Process
Edexcel A-Level Biology A 9BN0
Lifestyle, Health and Risk
Topic overviewWater and the carbohydratesCondensation, hydrolysis and glycosidic bondsLipids, food tests and unitsThe cardiac cycle and the structure of the heartArteries, veins and capillariesCore practical: caffeine and the heart rate of DaphniaThe blood clotting cascadeThrombus, embolus and their consequencesAtherosclerosis and the risk factors for CVDTreatments for CVD, and cholesterol transportBMI, waist-to-hip ratio and energy balanceCore practical 2: the vitamin C content of food and drinkCorrelation, causation and the design of health studiesRisk perception, and handling quantitative data
Genes and Health
Topic overviewGas exchange surfaces and Fick's LawThe fluid mosaic model of the cell membraneOsmosis, diffusion and active transportSurface area and volume calculationsThe structure of DNA and RNATranscriptionTranslation and the genetic codeAmino acids and the levels of protein structureGlobular and fibrous proteins: haemoglobin and collagenAlternative splicing and tissue-specific proteinsEnzyme specificity, the active site and activation energyRates of reaction, Vmax and Core Practical 4Semi-conservative replication and Meselson-StahlTypes of mutation and the CFTR geneAlleles, genotype and monohybrid inheritancePedigree diagrams and the inheritance of cystic fibrosisThe effects of cystic fibrosis, and the chi-squared testPrenatal genetic testing: PGD, amniocentesis and CVSThe ethics of genetic screening
Voice of the Genome
Topic overviewProkaryotic cellsEukaryotic organelles and their functionsIdentifying organelles in an electron micrographProtein secretion, and levels of organisationMicroscopy: the graticule, magnification and standard formThe cell cycle and the stages of mitosisCore practical: the root tip squashMeiosis, linkage and sex linkageThe structure of sperm and egg cellsFertilisation: the acrosome and cortical reactionsTotipotency, pluripotency and sources of stem cellsThe ethics and risks of stem cell therapyDifferential gene expression and specialisationThe lac operonEpigenetics: DNA methylation and histone modificationPolygenic inheritance, continuous variation and statistics
Biodiversity and Natural Resources
Topic overviewBiodiversity, species richness and the index of diversityNiches and the three kinds of adaptationNatural selection and evolutionThe Hardy-Weinberg equation and its assumptionsReproductive isolation and speciationClassificationThe plant cell wall, chloroplast and amyloplastThe vacuole, plasmodesmata, pits and middle lamellaPlant cells in the electron microscopeStarch and celluloseLignin, xylem vessels and sclerenchyma fibresIdentifying plant tissues under the microscopeThe structure of xylem, phloem and sclerenchymaWater and the mineral nutrition of plantsCore practical: investigating mineral deficiencyCore practical: the tensile strength of plant fibresDrug development from Withering to modern trialsGrowing bacteria and aseptic techniqueCore practical: the antimicrobial properties of plantsSustainability and Conservation
On the Wild Side
Topic overviewPhotosynthesis: the light-dependent reactionsPhotosynthesis: the Calvin cycleChloroplast structure and the products of photosynthesisProductivity: GPP, NPP and energy transferCore practicals on temperature and growthTemperature, enzymes and Q10Sampling: quadrats and transectsSuccessionBiotic and abiotic factors, niches and competitionEcosystem terms, evolution, speciation and validating evidenceEvidence for climate changeClimate models and their limitationsCorrelation, causation and scientific objectivityThe effects of climate change on organismsHuman activities that raise greenhouse gas levelsThe greenhouse effectEvolution and natural selectionSpeciationHow new scientific evidence is validatedThe carbon cycleReforestation, biofuels and sustainability
Immunity, Infection and Forensics
Topic overviewDecomposition, succession and forensic entomologyBody cooling and rigor mortisDNA profiling and the polymerase chain reactionGel electrophoresisThe structure of bacteria and virusesDecomposition, and how pathogens enter the bodyThe body's barriers, and modelling bacterial growthTuberculosis and HIVThe non-specific immune responseAntigens, antibodies and B cellsT cells and cell-mediated immunityActive and passive immunity, natural and artificialThe evolutionary race and pathogen evasionAntibiotics and testing their effectivenessHospital acquired infections and their control
Run for Your Life
Topic overviewMuscles and MovementThe myofibril and the sarcomereThe sliding filament theory, calcium and ATPSlow-twitch and fast-twitch muscle fibresGlycolysis and the link reactionThe Krebs cycle, oxidative phosphorylation and oxygen debtThe conduction system: SAN, AVN and Purkyne fibresThe sequence of cardiac excitationThe electrocardiogram, cardiac output and stroke volumeThe cardiovascular and ventilation control centresSpirometry and ventilation during exerciseHomeostasis, feedback and gene control by hormonesThermoregulation and the hypothalamusThe effects of too much and too little exerciseMedical technology and performance-enhancing substances
Grey Matter
Topic overviewThe structure of neurones and myelinationThe action potential and saltatory conductionThe structure of a synapse and calcium entryNeurotransmitter release and acetylcholineRod cells and the detection of lightEffectors, the neuromuscular junction and the pupil reflexPhytochrome and the response to lightIAA, phototropism and gravitropismNervous against hormonal coordinationThe regions of the brain and their functionsBrain imaging: MRI, fMRI, PET and CTCritical periods and the Hubel and Wiesel experimentsNature, nurture, habituation and research ethicsDopamine, serotonin and their imbalanceL-Dopa and MDMAGenome sequencing, personalised medicine and its ethicsGenetically modified organisms: benefits and risks
Grey Matter
- 17 subtopics
- 51 things to know
- Papers 2 and 3
What Grey Matter covers
Covers how information is carried and processed: the neurone and the action potential, the synapse, how the eye detects light, plant responses, the regions of the brain and how they are imaged, learning and its critical periods, and the drugs that act on the brain.
Where it is assessed
Papers 2 and 3
Energy, Exercise and Co-ordination, then the synoptic paper.
Check the Pearson Edexcel specification ↗The 17 subtopics
Each one has its own page.
- The structure of neurones and myelinationRecall questions on sensory, relay and motor neurones, Schwann cells and the myelin sheath, and the nodes of Ranvier.Open →
- The action potential and saltatory conductionRecall questions on the resting potential, depolarisation and repolarisation, the refractory period, and why myelination speeds conduction.Open →
- The structure of a synapse and calcium entryRecall questions on the presynaptic and postsynaptic neurones, the cleft, vesicles, and what calcium entry triggers.Open →
- Neurotransmitter release and acetylcholineRecall questions on how neurotransmitter crosses the cleft and binds, the role of acetylcholinesterase, and why transmission is one way.Open →
- Rod cells and the detection of lightRecall questions on rhodopsin and its two components, bleaching, and how hyperpolarisation of a rod cell signals to the bipolar neurone.Open →
- Effectors, the neuromuscular junction and the pupil reflexRecall questions on what happens at a neuromuscular junction, antagonistic muscles of the iris, and the autonomic control of the pupil.Open →
- Phytochrome and the response to lightRecall questions on the Pr and Pfr forms, which is active, and how Pfr changes transcription in the nucleus.Open →
- IAA, phototropism and gravitropismRecall questions on how IAA promotes cell elongation, how it redistributes in a shoot and a root, and why shoots and roots respond differently.Open →
- Nervous against hormonal coordinationRecall questions on the speed, duration and specificity of each system, and on how target cells respond to particular hormones.Open →
- The regions of the brain and their functionsRecall questions on the cerebral hemispheres, hypothalamus, cerebellum and medulla oblongata and what each controls.Open →
- Brain imaging: MRI, fMRI, PET and CTRecall questions on what each technique measures, which show structure and which show function, and which involve ionising radiation.Open →
- Critical periods and the Hubel and Wiesel experimentsRecall questions on what a critical period is, the visual cortex, and what Hubel and Wiesel's work showed.Open →
- Nature, nurture, habituation and research ethicsRecall questions on twin, cross-cultural and animal studies, habituation and Core Practical 18, and the three Rs.Open →
- Dopamine, serotonin and their imbalanceRecall questions on what each neurotransmitter does and the conditions linked to too little of each.Open →
- L-Dopa and MDMARecall questions on why L-Dopa is given rather than dopamine, and on how MDMA affects serotonin release and reuptake.Open →
- Genome sequencing, personalised medicine and its ethicsRecall questions on what sequencing data allows, and on privacy, consent, ownership and access by insurers and employers.Open →
- Genetically modified organisms: benefits and risksRecall questions on pharming and GM crops, and on gene flow, biodiversity, pest resistance and the economic risks to farmers.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
How is an impulse carried across a synapse?
Process
Describe the structure of a motor neurone in terms of cell body location and processes.
Numbers
What is the typical resting potential of an axon and what is the charge distribution?
Process
If calcium ion entry into the presynaptic neurone was blocked, what would happen to synaptic transmission?
Process
What is the consequence of ion channels opening in the postsynaptic membrane?
Process
What is the membrane potential of a rod cell in darkness, and why?
Key term
When cation channels close in a rod cell, why does the cell become more negative inside?
Key term
Which division of the autonomic nervous system controls pupil constriction in bright light?
Key term
What is IAA and what class of plant hormone does it belong to?
Process
How does IAA promote cell elongation at the level of gene expression?
Key term
How do hormones travel to their target organs?
Key term
Describe the location of the hypothalamus in the brain.
Key term
What physiological changes does fMRI detect in the brain?
Key term
Can CT scans detect brain tumours?
Numbers
What is the genetic difference between monozygotic and dizygotic twins that makes twin studies useful?
Process
Where does habituation occur in the nervous system, and how does this differ from sensory adaptation?
Process
What type of molecule is dopamine in the context of brain function?
Process
A patient presents with symptoms associated with altered brain chemistry. If serotonin is implicated, what would be the underlying issue?
Process
How does MDMA affect the release of serotonin from neurons?
Key term
State one moral issue raised by personalised medicine.
Key term
Who owns genetic information once it has been collected, and why is this an ethical concern?
Process
How can genetically modified animals be used to produce drugs?
Key term
State one agricultural benefit of genetically modified crops.
Key term
What is the function of sensory neurones in the nervous system?
Key term
What is a synapse?
Key term
What are effectors?
Key term
What wavelength of light does the Pr form of phytochrome absorb?
Key term
What wavelength of light does the Pfr form of phytochrome absorb?
Key term
What type of signals does the nervous system use to achieve coordination in animals?
Key term
Which part of the brain is responsible for conscious thought?
Process
What process occurs in the visual cortex during the critical period that shapes neural connections based on experience?
Key term
Explain how visual experience influences synaptic connections during the critical period.
Key term
What property of L-Dopa allows it to be effective as a treatment when dopamine itself cannot be used?
Key term
Describe the relative lengths of the dendron and axon in a sensory neurone.
Key term
Define an action potential.
Key term
What is the presynaptic neurone?
Key term
What happens when neurotransmitter binds to receptors on the postsynaptic membrane?
Key term
What are rod cells?
Key term
Describe what happens at a neuromuscular junction when an action potential arrives.
Key term
What happens to Pr when it absorbs red light?
Key term
Where does IAA bind to initiate its effects on gene expression?
Key term
Describe the speed of transmission in the nervous system.
Key term
Which brain region controls reasoning abilities?
Key term
What physical phenomena does MRI use to generate images?
Key term
What happens if an individual does not receive appropriate visual stimulation during the critical period?
Key term
What is the purpose of cross-cultural studies in nature-nurture research?
Key term
What health consequence can result from an imbalance of dopamine in the brain?
Key term
Explain how L-Dopa alleviates the symptoms of Parkinson's disease at the synaptic level.
Key term
What type of data from genome sequencing projects has enabled the development of personalised medicine?
Key term
Explain how genetically modified microorganisms can be used to produce therapeutic drugs.
Take Grey Matter further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Depolarisation vs Repolarisation
Depolarisation: membrane-potential change making the cell interior less negative. Repolarisation: membrane-potential change restoring the negative resting value.
Excitatory synapse vs Inhibitory synapse
Excitatory synapse: junction increasing the likelihood of postsynaptic firing. Inhibitory synapse: junction decreasing the likelihood of postsynaptic firing.
Habituation vs Sensitisation
Habituation: reduced response following repeated harmless stimulation. Sensitisation: increased response following strong or repeated stimulation.
Questions from this topic
Each one with the model answer underneath.
- 1
What is the function of sensory neurones in the nervous system?
Model answer
Sensory neurones transmit nerve impulses from receptors to the central nervous system (CNS).
- 2
Where is the cell body of a sensory neurone located?
Model answer
In a dorsal root ganglion, positioned off to one side of the axon.
- 3
Describe the relative lengths of the dendron and axon in a sensory neurone.
Model answer
Sensory neurones have one long dendron carrying impulses towards the cell body and a shorter axon carrying impulses away from it.
- 4
What is the location and function of relay neurones?
Model answer
Relay neurones are located entirely within the CNS and connect sensory neurones to motor neurones.
- 5
What structural features of relay neurones allow them to integrate signals from multiple sources?
Model answer
They have short axons and numerous dendrites.
- 6
What is the role of motor neurones?
Model answer
Motor neurones transmit nerve impulses from the CNS to effectors such as muscles and glands.
What is inside Levo
Six ways to work the same material.
Grey Matter revision questions
- What does Grey Matter cover in Edexcel A-Level Biology A?
- 17 subtopics: the structure of neurones and myelination, the action potential and saltatory conduction, the structure of a synapse and calcium entry, neurotransmitter release and acetylcholine, rod cells and the detection of light, effectors, the neuromuscular junction and the pupil reflex, phytochrome and the response to light, iaa, phototropism and gravitropism, nervous against hormonal coordination, the regions of the brain and their functions, brain imaging: mri, fmri, pet and ct, critical periods and the hubel and wiesel experiments, nature, nurture, habituation and research ethics, dopamine, serotonin and their imbalance, l-dopa and mdma, genome sequencing, personalised medicine and its ethics and genetically modified organisms: benefits and risks. Each one has its own page with questions and model answers.
- How is Grey Matter organised?
- By the Edexcel 9BN0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Grey Matter, 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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