Source: https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-1-5-protein-synthesis [Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [IGCSE](https://senecalearning.com/en-gb/revision-notes/igcse.md) › [Biology](https://senecalearning.com/en-gb/revision-notes/igcse/biology.md) › [Cambridge International](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international.md) › [Higher](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher.md) › Protein Synthesis # Protein Synthesis Biology: Cambridge International GCSE Supplement, topic 17.1.5 ## Protein Synthesis Protein synthesis is how our bodies make proteins. ### Codon ![Codon](https://image-v2.cdn.app.senecalearning.com/courseImages/biology/6.1.1%20-%20Reproduction/DNA_Coding.jpg) - Each amino acid is coded for by a specific sequence of three bases (called a codon). ### Order of bases ![Order of bases](https://image-v2.cdn.app.senecalearning.com/courseImages/biology/6.1.1%20-%20Reproduction/DNA_Coding.jpg) - The order of the bases on the DNA tells us the order for combining amino acids to create particular proteins. ### Different proteins ![Different proteins](https://image-v2.cdn.app.senecalearning.com/courseImages/biology/6.1.1%20-%20Reproduction/DNA_Coding.jpg) - We can change the protein made by a gene by altering the sequence of bases in that gene. ## Test yourself on Protein Synthesis - How long is the sequence of bases used to code for an amino acid? - If the order of bases on DNA changes, what happens to the proteins made using the DNA? - All these are part of the DNA. Which of each pair is the smaller unit? [Practise this topic for free](https://app.senecalearning.com/classroom/course/43a4d4e0-16f3-11e8-bb3b-679c0a39551b/section/abb633c0-215d-11e8-84f5-6d0f426af1ec/session) - Previous topic: [17.1.4 DNA Pairings](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-1-4-dna-pairings.md) - Next topic: [17.1.6 Synthesis Process](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-1-6-synthesis-process.md) ## Biology: Cambridge International GCSE Supplement contents ### 1 Classification of Living Organisms - 1.1 Characteristics of Living Organisms - [1.1.1 MRS GREN](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-1-1-mrs-gren.md) - [1.1.2 M.R.S.](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-1-2-mrs.md) - [1.1.3 G.R.E.N.](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-1-3-gren.md) - 1.2 Concept and Uses of Classification Systems - [1.2.1 Classification](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-2-1-classification.md) - [1.2.2 Linnaean Classification](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-2-2-linnaean-classification.md) - [1.2.3 Ancestors & DNA](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-2-3-ancestors-and-dna.md) - [1.2.4 Dichotomous Keys](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-2-4-dichotomous-keys.md) - 1.3 Features of Organisms - [1.3.1 Kingdoms - Animals & Plants](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-3-1-kingdoms-animals-and-plants.md) - [1.3.2 Kingdoms - Fungi, Prokaryotes, Protoctista](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-3-2-kingdoms-fungi-prokaryotes-protoctista.md) - [1.3.3 Vertebrates](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-3-3-vertebrates.md) - [1.3.4 Anthropods](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-3-4-anthropods.md) - [1.3.5 Plant Classification](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-3-5-plant-classification.md) - [1.3.6 Cellular Structures - Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-3-6-cellular-structures-cells.md) - [1.3.7 Cellular Structures - Viruses](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/1-3-7-cellular-structures-viruses.md) ### 2 Organisation of the Organism - 2.1 Cell Structure - [2.1.1 Animal Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-1-animal-cells.md) - [2.1.2 Plant Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-2-plant-cells.md) - [2.1.3 Properties of Prokaryotes](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-3-properties-of-prokaryotes.md) - [2.1.4 Cells & Tissues](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-4-cells-and-tissues.md) - [2.1.5 Organs](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-5-organs.md) - [2.1.6 Organ Systems](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-6-organ-systems.md) - [2.1.7 Organisms](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-7-organisms.md) - [2.1.8 Ciliated Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-8-ciliated-cells.md) - [2.1.9 Root Hair Cells & Palisade Mesophyll Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-9-root-hair-cells-and-palisade-mesophyll-cells.md) - [2.1.10 Neurones](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-10-neurones.md) - [2.1.11 Red Blood Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-11-red-blood-cells.md) - [2.1.12 Sperm & Egg Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-1-12-sperm-and-egg-cells.md) - 2.2 Size of Specimens - [2.2.1 Magnification](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-2-1-magnification.md) - [2.2.2 Microscopy](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-2-2-microscopy.md) - [2.2.3 Orders of Magnitude](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-2-3-orders-of-magnitude.md) - [2.2.4 Microscopy - Calculations](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-2-4-microscopy-calculations.md) - [2.2.5 Converting Measurements](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-2-5-converting-measurements.md) - [2.2.6 End of Topic Test - Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-2-6-end-of-topic-test-cells.md) - [2.2.7 Exam-Style Questions - Cell Structure & Microscopy](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/2-2-7-exam-style-questions-cell-structure-and-microscopy.md) ### 3 Movement Into & Out of Cells - 3.1 Diffusion - [3.1.1 Diffusion](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-1-1-diffusion.md) - [3.1.2 Factors Affecting Diffusion](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-1-2-factors-affecting-diffusion.md) - [3.1.3 Surface Area : Volume](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-1-3-surface-area-volume.md) - 3.2 Osmosis - [3.2.1 Water](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-2-1-water.md) - [3.2.2 Osmosis](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-2-2-osmosis.md) - [3.2.3 Osmosis Experiment](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-2-3-osmosis-experiment.md) - [3.2.4 Osmosis in Plants](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-2-4-osmosis-in-plants.md) - [3.2.5 Osmotic Balance](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-2-5-osmotic-balance.md) - [3.2.6 Required Practical - Osmosis](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-2-6-required-practical-osmosis.md) - 3.3 Active Transport - [3.3.1 Active Transport](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-3-1-active-transport.md) - [3.3.2 Transport in Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-3-2-transport-in-cells.md) - [3.3.3 Carrier Proteins](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-3-3-carrier-proteins.md) - [3.3.4 Grade 9 - Cell Transport](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-3-4-grade-9-cell-transport.md) - [3.3.5 End of Topic Test - Cell Transport](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-3-5-end-of-topic-test-cell-transport.md) - [3.3.6 Exam-Style Questions - Substance Exchange](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/3-3-6-exam-style-questions-substance-exchange.md) ### 4 Biological Molecules - 4.1 Biological Molecules - [4.1.1 Chemical Elements](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/4-1-1-chemical-elements.md) - [4.1.2 Larger Molecules](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/4-1-2-larger-molecules.md) - [4.1.3 Testing for Biological Molecules](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/4-1-3-testing-for-biological-molecules.md) - [4.1.4 DNA](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/4-1-4-dna.md) - [4.1.5 DNA Pairings](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/4-1-5-dna-pairings.md) ### 5 Enzymes - 5.1 Enzymes - [5.1.1 Enzymes](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/5-1-1-enzymes.md) - [5.1.2 Rate of Enzyme Action](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/5-1-2-rate-of-enzyme-action.md) - [5.1.3 Investigating Rate](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/5-1-3-investigating-rate.md) - [5.1.4 End of Topic Test - Enzymes](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/5-1-4-end-of-topic-test-enzymes.md) - [5.1.5 Grade 9 - Enzymes](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/5-1-5-grade-9-enzymes.md) ### 6 Plant Nutrition - 6.1 Photosynthesis - [6.1.1 Photosynthesis](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-1-photosynthesis.md) - [6.1.2 Photosynthesis - Plant Gas Exchange](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-2-photosynthesis-plant-gas-exchange.md) - [6.1.3 Uses of Glucose](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-3-uses-of-glucose.md) - [6.1.4 Ion Deficiency Conditions](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-4-ion-deficiency-conditions.md) - [6.1.5 Rate of Photosynthesis](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-5-rate-of-photosynthesis.md) - [6.1.6 Photosynthesis Experiments](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-6-photosynthesis-experiments.md) - [6.1.7 Photosynthesis Equation](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-7-photosynthesis-equation.md) - [6.1.8 Photosynthesis - Calculations](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-8-photosynthesis-calculations.md) - [6.1.9 Limiting Factors](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-9-limiting-factors.md) - [6.1.10 Limiting Factors 2](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-10-limiting-factors-2.md) - [6.1.11 Grade 9 - Photosynthesis Experiment](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-11-grade-9-photosynthesis-experiment.md) - [6.1.12 Exam-Style Questions - Photosynthesis](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-1-12-exam-style-questions-photosynthesis.md) - 6.2 Leaf Structure - [6.2.1 Leaf Structure](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-2-1-leaf-structure.md) - [6.2.2 Stomata](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-2-2-stomata.md) - [6.2.3 Plant Tissues](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-2-3-plant-tissues.md) - [6.2.4 Leaf Adaptations](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-2-4-leaf-adaptations.md) - [6.2.5 End of Topic Test - Photosynthesis](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/6-2-5-end-of-topic-test-photosynthesis.md) ### 7 Human Nutrition - 7.1 Diet - [7.1.1 Diet](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-1-1-diet.md) - [7.1.2 Vitamins & Minerals](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-1-2-vitamins-and-minerals.md) - [7.1.3 Scurvy & Rickets](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-1-3-scurvy-and-rickets.md) - 7.2 Digestive System - [7.2.1 Digestive System](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-2-1-digestive-system.md) - [7.2.2 Functions of the Digestive System](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-2-2-functions-of-the-digestive-system.md) - [7.2.3 Steps of Digestion](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-2-3-steps-of-digestion.md) - 7.3 Physical Digestion - [7.3.1 Physical Digestion - Human Tooth](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-3-1-physical-digestion-human-tooth.md) - [7.3.2 Teeth Types](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-3-2-teeth-types.md) - [7.3.3 Tooth Diseases](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-3-3-tooth-diseases.md) - 7.4 Chemical Digestion - [7.4.1 Digestive Enzymes](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-4-1-digestive-enzymes.md) - [7.4.2 Examples of Digestive Enzymes - Amylases](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-4-2-examples-of-digestive-enzymes-amylases.md) - [7.4.3 Examples of Digestive Enzymes - Proteases](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-4-3-examples-of-digestive-enzymes-proteases.md) - [7.4.4 Examples of Digestive Enzymes - Lipases](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-4-4-examples-of-digestive-enzymes-lipases.md) - [7.4.5 Chemical Digestion - Stomach](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-4-5-chemical-digestion-stomach.md) - [7.4.6 Exam-Style Questions - Digestive Enzymes](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-4-6-exam-style-questions-digestive-enzymes.md) - [7.4.7 Pepsin & Trypsin](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-4-7-pepsin-and-trypsin.md) - 7.5 Absorption - [7.5.1 Small Intestine](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-5-1-small-intestine.md) - [7.5.2 Villi](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/7-5-2-villi.md) ### 8 Transport in Plants - 8.1 Xylem & Phloem - [8.1.1 Plant Vessels](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-1-1-plant-vessels.md) - [8.1.2 Specialised Plant Cells - Xylem](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-1-2-specialised-plant-cells-xylem.md) - 8.2 Water Uptake - [8.2.1 Water Uptake](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-2-1-water-uptake.md) - [8.2.2 Specialised Plant Cells - Root Hair](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-2-2-specialised-plant-cells-root-hair.md) - [8.2.3 Exam-Style Questions - Transport in Plants](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-2-3-exam-style-questions-transport-in-plants.md) - 8.3 Transpiration - [8.3.1 Transpiration](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-3-1-transpiration.md) - [8.3.2 Transpiration Tissues - Xylem](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-3-2-transpiration-tissues-xylem.md) - [8.3.3 States of Stomata](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-3-3-states-of-stomata.md) - [8.3.4 Rate of Transpiration](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-3-4-rate-of-transpiration.md) - [8.3.5 Measuring Transpiration](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-3-5-measuring-transpiration.md) - 8.4 Translocation - [8.4.1 Translocation Tissues - Phloem](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-4-1-translocation-tissues-phloem.md) - [8.4.2 Translocation](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-4-2-translocation.md) - [8.4.3 End of Topic Test - Plant Transport](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/8-4-3-end-of-topic-test-plant-transport.md) ### 9 Transport in Animals - 9.1 Circulatory Systems - [9.1.1 Circulatory Systems](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-1-1-circulatory-systems.md) - [9.1.2 Double Circulatory Systems](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-1-2-double-circulatory-systems.md) - 9.2 Heart - [9.2.1 Mammal Heart Function](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-2-1-mammal-heart-function.md) - [9.2.2 Mammal Heart Structure](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-2-2-mammal-heart-structure.md) - [9.2.3 Heart Monitoring](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-2-3-heart-monitoring.md) - [9.2.4 Exercise Recovery](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-2-4-exercise-recovery.md) - [9.2.5 Heart Disease](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-2-5-heart-disease.md) - [9.2.6 Treatment of Heart Disease](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-2-6-treatment-of-heart-disease.md) - 9.3 Blood Vessels - [9.3.1 Types of Vessels - Arteries](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-3-1-types-of-vessels-arteries.md) - [9.3.2 Types of Vessels - Veins](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-3-2-types-of-vessels-veins.md) - [9.3.3 Types of Vessels - Capillaries](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-3-3-types-of-vessels-capillaries.md) - [9.3.4 Important Vessels](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-3-4-important-vessels.md) - [9.3.5 End of Topic Test - Circulatory System](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-3-5-end-of-topic-test-circulatory-system.md) - [9.3.6 Exam-Style Questions - Circulatory System](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-3-6-exam-style-questions-circulatory-system.md) - 9.4 Blood - [9.4.1 Blood Components](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-4-1-blood-components.md) - [9.4.2 Red Blood Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-4-2-red-blood-cells.md) - [9.4.3 White Blood Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-4-3-white-blood-cells.md) - [9.4.4 Platelets](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-4-4-platelets.md) - [9.4.5 Blood Clotting](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/9-4-5-blood-clotting.md) ### 10 Diseases & Immunity - 10.1 Diseases & Immunity - [10.1.1 Health Issues](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/10-1-1-health-issues.md) - [10.1.2 Causing Diseases](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/10-1-2-causing-diseases.md) - [10.1.3 Preventing Infection](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/10-1-3-preventing-infection.md) - [10.1.4 Human Defence Systems - Non-Specific Defences](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/10-1-4-human-defence-systems-non-specific-defences.md) - [10.1.5 Human Defence Systems - Immune Systems](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/10-1-5-human-defence-systems-immune-systems.md) - [10.1.6 Cholera](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/10-1-6-cholera.md) - [10.1.7 Antibodies](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/10-1-7-antibodies.md) - [10.1.8 Vaccination & Immunity](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/10-1-8-vaccination-and-immunity.md) - [10.1.9 Passive Immunity](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/10-1-9-passive-immunity.md) - [10.1.10 Viruses](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/10-1-10-viruses.md) - [10.1.11 End of Topic Test - Health & Disease](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/10-1-11-end-of-topic-test-health-and-disease.md) ### 11 Gas Exchange in Humans - 11.1 Gas Exchange in Humans - [11.1.1 Exchange Surface](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/11-1-1-exchange-surface.md) - [11.1.2 Lung Gas Exchange](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/11-1-2-lung-gas-exchange.md) - [11.1.3 Alveoli](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/11-1-3-alveoli.md) - [11.1.4 Breathing Process](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/11-1-4-breathing-process.md) - [11.1.5 Breathing Composition](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/11-1-5-breathing-composition.md) - [11.1.6 Breathing & Exercise](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/11-1-6-breathing-and-exercise.md) - [11.1.7 Thorax](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/11-1-7-thorax.md) ### 12 Respiration - 12.1 Respiration - [12.1.1 Respiration Uses](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/12-1-1-respiration-uses.md) - [12.1.2 Investigating Respiration](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/12-1-2-investigating-respiration.md) - [12.1.3 End of Topic Test - Respiration](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/12-1-3-end-of-topic-test-respiration.md) - [12.1.4 Exam-Style Questions - Respiration During Exercise](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/12-1-4-exam-style-questions-respiration-during-exercise.md) - 12.2 Aerobic & Anaerobic Respiration - [12.2.1 Respiration Reactions](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/12-2-1-respiration-reactions.md) - [12.2.2 Oxygen Use & Debt](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/12-2-2-oxygen-use-and-debt.md) - [12.2.3 Aerobic and Anaerobic Respiration](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/12-2-3-aerobic-and-anaerobic-respiration.md) ### 13 Excretion in Humans - 13.1 Excretion in Humans - [13.1.1 Excretion in Humans](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/13-1-1-excretion-in-humans.md) - [13.1.2 Urea](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/13-1-2-urea.md) - [13.1.3 Water Balance](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/13-1-3-water-balance.md) - [13.1.4 Water in Urine](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/13-1-4-water-in-urine.md) - [13.1.5 The Kidneys](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/13-1-5-the-kidneys.md) - [13.1.6 Urine Production](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/13-1-6-urine-production.md) - [13.1.7 Urinary System](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/13-1-7-urinary-system.md) - [13.1.8 Kidney Transplants](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/13-1-8-kidney-transplants.md) - [13.1.9 Kidney Transplants - Pros & Cons](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/13-1-9-kidney-transplants-pros-and-cons.md) ### 14 Coordination & Response - 14.1 Coordination & Response - [14.1.1 The Nervous System](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-1-1-the-nervous-system.md) - [14.1.2 Reflex Actions](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-1-2-reflex-actions.md) - [14.1.3 Reflex Arc](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-1-3-reflex-arc.md) - [14.1.4 Synapses](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-1-4-synapses.md) - [14.1.5 End of Topic Test - Nervous Control](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-1-5-end-of-topic-test-nervous-control.md) - [14.1.6 Exam-Style Questions - Nervous System](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-1-6-exam-style-questions-nervous-system.md) - 14.2 Sense Organs - [14.2.1 Sense Organs](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-2-1-sense-organs.md) - [14.2.2 Eye Anatomy](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-2-2-eye-anatomy.md) - [14.2.3 Eye Function - Light](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-2-3-eye-function-light.md) - [14.2.4 Eye Function - Focus](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-2-4-eye-function-focus.md) - [14.2.5 Eye Function - Detecting Colour](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-2-5-eye-function-detecting-colour.md) - 14.3 Hormones - [14.3.1 Hormones in Humans](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-3-1-hormones-in-humans.md) - [14.3.2 Endocrine Glands](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-3-2-endocrine-glands.md) - [14.3.3 Nervous vs Endocrine](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-3-3-nervous-vs-endocrine.md) - [14.3.4 Adrenaline](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-3-4-adrenaline.md) - 14.4 Homeostasis - [14.4.1 Homeostasis](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-1-homeostasis.md) - [14.4.2 Regulating Internal Conditions](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-2-regulating-internal-conditions.md) - [14.4.3 Control Systems](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-3-control-systems.md) - [14.4.4 Negative Feedback](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-4-negative-feedback.md) - [14.4.5 Thermoregulation](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-5-thermoregulation.md) - [14.4.6 Thermoregulation - Hot and Cold](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-6-thermoregulation-hot-and-cold.md) - [14.4.7 Thermoregulation - Skin](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-7-thermoregulation-skin.md) - [14.4.8 Thermoregulation - Sweating & Shivering](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-8-thermoregulation-sweating-and-shivering.md) - [14.4.9 Thermoregulation - Hairs](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-9-thermoregulation-hairs.md) - [14.4.10 Thermoregulation - Blood Vessels](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-10-thermoregulation-blood-vessels.md) - [14.4.11 Blood Glucose](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-11-blood-glucose.md) - [14.4.12 Detecting Glucose](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-12-detecting-glucose.md) - [14.4.13 Type 1 Diabetes](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-13-type-1-diabetes.md) - [14.4.14 End of Topic Test - Homeostasis & Hormones](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-14-end-of-topic-test-homeostasis-and-hormones.md) - [14.4.15 Grade 9 - Hormonal Coordination](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-4-15-grade-9-hormonal-coordination.md) - 14.5 Tropic Responses - [14.5.1 Types of Tropisms](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-5-1-types-of-tropisms.md) - [14.5.2 Auxins and Tropisms](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-5-2-auxins-and-tropisms.md) - [14.5.3 Required Practical - Plant Hormones](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/14-5-3-required-practical-plant-hormones.md) ### 15 Drugs - 15.1 Drugs - [15.1.1 Antibiotics](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/15-1-1-antibiotics.md) - [15.1.2 Antibiotic Resistance](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/15-1-2-antibiotic-resistance.md) - [15.1.3 Resistant Bacteria](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/15-1-3-resistant-bacteria.md) ### 16 Reproduction - 16.1 Asexual Reproduction - [16.1.1 Asexual Reproduction](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-1-1-asexual-reproduction.md) - [16.1.2 Advantages of Asexual Reproduction](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-1-2-advantages-of-asexual-reproduction.md) - 16.2 Sexual Reproduction - [16.2.1 Sexual Reproduction](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-2-1-sexual-reproduction.md) - [16.2.2 Gametes vs. Zygotes](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-2-2-gametes-vs-zygotes.md) - [16.2.3 Advantages of Sexual Reproduction](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-2-3-advantages-of-sexual-reproduction.md) - 16.3 Sexual Reproduction in Plants - [16.3.1 Flower Anatomy](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-3-1-flower-anatomy.md) - [16.3.2 Pollination Methods](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-3-2-pollination-methods.md) - [16.3.3 Self-pollination & Cross-polination](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-3-3-self-pollination-and-cross-polination.md) - [16.3.4 Germination](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-3-4-germination.md) - 16.4 Sexual Reproduction in Humans - [16.4.1 Human Reproductive Systems - Male](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-4-1-human-reproductive-systems-male.md) - [16.4.2 Human Reproductive Systems - Female](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-4-2-human-reproductive-systems-female.md) - [16.4.3 Human Gametes - Sperm Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-4-3-human-gametes-sperm-cells.md) - [16.4.4 Human Gametes - Egg Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-4-4-human-gametes-egg-cells.md) - [16.4.5 Human Gametes - Egg vs. Sperm](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-4-5-human-gametes-egg-vs-sperm.md) - [16.4.6 Pregnancy](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-4-6-pregnancy.md) - [16.4.7 Pregnancy Health](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-4-7-pregnancy-health.md) - [16.4.8 Birth - Labour](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-4-8-birth-labour.md) - [16.4.9 Birth - Breast-feeding](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-4-9-birth-breast-feeding.md) - 16.5 Sex Hormones in Humans - [16.5.1 Puberty](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-5-1-puberty.md) - [16.5.2 Menstruation](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-5-2-menstruation.md) - [16.5.3 Menstrual Cycle](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-5-3-menstrual-cycle.md) - [16.5.4 Menstrual Hormones](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-5-4-menstrual-hormones.md) - [16.5.5 Baby Planning](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-5-5-baby-planning.md) - [16.5.6 Infertility](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-5-6-infertility.md) - [16.5.7 Fertility Treatments Pros & Cons](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-5-7-fertility-treatments-pros-and-cons.md) - [16.5.8 End of Topic Test - Reproductive Hormones](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-5-8-end-of-topic-test-reproductive-hormones.md) - [16.5.9 Exam-Style Questions - Hormones & Contraception](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-5-9-exam-style-questions-hormones-and-contraception.md) - 16.6 Sexually Transmitted Infections - [16.6.1 HIV](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/16-6-1-hiv.md) ### 17 Inheritance - 17.1 Chromosomes, Genes & Proteins - [17.1.1 Genome](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-1-1-genome.md) - [17.1.2 Genome Diagram](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-1-2-genome-diagram.md) - [17.1.3 Gene Expression](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-1-3-gene-expression.md) - [17.1.4 DNA Pairings](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-1-4-dna-pairings.md) - [17.1.5 Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-1-5-protein-synthesis.md) - [17.1.6 Synthesis Process](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-1-6-synthesis-process.md) - 17.2 Mitosis & Meiosis - [17.2.1 Cell Division](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-2-1-cell-division.md) - [17.2.2 Stem Cells](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-2-2-stem-cells.md) - [17.2.3 Meiosis](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-2-3-meiosis.md) - 17.3 Monohybrid Inheritance - [17.3.1 Alleles](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-1-alleles.md) - [17.3.2 Phenotype](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-2-phenotype.md) - [17.3.3 Sex Determination](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-3-sex-determination.md) - [17.3.4 Monohybrid Inheritance](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-4-monohybrid-inheritance.md) - [17.3.5 Punnett Square](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-5-punnett-square.md) - [17.3.6 Blood Groups](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-6-blood-groups.md) - [17.3.7 Sex-linked Disorders](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-7-sex-linked-disorders.md) - [17.3.8 Cystic Fibrosis](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-8-cystic-fibrosis.md) - [17.3.9 Cystic Fibrosis - Punnett Square](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-9-cystic-fibrosis-punnett-square.md) - [17.3.10 Cystic Fibrosis - Pedigree Diagram](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-10-cystic-fibrosis-pedigree-diagram.md) - [17.3.11 Test Crosses](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-11-test-crosses.md) - [17.3.12 End of Topic Test - Genes & Inheritance](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/17-3-12-end-of-topic-test-genes-and-inheritance.md) ### 18 Variation & Selection - 18.1 Variation - [18.1.1 Variation](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-1-1-variation.md) - [18.1.2 Continuous & Discontinuous Variation](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-1-2-continuous-and-discontinuous-variation.md) - [18.1.3 Mutations](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-1-3-mutations.md) - [18.1.4 Sickle Cell Symptoms](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-1-4-sickle-cell-symptoms.md) - [18.1.5 Sickle Cell & Malaria](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-1-5-sickle-cell-and-malaria.md) - [18.1.6 Sickle Cell Inheritance](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-1-6-sickle-cell-inheritance.md) - 18.2 Adaptive Features - [18.2.1 Adaptive Features](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-2-1-adaptive-features.md) - [18.2.2 Plant Adaptations](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-2-2-plant-adaptations.md) - 18.3 Selection - [18.3.1 Natural Selection](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-3-1-natural-selection.md) - [18.3.2 Evolution](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-3-2-evolution.md) - [18.3.3 Antibiotic Resistance](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-3-3-antibiotic-resistance.md) - [18.3.4 Selective Breeding](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-3-4-selective-breeding.md) - [18.3.5 Selective Breeding Process](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-3-5-selective-breeding-process.md) - [18.3.6 Uses of Selective Breeding](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-3-6-uses-of-selective-breeding.md) - [18.3.7 Grade 9 - Evolution](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-3-7-grade-9-evolution.md) - [18.3.8 End of Topic Test - Variation & Evolution](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/18-3-8-end-of-topic-test-variation-and-evolution.md) ### 19 Organisms & Their Environment - 19.1 Energy Flow - [19.1.1 Energy Flow](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-1-1-energy-flow.md) - 19.2 Food Chains & Food Webs - [19.2.1 Food Chains & Webs](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-2-1-food-chains-and-webs.md) - [19.2.2 Decomposers](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-2-2-decomposers.md) - [19.2.3 Trophic Levels](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-2-3-trophic-levels.md) - [19.2.4 Pyramids of Biomass](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-2-4-pyramids-of-biomass.md) - [19.2.5 Editing Food Chains](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-2-5-editing-food-chains.md) - [19.2.6 Reasons for Energy Wastage](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-2-6-reasons-for-energy-wastage.md) - [19.2.7 Transfer Efficiency](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-2-7-transfer-efficiency.md) - [19.2.8 Exam-Style Questions - Biomass](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-2-8-exam-style-questions-biomass.md) - [19.2.9 End of Topic Test - Food and Trophic Levels](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-2-9-end-of-topic-test-food-and-trophic-levels.md) - 19.3 Nutrient Cycles - [19.3.1 Importance of Cycling](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-3-1-importance-of-cycling.md) - [19.3.2 Carbon Cycle](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-3-2-carbon-cycle.md) - [19.3.3 Peat Bog](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-3-3-peat-bog.md) - [19.3.4 Water Cycle](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-3-4-water-cycle.md) - [19.3.5 Nitrogen Cycle](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-3-5-nitrogen-cycle.md) - [19.3.6 Nitrogen Cycle & Microorganisms](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-3-6-nitrogen-cycle-and-microorganisms.md) - 19.4 Populations - [19.4.1 Ecosystems](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-4-1-ecosystems.md) - [19.4.2 Population Growth Factors](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-4-2-population-growth-factors.md) - [19.4.3 Population Growth](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-4-3-population-growth.md) - [19.4.4 Human Population](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-4-4-human-population.md) - [19.4.5 Grade 9 - Ecosystems](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-4-5-grade-9-ecosystems.md) - [19.4.6 End of Topic Test - Ecosystems](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/19-4-6-end-of-topic-test-ecosystems.md) ### 20 Human Influence on Ecosystems - 20.1 Food Supply - [20.1.1 Food Supply & Modern Technology](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-1-1-food-supply-and-modern-technology.md) - [20.1.2 Food Supply & Modern Technology Drawbacks](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-1-2-food-supply-and-modern-technology-drawbacks.md) - [20.1.3 Food Supply & Populations](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-1-3-food-supply-and-populations.md) - [20.1.4 Causes of Famine](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-1-4-causes-of-famine.md) - [20.1.5 Declining Fish Stock](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-1-5-declining-fish-stock.md) - 20.2 Habitat Destruction - [20.2.1 Habitat Destruction](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-2-1-habitat-destruction.md) - [20.2.2 Deforestation](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-2-2-deforestation.md) - [20.2.3 Exam-Style Questions - Deforestation](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-2-3-exam-style-questions-deforestation.md) - 20.3 Pollution - [20.3.1 Humans & Waste](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-3-1-humans-and-waste.md) - [20.3.2 Nuclear Waste](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-3-2-nuclear-waste.md) - [20.3.3 Land Pollution](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-3-3-land-pollution.md) - [20.3.4 Waste Production - Plastics](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-3-4-waste-production-plastics.md) - [20.3.5 Air Pollution](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-3-5-air-pollution.md) - [20.3.6 Greenhouse Effect](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-3-6-greenhouse-effect.md) - [20.3.7 Global Warming](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-3-7-global-warming.md) - [20.3.8 Eutrophication](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-3-8-eutrophication.md) - 20.4 Conservation - [20.4.1 Conservation](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-4-1-conservation.md) - [20.4.2 Reasons to Conserve Biodiversity](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-4-2-reasons-to-conserve-biodiversity.md) - [20.4.3 Renewable Resources](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-4-3-renewable-resources.md) - [20.4.4 Recycling](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-4-4-recycling.md) - [20.4.5 Sustainability](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-4-5-sustainability.md) - [20.4.6 Sewage Treatment](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-4-6-sewage-treatment.md) - [20.4.7 Sustainable Fishing](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-4-7-sustainable-fishing.md) - [20.4.8 Sustainable Forest](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-4-8-sustainable-forest.md) - [20.4.9 Endangered Species](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-4-9-endangered-species.md) - [20.4.10 Causes of Endangering](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/20-4-10-causes-of-endangering.md) ### 21 Biotechnology & Genetic Modification - 21.1 Biotechnology & Genetic Modification - [21.1.1 Bacteria in Biotechnology](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/21-1-1-bacteria-in-biotechnology.md) - 21.2 Biotechnology - [21.2.1 Yeast in Biotechnology](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/21-2-1-yeast-in-biotechnology.md) - [21.2.2 Enzymes in Biotechnology](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/21-2-2-enzymes-in-biotechnology.md) - [21.2.3 Penicillin](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/21-2-3-penicillin.md) - 21.3 Genetic Modification - [21.3.1 Genetic Modification](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/21-3-1-genetic-modification.md) - [21.3.2 Genetic Modification - Process](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/21-3-2-genetic-modification-process.md) - [21.3.3 Genetic Modification - Controversy](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/21-3-3-genetic-modification-controversy.md) - [21.3.4 Pros & Cons of Genetic Modification](https://senecalearning.com/en-gb/revision-notes/igcse/biology/cambridge-international/higher/21-3-4-pros-and-cons-of-genetic-modification.md)