Source: https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/15-2-8-kidneys-and-osmoregulation [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) › Kidneys & Osmoregulation # Kidneys & Osmoregulation Biology: IB Diploma Higher Level, topic 15.2.8 ## Excretion and the Kidneys The kidneys work alongside the liver in the excretion of waste products. Urea is produced in the liver through deamination of amino acids. Urea is toxic and is excreted by the kidneys. ### Kidney structure ![Kidney structure](https://image-v2.cdn.app.senecalearning.com/2018-10/e2d5d13d-79e5-4fdb-8b22-ad083fcca52c/Structure-kidney-kidneys-renal-medulla-nephron-.png) ### Kidney structure ![Kidney structure](https://image-v2.cdn.app.senecalearning.com/2018-10/e2d5d13d-79e5-4fdb-8b22-ad083fcca52c/Structure-kidney-kidneys-renal-medulla-nephron-.png) - The kidneys are surrounded by the capsule to protect the fragile structures underneath. - Nephrons extend from the cortex into the medulla and are the site of ultrafiltration, selective reabsorption and urine formation. - The renal tubule of each nephron is lined with microvilli to increase the surface area for absorption. ### Nephron structure ![Nephron structure](https://image-v2.cdn.app.senecalearning.com/2018-11/f300cacd-a852-43d9-9f6b-d5f75dd6d102/Nephron-kidney-henle-loop-homeostasis-.png) ### Ultrafiltration ![Ultrafiltration](https://image-v2.cdn.app.senecalearning.com/2018-11/f300cacd-a852-43d9-9f6b-d5f75dd6d102/Nephron-kidney-henle-loop-homeostasis-.png) - Ultrafiltration is carried out in the glomerular capsule (often called the Bowman's capsule). - Everything except larger proteins, red blood cells, and most white blood cells is forced out of the blood and into the glomerular capsule due to the high pressure caused by the difference in diameter between the afferent and efferent arterioles. - The afferent arteriole is much wider than the efferent arteriole. ### Selective reabsorption ![Selective reabsorption](https://image-v2.cdn.app.senecalearning.com/2018-09/7ab83efb-a245-4170-be86-c0f089c2f660/urine-test-sample-science-biology-.jpg) - Water, amino acids, glucose and ions are selectively reabsorbed first in the proximal convoluted tubule (PCT). - The final composition of urine produced is dependent on: - Selective reabsorption out of the nephron. - Secretion of nitrogenous waste into the nephron by surrounding capillaries. ### Loop of Henle ![Loop of Henle](https://image-v2.cdn.app.senecalearning.com/2018-11/f300cacd-a852-43d9-9f6b-d5f75dd6d102/Nephron-kidney-henle-loop-homeostasis-.png) - After the proximal convoluted tubule, water is also reabsorbed into the blood by osmosis in the descending limb of the loop of Henle. - Ions are reabsorbed in the ascending limb of the loop of Henle. - The ion concentration gradient set up in the area between the limbs drives osmosis in the descending limb. - Approximately 95% of urine is water. ### Urine excretion ![Urine excretion](https://image-v2.cdn.app.senecalearning.com/2018-11/6f605d36-61ec-4078-867e-18141c688915/urinary-tract-kidney-ureter-.png) - Urine is formed from each nephron in collecting ducts. - The collecting ducts converge in the renal pelvis to form the ureter of each kidney. - The urine passes down the ureters and into the bladder. - When the bladder is full, urine passes through the urethra and out of the body. ## Osmoregulation and the Kidneys The kidneys are vital in osmoregulation and control water balance by reabsorbing more water when the body is dehydrated. This affects blood pressure and volume and the amount of water in the tissues. ### Osmoreception ![Osmoreception](https://image-v2.cdn.app.senecalearning.com/2018-08/eab3e0d8-0985-4404-9609-a39b4f14d1a9/hypothalamus-brain.jpg) - Osmoreceptors in the hypothalamus detect water composition in the blood. - If the water level drops (due to increased sweating, decreased water intake or vomiting), the hypothalamus secretes antidiuretic hormone (ADH) and signals for the posterior pituitary gland to release it into the bloodstream. ### Antidiuretic hormone (ADH) ![Antidiuretic hormone (ADH)](https://image-v2.cdn.app.senecalearning.com/courseImages/biology/2.3.1%20-%20Blood%20vessels/bloodclot-min.jpg) - When the ADH reaches the cells in the collecting ducts, they become more permeable to water and so reabsorb more water. - This increases the concentration of the urine and it appears darker. - High concentrations of ADH constrict blood vessels, increasing blood pressure. ## Test yourself on Kidneys & Osmoregulation - Which of these is NOT selectively reabsorbed into the bloodstream from the nephron? - What is the kidney made up from? - Excretion of Urine - What does antidiuretic hormone do? - Avoiding Dehydration [Practise this topic for free](https://app.senecalearning.com/classroom/course/549189f7-f13a-4c5c-b80c-ea1bd3036d78/section/730f83d1-dd9e-444f-8e42-ef6a06917d01/session) - Previous topic: [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) - Next topic: [16.1.1 Natural Selection](https://senecalearning.com/en-gb/revision-notes/ib-diploma/biology/biology-ib-diploma/16-1-1-natural-selection.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)