Key term
CCEA A-Level Life and Health Sciences 0008
Experimental Techniques
Human Body Systems
Topic overviewBlood vessels, the heart and cardiac outputHeart sounds, ECG traces, pulse and blood pressureBody fluids, haemoglobin and the Bohr effectThe respiratory system, gas exchange and lung diseaseMonitoring breathing and lung volumesCellular respiration and ATPHomeostasis, blood glucose and thyroxineSodium, blood pH and oxygen saturationA balanced diet and nutritional needs through lifeCholesterol, minerals, vitamins, alcohol and exercise
Physical Chemistry in Industrial Processes
Topic overviewMoles, reacting masses and percentage yieldTitration types, indicators and standard solutionsTitration calculations and molarityEnthalpy changes and calorimetryHess's law and average bond enthalpiesCollision theory, rates and the Maxwell–Boltzmann distributionCatalysts, chemisorption and catalytic convertersReversible reactions, the Haber process and the Contact processScale-up, costs and siting a chemical plant
Brain ScienceDouble Award
Topic overviewBrain structure and frontal lobe damageNeurones, synapses and the endocrine systemAlzheimer's disease, Huntington's disease and stem cell therapySchizophrenia and mental health awareness in Northern IrelandThe biology of aggression and methods of studying the brainStress, the stress response and stress managementMemory models, forgetting and eyewitness testimonyAbnormality, phobias, depression and OCDExperiments, observations, self-report and research designHypotheses, sampling, ethics and descriptive statistics
Material ScienceDouble Award
Topic overviewMaterial properties and selectionStress, strain and the Young modulusStress–strain graphs, creep and fatigueDensity, hardness and conductivity testingMetals, ceramics, glasses, polymers and compositesAtomic and microscopic structure of materialsAlloys, annealing and biomaterialsSmart materialsNanomaterials and semiconductors
Medicine, Drugs and Clinical TrialsDouble Award
Topic overviewCategories of medicine and routes to drug discoveryMedicines from natural sources, drug names and the ATC systemDrug development, preclinical testing and the therapeutic indexPhases of clinical trials and trial designLicensing, UK regulators, Yellow Card and trial ethicsFormulations, routes of administration and drug absorptionDistribution, metabolism, elimination and sites of drug actionQuantitative analysis of medicines and antibacterial bioassays
Scientific Method, Investigation, Analysis and Evaluation
Topic overviewThe scientific method, literature reviews and Harvard referencingDescriptive statistics and the normal distributionNull hypotheses, significance and choosing a statistical testInvestigation design, Design of Experiments and project plansGood Laboratory Practice, risk assessment and COSHHExperimental error, scientific writing and evaluation
Organic Chemistry
Topic overviewOrganic formulae, homologous series and functional groupsIUPAC naming and types of organic reactionStructural isomerism and E/Z isomerismAlkanes from crude oil, combustion and halogenationVehicle pollutants, catalytic converters and biofuelsAlkenes, pi bonds and electrophilic additionClassifying alcohols, making ethanol and its effects as a drugOxidation of alcohols, IR spectroscopy and mass spectrometryAddition polymers, plastic waste and nylonPreparing and purifying aspirin
Medical PhysicsA2 option
Topic overviewBody temperature and clinical thermometersBlood pressure readings and the sphygmomanometerHeart activity experiments and EEG tracesX-ray tubes, radiographs and CT scansFlexible endoscopes, optical fibres and lasersUltrasound A-scans, B-scans and acoustic impedanceMRI scanning and gamma camera imagingAlpha, beta and gamma radiation and half-lifeRadiopharmaceuticals, radiotherapy and radiation protection
Sound and LightA2 option
Topic overviewTransverse and longitudinal waves and wave graphsPhase difference and the electromagnetic spectrumOuter, middle and inner earSound intensity and the decibel scaleStanding waves, harmonics and resonance tubesHearing response, phons and equal loudness curvesStructure of the eye, rods and conesAccommodation, lens power and correcting long sightTotal internal reflection and fibre-optic communicationDipole antennas, wireless networks and radarAttenuation of radio waves and the Doppler effect
Genetics, Stem Cell Research and CloningA2 option
Topic overviewDNA structure and the evidence for the double helixRNA, genes and the triplet codeGenotype, phenotype and monohybrid inheritanceDihybrid crosses, epistasis and the chi-squared testDNA replication and the Meselson–Stahl experimentMeiosis and genetic variationInsulin, factor VIII and chymosin from genetically modified microbesRecombinant DNA technology and gene cloningGenetic engineering, food supply and ethicsGene therapy and cystic fibrosisGenetic disease, screening and counsellingGenetic fingerprinting and gel electrophoresisStem cells, therapeutic cloning and their ethics
MicrobiologyDouble Award
Topic overviewBacteria, fungi and protozoaViruses, viroids and prionsClassifying bacteria, fungi and virusesLight and electron microscopyLaboratory safety, biocontainment and quality assuranceAseptic technique, growth media and inoculationCounting and measuring microbial growthGrowth requirements and growth inhibitionAntibiotics, PCR, gene therapy and pharmaceutical microbiologyThe gut microbiome in health and disease
Oral Health and DentistryDouble Award
Histology and PathologyDouble Award
Topic overviewSpecimen processing, data protection and safety lawClinical biochemistry tests and electrophoresisBlood smears and identifying blood cellsBlood grouping, cross-matching and transfusionDiagnostic and surveillance work in hospital microbiologyPreparing and staining tissue sectionsRecognising tissues, atheroma and emphysema on slides
Analytical Chemistry TechniquesDouble Award
Topic overviewVolumetric analysis in industry and healthcareApplied titrations of vinegar, indigestion tablets and bleachRedox titration of iron tablets and evaluating titrationsPrinciples of colorimetryColorimetric analysis of copper ore, aspirin and ironThin-layer chromatography and its usesVisualising chromatograms and identifying painkillers and pigmentsCalorimetry and combustionMolar enthalpy and bond energy calculationsQualitative tests for cations and gases
Enabling TechnologyDouble Award
Topic overviewECG and EEG machines in patient monitoringUltrasound and IVF equipment in fertility treatmentProsthetic limbs, hearing aids and cochlear implantsWorkflow and equipment in a medical laboratoryOngoing monitoring of a long-term conditionHealth data collection, databases and data protection
Microbiology
Counting and measuring microbial growth
- 3 things to know
- A2 6
Overview
Serial dilutions, viable and total counts with worked examples, colony-forming units, haemocytometers, turbidity, fungal growth rates, dry mass, plaque counts and microbiological assays.
What you need to know
Answer each one before you reveal it.
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Key term
How is a tenfold serial dilution carried out?
Key term
After six tenfold dilutions, what is the total dilution factor?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why are serial dilutions used before counting bacteria?
Model answer
A culture usually contains far too many cells to count directly. Serial dilutions reduce the number so a plate gives a countable number of colonies, usually 30 to 300.
- 2
How is a tenfold serial dilution carried out?
Model answer
1 cm³ of culture is added to 9 cm³ of sterile diluent and mixed. The step is repeated with a fresh sterile pipette each time.
- 3
After six tenfold dilutions, what is the total dilution factor?
Model answer
The total dilution factor is one million, or 10⁶. The working is 10 multiplied by itself six times.
- 4
A 0.1 cm³ sample from a 10⁻⁵ dilution gives 45 colonies. What was the concentration of the original culture?
Model answer
The original culture held 4.5 × 10⁷ viable cells per cm³. The working is 45 ÷ 0.1 = 450 per cm³, then 450 × 10⁵ = 4.5 × 10⁷.
- 5
What is the difference between a viable count and a total count?
Model answer
A viable count includes only living cells, which grow into colonies. A total count includes both living and dead cells.
- 6
What is a colony-forming unit?
Model answer
A colony-forming unit is a cell or clump of cells that grows into one visible colony. Viable counts are given as colony-forming units per cm³.
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