Key term
Edexcel A-Level Biology B 9BI0
Biological Molecules
Topic overviewMonosaccharides, disaccharides and polysaccharidesGlycosidic bonds and condensation reactionsStarch, glycogen and cellulose structureTriglycerides and phospholipidsSaturated and unsaturated fats and lipid propertiesAmino acid structure and the peptide bondPrimary, secondary, tertiary and quaternary structureFibrous and globular proteinsThe structure of DNADNA replication and gene mutationsThe structure of RNATranscription and translationEnzymes as globular proteinsFactors affecting enzyme activityMeasuring the rate of enzyme activityUnits, uncertainty and experimental errorEnzyme inhibitionInorganic ionsThe properties of water
Cells, Viruses and Reproduction of Living Things
Topic overviewCell theory and eukaryotic cell structureProkaryotic cells and Gram stainingMicroscopy, magnification and resolutionSignificant figures, estimates and mathematical symbolsVirus structure and classificationThe lytic cycle and latencyTreating viral disease and the ethics of untested drugsThe cell cycle and its regulationMitosis and the behaviour of chromosomesMitosis in growth, repair and root tip squashesMeiosis, genetic variation and chromosome mutationsGametogenesis in mammalsFertilisation and early embryo developmentPollen and embryo sac formationDouble fertilisation in flowering plantsInvestigating pollen tube growth
Classification and Biodiversity
Exchange and Transport
Topic overviewSurface area to volume ratioThe fluid mosaic modelDiffusion, osmosis and facilitated diffusionActive transport, endocytosis and exocytosisGas exchange in insects, fish and mammalsDissecting the insect gas exchange systemGas exchange in flowering plantsThe structure of the heart and blood vesselsThe double circulatory systemThe cardiac cycleMyogenic stimulation and ECG tracesThe composition of bloodThe functions of blood and clottingAtherosclerosis and its risk factorsHaemoglobin and the Bohr effectOxygen dissociation curvesFormation of tissue fluidThe lymphatic systemXylem and phloem structureApoplastic and symplastic pathwaysThe cohesion-tension theoryMeasuring transpiration with a potometerTranslocation and the mass flow hypothesis
Energy for Biological Processes
Topic overviewAn overview of aerobic respirationGlycolysisThe link reaction and the Krebs cycleThe electron transport chainChemiosmosis and ATP yieldAnaerobic respiration and ATP yieldMeasuring respiration with a respirometerAbsorption and action spectraPhotosynthetic pigments and chromatographyChloroplast structure and the light-dependent stageThe Calvin cycleLimiting factors in photosynthesis
Microbiology and Pathogens
Topic overviewCulturing microorganisms and aseptic techniqueMeasuring bacterial growthThe bacterial growth curveBacteria as pathogensThe action of antibioticsAntibiotic resistanceOther pathogenic agentsControlling endemic diseasePhagocytosis and the humoral responseThe cell-mediated immune responseMemory cells and the secondary responseNatural and artificial immunityVaccination and herd immunity
Modern Genetics
Origins of Genetic Variation
Topic overviewMutation, meiosis and random fertilisationGenotype, phenotype and monohybrid inheritanceDihybrid crosses and pedigree diagramsAutosomal linkage and sex linkageThe chi-squared test in geneticsSelection pressures and allele frequencyGenetic drift and the founder effectThe Hardy-Weinberg equation
Control Systems
Topic overviewHomeostasis and negative feedbackChemical control in mammalsPlant growth substancesAuxins, cytokinins and apical dominancePhytochrome and photomorphogenesisThe organisation of the nervous systemBrain regions and divisions of the peripheral nervous systemThe autonomic nervous systemResting potential and the action potentialPropagation and saltatory conductionSynaptic transmissionEffects of drugs on the nervous systemThe structure of the retina and rhodopsinRods, cones and visual acuityControl of heart rateKidney structure and ultrafiltrationSelective reabsorption and the loop of HenleADH and osmoregulationThermoregulation in endotherms
Ecosystems
Topic overviewEcosystems, habitats and nichesPyramids of numbers, biomass and energyEcological techniques for measuring distributionChoosing the right ecological techniquePresenting data in tables and graphsStatistical tests in ecologyProductivity and energy transfer efficiencyDecomposers and nutrient cyclingSuccessionBiotic and abiotic factors in population changeHuman influences on ecosystemsSustainability, resource management and peer review
Microbiology and Pathogens
The cell-mediated immune response
- 3 things to know
- Papers 1 and 3
Overview
Recall questions on antigens and antigen-presenting cells, why the lymphocyte response is specific, how it differs from the humoral response, and the roles of T helper, T killer and T memory cells in destroying infected cells.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What is the cell-mediated immune response?
Key term
Why is destroying an infected body cell an effective way of dealing with a virus?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Name two types of cell that can present antigens to T lymphocytes.
Model answer
A macrophage that has engulfed a pathogen, and a body cell infected by a virus that displays viral antigens on its surface.
- 2
Give one key difference between the humoral and cell-mediated immune responses.
Model answer
The humoral response uses B cells and secreted antibodies against pathogens and toxins in body fluids, whereas the cell-mediated response uses T cells to destroy the body's own infected or abnormal cells.
- 3
Define the term antigen.
Model answer
A molecule, usually a protein or glycoprotein on the surface of a cell or pathogen, that the immune system recognises as self or non-self and that can provoke an immune response.
- 4
Why is the lymphocyte response described as specific?
Model answer
Each lymphocyte carries membrane receptors of one particular shape, so it can bind to and respond to only one type of antigen.
- 5
What is the cell-mediated immune response?
Model answer
The part of the specific immune response carried out by T lymphocytes, which act directly on the body's own cells that are infected or abnormal rather than through antibodies in solution.
- 6
What is the role of T helper cells in the cell-mediated response?
Model answer
They bind to the antigen displayed on an antigen-presenting cell and release cytokines that stimulate T killer cells to divide and differentiate.
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