Models you can move.
Each simulation sits on its lesson. Open one here and you land on that model. The drawings are teaching models, not micrographs or published data, and the explanations are ScholarLab study material, not an official mark scheme.
Molecules, Transport and Health
- Core Practical 1 · Reducing sugar and starch
Make colour standards, then bracket an unknown
Dilute a 1% stock into standards, heat Benedict’s tubes in a water bath, then drag the unknown between the standards it matches. The samples are invented.
Open the model - Core Practical 2 · Vitamin C content
Titrate vitamin C with DCPIP
Use fictional DCPIP titres to estimate vitamin C in foods and drinks, then judge what the measurement cannot show.
Open the model - 1A 2 · Carbohydrates 1: Monosaccharides and Disaccharides
Join and split sugars
Join glucose, fructose and galactose by condensation into maltose, sucrose and lactose, follow the water, count every atom, then split them again by hydrolysis.
Open the model - 1A 3 · Carbohydrates 2: Polysaccharides
Release glucose from starch and glycogen
Compare amylose, amylopectin and glycogen of the same size: count 1,4 and 1,6 bonds and chain ends, release glucose with plenty of enzyme or only one, and see why a polymer has little osmotic effect.
Open the model - 1A 4 · Lipids
Order how a triglyceride forms
Order the condensation reactions that join glycerol to three fatty acids, forming three ester bonds and releasing three water molecules.
Open the model - 1A 5 · Proteins
Build up the levels of protein structure
Order protein structure from peptide bonds through primary, secondary and tertiary structure to a quaternary protein such as haemoglobin.
Open the model - 1B 1 · The Principles of Circulation
Trace the double circulation
Order one full trip of the blood through both circuits, from the vena cava through the lungs and back round the body.
Open the model - 1B 2 · The Roles of the Blood
Drag along the oxygen dissociation curve
Follow haemoglobin from lungs to tissue, shift the curve with CO₂ (Bohr effect), compare saturation with oxygen content and fetal with maternal haemoglobin.
Open the model - 1B 3 · Circulation in the Blood Vessels
Follow blood through the vessels
Compare the walls, pressure and speed in an artery, arterioles, capillaries and a vein; make the artery wall stiff, constrict the arterioles to cut flow, and squeeze a leg vein with and without valves.
Open the model - 1C 1 · Risk, Correlation and Cause
Is it a cause or a confounder?
Work out absolute and relative risk for two fictional groups, split them by age to unmask a confounder, add a real effect, and see how “doubles your risk” can mean a tiny absolute change.
Open the model - 1B 4 · The Mammalian Heart
Watch the cardiac cycle
A beating heart beside its pressure and volume graph: valves open and close where the atrium, ventricle and aorta lines cross. Predict the valves at any moment and speed up the heart.
Open the model - 1B 5 · Atherosclerosis
Put the clotting cascade in order
Drag, tap or use the keyboard to order the clotting cascade from a damaged vessel to a fibrin clot, then the chain from damaged endothelium to a plaque that ruptures. Hints escalate from a flag to a clue to a placed step.
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Membranes, Proteins, DNA and Gene Expression
- 2A 1 · Cell Membranes
Explore a fluid mosaic
Build a bilayer, then watch which molecules cross the lipid core, the aquaporin, the gated Na⁺ channel or the glucose carrier. Change temperature and cholesterol, and bleach a patch (FRAP).
Open the model - 2A 2 · Cell Transport and Diffusion
Watch diffusion and osmosis
Compare particles spreading with water moving through a partially permeable membrane.
Open the model - 2A 3 · Osmosis
Same solution, two cells
Put a plant cell and a red blood cell in the same salt solution, read their water potentials, then find a potato tissue’s water potential from a practical.
Open the model - 2A 4 · Active Transport
Active transport and vesicles
Follow an ATP-driven pump (one ion, or the real 3 Na⁺ out / 2 K⁺ in pump) against leak, then watch endocytosis and exocytosis.
Open the model - 2A 5 · The Need for Gas Exchange Surfaces
Grow a cube, then thin the barrier
Watch SA:V fall as a model organism grows until diffusion cannot meet demand, then change area, concentration difference and thickness to reproduce Fick’s-law ratios of 1.5 and 0.75.
Open the model - 2A 6 · The Mammalian Gas Exchange System
Breathe in, breathe out
Contract the diaphragm and intercostals of a model thorax and follow volume → pressure → airflow, then block the airway or break the pleural seal to see why each link matters.
Open the model - 2B 1 · Enzymes
Initial rate of one imaginary enzyme
Watch active sites at work, find the plateau, denature the enzyme for good with heat, compare inhibitors and see activation energy lowered.
Open the model - Core Practical 3 · Membrane permeability
Leak beetroot pigment, then read a colorimeter
Change temperature or ethanol concentration, zero a colorimeter with a blank and plot fictional absorbance against the independent variable.
Open the model - Core Practical 4 · Enzyme-catalysed reactions
Draw an initial-rate tangent for trypsin
Log fictional absorbance as milk clears, fit a tangent at t = 0 and compare temperature, pH, enzyme and substrate one at a time.
Open the model - 2B 4 · How DNA Works
Test three models of DNA replication
Predict the density bands for semi-conservative, conservative and dispersive replication over several generations, then compare them with Meselson and Stahl’s results.
Open the model - 2B 6 · DNA and Protein Synthesis
From gene to protein
Watch transcription base by base, then translation at a ribosome: tRNAs fill the A and P sites, a peptide bond forms, the ribosome moves on, and the empty tRNA leaves the E site.
Open the model - 2C 1 · Gene Mutation
Change one base, then read the protein
Substitute, insert or delete bases in a fictional gene and compare the codons and amino acids: silent, missense, nonsense, frameshift and in-frame changes.
Open the model - 2C 2 · Patterns of Inheritance
Cross two parents, then grow the family
Build gametes and a Punnett square for autosomal and ABO crosses, then simulate a fictional family and its pedigree to see why 3 : 1 is a probability, not a promise.
Open the model - 2C 3 · Sex Linkage
Follow X and Y into sons and daughters
Track red–green colour vision alleles on the X chromosome and compare the chance among sons with the chance among all children.
Open the model - 2C 4 · Cystic Fibrosis: A Genetic Disease
From the CFTR gene to the symptoms
Order the chain from two faulty CFTR alleles to sticky mucus, then follow it to the lungs and to the pancreas.
Open the model
Cell Structure, Reproduction and Development
- Core Practical 5 · Light microscope measurements
Calibrate a graticule, then measure cells
Focus safely, calibrate the eyepiece scale against a stage micrometer at each objective and measure fictional animal cells.
Open the model - 3A 2 · Eukaryotic Cells
Three cells, the same labels
Compare animal, plant and bacterial cells. Colour is a label, not a stain, and the drawing is not to scale.
Open the model - 3A 3 · Eukaryotic Cells 2: Protein Transport
Follow a secreted enzyme
Click the organelles in order to follow a digestive enzyme from gene to exocytosis, then run a pulse-chase experiment and block ER-to-Golgi transport, exocytosis or the ATP supply.
Open the model - 3B 2 · Mitosis
Mitosis and the cell cycle
Step one model cell through S phase, the four stages and cytokinesis, watch the DNA double and be shared out, then put the stages in order.
Open the model - 3C 2 · Interactions Between Genes and the Environment
Add genes, then the environment
Choose how many genes set a fictional plant’s height and how much its surroundings vary, grow an F2 sample, and watch three separate heights become a continuous, roughly bell-shaped range.
Open the model - 3B 3 · Sexual Reproduction and Meiosis
Meiosis: halving and shuffling chromosomes
Step a cell through one replication and two divisions, drag a chiasma between two linked genes, flip bivalents in metaphase I, then tally gametes from many meioses to see 2ⁿ combinations and linkage.
Open the model - 3C 3 · Controlling Gene Expression
Switch a gene up and down
Add or remove a transcription factor, methylate the promoter and change histone acetylation to set how much mRNA and protein a gene makes, keep the marks through cell division, and splice one gene into two proteins.
Open the model - 3C 4 · Stem Cells
Order early development and potency
Order development from a totipotent zygote through the morula and blastocyst to pluripotent inner cell mass cells and specialised cells.
Open the model - Core Practical 6 · Mitosis in a root tip squash
Score a root tip squash
Choose acid, stain and squash steps, classify fictional cells field by field and calculate a mitotic index.
Open the model - 3B 5 · Fertilisation in Mammals and Plants
Order fertilisation in mammals and plants
Order the acrosome and cortical reactions in a mammal, then pollen-tube growth and double fertilisation in a flowering plant.
Open the model - 3C 1 · Cell Differentiation
Order how a cell specialises
Order differential gene expression from a signal reaching an unspecialised cell to a specialised cell whose daughters keep the pattern.
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Plant Structure and Function, Biodiversity and Conservation
- Core Practical 7 · Plant tissues under a microscope
Find the three tissues in stem, root and leaf
Focus on fictional stained sections, label a stem plan, identify vessels, sieve tubes and fibres by position and structure, measure a vessel lumen with the graticule and compare a root and a leaf.
Open the model - Core Practical 8 · Tensile strength of plant fibres
Load plant fibres until they snap
Measure fictional strands with a micrometer, add masses gently until they break, calculate force per unit area and judge differences against the spread of repeats.
Open the model - Core Practical 9 · Antimicrobial properties of plants
Grow a lawn aseptically, then read zones
Disinfect, flame and spread a lawn of the school species, place fictional plant-extract discs with a solvent control, incubate at about 25 °C and measure zones through the base.
Open the model - 4A 7 · Developing New Drugs
Order the stages of drug testing
Order the stages from a candidate substance through preclinical testing and the three trial phases to licensing.
Open the model - 4B 1 · Principles of Classification
Order the taxonomic ranks
Order the eight ranks from domain to species, using the classification of humans as the example.
Open the model - 4C 2 · Measuring Biodiversity
Same richness, different diversity
Count every individual in fictional samples, work out D = N(N−1) ÷ Σn(n−1) for habitats P and Q, see sampling effort change D, then find the heterozygosity index of one species.
Open the model - 4C 4 · Gene Pool and Genetic Diversity
Watch a gene pool change
Start from the lesson’s Hardy–Weinberg numbers, then add selection, mutation, migration, a small population or isolation and watch p and q over generations.
Open the model - 4C 5 · Reproductive Isolation and Speciation
Order natural selection and speciation
Order natural selection from variation to a change in allele frequency, then allopatric speciation from a barrier to a new species.
Open the model
Energy Flow, Ecosystems and the Environment
- 5A 1 · The Importance of ATP
The ATP cycle
Hydrolyse ATP and rebuild it by a condensation reaction in a chloroplast or a mitochondrion. A small pool turns over fast: ATP is not a long-term store.
Open the model - 5A 2 · Chloroplasts and Chlorophyll
Light a chloroplast, then run a chromatogram
Shine one wavelength at a time on a chloroplast to compare absorption and action spectra, then separate a leaf extract, mark the solvent front and calculate Rf in two solvents.
Open the model - 5A 3 · The Biochemistry of Photosynthesis
Light reactions and the Calvin cycle
Follow electrons from water to NADP, then switch the light or CO₂ off and watch RuBP, GP and GALP respond; block cyclic flow and count six turns per glucose.
Open the model - 5B 2 · How Ecosystems Evolve
Order the stages of succession
Order primary succession from bare rock and pioneer species through soil formation to a climax community.
Open the model - 5B 3 · The Effect of Abiotic Factors on Populations
Find the limiting factor along a transect
Read light, soil water and nitrate in ten fictional quadrats from shade to meadow, find which factor limits each count, then water the dry end or starve the soil and compare two species’ tolerance curves.
Open the model - 5B 4 · The Effect of Biotic Factors on Populations
Add a competitor, a predator or a disease
Grow a fictional grassland population to its carrying capacity, then add competition, predation, disease or gut mutualists and watch where numbers settle and how predator and prey cycle.
Open the model - 5C 1 · Transfers Between Trophic Levels
Follow energy up a food chain
Split each trophic level’s energy into not eaten, faeces, excretion, heat and new biomass, calculate each transfer’s efficiency from NPP (not GPP) and compare fictional woodland, cattle and lake chains.
Open the model - 5C 2 · Net Primary Productivity
Balance GPP, R and NPP through a year
Watch a fictional woodland fix energy month by month, find winter months when NPP is negative, warm the nights or cloud the summer, and use NPP = GPP − R both ways.
Open the model - 5C 7 · Models of Climate Change and Their Limitations
Project warming to 2100
Test a simple CO₂ → forcing → warming model against measured warming, extrapolate CO₂ under different assumed futures, and see how climate sensitivity and a missing feedback widen the range.
Open the model - Core Practical 10 · Rate of photosynthesis
Count pondweed bubbles under a lamp
Move a lamp along a metre rule, wait for a steady state and count fictional oxygen bubbles, then plot rate against 1/d² and find what limits the plateau.
Open the model - 5C 3 · The Carbon Cycle in Nature
Follow one carbon atom
Follow one carbon atom round the fast loop from the air through a food chain and decomposers, then into a fossil store and back out by combustion.
Open the model - 5C 4 · Greenhouse Gases and Climate Change
Order the greenhouse effect
Order the greenhouse effect from short-wavelength sunlight through infrared emitted by the surface to warming when more gas traps more heat.
Open the model - 5C 9 · Climate Change and Evolution
Order natural selection and speciation
The same ordering activity as 4C 5: natural selection after a climate change, then allopatric speciation.
Open the model - Core Practical 12 · Temperature and development
Warm seedlings or brine shrimp, then find Q10
Check real vessel temperatures, incubate fictional seedlings or cysts for a fixed time, measure three replicates and calculate Q10 on the rising part only.
Open the model - Core Practical 11 · Ecology of a habitat
Lay a transect from shade into meadow
Lay a belt transect or random quadrats on a fictional woodland edge, count plants and estimate grass cover yourself, read light, soil moisture, temperature and pH, then test with Spearman’s rank or a t-test.
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Microbiology, Immunity and Forensics
- 6A 2 · How Viruses Reproduce
Burst the host, or wait as a prophage
Step λ phage through a bacterium by the lytic pathway and by latency, divide and induce the prophage, then compare HIV latency as a provirus.
Open the model - 6B 2 · The Specific Response to Infection
From phagocytosis to the specific response
Follow a bacterium or a virus from the non-specific opening through cytokines, antibody and memory.
Open the model - 6A 4 · Microbial Techniques
Order aseptic technique
Order the steps of streaking a plate aseptically, from disinfecting the bench to taping, labelling and incubating the dish.
Open the model - 6A 7 · Case Studies of Disease: Tuberculosis
Order the course of tuberculosis
Order TB from inhaled droplets, through bacteria surviving in macrophages and tubercles, to active disease and death.
Open the model - 6A 8 · Case Studies of Disease: HIV/AIDS
Order the course of HIV infection
Order HIV infection from binding to a T helper cell, through reverse transcription and the provirus, to AIDS and opportunistic infections.
Open the model - 6B 1 · Non-specific Responses to Infection
Order three non-specific responses
Order inflammation from damage to phagocytes at the site, then phagocytosis from attraction to digestion, then interferon from infection to slowed viral spread.
Open the model - 6B 3 · Developing Immunity
Sort four kinds of immunity
Sort six cases into natural or artificial, active or passive by asking who made the antibodies, then expose each person to the pathogen months later and see memory cells protect where borrowed antibodies have faded.
Open the model - 6B 5 · Antibiotic Resistance
Finish the course, then run a ward
Treat a fictional infection with a full course, an early stop or a low dose and watch partly resistant bacteria get selected, give an antibiotic for a cold, then cut MRSA on a ward with four codes of practice.
Open the model - Core Practical 13 · Growth of microorganisms
Follow yeast growth in liquid culture
Inoculate glucose broth aseptically, sample a fictional yeast culture every few hours against a sterile-broth blank, switch to a log₁₀ axis and calculate k from two points on the exponential phase.
Open the model - 6A 5 · Measuring the Growth of Bacterial Cultures
Dilute, plate and count colonies
Make a tenfold dilution series from a fictional broth, spread 0.10 cm³ from chosen tubes, incubate, pick a plate with 30–300 colonies and scale back to CFU per cm³.
Open the model - Core Practical 14 · The effect of antibiotics on bacteria
Compare antibiotic discs on a lawn
Spread an aseptic lawn, place fictional antibiotic discs and a sterile-water control, incubate at about 25 °C, compare A and B with a t-test and repeat a zero-zone disc with a fresh one.
Open the model - 6C 1 · Microorganisms and Decomposition
Order decomposition and carbon recycling
Order decomposition from death through detritivores and extracellular digestion by saprobionts to carbon dioxide released by respiration.
Open the model - 6C 2 · Forensic Science and the Time of Death
Cool a body, then read its muscles
Cool a simplified, fictional body in rooms, clothing and draughts against the one-degree rule, follow jaw, arm and leg stiffening as ATP runs out and easing as proteins break down, then turn two same-moment cases into one range.
Open the model - 6C 3 · The Process of Decay
Order decay and insect succession
Order the teaching stages of decay from fresh to dry remains, then the blowfly life cycle that forensic entomologists use.
Open the model - 6C 4 · Polymerase Chain Reaction (PCR)
Copy DNA with PCR
Step one molecule through 95, 55 and 72 °C, watch primers and Taq build new strands, reproduce 4 × 2⁵ = 128 and 2¹⁰ = 1024, and compare theory with a real tube and the controls.
Open the model - 6C 5 · DNA Profiling
Run a DNA profiling gel
Run fictional repeat-length samples beside a size ladder, stain the gel, read bands against a standard curve and see why one locus is not enough to identify a suspect or a father.
Open the model
Respiration, Muscles and the Internal Environment
- 7A 1 · Respiration in Cells
Respiration: carbon and hydrogen bookkeeping
Track every carbon of glucose to CO₂ and every reduced carrier to oxygen through glycolysis, the link reaction, the Krebs cycle and the chain. There is no single ATP total.
Open the model - 7A 2 · Glycolysis and Anaerobic Respiration
Respiration without oxygen
The same model without oxygen: run glycolysis until the NAD pool is reduced, then regenerate it with lactate or ethanol. The endings add no ATP.
Open the model - 7A 3 · The Krebs Cycle
Order the link reaction and Krebs cycle
Order the mitochondrial stages from pyruvate entering the matrix, through decarboxylation and dehydrogenation, to the four-carbon acceptor being regenerated.
Open the model - 7A 4 · The Electron Transport Chain
Follow the protons
Build the proton gradient across the inner mitochondrial membrane and watch ATP synthase turn; then take oxygen away, make the membrane leaky, or raise ATP use.
Open the model - Core Practical 15 · Respiration in yeast
Time yeast decolourising a redox dye
Pre-warm fictional yeast and glucose, add methylene blue under oil, stop the timer against a no-dye tube, watch boiled and no-glucose controls and plot 1/t against temperature.
Open the model - Core Practical 16 · Respirometer and RQ
Respirometer: rate and RQ of seeds
Weigh fictional germinating seeds, add soda lime under gauze and a bead control, equilibrate, calibrate the capillary, correct test − control, then swap in inert pellets to find CO₂ and the RQ.
Open the model - Core Practical 17 · Exercise and ventilation
Measure spirometer traces at rest and in exercise
Read the scales, measure trough-to-peak tidal volume, count breaths in a time bracket and fit the oxygen slope on fictional closed-spirometer traces, then compare rest with exercise.
Open the model - 7B 2 · What Is Muscle?
Zoom in on a skeletal muscle
Order the levels of a skeletal muscle from the whole muscle through fibres, myofibrils and sarcomeres to actin and myosin filaments.
Open the model - 7B 4 · How Muscles Contract
Slide the filaments
Release calcium ions, watch myosin heads cycle on actin and see the I band and H zone shorten while the A band stays the same; remove ATP to cause rigor.
Open the model - 7B 5 · Cardiac Muscle and Control of the Heartbeat
Follow the heartbeat to the ECG
Watch the wave spread from the SAN through the AVN delay, bundle of His and Purkyne fibres, matched to P, QRS and T on a schematic ECG; stretch the delay and explore a fictional trace with no P waves.
Open the model - 7B 6 · Principles of Homeostasis
Order a negative feedback loop
Order a negative feedback loop from a change away from the norm through receptors, coordinator and effectors back to the norm.
Open the model - 7B 7 · Controlling the Heart and Breathing Rates
Speed up the heart and the breathing
Run, recover or take a fright and follow CO₂ to the chemoreceptors and the medulla, work out cardiac output = 140 × 110 = 15.4 dm³ min⁻¹, cut the nerve to see the myogenic SAN keep beating, and watch adrenaline act.
Open the model - 7B 8 · The Response of the Breathing System to Exercise
Read the spirometer through a run
Watch a constructed trace go from 0.5 × 12 = 6 to 1.5 × 24 = 36 dm³ min⁻¹, read oxygen use from the slope only with soda lime, and see the lag and the recovery.
Open the model - 7C 1 · Homeostasis and Hormones
Order peptide and steroid hormone action
Order how a peptide hormone acts from outside the cell through a second messenger, then how a steroid hormone enters the cell and acts as a transcription factor.
Open the model - 7C 3 · Control of the Kidney and Homeostasis
Order the ADH feedback loop
Order the ADH negative feedback chain from water loss to concentrated urine, then the opposite chain after drinking a lot of water.
Open the model - 7C 2 · Osmoregulation in Mammals: The Kidney
Build the medulla gradient
Follow the filtrate from the glomerulus, pump and flow the loop of Henle until the medulla is salty, then use ADH to make the collecting duct reabsorb water.
Open the model - 7C 4 · Thermoregulation and Exercise
Hold core temperature near 37 °C
Exercise or change the air, watch the hypothalamus switch skin arterioles, sweating, hairs and shivering on and off, then switch the control off or overwhelm it with humid heat.
Open the model
Coordination, Response and Gene Technology
- Core Practical 18 · Amylase in cereal grains
Amylase from germinating grains
Surface-sterilise and cut fictional half-grains, soak embryo-free halves in gibberellin, flood starch agar with iodine and compare clear zones, with no-grain and gibberellin-only controls.
Open the model - 8A 2 · How the Nervous System Works
Order the spinal reflex arc
Order the route of a withdrawal reflex from stimulus through receptor, sensory, relay and motor neurones to the effector.
Open the model - 8A 3 · The Neurones in Action
Fire an action potential
Stimulate an axon membrane and watch Na⁺ and K⁺ channels drive the voltage trace: threshold, all-or-nothing, the refractory period and frequency coding, then race a myelinated axon.
Open the model - 8A 5 · Sensory Systems and the Detection of Light
Shine light on a rod
Watch the dark current, then let light change retinal from cis to trans, close Na⁺ channels and hyperpolarise the rod while the optic neurone fires; bleach the pigment, recover in the dark and hold the channels open with a drug.
Open the model - 8A 6 · Synapses and Habituation
Cross a cholinergic synapse
Send an impulse and follow Ca²⁺ entry, acetylcholine release and receptor opening to the postsynaptic trace; remove calcium, block the esterase, compare nicotine with cobra α-toxin and habituate a snail’s tentacle.
Open the model - 8B 5 · Chemical Control Systems in Plants
Order auxin and gibberellin action
Order how auxin makes a shoot bend toward one-sided light, then how gibberellin starts the use of starch in a germinating cereal grain.
Open the model - 8B 6 · Phytochrome and Flowering
Switch phytochrome to control flowering
Change the day length and flash red or far-red light in the night, follow Pr and Pfr through the day and see which fictional plant flowers: short-day plants need a long uninterrupted night, and the last flash counts.
Open the model - 8B 7 · Phytochrome and Transcription
Order phytochrome to transcription
Order the chain from red light converting Pr to Pfr, through transcription factors, to a plant response such as flowering.
Open the model - 8C 1 · Producing Recombinant DNA
Make recombinant DNA
Cut a plasmid and a gene with restriction enzymes, watch sticky ends base-pair and ligase seal the backbone base by base, transform bacteria and select with a resistance marker, then check which colonies really carry the gene.
Open the model - 8C 2 · Drugs from Genetically Modified Organisms
Order making a drug with GM bacteria
Order the steps from isolating a human gene and making recombinant DNA to growing GM bacteria and purifying the protein.
Open the model - 8C 3 · Microarrays and Bioinformatics
Order a microarray experiment
Order a microarray from extracting mRNA and making labelled cDNA to hybridisation, scanning and bioinformatics.
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