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BTEC Level 3 Applied Science – COMPLETE Biology Revision Pack This is your main revision guide based on all the B1, B2 and B3 notes you shared and everything we’ve been practising. It includes: * All the main topics you need to revise. * Definitions and key scientific terms. * Cell structures and their functions. * Specialised cells and immunity. * Tissues, lungs and circulation. * Muscles and the nervous system. * ECGs. * 6-mark practice questions. * Mnemonics with every letter explained. * Exam-ready answers. Important: Nobody can guarantee the exact questions that will come up. This covers the topics in your notes, including likely extended-answer areas. Use your official unit specification and teacher’s guidance alongside it. PART 1 – B1: CELL STRUCTURE 1. Levels of organisation Learn these definitions: Term Definition Cell Basic structural and functional unit of life. Tissue Group of similar specialised cells working together. Organ Different tissues working together to perform a function. Organ system Different organs working together. Organelle Specialised structure inside a cell. Mnemonic: Cats Take Over Sofas * Cats = Cells * Take = Tissues * Over = Organs * Sofas = Systems Order: Cell → Tissue → Organ → Organ system. 2. Differentiation Definition: Differentiation is when an unspecialised cell develops into a specialised cell to perform a particular function. Examples: * A stem cell can become a red blood cell. * A stem cell can become a neurone. * A stem cell can become a muscle cell. 3. Prokaryotic cells Prokaryotes are cells without a nucleus. Learn these structures: Structure Function Nucleoid Contains circular DNA. Plasmids Small extra rings of DNA. 70S ribosomes Protein synthesis. Capsule Protection and attachment. Cell wall Made of peptidoglycan; provides support. Cell membrane Controls substances entering and leaving. Cytoplasm Where chemical reactions occur. Mnemonic: Naughty Pigs Rarely Chase Wolves * N = Nucleoid * P = Plasmids * R = Ribosomes * C = Capsule * W = Wall Remember: Prokaryotes do not have a nucleus or membrane-bound organelles. 4. Eukaryotic cells Eukaryotic cells have: * A nucleus. * 80S ribosomes in the cytoplasm. * Membrane-bound organelles. Plant cells Structure Function Cellulose cell wall Support and protection. Chloroplasts Photosynthesis. Permanent vacuole Contains cell sap and helps maintain turgor. Tonoplast Membrane surrounding the vacuole. Amyloplasts Store starch. Plasmodesmata Connections between neighbouring plant cells. Pits Areas where the cell wall is thinner. Animal cells Animal cells can contain: * Nucleus. * Mitochondria. * Ribosomes. * Cell membrane. * Cytoplasm. * Centrioles. * Glycogen stores. Animal cells do not have cellulose cell walls or chloroplasts. 5. Organelles and their functions Organelle Function Cell membrane Controls movement of substances. Cytoplasm Site of many chemical reactions. Nucleus Contains DNA and controls cell activities. Nucleolus Produces ribosomal components. Ribosomes Protein synthesis. Rough ER Transports and processes proteins. Smooth ER Lipid and steroid synthesis. Golgi apparatus Modifies, sorts and packages proteins. Vesicles Transport substances. Lysosomes Contain digestive enzymes. Mitochondria Aerobic respiration and ATP production. Centrioles Help organise spindle fibres during cell division. Chloroplasts Photosynthesis. Identifying organelles in micrographs * Mitochondria: oval shape with folded inner membranes called cristae. * Nucleus: large structure with a double membrane and pores. * Rough ER: flattened membranes with ribosomes attached. * Chloroplast: contains stacks of membranes called grana. * Golgi: curved, flattened membrane sacs. * Bacteria: no nucleus; DNA lies free in the cytoplasm. 6. Light and electron microscopes Light microscope Electron microscope Uses light. Uses an electron beam. Lower resolution. Higher resolution. Lower magnification. Higher magnification. Can view living cells. Specimens must be dead. Can show natural colours. Original images are monochrome. Generally cheaper. Generally more expensive. Mnemonic: M R C L * M = Magnification * R = Resolution * C = Colour * L = Living specimens 7. Magnification calculations Learn these three formulas: M=\frac{I}{A}I=M\times AA=\frac{I}{M} Where: * M = Magnification * I = Image size * A = Actual size Conversions: * 1 mm = 1000 µm * 1 µm = 1000 nm Always make sure your measurements use the same units. Stage micrometer and eyepiece graticule A graticule is calibrated against a stage micrometer. Mnemonic: Lazy Chefs Dice Meat * L = Line up the scales. * C = Count the divisions. * D = Divide the known measurement by the number of divisions. * M = Measure the specimen. Recalibrate when changing magnification. PART 2 – GRAM STAINING AND ANTIBIOTICS 8. Gram-positive and Gram-negative bacteria Gram-positive Gram-negative Thick peptidoglycan wall. Thin peptidoglycan wall. No outer membrane. Has an outer membrane. Stains purple. Stains pink/red. Generally more susceptible to penicillin. Outer membrane provides additional protection. 9. Gram staining Mnemonic: Hot Cats In Autumn Spring * Hot = Heat-fix: Fix bacteria onto a microscope slide. * Cats = Crystal violet: Add purple dye. * In = Iodine: Helps retain the crystal violet. * Autumn = Alcohol: Removes the dye from Gram-negative bacteria. * Spring = Safranin: Counterstains Gram-negative bacteria pink. * Result: Gram-positive purple, Gram-negative pink/red. 10. Penicillin Penicillin prevents the formation of cross-links in bacterial peptidoglycan. This: * Weakens the bacterial cell wall. * Allows water to enter by osmosis. * Causes the bacterial cell to burst (lysis). Gram-positive bacteria are generally more susceptible because their peptidoglycan is more accessible. Gram-negative bacteria have an outer membrane that can prevent or reduce penicillin entry. PART 3 – B2: SPECIALISED CELLS 11. Palisade cells Adaptations: * Contain many chloroplasts for photosynthesis. * Tall, thin shape allows cells to be closely packed. * Found near the upper surface of leaves to receive light. * Large vacuole pushes chloroplasts towards the cell edge. * Thin cell wall helps carbon dioxide diffuse into the cell. 12. Sperm cells Mnemonic: A Happy Mouse Tails * A = Acrosome: Contains enzymes to digest the egg’s outer layers. * H = Haploid nucleus: Contains half the normal chromosome number. * M = Mitochondria: Produce ATP for movement. * T = Tail: Flagellum propels the sperm. * S = Streamlined: Helps movement through fluid. 13. Egg cells Adaptations: * Large cytoplasm containing nutrient reserves. * Haploid nucleus. * Zona pellucida surrounds the egg. * Cortical granules help prevent polyspermy after fertilisation. Polyspermy: When more than one sperm fertilises an egg. 14. Root hair cells Adaptations: * Long extension gives a large surface area. * Thin cell wall gives a short diffusion distance. * Cell sap helps water enter by osmosis. * Mitochondria supply ATP for active transport of mineral ions. 15. Red blood cells Adaptations: * Biconcave shape gives a large surface area. * No nucleus, leaving more room for haemoglobin. * Haemoglobin binds oxygen. * Flexible shape allows movement through narrow capillaries. * Thin centre gives a short diffusion distance. Oxygen + haemoglobin ⇌ oxyhaemoglobin. 16. White blood cells Two important types: Neutrophils * Have a lobed nucleus. * Engulf pathogens by phagocytosis. * Use lysosomes containing digestive enzymes. * Form part of the innate immune response. * Respond rapidly to infection. Lymphocytes * Have a large, round nucleus. * B lymphocytes can develop into plasma cells. * Plasma cells produce specific antibodies. * Some become memory cells. * T lymphocytes can destroy infected cells. 17. Neutrophils and lymphocytes: similarities and differences Similarities mnemonic: Both Need Protection * Both = Both are white blood cells. * Need = Both contain a nucleus. * Protection = Both protect against pathogens. Differences: Neutrophils Lymphocytes Phagocytosis. Specific immune response. Lobed nucleus. Large, round nucleus. Digest pathogens using lysosomes. B cells produce antibodies. Part of innate immunity. Part of adaptive immunity. Respond rapidly. Can form long-lasting memory cells. 18. Antibodies and immunity Learn: * An antigen is a molecule recognised by the immune system. * Antibodies have binding sites complementary to specific antigens. * Antibodies bind to antigens. * This can neutralise pathogens or help other immune cells destroy them. * B lymphocytes can form memory cells. * Memory cells help produce a faster secondary response. 19. Allergies Mnemonic: A M H * A = Allergen enters the body. * M = Mast cells become involved. * H = Histamine is released. Histamine causes: * Blood vessels to widen. * Capillaries to become more permeable. * Fluid to move into tissues. * Swelling, itching and other allergic symptoms. 20. Transplant rejection Learn this sequence: * Donor cells have antigens. * The recipient recognises these antigens as foreign. * T lymphocytes recognise the foreign cells. * T cells attack the transplanted tissue. * Tissue matching reduces the chance of rejection. * Immunosuppressants reduce immune activity. PART 4 – B3: TISSUES AND THE RESPIRATORY SYSTEM 21. Epithelial tissues Squamous epithelium * Thin, flat cells. * Usually one cell thick in diffusion surfaces. * Short diffusion distance. * Found in alveoli and capillary walls. Columnar epithelium * Tall cells. * Can contain goblet cells. * Ciliated columnar cells move mucus. * Microvilli in the gut increase surface area for absorption. Endothelium * Lines the inside of blood vessels. * Smooth surface reduces friction. * Thin capillary endothelium allows diffusion. 22. COPD COPD stands for chronic obstructive pulmonary disease. Two important conditions: Emphysema Mnemonic: Smoking Makes Every Alveolus Lose Elasticity * Smoking causes inflammation. * White blood cells release elastase. * Elastase destroys alveolar walls. * Alveoli merge into larger air spaces. * Surface area decreases. * Elastic recoil decreases, causing difficulty breathing out. Chronic bronchitis Mnemonic: Irritated Goblets Make Coughing Increase * I = Inflammation of the bronchi. * G = Goblet cells enlarge. * M = More mucus is produced. * C = Cilia become damaged. * I = Infections become more common. * B = Bronchi narrow, causing coughing and breathing difficulties. 23. Alveoli adaptations Mnemonic: Silly Tigers Carry Very Massive Eggs * S = Surface area: Millions of alveoli create a large surface area. * T = Thin walls: One cell thick, short diffusion distance. * C = Capillaries: Dense network maintains the concentration gradient. * V = Ventilation: Refreshes alveolar air. * M = Moisture: Gases dissolve in the lining. * E = Elasticity: Allows stretching and recoil. 24. Gas exchange Oxygen moves: Alveolar air → Alveolar epithelium → Basement membrane → Capillary endothelium → Plasma → Red blood cell → Haemoglobin. Carbon dioxide moves in the opposite direction. Fick’s law Diffusion is faster when: * Surface area is larger. * Diffusion distance is shorter. * Concentration gradient is steeper. 25. Breathing and inhalation Mnemonic: Dancing Rabbits Visit Pretty Amazing Places * D = Diaphragm contracts and flattens. * R = Ribs move upwards and outwards. * V = Thoracic volume increases. * P = Pressure inside lungs decreases. * A = Air moves into the lungs. * P = Pressure equalises as air enters. Exhalation * Diaphragm relaxes and becomes dome-shaped. * External intercostal muscles relax. * Ribs move downwards and inwards. * Thoracic volume decreases. * Pressure inside the lungs increases. * Air moves out. 26. Smoking effects Mnemonic: Cigarettes Make Every Lung Suffer * C = Cilia damaged. * M = More mucus produced. * E = Excess infections. * L = Loss of alveolar walls. * S = Surface area reduced. * S = Smoking reduces lung elasticity. Smoking also damages blood vessel endothelium and increases atherosclerosis risk. PART 5 – ATHEROSCLEROSIS AND CIRCULATION 27. Atherosclerosis High-priority 6-marker Mnemonic: Dirty Money’s Find Pipes Narrowing Today * Dirty = Damage: The endothelium lining the artery becomes damaged. * Money’s = Macrophages: Macrophages enter the artery wall and engulf LDL cholesterol. * Find = Foam cells: Macrophages become foam cells, forming fatty streaks. * Pipes = Plaque: Fatty material builds up and forms a plaque. * Narrowing = Narrowing: The plaque narrows the artery and reduces blood flow. * Today = Thrombus: A blood clot can form and block the artery, potentially causing a heart attack or stroke. Risk factors * Smoking. * High blood pressure. * High LDL cholesterol. * Diabetes. * Age. * Poor diet. PART 6 – MUSCLES 28. Skeletal muscle structure Learn these terms: Structure Function Sarcolemma Muscle fibre cell membrane. Sarcoplasm Muscle fibre cytoplasm. Myofibrils Contain actin and myosin. Sarcomere Contractile unit between Z lines. Actin Thin filament. Myosin Thick filament. Sarcoplasmic reticulum Stores and releases calcium ions. Mitochondria Produce ATP. Skeletal muscle fibres are: * Long and cylindrical. * Multinucleate. * Striated. * Packed with myofibrils. 29. Sarcomere changes Structure During contraction A band Stays the same length. I band Shortens. H zone Shortens. Z lines Move closer together. Sarcomere Shortens. Mnemonic: A stays Always the same; I and H get Hit. 30. Sliding filament theory High-priority 6-marker Mnemonic: Clever Tigers Make Powerful Animals Run * Clever = Calcium: Calcium is released from the sarcoplasmic reticulum. * Tigers = Troponin: Calcium binds to troponin, moving tropomyosin. * Make = Myosin: Myosin binds to actin, forming cross-bridges. * Powerful = Power stroke: Myosin pulls actin towards the centre of the sarcomere. * Animals = ATP: ATP binds to myosin, causing detachment. * Run = Reset: ATP is broken down, re-cocking the myosin head. Remember: Actin and myosin do not shorten; they slide past one another. 31. Slow-twitch and fast-twitch fibres Mnemonic: Slow Red Runners Have Endurance Slow-twitch Type I * Red. * Lots of myoglobin. * Many mitochondria. * Dense capillary supply. * Mainly aerobic respiration. * Resist fatigue. * Used for endurance activities such as marathons. Fast-twitch Type II * Paler. * Less myoglobin. * Fewer mitochondria. * Lower capillary density. * More reliance on anaerobic energy pathways. * Contract quickly and powerfully. * Fatigue more quickly. * Used for sprinting and weightlifting. Remember: Slow = Stamina. Fast = Force. PART 7 – NERVOUS SYSTEM 32. Motor neurone structure Mnemonic: Dogs Can Always Nip Toes * D = Dendrites receive signals. * C = Cell body contains nucleus. * A = Axon carries the impulse. * N = Nodes of Ranvier are gaps in myelin. * T = Terminals release neurotransmitters. Myelin sheath * Insulates the axon. * Increases conduction speed. * Schwann cells produce myelin in the peripheral nervous system. * Nodes of Ranvier allow saltatory conduction. 33. Resting potential Mnemonic: Three Naughty Cats Keep Purring Inside * Three = 3 sodium ions pumped out. * Naughty = 2 potassium ions pumped in. * Cats = Pump uses ATP. * Keep = Potassium ions leak out. * Purring = Negative proteins remain inside. * Inside = Inside becomes approximately −70 mV. 34. Action potential Mnemonic: Silly Dogs Run Happily Past Houses * S = Stimulus reaches threshold (−55 mV). * D = Depolarisation begins as sodium channels open. * R = Rising potential as sodium enters. * H = High positive potential, around +40 mV. * P = Potassium channels open and potassium leaves. * H = Hyperpolarisation before returning to resting potential. Important extra facts * Action potentials are all-or-nothing. * A stronger stimulus increases frequency, not the size of the action potential. * The refractory period prevents immediate re-firing. * It helps ensure impulses travel in one direction. 35. Myelinated and non-myelinated neurones Mnemonic: Myelin Jumps Fast * Myelinated neurones have a myelin sheath. * They have nodes of Ranvier. * Impulses jump from node to node. * This is called saltatory conduction. * Non-myelinated neurones conduct continuously. * Myelinated neurones are faster and generally use less energy for impulse transmission. 36. Synaptic transmission High-priority 6-marker Mnemonic: All Clever Vikings Drink Really Slowly * All = Action potential: Arrives at the presynaptic knob. * Clever = Calcium: Calcium channels open and calcium enters. * Vikings = Vesicles: Vesicles release neurotransmitter by exocytosis. * Drink = Diffusion: Neurotransmitter diffuses across the synaptic cleft. * Really = Receptors: Neurotransmitter binds to postsynaptic receptors. * Slowly = Sodium: Sodium channels open and sodium enters, causing depolarisation. Extra: * Neurotransmitter is removed by enzymes or reuptake. * Synapses are one-way because receptors are on the postsynaptic membrane. 37. Acetylcholine Mnemonic: Release, Bind, Sodium, Enzyme, Recycle * Release: Acetylcholine is released from vesicles. * Bind: It binds to postsynaptic receptors. * Sodium: Sodium channels open. * Depolarisation: The membrane becomes less negative. * Enzyme: Acetylcholinesterase breaks down acetylcholine. * Recycle: Choline is taken back into the presynaptic neurone. 38. Agonists and antagonists Mnemonic: Agonist Activates; Antagonist Blocks. * Agonist binds to a receptor and activates it. * It can mimic a natural neurotransmitter. * Antagonist binds without activating the receptor. * It blocks the natural neurotransmitter from binding. Examples: * Nicotine: agonist at certain acetylcholine receptors. * Curare: antagonist at acetylcholine receptors. Other examples to know: * L-dopa is converted into dopamine. * SSRIs block serotonin reuptake. * Botulinum toxin prevents acetylcholine release. * Organophosphates inhibit acetylcholinesterase. 39. Neurotransmitters Neurotransmitter Main role Acetylcholine Muscle contraction and signalling. Glutamate Main excitatory neurotransmitter in the brain. GABA Main inhibitory neurotransmitter in the brain. Dopamine Movement and reward. Serotonin Mood, sleep and appetite. Noradrenaline Alertness and attention. 40. Parkinson’s disease Mnemonic: Dying Dopamine Makes Movement Slow * Dopamine-producing neurones in the substantia nigra degenerate. * Less dopamine is released. * Movement control is disrupted. * Symptoms include tremors, rigidity and slow movement. * L-dopa can be converted into dopamine in the brain. * Dopamine agonists can also help manage symptoms. 41. Depression and SSRIs Mnemonic: Serotonin Reuptake is Controlled, Levels Last * Serotonin is involved in mood regulation. * Serotonin is released into the synaptic cleft. * Normally, some serotonin is taken back into the presynaptic neurone. * SSRIs block serotonin reuptake transporters. * Serotonin remains in the synaptic cleft longer. * It can continue binding to postsynaptic receptors. PART 8 – ECGs 42. ECG waves Mnemonic: Please Quit Rushing, Stay Tranquil * P wave: Atrial depolarisation. * QRS complex: Ventricular depolarisation. * T wave: Ventricular repolarisation. Remember: * Atrial depolarisation is followed by atrial contraction. * Ventricular depolarisation is followed by ventricular contraction. * Ventricular repolarisation is followed by ventricular relaxation. 43. Heart rate calculations \text{Heart rate}=\frac{60}{\text{R-R interval in seconds}} Example: If the R-R interval is 0.8 seconds: 60\div0.8=75\text{ bpm} Know: * Tachycardia: over 100 beats per minute. * Bradycardia: under 60 beats per minute. * Regular R-R intervals indicate a regular rhythm. PART 9 – ALL THE 6-MARK QUESTIONS TO PRACTISE These are the extended-answer questions I would use to test your knowledge. They are based on your notes, not guaranteed predictions. Your 30-question exam checklist Tick each question once you can answer it without notes. 0/30 All 1. B1 – CellsCompare prokaryotic and eukaryotic cells. (6 marks) 2. B1 – CellsCompare light and electron microscopes. (6 marks) 3. B1 – MicroscopyExplain how to calculate magnification and actual size. (6 marks) 4. B1 – Gram stainingDescribe how Gram staining is carried out and how it identifies bacteria. (6 marks) 5. B1 – AntibioticsExplain why penicillin is generally more effective against Gram-positive bacteria. (6 marks) 6. B2 – Specialised cellsExplain how a sperm cell is adapted for fertilisation. (6 marks) 7. B2 – Specialised cellsExplain how a red blood cell is adapted to transport oxygen. (6 marks) 8. B2 – ImmunityExplain how phagocytes destroy pathogens. (6 marks) 9. B2 – ImmunityExplain how lymphocytes defend the body against pathogens. (6 marks) 10. B2 – ImmunityCompare the similarities and differences between neutrophils and lymphocytes. (6 marks) 11. B2 – ImmunityExplain how allergies occur. (6 marks) 12. B2 – ImmunityExplain how organ transplants can be rejected. (6 marks) 13. B3 – TissuesExplain how atherosclerosis develops. (6 marks) 14. B3 – LungsExplain how emphysema affects gas exchange. (6 marks) 15. B3 – LungsExplain how chronic bronchitis develops. (6 marks) 16. B3 – LungsExplain how alveoli are adapted for gas exchange. (6 marks) 17. B3 – LungsExplain the mechanism of inhalation. (6 marks) 18. B3 – LungsExplain how smoking damages the respiratory system. (6 marks) 19. MusclesExplain the sliding filament mechanism of muscle contraction. (6 marks) 20. MusclesCompare slow-twitch and fast-twitch muscle fibres. (6 marks) 21. NervesExplain how resting potential is maintained. (6 marks) 22. NervesExplain how an action potential is generated. (6 marks) 23. NervesCompare myelinated and non-myelinated neurones. (6 marks) 24. NervesExplain how an impulse travels along a myelinated neurone. (6 marks) 25. NervesExplain how a synapse transmits a nerve impulse. (6 marks) 26. NervesExplain how acetylcholine works at a synapse. (6 marks) 27. NervesExplain the difference between agonists and antagonists. (6 marks) 28. NervesExplain how Parkinson’s disease affects the nervous system. (6 marks) 29. NervesExplain how SSRIs affect synaptic transmission. (6 marks) 30. ECGsExplain what the P wave, QRS complex and T wave represent. (6 marks) Reset checklist PART 10 – IMPORTANT DEFINITIONS TO MEMORISE Term Meaning Diffusion Net movement of particles from high to low concentration. Osmosis Net movement of water across a partially permeable membrane from higher to lower water potential. Active transport Movement against a concentration gradient using energy. Phagocytosis Engulfing and digesting pathogens. Antigen Molecule recognised by the immune system. Antibody Protein that binds to a specific antigen. Depolarisation Membrane potential becomes less negative. Repolarisation Membrane potential returns towards its resting value. Hyperpolarisation Membrane potential becomes more negative than resting potential. Synapse Junction between neurones where signals are transmitted. Neurotransmitter Chemical messenger released at a synapse. Exocytosis Release of substances when vesicles fuse with a cell membrane. Atheroma Fatty plaque in an artery wall. Thrombus Blood clot formed within a blood vessel. Sarcomere Contractile unit of a myofibril. Oxyhaemoglobin Haemoglobin bound to oxygen. COPD Chronic obstructive pulmonary disease. Differentiation Process by which cells become specialised. PART 11 – THE MOST IMPORTANT MNEMONICS TO KNOW Here is your quick podcast-style recap. Read these aloud every day. Topic Mnemonic Cell organisation Cats Take Over Sofas Prokaryotic structures Naughty Pigs Rarely Chase Wolves Graticule calibration Lazy Chefs Dice Meat Gram staining Hot Cats In Autumn Spring Sperm cell A Happy Mouse Tails Atherosclerosis Dirty Money’s Find Pipes Narrowing Today Neutrophil and lymphocyte similarities Both Need Protection Alveoli Silly Tigers Carry Very Massive Eggs Inhalation Dancing Rabbits Visit Pretty Amazing Places Chronic bronchitis Irritated Goblets Make Coughing Increase Emphysema Smoking Makes Every Alveolus Lose Elasticity Sliding filament Clever Tigers Make Powerful Animals Run Slow-twitch fibres Slow Red Runners Have Endurance Motor neurone Dogs Can Always Nip Toes Action potential Silly Dogs Run Happily Past Houses Resting potential Three Naughty Cats Keep Purring Inside Synapse All Clever Vikings Drink Really Slowly Parkinson’s Dying Dopamine Makes Movement Slow ECG Please Quit Rushing, Stay Tranquil PART 12 – HOW TO REVISE THIS FOR YOUR EXAM I would revise in this order: Your 7-day revision plan * Day 1 – Cells Cell structures, prokaryotes, eukaryotes, microscopes and magnification. * Day 2 – Specialised cells Sperm, egg, root hair, palisade and red blood cells. * Day 3 – Immunity Neutrophils, lymphocytes, antibodies, allergies and transplant rejection. * Day 4 – Lungs and circulation Alveoli, inhalation, COPD, smoking and atherosclerosis. * Day 5 – Muscles Sarcomeres, sliding filament theory and muscle fibre comparisons. * Day 6 – Nervous system Resting potential, action potentials, synapses, neurotransmitters and Parkinson’s. * Day 7 – Exam practice Attempt the 6-mark questions without notes, then check your answers. My final advice For every 6-marker, learn: * The mnemonic. * What every letter stands for. * The scientific explanation. * The correct order of events. You have already shown that you can remember the atherosclerosis sequence and explain it in your own words. That’s exactly how you should practise the rest. Don’t just memorise the mnemonics. Make sure you understand what each biological process actually means. That’s what will help you answer the question even if the examiner words it differently.