Key term
CCEA AS-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
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. CCEA AS Biology students sit this topic in the first year.
- 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.
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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?
Key term
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
- Is Transport in Plants examined at AS in CCEA Biology?
- Yes. It sits in Unit AS 2, which you take in the first year, so it is on the AS paper as well as counting towards the full A level.
- What does Transport in Plants cover in CCEA AS-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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