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
Phagocytosis and the humoral response
- 6 things to know
- Papers 1 and 3
Overview
Recall questions on phagocytosis by neutrophils and macrophages, antigen-presenting cells, where lymphocytes mature, the humoral response through T helper cells, cytokines, clonal selection and expansion, plasma cells, and antibody structure and action.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Where do B lymphocytes and T lymphocytes mature?
Key term
What is an antigen-antibody complex?
Key term
Which acts first against a newly arrived pathogen, phagocytosis or the lymphocyte response, and why does this matter?
Key term
What is an antigen-presenting cell?
Key term
What is phagocytosis?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is phagocytosis?
Model answer
The non-specific engulfing and digestion of pathogens and cell debris by a phagocytic white blood cell.
- 2
Describe how a neutrophil destroys a bacterium.
Model answer
It is attracted to chemicals released at the site of infection, attaches to antigens on the bacterium and engulfs it into a vacuole called a phagosome. Lysosomes then fuse with the phagosome and release hydrolytic enzymes that digest the bacterium.
- 3
How does the action of a macrophage differ from that of a neutrophil after it has engulfed a pathogen?
Model answer
A macrophage does not destroy all of the pathogen but displays its antigens on its own surface membrane, becoming an antigen-presenting cell that triggers the specific immune response.
- 4
Which acts first against a newly arrived pathogen, phagocytosis or the lymphocyte response, and why does this matter?
Model answer
Phagocytosis acts first, within hours, because it needs no prior recognition of the pathogen, whereas the lymphocyte response takes several days to develop and so cannot contain an infection immediately.
- 5
Why does a neutrophil die shortly after dealing with several pathogens, and what is the visible result?
Model answer
Its store of lysosomal enzymes is used up and cannot be replaced, so it dies; the dead neutrophils accumulate at the site of infection as pus.
- 6
Where do B lymphocytes and T lymphocytes mature?
Model answer
B lymphocytes mature in the bone marrow and T lymphocytes mature in the thymus gland.
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