Source: https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/6-1-1-passive-movement-across-membranes [Revision notes](https://senecalearning.com/en-gb/revision-notes.md) › [IB Diploma](https://senecalearning.com/en-gb/revision-notes/ib-diploma.md) › [Biology](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology.md) › [Biology: IB Diploma](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma.md) › Passive Movement Across Membranes # Passive Movement Across Membranes Biology: IB Diploma Higher Level, topic 6.1.1 ## Passive Movement Passive movement is the net movement of particles from an area of high concentration to an area of lower concentration without the direct input of energy. ### Diffusion ![Diffusion](https://image-v2.cdn.app.senecalearning.com/courseImages/biology/1.3.1%20Diffusion%20of%20gases-min.png) - Diffusion describes the passive movement of particles in fluids (liquids and gases). - Molecules move randomly but tend to move into any space available until it is evenly distributed. - So, the net movement of particles will be towards the area of lower concentration or down a concentration gradient. - Substances such as CO2, O2 and urea can move in and out of cells across cell membranes via diffusion. ### E.g. Perfume ![E.g. Perfume](https://image-v2.cdn.app.senecalearning.com/courseImages/chemistry/10.4.2%20NPK%20fertilisers/perfume-min.jpg) - When you spray perfume, the smell diffuses across the room from the area of high concentration (where you just sprayed it) to the area of low concentration (the other side of the room). ### Filtration ![Filtration](https://image-v2.cdn.app.senecalearning.com/2018-10/e2d5d13d-79e5-4fdb-8b22-ad083fcca52c/Structure-kidney-kidneys-renal-medulla-nephron-.png) - A variation of diffusion is the process of filtration. - In filtration, material moves according to its concentration gradient through a membrane. Sometimes the rate of diffusion is enhanced by pressure, causing the substances to filter more rapidly. - This occurs in the kidney, where blood pressure forces large amounts of water and accompanying dissolved substances, or solutes, out of the blood and into the renal tubules. - The rate of diffusion in this instance is almost totally dependent on pressure. ## Test yourself on Passive Movement Across Membranes - What do we call the net movement of particles from an area of high concentration to an area of lower concentration? - In which state of substance does diffusion NOT happen? - Which of the following substances can diffuse across cell membranes? [Practise this topic for free](https://app.senecalearning.com/classroom/course/549189f7-f13a-4c5c-b80c-ea1bd3036d78/section/cef057d8-86bc-4a34-9546-693822d88507/session) - Previous topic: [5.2.1 Structure & Functions of Proteins](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/5-2-1-structure-and-functions-of-proteins.md) - Next topic: [6.1.2 Active Movement Across Membranes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/6-1-2-active-movement-across-membranes.md) ## Biology: IB Diploma Higher Level contents ### 1 Unity & Diversity - Molecules - 1.1 Water - [1.1.1 The Importance of Water](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-1-1-the-importance-of-water.md) - [1.1.2 The Structure of Water](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-1-2-the-structure-of-water.md) - [1.1.3 The Properties of Water](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-1-3-the-properties-of-water.md) - [1.1.4 IB Multiple Choice - Water & Hydrogen Bonding](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-1-4-ib-multiple-choice-water-and-hydrogen-bonding.md) - [1.1.5 Extended Response - Water](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-1-5-extended-response-water.md) - 1.2 DNA Structure & Replication - [1.2.1 DNA](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-2-1-dna.md) - [1.2.2 RNA](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-2-2-rna.md) - [1.2.3 Semi-Conservative DNA Replication](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-2-3-semi-conservative-dna-replication.md) - [1.2.4 DNA Replication](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-2-4-dna-replication.md) - [1.2.5 DNA Replication - Summary](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-2-5-dna-replication-summary.md) - [1.2.6 IB Multiple Choice - DNA Replication](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-2-6-ib-multiple-choice-dna-replication.md) - 1.3 Transcription & Gene Expression - [1.3.1 Introduction to Transcription & Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-3-1-introduction-to-transcription-and-protein-synthesis.md) - [1.3.2 Types of RNA](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-3-2-types-of-rna.md) - [1.3.3 Transcription](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-3-3-transcription.md) - [1.3.4 RNA Processing in Eukaryotes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-3-4-rna-processing-in-eukaryotes.md) - [1.3.5 IB Multiple Choice - Transcription](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-3-5-ib-multiple-choice-transcription.md) - 1.4 Translation - [1.4.1 Translation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-4-1-translation.md) - [1.4.2 Retroviruses](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-4-2-retroviruses.md) - [1.4.3 Scientific Practices: Coronavirus](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-4-3-scientific-practices-coronavirus.md) - [1.4.4 IB Multiple Choice - Translation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/1-4-4-ib-multiple-choice-translation.md) ### 2 Unity & Diversity - Cells - 2.1 The Origin of Cells - [2.1.1 Origins - Endosymbiosis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-1-1-origins-endosymbiosis.md) - 2.2 Introduction to Cells - [2.2.1 Introduction to Cells](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-2-1-introduction-to-cells.md) - [2.2.2 Cell Size & Surface Area](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-2-2-cell-size-and-surface-area.md) - [2.2.3 Surface Area to Volume Ratio](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-2-3-surface-area-to-volume-ratio.md) - [2.2.4 Eukaryotic vs Prokaryotic Cells](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-2-4-eukaryotic-vs-prokaryotic-cells.md) - [2.2.5 Stem Cells](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-2-5-stem-cells.md) - [2.2.6 Stem Cells in Disease](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-2-6-stem-cells-in-disease.md) - 2.3 Ultrastructure of Cells - [2.3.1 Golgi, Lysosomes & Ribosomes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-3-1-golgi-lysosomes-and-ribosomes.md) - [2.3.2 Cell Walls & Vacuole](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-3-2-cell-walls-and-vacuole.md) - [2.3.3 Prokaryotes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-3-3-prokaryotes.md) - [2.3.4 Binary Fission](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-3-4-binary-fission.md) - 2.4 Cell Division - [2.4.1 The Cell Cycle](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-4-1-the-cell-cycle.md) - [2.4.2 Mitosis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-4-2-mitosis.md) - [2.4.3 Regulation of the Cell Cycle](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-4-3-regulation-of-the-cell-cycle.md) - [2.4.4 End of Topic Quiz - The Cell Cycle](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-4-4-end-of-topic-quiz-the-cell-cycle.md) - [2.4.5 IB Multiple Choice - The Cell Cycle](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-4-5-ib-multiple-choice-the-cell-cycle.md) - [2.4.6 Extended Response - Mitosis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-4-6-extended-response-mitosis.md) - 2.5 Structure of DNA & RNA - [2.5.1 DNA & RNA](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-5-1-dna-and-rna.md) - 2.6 DNA Replication, Transcription & Translation - [2.6.1 Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-6-1-protein-synthesis.md) - [2.6.2 Transcription & Translation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-6-2-transcription-and-translation.md) - [2.6.3 End of Topic Test - DNA, Genes & Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-6-3-end-of-topic-test-dna-genes-and-protein-synthesis.md) - [2.6.4 Exam-Style Question - Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-6-4-exam-style-question-protein-synthesis.md) - [2.6.5 End of Topic Test - Coronavirus Translation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-6-5-end-of-topic-test-coronavirus-translation.md) - [2.6.6 IB Multiple Choice - Transcription](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-6-6-ib-multiple-choice-transcription.md) - [2.6.7 IB Multiple Choice - Translation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-6-7-ib-multiple-choice-translation.md) - 2.7 Cell Respiration - [2.7.1 Overview of Respiration](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-7-1-overview-of-respiration.md) - [2.7.2 Anaerobic Respiration](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-7-2-anaerobic-respiration.md) - [2.7.3 End of Topic Test - Anaerobic Respiration](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-7-3-end-of-topic-test-anaerobic-respiration.md) - [2.7.4 Respiration Experiments](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-7-4-respiration-experiments.md) - [2.7.5 End of Topic Test - Respiration](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-7-5-end-of-topic-test-respiration.md) - [2.7.6 IB Multiple Choice - Respiration](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-7-6-ib-multiple-choice-respiration.md) - 2.8 Photosynthesis - [2.8.1 Overview of Photosynthesis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-8-1-overview-of-photosynthesis.md) - 2.9 Viruses - [2.9.1 Viruses](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/2-9-1-viruses.md) ### 3 Unity & Diversity - Organisms - 3.1 Diversity of Organisms - [3.1.1 Chromosomal Theory of Inheritance](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-1-1-chromosomal-theory-of-inheritance.md) - [3.1.2 Chromosomal Basis of Inherited Disorders](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-1-2-chromosomal-basis-of-inherited-disorders.md) - [3.1.3 IB Multiple Choice - Chromosomal Inheritance](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-1-3-ib-multiple-choice-chromosomal-inheritance.md) - 3.2 Evidence for Evolution - [3.2.1 Evidence for Evolution - Fossils & DNA](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-2-1-evidence-for-evolution-fossils-and-dna.md) - [3.2.2 Evidence for Evolution - Anatomy & Geography](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-2-2-evidence-for-evolution-anatomy-and-geography.md) - [3.2.3 IB Multiple Choice - Evidence for Evolution](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-2-3-ib-multiple-choice-evidence-for-evolution.md) - [3.2.4 Extended Response - DNA & Evolution](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-2-4-extended-response-dna-and-evolution.md) - 3.3 Natural Selection - [3.3.1 Introduction](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-3-1-introduction.md) - [3.3.2 Evolutionary Fitness](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-3-2-evolutionary-fitness.md) - [3.3.3 Natural Selection & Variation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-3-3-natural-selection-and-variation.md) - [3.3.4 End of Topic Quiz - Natural Selection](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-3-4-end-of-topic-quiz-natural-selection.md) - [3.3.5 IB Multiple Choice - Natural Selection](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-3-5-ib-multiple-choice-natural-selection.md) - [3.3.6 Speciation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/3-3-6-speciation.md) ### 4 Unity & Diversity - Ecosystems - 4.1 Classification - [4.1.1 Introduction to Biodiversity](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-1-1-introduction-to-biodiversity.md) - [4.1.2 Keystone Species](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-1-2-keystone-species.md) - [4.1.3 Courtship & Ancestry](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-1-3-courtship-and-ancestry.md) - [4.1.4 Classification](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-1-4-classification.md) - 4.2 Cladistics - [4.2.1 Evolutionary Relationships](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-2-1-evolutionary-relationships.md) - [4.2.2 IB Multiple Choice - Species & Taxonomy](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-2-2-ib-multiple-choice-species-and-taxonomy.md) - 4.3 Evolution & Speciation - [4.3.1 Evidence for Evolution - Fossils & DNA](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-3-1-evidence-for-evolution-fossils-and-dna.md) - [4.3.2 Evidence for Evolution - Anatomy & Geography](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-3-2-evidence-for-evolution-anatomy-and-geography.md) - [4.3.3 IB Multiple Choice - Evidence for Evolution](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-3-3-ib-multiple-choice-evidence-for-evolution.md) - [4.3.4 Extended Response - DNA & Evolution](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-3-4-extended-response-dna-and-evolution.md) - [4.3.5 Populations](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-3-5-populations.md) - [4.3.6 Mutations, Genetic Drift, & Gene Flow](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-3-6-mutations-genetic-drift-and-gene-flow.md) - [4.3.7 Speciation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-3-7-speciation.md) - [4.3.8 Rate of Speciation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-3-8-rate-of-speciation.md) - [4.3.9 Allopatric & Sympatric Speciation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-3-9-allopatric-and-sympatric-speciation.md) - 4.4 Conservation of Biodiversity - [4.4.1 Coming Soon!](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/4-4-1-coming-soon.md) ### 5 Form & Function - Molecules - 5.1 Carbohydrates & Lipids - [5.1.1 Monosaccharides](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/5-1-1-monosaccharides.md) - [5.1.2 Disaccharides & Polysaccharides](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/5-1-2-disaccharides-and-polysaccharides.md) - [5.1.3 Triglycerides & Phospholipids](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/5-1-3-triglycerides-and-phospholipids.md) - [5.1.4 Cellulose](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/5-1-4-cellulose.md) - [5.1.5 Starch & Glycogen](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/5-1-5-starch-and-glycogen.md) - 5.2 Proteins - [5.2.1 Structure & Functions of Proteins](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/5-2-1-structure-and-functions-of-proteins.md) ### 6 Form & Function - Cells - 6.1 Membranes & Membrane Transport - [6.1.1 Passive Movement Across Membranes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/6-1-1-passive-movement-across-membranes.md) - [6.1.2 Active Movement Across Membranes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/6-1-2-active-movement-across-membranes.md) - [6.1.3 Endocytosis & Exocystosis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/6-1-3-endocytosis-and-exocystosis.md) - [6.1.4 Cell Membrane Structure & Permeability](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/6-1-4-cell-membrane-structure-and-permeability.md) - 6.2 Organelles & Compartmentalization - [6.2.1 Eukaryotic Cells & Organelles](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/6-2-1-eukaryotic-cells-and-organelles.md) - [6.2.2 Subcellular Components & Organelles](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/6-2-2-subcellular-components-and-organelles.md) - 6.3 Cell Specialization - [6.3.1 Cell Specialization](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/6-3-1-cell-specialization.md) ### 7 Form & Function - Organisms - 7.1 Gas Exchange - [7.1.1 Lung Structure & Alveoli](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-1-1-lung-structure-and-alveoli.md) - [7.1.2 Ventilation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-1-2-ventilation.md) - [7.1.3 Lung Disease](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-1-3-lung-disease.md) - [7.1.4 Lung Disease Data](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-1-4-lung-disease-data.md) - 7.2 Transport - [7.2.1 The Circulatory System](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-2-1-the-circulatory-system.md) - [7.2.2 The Heart](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-2-2-the-heart.md) - [7.2.3 Blood Vessels](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-2-3-blood-vessels.md) - [7.2.4 Cardiovascular Disease](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-2-4-cardiovascular-disease.md) - [7.2.5 Xylem Structure](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-2-5-xylem-structure.md) - [7.2.6 Cohesion-Tension Theory](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-2-6-cohesion-tension-theory.md) - [7.2.7 Investigating Transpiration Rate](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-2-7-investigating-transpiration-rate.md) - [7.2.8 Phloem Structure](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-2-8-phloem-structure.md) - [7.2.9 Translocation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-2-9-translocation.md) - 7.3 Muscle & Motility - [7.3.1 Skeletal Muscle](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-3-1-skeletal-muscle.md) - [7.3.2 Sliding Filament Theory](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-3-2-sliding-filament-theory.md) - [7.3.3 Contraction](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/7-3-3-contraction.md) ### 8 Form & Function - Ecosystems - 8.1 Species, Communities & Ecosytems - [8.1.1 Population Dynamics](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-1-1-population-dynamics.md) - [8.1.2 Communities & Measuring Diversity](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-1-2-communities-and-measuring-diversity.md) - [8.1.3 Relationships Between Populations](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-1-3-relationships-between-populations.md) - [8.1.4 Overview of Ecosystems](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-1-4-overview-of-ecosystems.md) - [8.1.5 Nutrient Cycles](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-1-5-nutrient-cycles.md) - [8.1.6 Fertilisers](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-1-6-fertilisers.md) - [8.1.7 Eutrophication](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-1-7-eutrophication.md) - [8.1.8 Chi-Squared Test](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-1-8-chi-squared-test.md) - 8.2 Energy Flow - [8.2.1 Energy](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-2-1-energy.md) - [8.2.2 Energy Flow](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-2-2-energy-flow.md) - [8.2.3 Biomass & Food Chains](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-2-3-biomass-and-food-chains.md) - [8.2.4 Heterotrophs & Autotrophs](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-2-4-heterotrophs-and-autotrophs.md) - 8.3 Carbon Cycle - [8.3.1 Carbon Cycle](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-3-1-carbon-cycle.md) - 8.4 Climate Change - [8.4.1 Carbon Dioxide](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-4-1-carbon-dioxide.md) - [8.4.2 The Greenhouse Effect](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-4-2-the-greenhouse-effect.md) - [8.4.3 Global Warming](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-4-3-global-warming.md) - [8.4.4 Maintaining Biodiversity](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/8-4-4-maintaining-biodiversity.md) ### 9 Interaction & Interdependence - Molecules - 9.1 Enzymes - [9.1.1 Enzymes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-1-1-enzymes.md) - [9.1.2 Factors Affecting Enzyme Activity](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-1-2-factors-affecting-enzyme-activity.md) - [9.1.3 Enzyme-Controlled Reactions](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-1-3-enzyme-controlled-reactions.md) - [9.1.4 End of Topic Test - Enzymes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-1-4-end-of-topic-test-enzymes.md) - 9.2 Metabolism - [9.2.1 Molecules to Metabolism](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-2-1-molecules-to-metabolism.md) - 9.3 Cell Respiration - [9.3.1 Glycolysis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-3-1-glycolysis.md) - [9.3.2 Aerobic Respiration](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-3-2-aerobic-respiration.md) - 9.4 Photosynthesis - [9.4.1 Light-Dependent Reaction](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-4-1-light-dependent-reaction.md) - [9.4.2 Light-Independent Reaction](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-4-2-light-independent-reaction.md) - [9.4.3 End of Topic Test - Photosynthesis Reactions](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-4-3-end-of-topic-test-photosynthesis-reactions.md) - [9.4.4 Limiting Factors](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-4-4-limiting-factors.md) - [9.4.5 Photosynthesis Experiments](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-4-5-photosynthesis-experiments.md) - [9.4.6 End of Topic Test - Photosynthesis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-4-6-end-of-topic-test-photosynthesis.md) - [9.4.7 End of Topic Test - Photosynthesis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/9-4-7-end-of-topic-test-photosynthesis.md) ### 10 Interaction & Interdependence - Cells - 10.1 Chemical Signalling - [10.1.1 Coming Soon!](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-1-1-coming-soon.md) - 10.2 Neural Signalling - [10.2.1 Medical Application](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-2-1-medical-application.md) - [10.2.2 Speed of Transmission](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-2-2-speed-of-transmission.md) - [10.2.3 Synapses](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-2-3-synapses.md) - [10.2.4 End of Topic Test - Nervous Comm&Coord](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-2-4-end-of-topic-test-nervous-commandcoord.md) - [10.2.5 Neuron Structure](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-2-5-neuron-structure.md) - [10.2.6 Types of Synapse](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-2-6-types-of-synapse.md) - [10.2.7 End of Topic Test - Neurones & Action Potentials](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-2-7-end-of-topic-test-neurones-and-action-potentials.md) - [10.2.8 Transmission of an Impulse](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-2-8-transmission-of-an-impulse.md) - [10.2.9 End of Topic Test - Synapses](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-2-9-end-of-topic-test-synapses.md) - 10.3 Adaptation to Environment - [10.3.1 Coming Soon!](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-3-1-coming-soon.md) - 10.4 Ecological Niches - [10.4.1 Coming Soon!](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/10-4-1-coming-soon.md) ### 11 Interaction & Interdependence - Organisms - 11.1 Integration of Body Systems - [11.1.1 Plant Tropisms](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/11-1-1-plant-tropisms.md) - 11.2 Defence Against Disease - [11.2.1 Immune System](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/11-2-1-immune-system.md) - [11.2.2 The Immune Response](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/11-2-2-the-immune-response.md) - [11.2.3 Antibodies](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/11-2-3-antibodies.md) - [11.2.4 Primary & Secondary Response](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/11-2-4-primary-and-secondary-response.md) - [11.2.5 Vaccines](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/11-2-5-vaccines.md) - [11.2.6 HIV](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/11-2-6-hiv.md) - [11.2.7 End of Topic Test - Immune System](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/11-2-7-end-of-topic-test-immune-system.md) ### 12 Interaction & Interdependence - Ecosystems - 12.1 Populations & Communities - [12.1.1 Coming Soon!](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/12-1-1-coming-soon.md) - 12.2 Transfers of Energy & Matter - [12.2.1 Coming Soon!](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/12-2-1-coming-soon.md) ### 13 Continuity & Change - Molecules - 13.1 DNA Replication - [13.1.1 DNA Replication](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/13-1-1-dna-replication.md) - 13.2 Protein Synthesis - [13.2.1 Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/13-2-1-protein-synthesis.md) - [13.2.2 Transcription & Translation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/13-2-2-transcription-and-translation.md) - [13.2.3 End of Topic Test - DNA, Genes & Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/13-2-3-end-of-topic-test-dna-genes-and-protein-synthesis.md) - 13.3 Mutation & Gene Editing - [13.3.1 Genes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/13-3-1-genes.md) - [13.3.2 Mutations](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/13-3-2-mutations.md) - [13.3.3 DNA Technology](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/13-3-3-dna-technology.md) - [13.3.4 PCR & Gel Electrophoresis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/13-3-4-pcr-and-gel-electrophoresis.md) - [13.3.5 Genetic Modification](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/13-3-5-genetic-modification.md) - [13.3.6 Cloning](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/13-3-6-cloning.md) ### 14 Continuity & Change - Cells - 14.1 Gene Expression - [14.1.1 Introduction to Transcription & Protein Synthesis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/14-1-1-introduction-to-transcription-and-protein-synthesis.md) - [14.1.2 Types of RNA](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/14-1-2-types-of-rna.md) - [14.1.3 Transcription](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/14-1-3-transcription.md) - [14.1.4 RNA Processing in Eukaryotes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/14-1-4-rna-processing-in-eukaryotes.md) - [14.1.5 IB Multiple Choice - Transcription](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/14-1-5-ib-multiple-choice-transcription.md) - 14.2 Water Potential - [14.2.1 Controlling Blood Water Potential](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/14-2-1-controlling-blood-water-potential.md) ### 15 Continuity & Change - Organisms - 15.1 Inheritance - [15.1.1 Non-Nuclear Inheritance](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-1-1-non-nuclear-inheritance.md) - [15.1.2 Linked Genes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-1-2-linked-genes.md) - [15.1.3 IB Multiple Choice - Non-Mendelian Genetics](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-1-3-ib-multiple-choice-non-mendelian-genetics.md) - [15.1.4 Extended Response - Inheritance](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-1-4-extended-response-inheritance.md) - [15.1.5 Introduction to Non-Mendelian Inheritance](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-1-5-introduction-to-non-mendelian-inheritance.md) - [15.1.6 Chi-Squared Test](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-1-6-chi-squared-test.md) - [15.1.7 End of Topic Quiz - Inheritance](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-1-7-end-of-topic-quiz-inheritance.md) - [15.1.8 Sex-Linked Genes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-1-8-sex-linked-genes.md) - [15.1.9 Grade 4-5 (Scientific Practices) - Inheritance](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-1-9-grade-4-5-scientific-practices-inheritance.md) - 15.2 Homeostasis - [15.2.1 Overview of Homeostasis](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-2-1-overview-of-homeostasis.md) - [15.2.2 Blood Glucose Concentration](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-2-2-blood-glucose-concentration.md) - [15.2.3 Controlling Blood Glucose Concentration](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-2-3-controlling-blood-glucose-concentration.md) - [15.2.4 End of Topic Test - Blood Glucose](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-2-4-end-of-topic-test-blood-glucose.md) - [15.2.5 Type I & Type II Diabetes](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-2-5-type-i-and-type-ii-diabetes.md) - [15.2.6 Human Reproductive Systems](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-2-6-human-reproductive-systems.md) - [15.2.7 Hormonal Control of the Menstrual Cycle](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-2-7-hormonal-control-of-the-menstrual-cycle.md) - [15.2.8 Kidneys & Osmoregulation](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-2-8-kidneys-and-osmoregulation.md) ### 16 Continuity & Change - Ecosystems - 16.1 Natural Selection - [16.1.1 Natural Selection](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/16-1-1-natural-selection.md) - 16.2 Stability & Change - [16.2.1 Coming Soon!](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/16-2-1-coming-soon.md) - 16.3 Climate Change - [16.3.1 Carbon Dioxide](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/16-3-1-carbon-dioxide.md) - [16.3.2 The Greenhouse Effect](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/16-3-2-the-greenhouse-effect.md) - [16.3.3 Global Warming](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/16-3-3-global-warming.md) - [16.3.4 Maintaining Biodiversity](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/16-3-4-maintaining-biodiversity.md)