Source: https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-6-oxygen-debt [Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [GCSE](https://senecalearning.com/en-gb/revision-notes/gcse.md) › [Biology](https://senecalearning.com/en-gb/revision-notes/gcse/biology.md) › [AQA](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa.md) › [Higher](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher.md) › Oxygen Debt # Oxygen Debt Biology: AQA GCSE Higher, topic 4.2.6 ## Anaerobic Respiration If muscles are not supplied with enough oxygen during long periods of activity (like exercise), then muscle cells may start to respire anaerobically. This can lead to oxygen debt: ### Lactic acid ![Lactic acid](https://image-v2.cdn.app.senecalearning.com/courseImages/biology/4.2.1-%20Respiration/relay-race-655353_640-min.jpg) - Lactic acid is a by-product of anaerobic respiration. - Lactic acid is toxic. When it builds up in muscles, this can cause muscular pain and fatigue. - Lactic acid also stops muscles contracting efficiently. ### Oxygen debt ![Oxygen debt](https://image-v2.cdn.app.senecalearning.com/courseImages/biology/4.2.1-%20Respiration/no-money-2070384_640-min.jpg) - Oxygen debt refers to the extra oxygen that is needed after exercise to oxidise lactic acid and get it out of cells. ### Repaying the debt ![Repaying the debt](https://image-v2.cdn.app.senecalearning.com/courseImages/biology/4.2.1-%20Respiration/euro-1144835_640-min.jpg) - Blood transports the lactic acid to the liver, where it reacts with oxygen to produce carbon dioxide and water. - Heavy breathing after exercise helps to repay the oxygen debt by taking more oxygen into the lungs. ## Test yourself on Oxygen Debt - Why do muscle cells begin to respire anaerobically during long periods of intense exercise? - Why can a build-up of lactic acid cause muscular pain and fatigue during exercise? - A runner's muscles stop contracting efficiently near the end of a long race. What is the most likely cause of this? - Why does an athlete continue to breathe heavily for some time after finishing hard exercise? - Why does the liver react lactic acid with oxygen after exercise? [Practise this topic for free](https://app.senecalearning.com/classroom/course/6b76a6e0-cf79-11e7-83a9-29a486db2c9f/section/a839ffc8-39ba-4542-b5ee-a4f516fee630/session) - Previous topic: [4.2.5 Respiration During Exercise](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-5-respiration-during-exercise.md) - Next topic: [4.2.7 Respiration HyperLearning](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-7-respiration-hyperlearning.md) ## Biology: AQA GCSE Higher contents ### 1 Cell Biology - 1.1 What's in Cells? - [1.1.1 Types of Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-1-types-of-cells.md) - [1.1.2 Properties of Prokaryotes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-2-properties-of-prokaryotes.md) - [1.1.3 Orders of Magnitude](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-3-orders-of-magnitude.md) - [1.1.4 Standard Form](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-4-standard-form.md) - [1.1.5 Standard Form - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-5-standard-form-calculations.md) - [1.1.6 Addition in Standard Form - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-6-addition-in-standard-form-calculations.md) - [1.1.7 Subtraction in Standard Form - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-7-subtraction-in-standard-form-calculations.md) - [1.1.8 Multiplication in Standard Form - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-8-multiplication-in-standard-form-calculations.md) - [1.1.9 Division in Standard Form - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-9-division-in-standard-form-calculations.md) - [1.1.10 Animal Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-10-animal-cells.md) - [1.1.11 Plant Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-11-plant-cells.md) - [1.1.12 Differentiation in Plants & Animals](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-12-differentiation-in-plants-and-animals.md) - [1.1.13 Bacterial Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-13-bacterial-cells.md) - [1.1.14 Types of Cells HyperLearning](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-14-types-of-cells-hyperlearning.md) - [1.1.15 Cell Specialisation in Animals](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-15-cell-specialisation-in-animals.md) - [1.1.16 Sperm Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-16-sperm-cells.md) - [1.1.17 Nerve Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-17-nerve-cells.md) - [1.1.18 Muscle Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-18-muscle-cells.md) - [1.1.19 Cell Specialisation in Plants - Root Hair Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-19-cell-specialisation-in-plants-root-hair-cells.md) - [1.1.20 Cell Specialisation in Plants - Xylem](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-20-cell-specialisation-in-plants-xylem.md) - [1.1.21 Cell Specialisation in Plants - Phloem](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-21-cell-specialisation-in-plants-phloem.md) - [1.1.22 Microscopy](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-22-microscopy.md) - [1.1.23 Magnification](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-23-magnification.md) - [1.1.24 Developments in Microscopy](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-24-developments-in-microscopy.md) - [1.1.25 Required Practical - Microscopy](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-25-required-practical-microscopy.md) - [1.1.26 Microscopy - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-26-microscopy-calculations.md) - [1.1.27 Culturing Microorganisms](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-27-culturing-microorganisms.md) - [1.1.28 Contamination](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-28-contamination.md) - [1.1.29 Avoiding Contamination](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-29-avoiding-contamination.md) - [1.1.30 Calculating Bacteria](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-30-calculating-bacteria.md) - [1.1.31 Calculating Bacteria - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-31-calculating-bacteria-calculations.md) - [1.1.32 Required Practical - Bacteria](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-32-required-practical-bacteria.md) - [1.1.33 Exam-Style Questions - Cell Structure & Microscopy](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-33-exam-style-questions-cell-structure-and-microscopy.md) - [1.1.34 Diagnostic Misconceptions - Converting](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-34-diagnostic-misconceptions-converting.md) - [1.1.35 Diagnostic Misconceptions - Animal Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-35-diagnostic-misconceptions-animal-cells.md) - [1.1.36 Diagnostic Misconceptions - Mitochondria](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-36-diagnostic-misconceptions-mitochondria.md) - [1.1.37 End of Topic Test - What's in Cells?](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-1-37-end-of-topic-test-whats-in-cells.md) - 1.2 Cell Division - [1.2.1 Chromosomes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-2-1-chromosomes.md) - [1.2.2 The Cell Cycle](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-2-2-the-cell-cycle.md) - [1.2.3 Mitosis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-2-3-mitosis.md) - [1.2.4 Stem Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-2-4-stem-cells.md) - [1.2.5 Use of Stem Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-2-5-use-of-stem-cells.md) - [1.2.6 Disadvantages of Stem Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-2-6-disadvantages-of-stem-cells.md) - [1.2.7 Exam-Style Questions - Mitosis & Cell Cycle](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-2-7-exam-style-questions-mitosis-and-cell-cycle.md) - [1.2.8 Diagnostic Misconceptions - Mitosis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-2-8-diagnostic-misconceptions-mitosis.md) - 1.3 Transport in Cells - [1.3.1 Diffusion](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-1-diffusion.md) - [1.3.2 Factors Affecting Diffusion](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-2-factors-affecting-diffusion.md) - [1.3.3 Surface Area : Volume](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-3-surface-area-volume.md) - [1.3.4 Surface Area : Volume - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-4-surface-area-volume-calculations.md) - [1.3.5 Exchange Surfaces](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-5-exchange-surfaces.md) - [1.3.6 Examples of Exchange Surfaces](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-6-examples-of-exchange-surfaces.md) - [1.3.7 Osmosis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-7-osmosis.md) - [1.3.8 Osmosis 2](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-8-osmosis-2.md) - [1.3.9 Required Practical - Osmosis in Plant Tissue](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-9-required-practical-osmosis-in-plant-tissue.md) - [1.3.10 Active Transport](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-10-active-transport.md) - [1.3.11 Transport in Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-11-transport-in-cells.md) - [1.3.12 Grade 9 - Cell Transport](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-12-grade-9-cell-transport.md) - [1.3.13 Diagnostic Misconceptions - Water Moving](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-13-diagnostic-misconceptions-water-moving.md) - [1.3.14 Diagnostic Misconceptions - Active Transport](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-14-diagnostic-misconceptions-active-transport.md) - [1.3.15 End of Topic Test - Cell Division & Transport](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/1-3-15-end-of-topic-test-cell-division-and-transport.md) ### 2 Organisation - 2.1 Principles of Organisation - [2.1.1 Cells & Tissues](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-1-1-cells-and-tissues.md) - [2.1.2 Organs](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-1-2-organs.md) - [2.1.3 Organ Systems](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-1-3-organ-systems.md) - [2.1.4 Organisms](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-1-4-organisms.md) - 2.2 Enzymes - [2.2.1 Enzymes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-1-enzymes.md) - [2.2.2 Enzymes HyperFlashcards](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-2-enzymes-hyperflashcards.md) - [2.2.3 Rate of Reaction](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-3-rate-of-reaction.md) - [2.2.4 Calculating Rate of Reaction](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-4-calculating-rate-of-reaction.md) - [2.2.5 Rate of Reaction - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-5-rate-of-reaction-calculations.md) - [2.2.6 Digestion](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-6-digestion.md) - [2.2.7 Bile](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-7-bile.md) - [2.2.8 Examples of Digestive Enzymes - Amylase](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-8-examples-of-digestive-enzymes-amylase.md) - [2.2.9 Examples of Digestive Enzymes - Protease](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-9-examples-of-digestive-enzymes-protease.md) - [2.2.10 Examples of Digestive Enzymes - Lipase](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-10-examples-of-digestive-enzymes-lipase.md) - [2.2.11 Testing for Biological Molecules](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-11-testing-for-biological-molecules.md) - [2.2.12 Required Practical - Testing for Food Chemicals](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-12-required-practical-testing-for-food-chemicals.md) - [2.2.13 Required Practical - Enzymes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-13-required-practical-enzymes.md) - [2.2.14 Grade 9 - Enzymes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-14-grade-9-enzymes.md) - [2.2.15 Exam-Style Questions - Enzymes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-15-exam-style-questions-enzymes.md) - [2.2.16 Diagnostic Misconceptions - High Temperatures](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-16-diagnostic-misconceptions-high-temperatures.md) - [2.2.17 Diagnostic Misconceptions - Low Temperatures](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-17-diagnostic-misconceptions-low-temperatures.md) - [2.2.18 Diagnostic Misconceptions - Stomach Acid](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-18-diagnostic-misconceptions-stomach-acid.md) - [2.2.19 Diagnostic Misconceptions - Substrate Shape](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-19-diagnostic-misconceptions-substrate-shape.md) - [2.2.20 End of Topic Test - Organisation & Enzymes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-2-20-end-of-topic-test-organisation-and-enzymes.md) - 2.3 Circulatory System - [2.3.1 Types of Blood Vessels](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-1-types-of-blood-vessels.md) - [2.3.2 Blood Vessels - Arteries](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-2-blood-vessels-arteries.md) - [2.3.3 Blood Vessels - Capillaries](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-3-blood-vessels-capillaries.md) - [2.3.4 Blood Vessels - Veins](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-4-blood-vessels-veins.md) - [2.3.5 The Heart - Structure](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-5-the-heart-structure.md) - [2.3.6 The Heart - Function](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-6-the-heart-function.md) - [2.3.7 Important Blood Vessels](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-7-important-blood-vessels.md) - [2.3.8 Double Circulatory System](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-8-double-circulatory-system.md) - [2.3.9 Gas Exchange](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-9-gas-exchange.md) - [2.3.10 Gas Exchange - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-10-gas-exchange-calculations.md) - [2.3.11 Alveoli](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-11-alveoli.md) - [2.3.12 Blood Components](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-12-blood-components.md) - [2.3.13 Platelets](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-13-platelets.md) - [2.3.14 Red Blood Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-14-red-blood-cells.md) - [2.3.15 White Blood Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-15-white-blood-cells.md) - [2.3.16 End of Topic Test - Circulatory System](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-3-16-end-of-topic-test-circulatory-system.md) - 2.4 Non-Communicable Diseases - [2.4.1 Health Issues](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-1-health-issues.md) - [2.4.2 Disease Interactions](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-2-disease-interactions.md) - [2.4.3 Sampling](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-3-sampling.md) - [2.4.4 Sampling - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-4-sampling-calculations.md) - [2.4.5 Risk Factors](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-5-risk-factors.md) - [2.4.6 Examples of Risk Factors](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-6-examples-of-risk-factors.md) - [2.4.7 Risk Factor Graphs](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-7-risk-factor-graphs.md) - [2.4.8 Coronary Heart Disease](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-8-coronary-heart-disease.md) - [2.4.9 Heart Valve Disease](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-9-heart-valve-disease.md) - [2.4.10 Heart Failure](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-10-heart-failure.md) - [2.4.11 Treating Heart Disease](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-11-treating-heart-disease.md) - [2.4.12 Comparing Treatments of Heart Disease](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-12-comparing-treatments-of-heart-disease.md) - [2.4.13 Cancer](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-13-cancer.md) - [2.4.14 Cancer Risk Factors](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-14-cancer-risk-factors.md) - [2.4.15 End of Topic Test - Non-Communicable Diseases](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-15-end-of-topic-test-non-communicable-diseases.md) - [2.4.16 Exam-Style Questions - Coronary Heart Disease](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-4-16-exam-style-questions-coronary-heart-disease.md) - 2.5 Plant Tissues, Organs & Systems - [2.5.1 Plant Organs](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-1-plant-organs.md) - [2.5.2 Leaves](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-2-leaves.md) - [2.5.3 Transpiration](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-3-transpiration.md) - [2.5.4 Rate of Transpiration](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-4-rate-of-transpiration.md) - [2.5.5 Measuring Transpiration](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-5-measuring-transpiration.md) - [2.5.6 Translocation](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-6-translocation.md) - [2.5.7 Transpiration Tissues - Xylem Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-7-transpiration-tissues-xylem-cells.md) - [2.5.8 Transpiration Tissues - Root Hair Cells](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-8-transpiration-tissues-root-hair-cells.md) - [2.5.9 Stomata](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-9-stomata.md) - [2.5.10 States of Stomata](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-10-states-of-stomata.md) - [2.5.11 Premium Knowledge - Transpiration](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-11-premium-knowledge-transpiration.md) - [2.5.12 End of Topic Test - Plants](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-12-end-of-topic-test-plants.md) - [2.5.13 Exam-Style Questions - Plant Tissues](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-13-exam-style-questions-plant-tissues.md) - [2.5.14 Diagnostic Misconceptions - Plant Food](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-14-diagnostic-misconceptions-plant-food.md) - [2.5.15 Diagnostic Misconceptions - Plants & Water](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-15-diagnostic-misconceptions-plants-and-water.md) - [2.5.16 Diagnostic Misconceptions - Plants Don't Breathe](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/2-5-16-diagnostic-misconceptions-plants-dont-breathe.md) ### 3 Infection & Response - 3.1 Communicable Disease - [3.1.1 Spreading Disease](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-1-spreading-disease.md) - [3.1.2 Causing Diseases](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-2-causing-diseases.md) - [3.1.3 Preventing Infection](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-3-preventing-infection.md) - [3.1.4 Communicable Disease - Viruses](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-4-communicable-disease-viruses.md) - [3.1.5 Examples of Viruses](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-5-examples-of-viruses.md) - [3.1.6 Communicable Disease - Bacteria](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-6-communicable-disease-bacteria.md) - [3.1.7 Communicable Disease - Fungi](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-7-communicable-disease-fungi.md) - [3.1.8 Communicable Disease - Protists](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-8-communicable-disease-protists.md) - [3.1.9 Human Defence Systems - Non-Specific Defences](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-9-human-defence-systems-non-specific-defences.md) - [3.1.10 Human Defence Systems - Immune Systems](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-10-human-defence-systems-immune-systems.md) - [3.1.11 Antibodies](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-11-antibodies.md) - [3.1.12 Vaccinations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-12-vaccinations.md) - [3.1.13 The Immune System](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-13-the-immune-system.md) - [3.1.14 The Immune System 2](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-14-the-immune-system-2.md) - [3.1.15 Antibiotics](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-15-antibiotics.md) - [3.1.16 Antibiotic Resistance](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-16-antibiotic-resistance.md) - [3.1.17 Antibiotic Resistance 2](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-17-antibiotic-resistance-2.md) - [3.1.18 Drug Discovery](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-18-drug-discovery.md) - [3.1.19 Developing New Drugs](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-19-developing-new-drugs.md) - [3.1.20 Drug Testing](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-20-drug-testing.md) - [3.1.21 Drug Testing in Laboratories](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-21-drug-testing-in-laboratories.md) - [3.1.22 Double-Blind Trials](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-22-double-blind-trials.md) - [3.1.23 Drug Testing / Efficacy - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-23-drug-testing-efficacy-calculations.md) - [3.1.24 End of Topic Test - Communicable Diseases](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-24-end-of-topic-test-communicable-diseases.md) - [3.1.25 Exam-Style Questions - Microorganisms & Disease](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-25-exam-style-questions-microorganisms-and-disease.md) - [3.1.26 Diagnostic Misconceptions - Antibiotics](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-1-26-diagnostic-misconceptions-antibiotics.md) - 3.2 Monoclonal Antibodies - [3.2.1 Monoclonal Antibodies](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-2-1-monoclonal-antibodies.md) - [3.2.2 Producing Monoclonal Antibodies](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-2-2-producing-monoclonal-antibodies.md) - [3.2.3 Uses of Monoclonal Antibodies](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-2-3-uses-of-monoclonal-antibodies.md) - [3.2.4 Grade 9 - Monoclonal Antibodies](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-2-4-grade-9-monoclonal-antibodies.md) - 3.3 Plant Diseases - [3.3.1 Ion Deficiencies in Plants](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-3-1-ion-deficiencies-in-plants.md) - [3.3.2 Plant Defences](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-3-2-plant-defences.md) - [3.3.3 Signs of Plant Disease](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-3-3-signs-of-plant-disease.md) - [3.3.4 Identifying Disease](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-3-4-identifying-disease.md) - [3.3.5 Other Plant Diseases](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-3-5-other-plant-diseases.md) - [3.3.6 End of Topic Test - Antibodies & Plant Disease](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/3-3-6-end-of-topic-test-antibodies-and-plant-disease.md) ### 4 Bioenergetics - 4.1 Photosynthesis - [4.1.1 Photosynthesis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-1-photosynthesis.md) - [4.1.2 Photosynthesis Equation](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-2-photosynthesis-equation.md) - [4.1.3 Rate of Photosynthesis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-3-rate-of-photosynthesis.md) - [4.1.4 Limiting Factors](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-4-limiting-factors.md) - [4.1.5 Photosynthesis in Farming](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-5-photosynthesis-in-farming.md) - [4.1.6 Uses of Glucose](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-6-uses-of-glucose.md) - [4.1.7 Photosynthesis - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-7-photosynthesis-calculations.md) - [4.1.8 Required Practical - Light Intensity](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-8-required-practical-light-intensity.md) - [4.1.9 Grade 9 - Photosynthesis Experiment](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-9-grade-9-photosynthesis-experiment.md) - [4.1.10 Exam-Style Questions - Rate of Photosynthesis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-10-exam-style-questions-rate-of-photosynthesis.md) - [4.1.11 Diagnostic Misconceptions - Photosynthesis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-11-diagnostic-misconceptions-photosynthesis.md) - [4.1.12 Diagnostic Misconceptions - Plants Respiration](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-1-12-diagnostic-misconceptions-plants-respiration.md) - 4.2 Respiration - [4.2.1 Organisms and Energy](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-1-organisms-and-energy.md) - [4.2.2 Respiration](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-2-respiration.md) - [4.2.3 Metabolism](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-3-metabolism.md) - [4.2.4 Respiration - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-4-respiration-calculations.md) - [4.2.5 Respiration During Exercise](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-5-respiration-during-exercise.md) - [4.2.6 Oxygen Debt](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-6-oxygen-debt.md) - [4.2.7 Respiration HyperLearning](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-7-respiration-hyperlearning.md) - [4.2.8 End of Topic Test - Photosynthesis and Respiration](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-8-end-of-topic-test-photosynthesis-and-respiration.md) - [4.2.9 Exam-Style Questions - Anaerobic Respiration](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/4-2-9-exam-style-questions-anaerobic-respiration.md) ### 5 Homeostasis & Response - 5.1 Homeostasis - [5.1.1 Homeostasis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-1-1-homeostasis.md) - [5.1.2 Regulating Internal Conditions](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-1-2-regulating-internal-conditions.md) - [5.1.3 Homeostasis & Negative Feedback](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-1-3-homeostasis-and-negative-feedback.md) - [5.1.4 The Body's Negative Feedback Loop](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-1-4-the-bodys-negative-feedback-loop.md) - [5.1.5 Exam-Style Questions - Exercise & Homeostasis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-1-5-exam-style-questions-exercise-and-homeostasis.md) - 5.2 The Human Nervous System - [5.2.1 The Nervous System](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-1-the-nervous-system.md) - [5.2.2 The Nervous System HyperFlashcards](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-2-the-nervous-system-hyperflashcards.md) - [5.2.3 Synapses](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-3-synapses.md) - [5.2.4 Reflexes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-4-reflexes.md) - [5.2.5 Components of a Reflex Arc](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-5-components-of-a-reflex-arc.md) - [5.2.6 Required Practical - Human Reaction Times](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-6-required-practical-human-reaction-times.md) - [5.2.7 The Brain](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-7-the-brain.md) - [5.2.8 Parts of the Brain](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-8-parts-of-the-brain.md) - [5.2.9 The Brain: Neuro Techniques](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-9-the-brain-neuro-techniques.md) - [5.2.10 Retina Scanning](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-10-retina-scanning.md) - [5.2.11 Eye Anatomy](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-11-eye-anatomy.md) - [5.2.12 Eye Function - Focus](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-12-eye-function-focus.md) - [5.2.13 Eye Function - Light](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-13-eye-function-light.md) - [5.2.14 Eye Defects](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-14-eye-defects.md) - [5.2.15 Thermoregulation](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-15-thermoregulation.md) - [5.2.16 Hot & Cold](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-16-hot-and-cold.md) - [5.2.17 Thermoregulation - Sweating & Shivering](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-17-thermoregulation-sweating-and-shivering.md) - [5.2.18 Thermoregulation - Body Hair](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-18-thermoregulation-body-hair.md) - [5.2.19 Thermoregulation - Blood Vessels](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-19-thermoregulation-blood-vessels.md) - [5.2.20 Body Temperature HyperLearning](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-20-body-temperature-hyperlearning.md) - [5.2.21 End of Topic Test - Human Nervous System](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-21-end-of-topic-test-human-nervous-system.md) - [5.2.22 Exam-Style Questions - Nervous System](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-22-exam-style-questions-nervous-system.md) - [5.2.23 Diagnostic Misconceptions - Nervous System](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-2-23-diagnostic-misconceptions-nervous-system.md) - 5.3 Hormonal Coordination in Humans - [5.3.1 Endocrine Glands](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-1-endocrine-glands.md) - [5.3.2 The Endocrine System](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-2-the-endocrine-system.md) - [5.3.3 Thyroxine](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-3-thyroxine.md) - [5.3.4 Adrenaline](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-4-adrenaline.md) - [5.3.5 Blood Glucose](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-5-blood-glucose.md) - [5.3.6 Detecting Glucose](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-6-detecting-glucose.md) - [5.3.7 Diabetes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-7-diabetes.md) - [5.3.8 Type 1 Diabetes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-8-type-1-diabetes.md) - [5.3.9 Type 2 Diabetes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-9-type-2-diabetes.md) - [5.3.10 Water Balance](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-10-water-balance.md) - [5.3.11 Kidneys](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-11-kidneys.md) - [5.3.12 Urea](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-12-urea.md) - [5.3.13 Urine Production](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-13-urine-production.md) - [5.3.14 Urine](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-14-urine.md) - [5.3.15 Dialysis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-15-dialysis.md) - [5.3.16 Dialysis - Pros & Cons](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-16-dialysis-pros-and-cons.md) - [5.3.17 Transplants](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-17-transplants.md) - [5.3.18 Transplants - Pros & Cons](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-18-transplants-pros-and-cons.md) - [5.3.19 Puberty](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-19-puberty.md) - [5.3.20 Menstruation](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-20-menstruation.md) - [5.3.21 Menstrual Hormones](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-21-menstrual-hormones.md) - [5.3.22 Menstrual Cycle](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-22-menstrual-cycle.md) - [5.3.23 Contraception - 'Natural Methods'](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-23-contraception-natural-methods.md) - [5.3.24 Contraception - Sterilisation](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-24-contraception-sterilisation.md) - [5.3.25 Contraception - Condoms](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-25-contraception-condoms.md) - [5.3.26 Contraception - The Pill](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-26-contraception-the-pill.md) - [5.3.27 Contraception - Diaphragm & IUDs](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-27-contraception-diaphragm-and-iuds.md) - [5.3.28 Contraception - Other Options](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-28-contraception-other-options.md) - [5.3.29 Hormones for Infertility](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-29-hormones-for-infertility.md) - [5.3.30 In Vitro Fertilisation](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-30-in-vitro-fertilisation.md) - [5.3.31 Fertility Treatments - Pros & Cons](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-31-fertility-treatments-pros-and-cons.md) - [5.3.32 End of Topic Test - Homeostasis & Hormones](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-32-end-of-topic-test-homeostasis-and-hormones.md) - [5.3.33 Grade 9 - Hormonal Coordination](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-33-grade-9-hormonal-coordination.md) - [5.3.34 Exam-Style Questions - Hormones & Contraception](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-3-34-exam-style-questions-hormones-and-contraception.md) - 5.4 Plant Hormones - [5.4.1 Plant Hormones](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-4-1-plant-hormones.md) - [5.4.2 Types of Tropisms](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-4-2-types-of-tropisms.md) - [5.4.3 Auxins & Tropisms](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-4-3-auxins-and-tropisms.md) - [5.4.4 Effect of Light on Seedlings](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-4-4-effect-of-light-on-seedlings.md) - [5.4.5 Required Practical - Light or Gravity on Seedlings](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-4-5-required-practical-light-or-gravity-on-seedlings.md) - [5.4.6 Uses of Plant Hormones](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-4-6-uses-of-plant-hormones.md) - [5.4.7 End of Topic Test - Hormones](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/5-4-7-end-of-topic-test-hormones.md) ### 6 Inheritance, Variation & Evolution - 6.1 Reproduction - [6.1.1 Cell Division](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-1-cell-division.md) - [6.1.2 Meiosis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-2-meiosis.md) - [6.1.3 Sexual Reproduction](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-3-sexual-reproduction.md) - [6.1.4 Asexual Reproduction](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-4-asexual-reproduction.md) - [6.1.5 Sexual Reproduction Advantages](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-5-sexual-reproduction-advantages.md) - [6.1.6 Asexual Reproduction Advantages](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-6-asexual-reproduction-advantages.md) - [6.1.7 Genome](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-7-genome.md) - [6.1.8 Genome - Diagram](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-8-genome-diagram.md) - [6.1.9 Genome Sequencing](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-9-genome-sequencing.md) - [6.1.10 Nucleotide](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-10-nucleotide.md) - [6.1.11 DNA Structure](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-11-dna-structure.md) - [6.1.12 Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-12-protein-synthesis.md) - [6.1.13 Protein Synthesis 2](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-13-protein-synthesis-2.md) - [6.1.14 Mutations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-14-mutations.md) - [6.1.15 Alleles](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-15-alleles.md) - [6.1.16 Genotype vs Phenotype](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-16-genotype-vs-phenotype.md) - [6.1.17 Punnett Squares](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-17-punnett-squares.md) - [6.1.18 Punnett Squares 2](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-18-punnett-squares-2.md) - [6.1.19 Inherited Disorders](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-19-inherited-disorders.md) - [6.1.20 Cystic Fibrosis Punnett Square](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-20-cystic-fibrosis-punnett-square.md) - [6.1.21 Family Trees](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-21-family-trees.md) - [6.1.22 Polydactyly](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-22-polydactyly.md) - [6.1.23 Genetic Crosses - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-23-genetic-crosses-calculations.md) - [6.1.24 Genome Screening](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-24-genome-screening.md) - [6.1.25 Disadvantages of Embryonic Screening](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-25-disadvantages-of-embryonic-screening.md) - [6.1.26 Sex Determination](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-26-sex-determination.md) - [6.1.27 End of Topic Test - Reproduction](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-27-end-of-topic-test-reproduction.md) - [6.1.28 Exam-Style Questions - DNA & Genetics](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-28-exam-style-questions-dna-and-genetics.md) - [6.1.29 Diagnostic Misconceptions - Mutations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-29-diagnostic-misconceptions-mutations.md) - [6.1.30 Diagnostic Misconceptions - Chromosomes](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-30-diagnostic-misconceptions-chromosomes.md) - [6.1.31 Diagnostic Misconceptions - Genes & Alleles](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-1-31-diagnostic-misconceptions-genes-and-alleles.md) - 6.2 Variation & Evolution - [6.2.1 Variation](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-1-variation.md) - [6.2.2 Evolution & Speciation](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-2-evolution-and-speciation.md) - [6.2.3 Natural Selection](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-3-natural-selection.md) - [6.2.4 Selective Breeding](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-4-selective-breeding.md) - [6.2.5 Selective Breeding 2](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-5-selective-breeding-2.md) - [6.2.6 Uses of Selective Breeding](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-6-uses-of-selective-breeding.md) - [6.2.7 Dangers of Selective Breeding](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-7-dangers-of-selective-breeding.md) - [6.2.8 Genetic Engineering](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-8-genetic-engineering.md) - [6.2.9 Genetic Engineering 2](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-9-genetic-engineering-2.md) - [6.2.10 Uses of Genetic Modification](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-10-uses-of-genetic-modification.md) - [6.2.11 Advantages of Genetic Modification](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-11-advantages-of-genetic-modification.md) - [6.2.12 Disadvantages of Genetic Modification](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-12-disadvantages-of-genetic-modification.md) - [6.2.13 Cloning](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-13-cloning.md) - [6.2.14 Cloning Plants](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-14-cloning-plants.md) - [6.2.15 Cloning Animals](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-15-cloning-animals.md) - [6.2.16 Adult Cell Cloning](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-16-adult-cell-cloning.md) - [6.2.17 End of Topic Test - Variation & Evolution](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-17-end-of-topic-test-variation-and-evolution.md) - [6.2.18 Exam-Style Questions - Selective Breeding](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-2-18-exam-style-questions-selective-breeding.md) - 6.3 Genetics & Evolution - [6.3.1 Natural Selection](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-1-natural-selection.md) - [6.3.2 Controversy Around Natural Selection](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-2-controversy-around-natural-selection.md) - [6.3.3 Darwin's Theory of Evolution](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-3-darwins-theory-of-evolution.md) - [6.3.4 Inheritance Theory](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-4-inheritance-theory.md) - [6.3.5 Speciation](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-5-speciation.md) - [6.3.6 Alfred Russel Wallace](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-6-alfred-russel-wallace.md) - [6.3.7 Evidence for Evolution](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-7-evidence-for-evolution.md) - [6.3.8 Fossils](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-8-fossils.md) - [6.3.9 Resistant Bacteria](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-9-resistant-bacteria.md) - [6.3.10 Genetics](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-10-genetics.md) - [6.3.11 Extinctions](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-11-extinctions.md) - [6.3.12 Grade 9 - Evolution](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-12-grade-9-evolution.md) - [6.3.13 Diagnostic Misconceptions - Natural Selection](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-3-13-diagnostic-misconceptions-natural-selection.md) - 6.4 Classification - [6.4.1 Classification of Living Organisms](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-4-1-classification-of-living-organisms.md) - [6.4.2 Traditional System](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-4-2-traditional-system.md) - [6.4.3 Classification of Living Organisms: Updated System](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-4-3-classification-of-living-organisms-updated-system.md) - [6.4.4 Evolutionary Trees](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-4-4-evolutionary-trees.md) - [6.4.5 End of Topic Test - Genetics & Classification](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/6-4-5-end-of-topic-test-genetics-and-classification.md) ### 7 Ecology - 7.1 Adaptations & Interdependence - [7.1.1 Communities: Ecosystems](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-1-1-communities-ecosystems.md) - [7.1.2 Communities: Resources](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-1-2-communities-resources.md) - [7.1.3 Species Interdependence](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-1-3-species-interdependence.md) - [7.1.4 Stable Communities](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-1-4-stable-communities.md) - 7.2 Organisation of Ecosystems - [7.2.1 Population Dynamics](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-1-population-dynamics.md) - [7.2.2 Predator-Prey Graphs](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-2-predator-prey-graphs.md) - [7.2.3 Impact of Environmental Change](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-3-impact-of-environmental-change.md) - [7.2.4 Causes of Environmental Change](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-4-causes-of-environmental-change.md) - [7.2.5 Assessing Ecosystems](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-5-assessing-ecosystems.md) - [7.2.6 Organism Abundance](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-6-organism-abundance.md) - [7.2.7 Required Practical - Population Size](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-7-required-practical-population-size.md) - [7.2.8 Assessing Ecosystems - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-8-assessing-ecosystems-calculations.md) - [7.2.9 The Carbon Cycle](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-9-the-carbon-cycle.md) - [7.2.10 The Water Cycle](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-10-the-water-cycle.md) - [7.2.11 The Cycling of Materials](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-11-the-cycling-of-materials.md) - [7.2.12 Decay](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-12-decay.md) - [7.2.13 Anaerobic Decay](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-13-anaerobic-decay.md) - [7.2.14 Biogas Generators](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-14-biogas-generators.md) - [7.2.15 Required Practical - Decay](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-15-required-practical-decay.md) - [7.2.16 End of Topic Test - Organisation of Ecosystems](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-16-end-of-topic-test-organisation-of-ecosystems.md) - [7.2.17 Grade 9 - Ecosystems](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-17-grade-9-ecosystems.md) - [7.2.18 Exam-Style Questions - Decomposition](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-2-18-exam-style-questions-decomposition.md) - 7.3 Biodiversity - [7.3.1 Humans & Biodiversity](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-3-1-humans-and-biodiversity.md) - [7.3.2 Waste Management](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-3-2-waste-management.md) - [7.3.3 Human Activities](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-3-3-human-activities.md) - [7.3.4 Land Use](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-3-4-land-use.md) - [7.3.5 Deforestation](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-3-5-deforestation.md) - [7.3.6 Carbon Dioxide](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-3-6-carbon-dioxide.md) - [7.3.7 The Greenhouse Effect](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-3-7-the-greenhouse-effect.md) - [7.3.8 Global Warming](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-3-8-global-warming.md) - [7.3.9 Maintaining Biodiversity](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-3-9-maintaining-biodiversity.md) - [7.3.10 End of Topic Test - Adaptations & Biodiversity](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-3-10-end-of-topic-test-adaptations-and-biodiversity.md) - 7.4 Trophic Levels - [7.4.1 Trophic Levels](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-4-1-trophic-levels.md) - [7.4.2 Trophic Levels: Food Chains](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-4-2-trophic-levels-food-chains.md) - [7.4.3 Trophic Levels: Decomposers](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-4-3-trophic-levels-decomposers.md) - [7.4.4 Pyramids of Biomass](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-4-4-pyramids-of-biomass.md) - [7.4.5 Transfer Efficiency](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-4-5-transfer-efficiency.md) - [7.4.6 Reasons for Energy Wastage](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-4-6-reasons-for-energy-wastage.md) - [7.4.7 Transfer Efficiency - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-4-7-transfer-efficiency-calculations.md) - [7.4.8 Premium Knowledge - Trophic Levels & Food Chains](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-4-8-premium-knowledge-trophic-levels-and-food-chains.md) - [7.4.9 Exam-Style Questions - Food Chains](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-4-9-exam-style-questions-food-chains.md) - [7.4.10 Diagnostic Misconceptions - Arrows](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-4-10-diagnostic-misconceptions-arrows.md) - 7.5 Food Production - [7.5.1 Food Security](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-5-1-food-security.md) - [7.5.2 Food Production: Biotechnology](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-5-2-food-production-biotechnology.md) - [7.5.3 Declining Fish Stock](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-5-3-declining-fish-stock.md) - [7.5.4 Sustainable Fishing](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-5-4-sustainable-fishing.md) - [7.5.5 Farming](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-5-5-farming.md) - [7.5.6 Food Production - Calculations](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-5-6-food-production-calculations.md) - [7.5.7 End of Topic Test - Food & Trophic Levels](https://senecalearning.com/en-gb/revision-notes/gcse/biology/aqa/higher/7-5-7-end-of-topic-test-food-and-trophic-levels.md)