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
- 13 subtopics
- 39 things to know
- Papers 1 and 3
What Microbiology and Pathogens covers
How microorganisms are cultured and measured, how bacteria and other agents cause disease, how antibiotics work and why resistance spreads, and the specific and non-specific ways the body responds to infection.
Where it is assessed
Papers 1 and 3
Advanced Biochemistry, Microbiology and Genetics, then the general and practical principles paper.
Check the Pearson Edexcel specification ↗The 13 subtopics
Each one has its own page.
- Culturing microorganisms and aseptic techniqueRecall questions on aseptic technique with loops, flames and lids, sterilising media and what they must contain, agar, broth and selective media, incubation temperature, safety and ethics, and streak plating to isolate pure colonies.Open →
- Measuring bacterial growthRecall questions on total and viable counts, dilution plating, turbidity, and the haemocytometer.Open →
- The bacterial growth curveRecall questions on the lag, log, stationary and death phases and their causes, the growth rate constant k and how to calculate it, generation time, and why logarithms are used to plot bacterial growth.Open →
- Bacteria as pathogensRecall questions on how bacteria damage the host through toxins and invasion, with named examples.Open →
- The action of antibioticsRecall questions on bactericidal and bacteriostatic antibiotics, how penicillin inhibits transpeptidase and causes osmotic lysis, how tetracycline blocks protein synthesis at 70S ribosomes, and why these antibiotics spare human cells.Open →
- Antibiotic resistanceRecall questions on how resistance arises by mutation and spreads by natural selection, vertical transmission, conjugation, transformation, transduction and R-plasmids, the misuse that accelerates it, and the control measures and why each is limited.Open →
- Other pathogenic agentsRecall questions on how stem rust fungus spreads and damages wheat, how influenza virus is transmitted, enters cells and causes symptoms, and how Plasmodium is transmitted and causes cyclical fever, anaemia and cerebral malaria.Open →
- Controlling endemic diseaseRecall questions on the social and economic implications of controlling endemic malaria, the ethics of consent, equity and environmental harm, how peer review, clinical trials and epidemiology validate control methods, and the control methods themselves.Open →
- Phagocytosis and the humoral responseRecall 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.Open →
- The cell-mediated immune responseRecall 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.Open →
- Memory cells and the secondary responseRecall questions on how B and T memory cells persist and respond on re-exposure, and how the secondary response compares with the primary response in speed, lag, peak antibody concentration and duration.Open →
- Natural and artificial immunityRecall questions on the four combinations of active and passive, natural and artificial immunity, with examples of each.Open →
- Vaccination and herd immunityRecall questions on how the safe antigen in a vaccine activates B and T cells and produces memory cells, the secondary response on later exposure, herd immunity and its threshold, and what happens when vaccination rates fall.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
State two ethical considerations when using microorganisms in practical work.
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How can the four phases of bacterial growth be identified from a growth curve?
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How can bacteria cause damage to the host by physically entering body tissues?
Process
Define endotoxins, and name a genus of bacteria that causes disease primarily through endotoxin release.
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Explain why inhibition of transpeptidase by penicillin leads to bacterial death.
Process
Why is horizontal gene transfer significant for antibiotic resistance, and what are transduction and transformation?
Process
Give two examples of how malaria control programmes can impact daily life and cultural practices.
Process
How does endemic malaria affect workforce productivity, and how might control programmes address this?
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What is active immunity, and how are natural and artificial active immunity acquired?
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What is natural immunity, and how does it differ from artificial immunity?
Process
What determines the herd immunity threshold, and what follows when vaccination rates fall below the threshold?
Evaluation
Describe the principle of dilution plating for counting bacteria.
Key term
How is optical density measured when monitoring bacterial growth?
Process
Which ribosomal subunit does tetracycline bind to?
Evaluation
Explain why resistant bacteria become more common in a population when antibiotics are applied.
Key term
Describe how Puccinia graminis spores initiate infection of wheat plants.
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Explain how influenza virus gains entry into host cells.
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Why is active immunity long-lasting while passive immunity is only temporary?
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Which types of lymphocytes are activated during vaccination?
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What is the purpose of working near a Bunsen flame during aseptic technique?
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Why do microorganisms require a carbon source in culture media?
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Where do B lymphocytes and T lymphocytes mature?
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Why is the lymphocyte response described as specific?
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What is an antigen-antibody complex?
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Which acts first against a newly arrived pathogen, phagocytosis or the lymphocyte response, and why does this matter?
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How does the antibody production during a secondary immune response compare to the primary response?
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Why do microorganisms require a nitrogen source in culture media?
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What role do growth factors play in microbial culture media?
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In what way do bacteria cause harm by breaking down host structures?
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What is a bactericidal antibiotic?
Process
Define conjugation as a mechanism of horizontal gene transfer.
Key term
What effect does stem rust infection have on the photosynthetic capacity of wheat?
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State two economic costs associated with implementing malaria control methods.
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What is an antigen-presenting cell?
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What is the cell-mediated immune response?
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How does the lag phase of the secondary immune response compare to that of the primary response?
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What is phagocytosis?
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Why is destroying an infected body cell an effective way of dealing with a virus?
Take Microbiology and Pathogens further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Antigen vs Antibody
Antigen: foreign molecule triggering a specific immune response. Antibody: protein with a binding site complementary to a foreign molecule.
Bactericidal antibiotic vs Bacteriostatic antibiotic
Bactericidal antibiotic: drug that kills bacterial cells. Bacteriostatic antibiotic: drug that prevents bacterial growth and reproduction.
Questions from this topic
Each one with the model answer underneath.
- 1
Why is an inoculating loop heated until red hot before and after use?
Model answer
To sterilise the loop by killing all microorganisms, preventing contamination of cultures and cross-contamination between samples.
- 2
What is the purpose of working near a Bunsen flame during aseptic technique?
Model answer
The flame creates an updraft that carries airborne contaminants away from the work area, reducing the risk of contamination.
- 3
Why are the necks of culture bottles and tubes flamed before and after opening?
Model answer
To kill microorganisms present at the rim, preventing contamination when transferring cultures.
- 4
Why should lids be kept off containers for the minimum time necessary during aseptic technique?
Model answer
To reduce the risk of airborne microorganisms entering and contaminating the culture.
- 5
How is culture media typically sterilised before use?
Model answer
By autoclaving at 121°C under pressure.
- 6
Why do microorganisms require a carbon source in culture media?
Model answer
Carbon is needed for synthesising organic molecules and as an energy source for metabolism.
What is inside Levo
Six ways to work the same material.
Microbiology and Pathogens revision questions
- What does Microbiology and Pathogens cover in Edexcel A-Level Biology B?
- 13 subtopics: culturing microorganisms and aseptic technique, measuring bacterial growth, the bacterial growth curve, bacteria as pathogens, the action of antibiotics, antibiotic resistance, other pathogenic agents, controlling endemic disease, phagocytosis and the humoral response, the cell-mediated immune response, memory cells and the secondary response, natural and artificial immunity and vaccination and herd immunity. Each one has its own page with questions and model answers.
- How is Microbiology and Pathogens organised?
- By the Edexcel 9BI0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Microbiology and Pathogens, on a schedule.
Attempt a question from memory, write the correct version, then attempt it again. Levo records the jump between your first attempt and your last, and brings each question back on the day you are due to forget it.
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