Evaluation
CCEA A-Level Biology 1010
Biological Molecules
Topic overviewWater as a solventInorganic ions and their rolesMonosaccharides and the glycosidic bondDisaccharides and polysaccharidesLipids, triglycerides and phospholipidsAmino acids and protein structureProtein shape, conjugated proteins and prionsNucleic acids: nucleotides, DNA and RNADNA replication and the Meselson–Stahl experimentBiochemical tests and paper chromatography
Enzymes
Topic overviewEnzymes as globular proteins and the active siteSpecificity, cofactors and coenzymesActivation energy and models of enzyme actionThe effect of temperature and pHThe effect of substrate and enzyme concentrationCompetitive and non-competitive inhibitionEnzymes as biomarkers of disease and inhibitors as drugsImmobilised enzymes and biosensors
Viruses and Cell Structure
Topic overviewBacteriophage and HIV structureViral replication in host cellsProkaryotic and eukaryotic cells comparedMembrane structure: the fluid mosaic modelFunctions of membrane componentsMitochondria and chloroplastsRibosomes, endoplasmic reticulum, Golgi apparatus and lysosomesThe nucleus, the cytoskeleton and plasmodesmataPlant, fungal and animal cellsMicroscopy, cell measurement and cell fractionation
Cell Physiology and Transport
Continuity of Cells
Topic overviewThe cell cycle: interphase and the gap phasesControl points in the cell cycle and cancerChromosome structure, haploidy and diploidyMitosis: the events of the four stagesCytokinesis and the significance of mitosisAnticancer drugs and the cell cycleMeiosis I and the first divisionMeiosis II and the significance of meiosisPreparing and examining slides of cell division
Tissues and Organs
Exchange Surfaces and Gas Exchange
Topic overviewSurface area, volume and the surface area to volume ratioFeatures of efficient exchange surfacesThe need for mass transport systemsFick's law and the rate of gas exchangeGas exchange in plants and the compensation pointGas exchange at the alveolusThe respiratory tree and the mechanism of ventilationThe effects of smoking on the breathing systemUsing a respirometer to measure gas exchange
Transport in Plants
Topic overviewEpidermis, endodermis and the tissues of the rootXylem vessels and their lignification patternsPhloem: sieve-tube elements and companion cellsWater and mineral ion uptake by root hairsThe apoplast and symplast pathwaysTranspiration and the factors affecting its rateCohesion-tension theory and the transpiration streamTranslocation of organic solutes in the phloemXerophytes and hydrophytes
The Circulatory System in Mammals
Topic overviewDouble circulation and the major blood vesselsThe structure and function of arteries, veins and capillariesAtherosclerosis, atheroma and the investigation of blood vesselsThe structure of the mammalian heartThe cardiac cycle and the operation of the valvesMyogenic stimulation and the electrocardiogramBlood cells and the stained blood filmPlasma, tissue fluid and blood clottingHaemoglobin and the oxygen dissociation curveThe Bohr effect, myoglobin and altitude
Adaptation and Biodiversity
Topic overviewAdaptation and the ways organisms meet environmental challengesEcological factors and the ecological nicheSampling procedures and sampling devicesEstimating abundance, density, frequency and percentage coverThe biochemical basis of life and the levels of biodiversityMeasuring species diversity with Simpson's indexHandling data: averages, spread and the t-testTaxonomy, nomenclature and the binomial systemThe concept of a speciesThe taxonomic hierarchy from genus to kingdomPhylogenetic taxonomy and molecular evidenceThe five kingdom system: prokaryotae, protoctista and fungiPlantae, animalia and alternative classification systems
Human Impact on Biodiversity
Topic overviewMonoculture, polyculture and intensive agricultureCrop rotation and hedgerow conservationPredator strips, pesticides and integrated pest managementOrganic pollution of waterways by slurry and silage effluentEutrophication and fertiliser run-offBiological oxygen demand and reducing aquatic pollutionConservation initiatives and habitat protectionGlobal warming, climate change and biodiversity
Homeostasis and Excretion
Topic overviewPrinciples of homeostasis and negative feedbackExcretion, osmoregulation and nitrogenous wasteGross structure of the kidney and the urinary systemStructure of the nephron and its blood supplyEpithelia of the nephron and their adaptationsThe glomerular filterUltrafiltration and the forces that drive itSelective reabsorption in the proximal convoluted tubuleThe loop of Henlé and the medullary salt gradientADH, osmoreceptors and the control of water balance
Immunity
Topic overviewNatural barriers to infectionAntigens, antibodies and the antigen–antibody reactionAntibody-mediated immunity and B-lymphocytesCell-mediated immunity and T-lymphocytesActive immunity, passive immunity and vaccinationTransplant rejection and immunosuppressionBlood group polymorphism and the rhesus factorTransfusion compatibility and its consequencesAntibiotic resistance and the search for new antimicrobialsELISA and the detection of disease biomarkers
Co-Ordination and Control
Topic overviewPhytochromes and the control of floweringPlant growth substances and stem elongationThe structure of a neuroneResting potential, threshold and the action potentialImpulse propagation and the speed of conductionSynapse structure and chemical transmissionExcitatory and inhibitory post-synaptic potentialsGross structure of the eye and accommodationThe retina, rods and conesSkeletal muscle and the sliding filament theory
Populations and Communities
Topic overviewPopulation growth curves, carrying capacity and environmental resistancer-selected and K-selected speciesInteractions between populationsBiological control of pest speciesPopulation dynamics and changes in population sizeEstimating population size in the field and the laboratoryCommunities and ecosystemsSuccession and climax communities
Ecological Energetics and Nutrient Cycling
Topic overviewFood chains, food webs and detritus food chainsTrophic levels, gross and net primary productionEcological pyramids and their usefulnessEnergy transfer efficiency between trophic levelsWhy energy is lost at each trophic levelImplications for agriculture and intensive farmingThe carbon cycleThe nitrogen cycle and the role of bacteria
Respiration
Topic overviewATP and the ATP/ADP cycleGlycolysisThe mitochondrion and the sites of aerobic respirationThe link reaction and the Krebs cycleThe electron transport chain and oxidative phosphorylationATP yield from one molecule of glucoseAnaerobic respiration in animals, plants and fungiAerobic and anaerobic respiration compared, and oxygen debtRespiratory quotient and measuring respiration
Photosynthesis
Topic overviewChloroplast structure and the sites of photosynthesisPhotosynthetic pigments and paper chromatographyAbsorption spectra and action spectraPhotosystems, photoactivation and the Z-schemePhotolysis of water, reduced NADP and redox indicatorsCarbon dioxide fixation and rubiscoReduction of glycerate phosphate and regeneration of ribulose bisphosphateLimiting factors, the compensation point and measuring photosynthesis
DNA as the Genetic Code
Topic overviewGenes and the nature of the genetic codeExons, introns and RNA splicingComparing DNA and RNATranscription and RNA polymeraseTransfer RNA, ribosomes and the sites of translationTranslation and polypeptide synthesisOne gene, one polypeptide and the control of the phenotypeEpigenetics, methylation and histone modification
Gene Technology
Topic overviewThe polymerase chain reactionDNA probes and genetic markersMicroarrays, pharmacogenetics and personalised medicineGenetic fingerprinting and gel electrophoresisThe stages of gene transferGenetically modified microorganismsTransgenic animals and plantsGene therapyGenome sequencing and the Human Genome ProjectGene inactivation and knockout organismsSocial, ethical and ecological issues of gene technology
Genes and Patterns of Inheritance
Topic overviewGenotype, phenotype and the environmentChromosomes, genes and allelesMonohybrid inheritance and Mendel's first lawCodominance, multiple alleles and lethal allelesTest crossesDihybrid inheritance and Mendel's second lawAutosomes, sex chromosomes and sex determinationGene interaction and epistasisPolygenic inheritance and continuous variationThe chi-squared test
Population Genetics and Evolution
Evolutionary Trends in Plants
DNA as the Genetic Code
- 8 subtopics
- 24 things to know
- Unit A2 2
What DNA as the Genetic Code covers
DNA as the Genetic Code is examined in Unit A2 2, Biochemistry, Genetics and Evolutionary Trends, and drawn on again in Unit A2 3, the practical skills examination. It covers genes and the nature of the genetic code, exons, introns and RNA splicing, comparing DNA and RNA, transcription and RNA polymerase, transfer RNA, ribosomes and the sites of translation, translation and polypeptide synthesis, one gene, one polypeptide and the control of the phenotype and epigenetics, methylation and histone modification.
Where it is assessed
Unit A2 2
Biochemistry, Genetics and Evolutionary Trends, and again in Unit A2 3, Practical Skills in Biology.
Check the CCEA specification ↗The 8 subtopics
Each one has its own page.
- Genes and the nature of the genetic codeTerm gene, saying the genetic code is non-overlapping and saying the genetic code is degenerate.Open →
- Exons, introns and RNA splicingWhat happens during RNA splicing and why bacterial genes generally need no splicing.Open →
- Comparing DNA and RNAPentose sugar found in RNA, three components of a single RNA nucleotide and three types of RNA involved in protein synthesis.Open →
- Transcription and RNA polymeraseHow the free RNA nucleotides are positioned during transcription, role of RNA polymerase in transcription and why transcription of a gene amplifies the information it carries.Open →
- Transfer RNA, ribosomes and the sites of translationOverall shape of a transfer RNA molecule, function of transfer RNA and structure of a ribosome.Open →
- Translation and polypeptide synthesisHow translation begins, reaction joins two amino acids together at the ribosome and why translation requires a supply of ATP.Open →
- One gene, one polypeptide and the control of the phenotypeOne gene, one polypeptide theory, protein made from polypeptides coded by more than one gene and how genes determine the phenotype of an organism through enzymes.Open →
- Epigenetics, methylation and histone modificationTwo main epigenetic mechanisms, what happens during DNA methylation and how methylation of a gene affects its expression.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Describe what happens after a peptide bond has been formed at the ribosome.
Key term
Explain why the insertion of one extra base near the start of a gene is usually more damaging than a substitution.
Key term
Explain why the one gene, one polypeptide theory is expressed in terms of a polypeptide rather than a protein
Key term
Explain how a single mutated gene can cause an inherited disorder.
Process
Trace the chain of events from a base sequence to an observable characteristic.
Key term
Describe the effect of removing acetyl groups from histones.
Key term
How many bases of DNA code for a single amino acid?
Key term
What is an intron?
Key term
Define transcription.
Key term
Describe the overall shape of a transfer RNA molecule.
Key term
Explain why a code of two bases could not specify all the amino acids found in proteins.
Key term
How does mature mRNA leave the nucleus?
Key term
Name the pentose sugar found in RNA.
Key term
In which part of a eukaryotic cell does transcription occur?
Key term
Where on a transfer RNA molecule is the amino acid attached?
Process
Name the two main epigenetic mechanisms.
Numbers
How many of the 64 triplets code for an amino acid?
Key term
Explain why bacterial genes generally need no splicing.
Key term
Which base is present in RNA in place of thymine?
Key term
What happens to the DNA double helix at the start of transcription?
Key term
Explain why each transfer RNA molecule can carry only one kind of amino acid.
Key term
In which part of the cell does translation occur?
Key term
Describe what happens during DNA methylation.
Take DNA as the Genetic Code further
The same content, four other ways.
Commonly confused
Pairs that lose marks when they are blurred together.
A degenerate code vs A non-overlapping code
A degenerate code: several triplets can specify the same amino acid. A non-overlapping code: it means each base is read only once and belongs to a single triplet.
Genotype vs Phenotype
Genotype: the set of alleles an organism carries. Phenotype: the set of characteristics that result from those alleles interacting with the environment.
Questions from this topic
Each one with the model answer underneath.
- 1
Define the term gene.
Model answer
A gene is a sequence of bases on a DNA molecule that codes for the sequence of amino acids in a polypeptide chain.
- 2
How many bases of DNA code for a single amino acid?
Model answer
Three consecutive bases, called a triplet, code for one amino acid.
- 3
Explain why a code of two bases could not specify all the amino acids found in proteins.
Model answer
With four bases there are only 4 × 4 = 16 possible pairs, which is fewer than the 20 amino acids that must be specified, whereas triplets give 4 × 4 × 4 = 64 combinations and are more than enough.
- 4
How many different triplets are possible in the genetic code?
Model answer
There are 64 different triplets, because four different bases can be arranged three at a time in 4³ ways.
- 5
How many of the 64 triplets code for an amino acid?
Model answer
61 triplets code for amino acids and the remaining three act as stop signals.
- 6
What is meant by saying the genetic code is non-overlapping?
Model answer
Each base belongs to one triplet only and is read once, so the triplets are read end to end without sharing bases.
What is inside Levo
Six ways to work the same material.
DNA as the Genetic Code revision questions
- What does DNA as the Genetic Code cover in CCEA A-Level Biology?
- 8 subtopics: genes and the nature of the genetic code, exons, introns and rna splicing, comparing dna and rna, transcription and rna polymerase, transfer rna, ribosomes and the sites of translation, translation and polypeptide synthesis, one gene, one polypeptide and the control of the phenotype and epigenetics, methylation and histone modification. Each one has its own page with questions and model answers.
- How is DNA as the Genetic Code organised?
- By the CCEA 1010 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in DNA as the Genetic Code, 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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