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
Genes and Health
- 19 subtopics
- 57 things to know
- Papers 1, 2 and 3
What Genes and Health covers
Covers gas exchange and how substances cross membranes, the structure of DNA and how it is read into protein, enzymes, replication and mutation, and the inheritance, effects and screening of cystic fibrosis.
Where it is assessed
Papers 1, 2 and 3
Core content, examined on every paper.
Check the Pearson Edexcel specification ↗The 19 subtopics
Each one has its own page.
- Gas exchange surfaces and Fick's LawRecall questions on what makes a good exchange surface, Fick's Law and its terms, and how the alveoli are adapted for gas exchange.Open →
- The fluid mosaic model of the cell membraneRecall questions on the phospholipid bilayer, cholesterol, proteins, glycoproteins and glycolipids, and on how temperature and alcohol affect permeability.Open →
- Osmosis, diffusion and active transportRecall questions on osmosis, diffusion, facilitated diffusion, active transport, endocytosis and exocytosis, and the proteins each uses.Open →
- Surface area and volume calculationsRecall questions on the formulae for the area and volume of common shapes, and on why the ratio between them matters biologically.Open →
- The structure of DNA and RNARecall questions on mononucleotides, purines and pyrimidines, base pairing and hydrogen bonding, and the double helix.Open →
- TranscriptionRecall questions on RNA polymerase, the template strand, and how messenger RNA is built.Open →
- Translation and the genetic codeRecall questions on ribosomes, transfer RNA, codons and anticodons, start and stop codons, and why the code is described as triplet, non-overlapping and degenerate.Open →
- Amino acids and the levels of protein structureRecall questions on the structure of an amino acid, the peptide bond, and the primary, secondary, tertiary and quaternary levels.Open →
- Globular and fibrous proteins: haemoglobin and collagenRecall questions on what distinguishes globular from fibrous proteins, and on the structures of haemoglobin and collagen.Open →
- Alternative splicing and tissue-specific proteinsRecall questions on how one gene can produce several proteins, and on post-transcriptional modification.Open →
- Enzyme specificity, the active site and activation energyRecall questions on the lock and key and induced fit models, activation energy, and intracellular against extracellular enzymes.Open →
- Rates of reaction, Vmax and Core Practical 4Recall questions on measuring initial rate, the effect of enzyme and substrate concentration, Vmax, and the controls in Core Practical 4.Open →
- Semi-conservative replication and Meselson-StahlRecall questions on the role of DNA polymerase, and on how Meselson and Stahl showed replication to be semi-conservative.Open →
- Types of mutation and the CFTR geneRecall questions on substitution, deletion, insertion and frameshift mutations, and on the mutation that causes cystic fibrosis.Open →
- Alleles, genotype and monohybrid inheritanceRecall questions on genes, alleles, genotype and phenotype, dominance, and the ratios expected from a monohybrid cross.Open →
- Pedigree diagrams and the inheritance of cystic fibrosisRecall questions on reading a pedigree, identifying carriers, and the inheritance pattern of cystic fibrosis.Open →
- The effects of cystic fibrosis, and the chi-squared testRecall questions on the CFTR protein and the effects on the lungs, digestion and fertility, and on using the chi-squared test.Open →
- Prenatal genetic testing: PGD, amniocentesis and CVSRecall questions on what each test involves, when it can be carried out, and the risks attached.Open →
- The ethics of genetic screeningRecall questions on false positives and negatives, confidentiality, and the ethical arguments for and against screening.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
How do the four transport processes across a membrane differ?
Key term
Explain how Meselson and Stahl's results refuted both conservative and dispersive models of replication.
Key term
What is the relationship between the thickness of an exchange surface and the rate of diffusion?
Key term
In Fick's Law, what does ΔC represent?
Key term
What is the function of cholesterol in cell membranes?
Key term
Define facilitated diffusion.
Numbers
State the formula for the circumference of a circle.
Numbers
State the formula for the surface area of a sphere.
Process
Define transcription.
Process
Define translation.
Process
Define a gene.
Process
Explain why the primary structure determines the three-dimensional structure of a protein.
Key term
How many polypeptide subunits make up haemoglobin?
Key term
What prosthetic group is found in each haemoglobin subunit?
Process
What does the primary mRNA transcript contain before processing?
Key term
What are intracellular enzymes?
Key term
Why does increasing enzyme concentration increase the initial rate of reaction?
Key term
What does the term in the denominator represent in the formula rate = 1/time?
Key term
What is the function of DNA polymerase in DNA replication?
Process
What is an allele?
Key term
What is incomplete dominance?
Key term
How can you identify a recessive condition from a pedigree diagram?
Key term
What is the inheritance pattern of cystic fibrosis?
Process
Why are cilia ineffective at clearing mucus in cystic fibrosis patients?
Process
What nutritional consequences result from pancreatic duct blockage in cystic fibrosis?
Process
Describe the procedure of amniocentesis.
Key term
What is chorionic villus sampling (CVS)?
Evaluation
Why might parents face difficult decisions following prenatal genetic screening?
Key term
If a person tests positive as a carrier for a recessive genetic condition, why might their siblings want to know?
Key term
What is the basic structural component of cell membranes?
Key term
What type of sugar is found in a DNA mononucleotide?
Key term
What type of sugar is found in an RNA mononucleotide?
Key term
What does RNA polymerase add to the growing mRNA strand during transcription?
Key term
What would happen if a cell type changed which exons it included during splicing of a particular gene?
Key term
Describe the structural feature of an enzyme that allows it to bind with its substrate.
Key term
Define the term mutation.
Key term
How can mutations arise during DNA replication?
Key term
How does the thickness of a gas exchange surface affect its efficiency?
Key term
Describe the orientation of phospholipids in a cell membrane.
Key term
What is a partially permeable membrane?
Numbers
State the formula for the area of a circle.
Key term
Name the third component of a mononucleotide besides the pentose sugar and phosphate group.
Key term
What is the product synthesised by RNA polymerase?
Key term
What molecule does tRNA carry to the ribosome?
Key term
To what is the central carbon atom of an amino acid bonded?
Key term
Describe the shape of a globular protein.
Key term
During alternative splicing, what happens to the exons from the primary transcript?
Key term
Why can an enzyme only catalyse a specific reaction?
Key term
What effect does increasing enzyme concentration have on the initial rate of reaction when substrate is in excess?
Key term
What does it mean to say that DNA replication is semi-conservative?
Key term
What is a substitution mutation?
Key term
Define the term 'gene' in molecular terms.
Key term
In a genetic pedigree diagram, what do squares and circles represent?
Key term
What happens to mucus consistency as a result of defective CFTR channels?
Key term
What is pre-implantation genetic diagnosis (PGD)?
Key term
Why might genetic screening results have implications beyond the individual being tested?
Take Genes and Health further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
Gene vs Allele
Gene: base sequence coding for a polypeptide or functional RNA. Allele: alternative version found at a particular locus.
Transcription vs Translation
Transcription: production of messenger RNA from a DNA template. Translation: assembly of a polypeptide using a messenger RNA template.
Carrier vs Affected individual
Carrier: heterozygous individual possessing a recessive disease version. Affected individual: person expressing the disease phenotype.
Questions from this topic
Each one with the model answer underneath.
- 1
Why do gas exchange surfaces have a large surface area to volume ratio?
Model answer
To maximise the area available for diffusion.
- 2
How does the thickness of a gas exchange surface affect its efficiency?
Model answer
Gas exchange surfaces are thin to minimise the diffusion distance, which increases the rate of diffusion.
- 3
Why must gas exchange surfaces maintain a steep concentration gradient?
Model answer
To maximise the rate of diffusion across the surface.
- 4
How does surface area affect the rate of diffusion?
Model answer
The rate of diffusion is directly proportional to the surface area.
- 5
What is the relationship between the thickness of an exchange surface and the rate of diffusion?
Model answer
The rate of diffusion is inversely proportional to the thickness of the exchange surface.
- 6
How does concentration difference affect the rate of diffusion?
Model answer
The rate of diffusion is directly proportional to the concentration difference.
What is inside Levo
Six ways to work the same material.
Genes and Health revision questions
- What does Genes and Health cover in Edexcel A-Level Biology A?
- 19 subtopics: gas exchange surfaces and fick's law, the fluid mosaic model of the cell membrane, osmosis, diffusion and active transport, surface area and volume calculations, the structure of dna and rna, transcription, translation and the genetic code, amino acids and the levels of protein structure, globular and fibrous proteins: haemoglobin and collagen, alternative splicing and tissue-specific proteins, enzyme specificity, the active site and activation energy, rates of reaction, vmax and core practical 4, semi-conservative replication and meselson-stahl, types of mutation and the cftr gene, alleles, genotype and monohybrid inheritance, pedigree diagrams and the inheritance of cystic fibrosis, the effects of cystic fibrosis, and the chi-squared test, prenatal genetic testing: pgd, amniocentesis and cvs and the ethics of genetic screening. Each one has its own page with questions and model answers.
- How is Genes and Health organised?
- By the Edexcel 9BN0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Genes and Health, 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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