems&NutrientCycles](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/5-4-5-a-a-ao34-energyecosystemsandnutrientcycles.md) ### 6 Responding to Change (A2 only) - 6.1 Nervous Communication - [6.1.1 Survival](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-1-1-survival.md) - [6.1.2 Plant Responses](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-1-2-plant-responses.md) - [6.1.3 Animal Responses](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-1-3-animal-responses.md) - [6.1.4 Reflexes](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-1-4-reflexes.md) - [6.1.5 End of Topic Test - Reflexes, Responses & Survival](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-1-5-end-of-topic-test-reflexes-responses-and-survival.md) - [6.1.6 Receptors](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-1-6-receptors.md) - [6.1.7 The Human Retina](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-1-7-the-human-retina.md) - [6.1.8 Control of Heart Rate](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-1-8-control-of-heart-rate.md) - [6.1.9 End of Topic Test - Receptors, Retina & Heart Rate](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-1-9-end-of-topic-test-receptors-retina-and-heart-rate.md) - 6.2 Nervous Coordination - [6.2.1 Neurones](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-2-1-neurones.md) - [6.2.2 Action Potentials](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-2-2-action-potentials.md) - [6.2.3 Speed of Transmission](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-2-3-speed-of-transmission.md) - [6.2.4 End of Topic Test - Neurones & Action Potentials](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-2-4-end-of-topic-test-neurones-and-action-potentials.md) - [6.2.5 Synapses](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-2-5-synapses.md) - [6.2.6 Types of Synapse](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-2-6-types-of-synapse.md) - [6.2.7 Medical Application](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-2-7-medical-application.md) - [6.2.8 End of Topic Test - Synapses](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-2-8-end-of-topic-test-synapses.md) - [6.2.9 A-A* (AO3/4) - Nervous Comm&Coord](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-2-9-a-a-ao34-nervous-commandcoord.md) - 6.3 Muscle Contraction - [6.3.1 Skeletal Muscle](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-3-1-skeletal-muscle.md) - [6.3.2 Sliding Filament Theory](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-3-2-sliding-filament-theory.md) - [6.3.3 Contraction](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-3-3-contraction.md) - [6.3.4 Slow & Fast Twitch Fibres](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-3-4-slow-and-fast-twitch-fibres.md) - [6.3.5 End of Topic Test - Muscles](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-3-5-end-of-topic-test-muscles.md) - [6.3.6 A-A* (AO3/4) - Muscle Contraction](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-3-6-a-a-ao34-muscle-contraction.md) - 6.4 Homeostasis - [6.4.1 Overview of Homeostasis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-1-overview-of-homeostasis.md) - [6.4.2 Blood Glucose Concentration](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-2-blood-glucose-concentration.md) - [6.4.3 Controlling Blood Glucose Concentration](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-3-controlling-blood-glucose-concentration.md) - [6.4.4 End of Topic Test - Blood Glucose](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-4-end-of-topic-test-blood-glucose.md) - [6.4.5 Primary & Secondary Messengers](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-5-primary-and-secondary-messengers.md) - [6.4.6 Diabetes Mellitus](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-6-diabetes-mellitus.md) - [6.4.7 Measuring Glucose Concentration](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-7-measuring-glucose-concentration.md) - [6.4.8 Osmoregulation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-8-osmoregulation.md) - [6.4.9 Controlling Blood Water Potential](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-9-controlling-blood-water-potential.md) - [6.4.10 ADH](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-10-adh.md) - [6.4.11 End of Topic Test - Diabetes & Osmoregulation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-11-end-of-topic-test-diabetes-and-osmoregulation.md) - [6.4.12 A-A* (AO3/4) - Homeostasis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-12-a-a-ao34-homeostasis.md) - [6.4.13 Diagnostic Misconceptions - Effect of ADH](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/6-4-13-diagnostic-misconceptions-effect-of-adh.md) ### 7 Genetics & Ecosystems (A2 only) - 7.1 Genetics - [7.1.1 Key Terms in Genetics](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-1-1-key-terms-in-genetics.md) - [7.1.2 Inheritance](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-1-2-inheritance.md) - [7.1.3 Linkage](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-1-3-linkage.md) - [7.1.4 Multiple Alleles & Epistasis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-1-4-multiple-alleles-and-epistasis.md) - [7.1.5 Chi-Squared Test](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-1-5-chi-squared-test.md) - [7.1.6 End of Topic Test - Genetics](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-1-6-end-of-topic-test-genetics.md) - [7.1.7 A-A* (AO3/4) - Genetics](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-1-7-a-a-ao34-genetics.md) - [7.1.8 Diagnostic Misconceptions - Dihybrid Inheritance](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-1-8-diagnostic-misconceptions-dihybrid-inheritance.md) - [7.1.9 Diagnostic Misconceptions - Sex Linkage](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-1-9-diagnostic-misconceptions-sex-linkage.md) - 7.2 Populations - [7.2.1 Populations](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-2-1-populations.md) - [7.2.2 Hardy-Weinberg Principle](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-2-2-hardy-weinberg-principle.md) - 7.3 Evolution - [7.3.1 Variation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-3-1-variation.md) - [7.3.2 Natural Selection & Evolution](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-3-2-natural-selection-and-evolution.md) - [7.3.3 End of Topic Test - Populations & Evolution](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-3-3-end-of-topic-test-populations-and-evolution.md) - [7.3.4 Types of Selection](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-3-4-types-of-selection.md) - [7.3.5 Types of Selection Summary](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-3-5-types-of-selection-summary.md) - [7.3.6 Overview of Speciation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-3-6-overview-of-speciation.md) - [7.3.7 Causes of Speciation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-3-7-causes-of-speciation.md) - [7.3.8 Diversity](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-3-8-diversity.md) - [7.3.9 End of Topic Test - Selection & Speciation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-3-9-end-of-topic-test-selection-and-speciation.md) - [7.3.10 A-A* (AO3/4) - Populations & Evolution](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-3-10-a-a-ao34-populations-and-evolution.md) - [7.3.11 Diagnostic Misconceptions - Types of Speciation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-3-11-diagnostic-misconceptions-types-of-speciation.md) - 7.4 Populations in Ecosystems - [7.4.1 Overview of Ecosystems](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-4-1-overview-of-ecosystems.md) - [7.4.2 Niche](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-4-2-niche.md) - [7.4.3 Population Size](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-4-3-population-size.md) - [7.4.4 Investigating Population Size](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-4-4-investigating-population-size.md) - [7.4.5 End of Topic Test - Ecosystems & Population Size](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-4-5-end-of-topic-test-ecosystems-and-population-size.md) - [7.4.6 Succession](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-4-6-succession.md) - [7.4.7 Conservation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-4-7-conservation.md) - [7.4.8 End of Topic Test - Succession & Conservation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-4-8-end-of-topic-test-succession-and-conservation.md) - [7.4.9 A-A* (AO3/4) - Ecosystems](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/7-4-9-a-a-ao34-ecosystems.md) ### 8 The Control of Gene Expression (A2 only) - 8.1 Mutation - [8.1.1 Mutations](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-1-1-mutations.md) - [8.1.2 Effects of Mutations](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-1-2-effects-of-mutations.md) - [8.1.3 Causes of Mutations](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-1-3-causes-of-mutations.md) - [8.1.4 Diagnostic Misconceptions - Gene Expression](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-1-4-diagnostic-misconceptions-gene-expression.md) - 8.2 Gene Expression - [8.2.1 Stem Cells](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-1-stem-cells.md) - [8.2.2 Stem Cells in Disease](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-2-stem-cells-in-disease.md) - [8.2.3 End of Topic Test - Mutation & Gene Epression](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-3-end-of-topic-test-mutation-and-gene-epression.md) - [8.2.4 A-A* (AO3/4) - Mutation & Stem Cells](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-4-a-a-ao34-mutation-and-stem-cells.md) - [8.2.5 Regulating Transcription](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-5-regulating-transcription.md) - [8.2.6 Epigenetics](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-6-epigenetics.md) - [8.2.7 Epigenetics & Disease](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-7-epigenetics-and-disease.md) - [8.2.8 Regulating Translation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-8-regulating-translation.md) - [8.2.9 Experimental Data](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-9-experimental-data.md) - [8.2.10 End of Topic Test - Transcription & Translation](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-10-end-of-topic-test-transcription-and-translation.md) - [8.2.11 Tumours](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-11-tumours.md) - [8.2.12 Correlations & Causes](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-12-correlations-and-causes.md) - [8.2.13 Prevention & Treatment](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-13-prevention-and-treatment.md) - [8.2.14 End of Topic Test - Cancer](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-14-end-of-topic-test-cancer.md) - [8.2.15 A-A* (AO3/4) - Gene Expression & Cancer](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-2-15-a-a-ao34-gene-expression-and-cancer.md) - 8.3 Genome Projects - [8.3.1 Using Genome Projects](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-3-1-using-genome-projects.md) - 8.4 Gene Technology - [8.4.1 Recombinant DNA](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-4-1-recombinant-dna.md) - [8.4.2 Producing Fragments](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-4-2-producing-fragments.md) - [8.4.3 Amplification](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-4-3-amplification.md) - [8.4.4 End of Topic Test - Genome Project & Amplification](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-4-4-end-of-topic-test-genome-project-and-amplification.md) - [8.4.5 Using Recombinant DNA](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-4-5-using-recombinant-dna.md) - [8.4.6 Medical Diagnosis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-4-6-medical-diagnosis.md) - [8.4.7 Genetic Fingerprinting](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-4-7-genetic-fingerprinting.md) - [8.4.8 End of Topic Test - Gene Technologies](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-4-8-end-of-topic-test-gene-technologies.md) - [8.4.9 A-A* (AO3/4) - Gene Technology](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/8-4-9-a-a-ao34-gene-technology.md) ### 9 Mathematical Skills - 9.1 Mathematical Skills - [9.1.1 Diagnostic Misconceptions - Converting Units](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/9-1-1-diagnostic-misconceptions-converting-units.md) - [9.1.2 Diagnostic Misconceptions - Correct Hypothesis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/9-1-2-diagnostic-misconceptions-correct-hypothesis.md) - [9.1.3 Diagnostic Misconceptions - Interpret Hypothesis](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/9-1-3-diagnostic-misconceptions-interpret-hypothesis.md) - [9.1.4 Diagnostic Misconceptions - Calculate Uncertainty](https://senecalearning.com/en-gb/revision-notes/a-level/biology/aqa/9-1-4-diagnostic-misconceptions-calculate-uncertainty.md)