Key term
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
Transport in Plants
- 9 subtopics
- 27 things to know
- Unit AS 2
What Transport in Plants covers
Transport in Plants is examined in Unit AS 2, Organisms and Biodiversity, and drawn on again in Unit AS 3, the practical skills examination. It covers epidermis, endodermis and the tissues of the root, xylem vessels and their lignification patterns, phloem: sieve-tube elements and companion cells, water and mineral ion uptake by root hairs, the apoplast and symplast pathways, transpiration and the factors affecting its rate, cohesion-tension theory and the transpiration stream, translocation of organic solutes in the phloem and Xerophytes and hydrophytes.
Where it is assessed
Unit AS 2
Organisms and Biodiversity, and again in Unit AS 3, Practical Skills in AS Biology.
Check the CCEA specification ↗The 9 subtopics
Each one has its own page.
- Epidermis, endodermis and the tissues of the rootEpidermis of a young root, cortex of a root and band of waterproof material in the walls of endodermal cells.Open →
- Xylem vessels and their lignification patternsTwo functions of xylem tissue, substance that impregnates the walls of xylem vessels and why a xylem vessel must be strengthened against collapse.Open →
- Phloem: sieve-tube elements and companion cellsFunction of phloem tissue, how a sieve tube is formed and sieve plate.Open →
- Water and mineral ion uptake by root hairsRecall questions on the root hair as an extension of an epidermal cell, water entering down a water potential gradient, mineral ions taken up actively against a concentration gradient, and why the two mechanisms differ.Open →
- The apoplast and symplast pathwaysApoplast pathway and symplast pathway.Open →
- Transpiration and the factors affecting its rateEffect of increasing light intensity on the rate of transpiration, how air currents increase the rate of transpiration and effect of high humidity on the rate of transpiration.Open →
- Cohesion-tension theory and the transpiration streamTranspiration stream, cohesion-tension theory in outline and cohesion as it applies to water in the xylem.Open →
- Translocation of organic solutes in the phloemMain organic solute translocated in the phloem, two properties of translocation that the specification requires and how a lack of oxygen affects translocation.Open →
- Xerophytes and hydrophytesAdvantage of a thickened cuticle in a xerophyte, how sunken stomata reduce the rate of water loss and succulent tissue.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Explain why a hydrophyte typically has a very thin cuticle and little supporting tissue.
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Why does the epidermis of a young root lack a thick waxy cuticle?
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State the two functions of xylem tissue.
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State the function of phloem tissue.
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Describe the structure of a root hair.
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Define the apoplast pathway.
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Which structure is the main route by which water vapour leaves a leaf?
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Define translocation.
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What is the cortex of a root?
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Describe how a xylem vessel is formed from a column of cells.
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What is a sieve plate?
Process
By which process does water enter a root hair cell?
Key term
Define the symplast pathway.
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Name the minor alternative route by which water is lost from a leaf.
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What is the transpiration stream?
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Name the main organic solute translocated in the phloem.
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Define a xerophyte.
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Where is the endodermis found in a root?
Evaluation
Why is it an advantage that mature xylem vessels contain no cytoplasm?
Key term
Which organelle is absent from a mature sieve-tube element?
Key term
Compare the water potential of the soil solution with that inside a root hair cell.
Key term
Why is the apoplast pathway generally the faster of the two routes?
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Why does the cuticle account for only a small share of the water lost?
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Define cohesion as it applies to water in the xylem.
Key term
Name one organic solute other than sugar that is carried in the phloem.
Key term
Define a hydrophyte.
Take Transport in Plants further
The same content, four other ways.
Questions from this topic
Each one with the model answer underneath.
- 1
Describe the epidermis of a young root.
Model answer
It is the single outer layer of cells covering the root, and many of its cells are drawn out into root hairs.
- 2
Why does the epidermis of a young root lack a thick waxy cuticle?
Model answer
A waterproof cuticle would prevent the absorption of water and mineral ions from the soil solution.
- 3
What is the cortex of a root?
Model answer
The cortex is the layer of unspecialised packing cells lying between the epidermis and the endodermis.
- 4
Where is the endodermis found in a root?
Model answer
The endodermis is the innermost layer of the cortex, forming a continuous single-cell sheath around the vascular tissue.
- 5
Name the band of waterproof material in the walls of endodermal cells.
Model answer
It is the Casparian strip, made of suberin.
- 6
Which walls of an endodermal cell carry the Casparian strip?
Model answer
It runs around the radial and transverse walls of each endodermal cell, forming a continuous band around the layer.
What is inside Levo
Six ways to work the same material.
Transport in Plants revision questions
- What does Transport in Plants cover in CCEA A-Level Biology?
- 9 subtopics: epidermis, endodermis and the tissues of the root, xylem vessels and their lignification patterns, phloem: sieve-tube elements and companion cells, water and mineral ion uptake by root hairs, the apoplast and symplast pathways, transpiration and the factors affecting its rate, cohesion-tension theory and the transpiration stream, translocation of organic solutes in the phloem and xerophytes and hydrophytes. Each one has its own page with questions and model answers.
- How is Transport in Plants organised?
- By the CCEA 1010 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Transport in Plants, 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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