Key term
AQA A-Level Biology 7402
Biological Molecules
Topic overviewMonomers, polymers, condensation and hydrolysisMonosaccharides, disaccharides and glycosidic bondsAlpha and beta glucose, amylose and amylopectinHow starch, glycogen and cellulose suit their functionsCellulose microfibrils and tests for sugars and starchTriglycerides, fatty acids and phospholipid structureProperties of lipids and the emulsion testThe general structure of amino acidsPeptide bonds, polypeptides and bonds in proteinsLevels of protein structure, the biuret test and chromatographyActivation energy, induced fit and enzyme specificityEnzyme and substrate concentration and inhibitionpH, temperature, initial rates and measurement uncertaintyDNA, RNA and the components of a nucleotideBase pairing in DNA and RNAPhosphodiester bonds and the DNA double helixDoubts about DNA, base ratios and RNA structureSemi-conservative replication, helicase and DNA polymeraseSteps of replication and the Meselson-Stahl experimentATP structure, hydrolysis and resynthesisWater as a metabolite, solvent and coolantHydrogen, iron, sodium and phosphate ions
Cells
Topic overviewCell-surface membrane, nucleus and mitochondriaChloroplasts, Golgi apparatus and lysosomesRibosomes, endoplasmic reticulum, cell walls and vacuolesCell specialisation, levels of organisation and organelle rolesProkaryotic cell structure and virus particlesOptical and transmission electron microscopesScanning electron microscopes, magnification and graticulesCell fractionation, homogenisation and ultracentrifugationOrder of sedimentation, artefacts and fractionation conditionsThe cell cycle, interphase and the stages of mitosisSpindle fibres, cytokinesis and uncontrolled cell divisionBinary fission, viral replication and root tip squashesMitotic index, mitosis stages and size calculationsThe fluid-mosaic model and cholesterolSimple diffusion, facilitated diffusion and membrane proteinsOsmosis, water potential and active transportCo-transport in the ileum and adaptations for rapid transportTransport rates, dilution series and membrane permeabilityAntigens, cell recognition and phagocytosisAntigen-presenting cells, T cells and clonal selectionAntibody structure, agglutination and antigen-antibody complexesMemory cells, vaccination and active and passive immunityHIV structure and replicationAIDS, monoclonal antibodies, ELISA and clinical trials
Organisms Exchange Substances with Their Environment
Topic overviewSurface area to volume ratio, metabolic rate and calculationsGas exchange in single-celled organisms, insects and fishLeaf gas exchange, insect water loss and xerophytesTrachea, bronchi, alveoli and lung dissectionInspiration, expiration and pulmonary ventilation rateLung disease, correlation, insect tracheae and Spearman's rankDigestion of carbohydrates and lipidsEndopeptidases, exopeptidases and dipeptidasesCo-transport of amino acids, micelles and chylomicronsHaemoglobin, red blood cells and the dissociation curveCooperative binding, the Bohr effect and different haemoglobinsDouble circulation and the major blood vesselsHeart chambers, the cardiac cycle and heart dissectionArteries, arterioles, veins and capillariesTissue fluid, cardiovascular risk factors and semilunar valvesXylem structure and the cohesion-tension theoryPhloem structure, companion cells and translocationMass flow from source to sink, tracers and ringingEvaluating mass flow, potometers and transpiration rate
Genetic Information, Variation and Relationships Between Organisms
Topic overviewProkaryotic and eukaryotic DNA, chromosomes and histonesDNA in mitochondria and chloroplasts, genes and lociFeatures of the genetic code, exons and intronsGenome, proteome, mRNA and tRNATranscription, RNA polymerase and splicingTranslation at the ribosome and the role of tRNAGene mutations, mutagens and chromosome non-disjunctionMeiosis, independent segregation and crossing overMeiosis compared with mitosis and random fertilisationGenetic diversity and the spread of advantageous allelesDirectional and stabilising selectionDefining adaptations and how antibiotic resistance spreadsSelection on birth weight, aseptic technique and antimicrobialsClassifying anatomical, physiological and behavioural adaptationsDefining a species, courtship and phylogenetic classificationThe taxonomic hierarchy, binomial names and molecular evidenceSpecies richness, the index of diversity and farmingComparing genetic diversity, standard deviation and the t-test
Energy Transfers in and Between Organisms
Topic overviewPhotoionisation and ATP from the light-dependent reactionChemiosmosis, photolysis and products for the Calvin cycleCarbon fixation, triose phosphate and limiting factorsGlasshouse conditions, pigment chromatography and DCPIPGlycolysis and its productsAnaerobic respiration and the oxidation of pyruvateAcetylcoenzyme A and the Krebs cycleOxidative phosphorylation, other substrates and respirometersBiomass and gross and net primary productionNet production of consumers and productivityFarming practices, transfer efficiency and the production equationsSaprobionts and the phosphorus cycleMycorrhizae, ammonification and nitrificationNitrogen fixation, denitrification and fertilisersLeaching, eutrophication and nutrient cycles reviewed
Organisms Respond to Changes in Their Internal and External Environments
Topic overviewIAA, gravitropism and phototropismTaxes, kineses, reflex arcs and choice chambersThe Pacinian corpuscle and generator potentialsRods, cones, colour vision and visual acuityThe SAN, AVN, bundle of His and Purkyne tissueChemoreceptors, baroreceptors and cardiac outputMotor neurone structure and the resting potentialDepolarisation, action potentials and saltatory conductionThe refractory period and speed of conductionSynapse structure and the neuromuscular junctionTransmission at a cholinergic synapseAcetylcholinesterase, summation and inhibitory synapsesNeuromuscular junctions compared, agonists and antagonistsDrug effects and potassium channels in hyperpolarisationAntagonistic muscle pairs and muscle fibre structureSarcomere bands, actin, myosin and tropomyosinThe sliding filament cycle, ATP and phosphocreatineSlow twitch and fast twitch muscle fibresControl systems and why temperature, pH and glucose matterNegative and positive feedbackGlycogenesis, glycogenolysis and gluconeogenesisHow insulin, glucagon and adrenaline actThe second messenger model, diabetes and the sugar debateGlucose calibration curves and hormones affecting blood glucoseOsmoregulation, osmoreceptors and ADHNephron structure and ultrafiltrationThe proximal convoluted tubule and the loop of HenleThe distal tubule, collecting duct and urine concentration
Genetics, Populations, Evolution and Ecosystems
Topic overviewGenotype, phenotype and types of alleleMonohybrid and dihybrid crosses, sex linkage and autosomal linkageEpistasis, genetic diagrams and the chi-squared testGene pools, allele frequency and Hardy–WeinbergSources of variation and selection pressuresTypes of selection and allopatric and sympatric speciationGenetic drift, founder effects and the route to speciationCommunities, ecosystems, niches and carrying capacityCompetition, predation, quadrats and mark-release-recaptureMark-release-recapture assumptions and successionSuccession, conservation and evaluating the evidence
The Control of Gene Expression
Topic overviewTypes of gene mutation and mutagenic agentsSilent, frameshift, missense and nonsense mutationsTotipotent, pluripotent and induced pluripotent stem cellsTranscription factors, oestrogen, epigenetics and twin studiesDNA methylation, histone acetylation and cancerRNA interference and epigenetic drug targetsBenign and malignant tumours, suppressor genes and oncogenesAbnormal methylation, oestrogen and evidence on causes of cancerGenome projects, the proteome and sequencing methodsTransgenic organisms and making DNA fragmentsThe polymerase chain reactionPromoters, restriction endonucleases, sticky ends and ligaseTransformation, marker genes and uses of recombinant DNAThe humanitarian debate, cDNA and in vivo cloningDNA probes, hybridisation and screening for allelesGenetic counselling, personalised medicine and screening ethicsVNTRs, PCR and gel electrophoresisUsing and interpreting genetic fingerprints
The Control of Gene Expression
- 18 subtopics
- 54 things to know
- Papers 2 and 3
What The Control of Gene Expression covers
The Control of Gene Expression is examined on Paper 2 of AQA Biology, which covers topics 5 to 8, and on Paper 3, which can draw on any topic. 229 recall questions across 18 subtopics.
Where it is assessed
Papers 2 and 3
Topics 5 to 8, then the synoptic paper.
Check the AQA specification ↗The 18 subtopics
Each one has its own page.
- Types of gene mutation and mutagenic agentsRecall questions on addition, deletion, substitution, inversion, duplication and translocation of bases, spontaneous mutation and mutagenic agents, and how a mutation can change the polypeptide.Open →
- Silent, frameshift, missense and nonsense mutationsRecall questions on why degeneracy makes some substitutions silent, frameshifts from additions and deletions, missense and nonsense mutations, and why a change at an active site matters most.Open →
- Totipotent, pluripotent and induced pluripotent stem cellsRecall questions on totipotent, pluripotent, multipotent and unipotent cells, how cells translate only part of their DNA as they specialise, induced pluripotent stem cells, and the uses and ethics of stem cell therapy.Open →
- Transcription factors, oestrogen, epigenetics and twin studiesRecall questions on how transcriptional factors and oestrogen switch on target genes, epigenetics, and how twin studies and cloned plants separate the effects of genes and environment.Open →
- DNA methylation, histone acetylation and cancerRecall questions on how increased DNA methylation and decreased histone acetylation stop transcription, whether epigenetic changes are inherited, and how abnormal methylation relates to cancer and its treatment.Open →
- RNA interference and epigenetic drug targetsRecall questions on why epigenetic changes suit drug therapy, how small double-stranded RNA breaks down or blocks target mRNA in RNA interference, and how epigenetic changes differ from mutations.Open →
- Benign and malignant tumours, suppressor genes and oncogenesRecall questions on how benign and malignant tumours differ in growth, encapsulation, metastasis and recurrence, and the roles of tumour suppressor genes, proto-oncogenes and oncogenes.Open →
- Abnormal methylation, oestrogen and evidence on causes of cancerRecall questions on hypermethylation of tumour suppressor genes and hypomethylation of oncogenes, oestrogen and breast cancer, and evaluating genetic and environmental evidence from migrant and population studies.Open →
- Genome projects, the proteome and sequencing methodsRecall questions on sequencing the genomes of simple and complex organisms, why the proteome is easier to predict in simpler organisms, uses in vaccine development, and how sequencing methods have changed.Open →
- Transgenic organisms and making DNA fragmentsRecall questions on recombinant DNA technology and why a universal code lets transferred genes be expressed, and making fragments with reverse transcriptase, restriction endonucleases or a gene machine.Open →
- The polymerase chain reactionRecall questions on in vitro amplification by PCR, the roles of the template, primers, free nucleotides and heat-stable DNA polymerase, and the denaturation, annealing and extension steps of each cycle.Open →
- Promoters, restriction endonucleases, sticky ends and ligaseRecall questions on in vivo amplification, adding promoter and terminator regions, how restriction endonucleases make sticky or blunt ends, and joining fragments to a vector with DNA ligase.Open →
- Transformation, marker genes and uses of recombinant DNARecall questions on transforming host cells, how marker genes identify transformed cells, gene therapy, and the applications and ethical, financial and social issues of recombinant DNA technology.Open →
- The humanitarian debate, cDNA and in vivo cloningRecall questions on the humanitarian benefits of recombinant DNA and why some groups oppose it, why cDNA lacks introns, and cloning fragments in vivo with restriction endonucleases, sticky ends and ligase.Open →
- DNA probes, hybridisation and screening for allelesRecall questions on labelled DNA probes and DNA hybridisation, screening for heritable conditions and carriers, and pharmacogenomics and screening for drug responses.Open →
- Genetic counselling, personalised medicine and screening ethicsRecall questions on genetic counselling and personalised medicine, the advantages and psychological and ethical costs of genetic screening, and false positives, false negatives and reliability.Open →
- VNTRs, PCR and gel electrophoresisRecall questions on variable number tandem repeats, amplifying them with PCR, and how gel electrophoresis separates DNA fragments by size to produce a genetic fingerprint.Open →
- Using and interpreting genetic fingerprintsRecall questions on reading shared bands to judge relatedness and genetic variability, and the uses of genetic fingerprinting in forensic science, medical diagnosis and animal and plant breeding.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
What is a totipotent cell?
Evaluation
Why does a base substitution not always change the protein?
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State one humanitarian benefit of recombinant DNA technology.
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Define an addition mutation.
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What does it mean that the genetic code is degenerate?
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What is the defining characteristic of totipotent cells in terms of their developmental potential?
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What type of molecule is oestrogen, and what role can it play in gene expression?
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What happens when oestrogen enters a cell and encounters its receptor in the cytoplasm?
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What are histones?
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How does acetylation affect the charge on histone tails and their interaction with DNA?
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What property of epigenetic changes makes them suitable targets for drug therapy?
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After the short RNA fragments are produced in RNAi, what does one strand of the fragment do?
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What is a benign tumour?
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What is a malignant tumour?
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How do increased oestrogen concentrations raise the risk of breast cancer?
Process
Describe the mechanism by which oestrogen promotes cell proliferation in breast cells.
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What is the genome?
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Define the proteome.
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Is the genetic code the same in all organisms?
Process
Are transcription mechanisms shared between different organisms?
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What is the polymerase chain reaction (PCR)?
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What must be present in a PCR reaction to provide the sequence to be copied?
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Why must a promoter region be added to a DNA fragment before expression in a host cell?
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Why must a terminator region be added to a DNA fragment for expression in host cells?
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Define transformation in the context of genetic engineering.
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Name three sectors where recombinant DNA technology has applications.
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Why might environmentalists oppose recombinant DNA technology?
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What is a DNA probe?
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What must happen to target DNA before hybridisation with a probe can occur?
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What is genetic counselling?
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What types of decisions does genetic counselling support?
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Define genetic fingerprinting.
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What is the first step in genetic fingerprinting before PCR amplification can occur?
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How does the number of shared bands relate to genetic relatedness between individuals?
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What does it indicate when bands appear at the same position in different lanes on a gel?
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What is a deletion mutation?
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What is a silent mutation?
Process
How do totipotent cells use their DNA during the process of development?
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Define epigenetics.
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What is the state of chromatin when histones are acetylated, and how does this affect transcription?
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What are the two possible outcomes when the RNA-protein complex binds to mRNA during RNAi?
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How does the growth rate of benign tumours compare to malignant tumours?
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Name four factors that increase lifetime oestrogen exposure.
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What is the relationship between the genome and the proteome?
Process
Are translation mechanisms the same in all living things?
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What occurs when the PCR mixture is cooled after denaturation?
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What two types of ends can restriction endonucleases produce when cutting DNA?
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Give one ethical concern associated with recombinant DNA technology.
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Why might anti-globalisation activists oppose recombinant DNA technology?
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What happens to probe binding stability if there are mismatches between the probe and target sequence?
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What is personalised medicine?
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What type of primers are used in PCR during genetic fingerprinting?
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What would you expect to see when comparing a child's genetic fingerprint to those of their biological parents?
Take The Control of Gene Expression further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
A totipotent cell vs A pluripotent cell
A totipotent cell: a cell able to divide and produce any type of body cell, including the placenta. A pluripotent cell: a cell found in an embryo that can become any body cell but not a placental one.
A multipotent cell vs A unipotent cell
A multipotent cell: a cell in a mature mammal that can form a limited number of related cell types. A unipotent cell: a cell that can form only one type, such as the cardiomyocyte.
A tumour suppressor gene vs A proto-oncogene
A tumour suppressor gene: a gene whose normal product slows cell division, so that its inactivation allows a tumour to form. A proto-oncogene: a gene whose normal product stimulates cell division, so that a mutation to it can drive uncontrolled division.
Questions from this topic
Each one with the model answer underneath.
- 1
At what point in the cell cycle can gene mutations arise?
Model answer
During DNA replication
- 2
Define an addition mutation.
Model answer
A type of gene mutation involving the insertion of one or more extra bases into the DNA sequence
- 3
What is a deletion mutation?
Model answer
A type of gene mutation involving the removal of one or more bases from the DNA sequence
- 4
Define a substitution mutation.
Model answer
A type of gene mutation where one base is replaced by a different base
- 5
What is an inversion mutation?
Model answer
A type of gene mutation where a segment of bases is reversed in orientation
- 6
Define a duplication mutation.
Model answer
A type of gene mutation where a segment of bases is copied and inserted into the sequence
What is inside Levo
Six ways to work the same material.
The Control of Gene Expression revision questions
- What does The Control of Gene Expression cover in AQA A-Level Biology?
- 18 subtopics: types of gene mutation and mutagenic agents, silent, frameshift, missense and nonsense mutations, totipotent, pluripotent and induced pluripotent stem cells, transcription factors, oestrogen, epigenetics and twin studies, dna methylation, histone acetylation and cancer, rna interference and epigenetic drug targets, benign and malignant tumours, suppressor genes and oncogenes, abnormal methylation, oestrogen and evidence on causes of cancer, genome projects, the proteome and sequencing methods, transgenic organisms and making dna fragments, the polymerase chain reaction, promoters, restriction endonucleases, sticky ends and ligase, transformation, marker genes and uses of recombinant dna, the humanitarian debate, cdna and in vivo cloning, dna probes, hybridisation and screening for alleles, genetic counselling, personalised medicine and screening ethics, vntrs, pcr and gel electrophoresis and using and interpreting genetic fingerprints. Each one has its own page with questions and model answers.
- How is The Control of Gene Expression organised?
- By the AQA 7402 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in The Control of Gene Expression, 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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