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
Ecosystems
Productivity and energy transfer efficiency
- 6 things to know
- Papers 2 and 3
Overview
Recall questions on gross and net primary productivity, calculating the efficiency of transfer, and why energy is lost at each level.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Numbers
Define 'energy transferred' and 'energy available', and state the formula for energy transfer efficiency between trophic levels.
Key term
Explain why the equation NPP = GPP − R is used to determine energy available to consumers.
Key term
In a calculation of NPP, what information do you need about respiratory losses?
Key term
What is gross primary productivity (GPP)?
Key term
In the equation NPP = GPP − R, what does the term R represent?
Questions from this subtopic
Each one with the model answer underneath.
- 1
What is gross primary productivity (GPP)?
Model answer
The total rate of energy capture by producers through photosynthesis in an ecosystem, measured per unit area per unit time.
- 2
What units are typically used to express gross primary productivity?
Model answer
Energy per unit area per unit time, such as kJ m⁻² yr⁻¹.
- 3
Define net primary productivity (NPP).
Model answer
The rate of energy storage in plant biomass available to consumers, calculated as GPP minus respiratory losses by the producers.
- 4
State the equation that relates net primary productivity to gross primary productivity.
Model answer
NPP = GPP − R, where R represents the energy lost through respiration by producers.
- 5
Calculate the net primary productivity when gross primary productivity = 15500 kJ m⁻² year⁻¹, respiratory loss = 6000 kJ m⁻² year⁻¹.
Model answer
Net primary productivity = 15500 - 6000 = 9500 kJ m⁻² year⁻¹.
- 6
What does energy transfer efficiency between trophic levels measure?
Model answer
The percentage of energy available at one trophic level that is incorporated into biomass at the next trophic level.
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