Key term
WJEC AS-Level Biology 601-5290-0
Chemical Elements Are Joined Together to Form Biological Compounds
Topic overviewInorganic IonsBiological Importance of WaterCarbohydrates: Monosaccharides and DisaccharidesCarbohydrates: Polysaccharides and Alpha/Beta Glucose IsomerismLipids: Triglycerides and PhospholipidsLipids: Saturated and Unsaturated Fat in Human HealthAmino Acids and Proteins: Primary to Quaternary StructureAmino Acids and Proteins: Fibrous and Globular FormsCondensation and Hydrolysis: Peptide and GlycosidicFood Tests for Biological Molecules
Cell Structure and Organisation
Topic overviewEukaryotic Cell Ultrastructure: OrganellesEukaryotic Cell Ultrastructure: FunctionsProkaryotic Cells, Viruses and Cell Theory: Comparing Cell StructuresProkaryotic Cells, Viruses and Cell Theory: Electron MicrographsLevels of Organisation and Light Microscopy: Tissues and OrgansLevels of Organisation and Light Microscopy: Organ Systems and Microscope CalibrationLevels of Organisation and Light Microscopy: Magnification and Scientific Drawing
Cell Membranes and Transport
Topic overviewPlasma Membrane Structure and Permeability: Fluid-Mosaic ModelPlasma Membrane Structure and Permeability: Factors Affecting PermeabilityTransport Across Membranes: Diffusion, Osmosis and Water PotentialTransport Across Membranes: Facilitated Diffusion, Active Transport and PinocytosisTransport Across Membranes: Phagocytosis and Exocytosis
Biological Reactions Are Regulated by Enzymes
Topic overviewEnzymes as Biological Catalysts: Metabolism, Extracellular Action and Induced FitEnzymes as Biological Catalysts: Activation EnergyFactors Affecting Enzyme Activity: Temperature and SubstrateFactors Affecting Enzyme Activity: Enzyme Concentration, Denaturation and BuffersEnzyme InhibitionImmobilised Enzymes in Industry
Nucleic Acids and Their Functions
Topic overviewNucleotides, Chemical Energy and ATP: StructureNucleotides, Chemical Energy and ATP: Role as Energy CarrierDNA and RNA StructureSemi-conservative Replication, Meselson and Stahl experimentThe Genetic Code: Triplet CodeThe Genetic Code: Exons and IntronsProtein Synthesis: Transcription, Translation and tRNAProtein Synthesis: One Gene-One Polypeptide and Polypeptide Modification
Genetic Information Is Copied and Passed on to Daughter Cells
Topic overviewThe Cell Cycle and Mitosis: Interphase and StagesThe Cell Cycle and Mitosis: Cytokinesis, Significance in Renewal and RepairThe Cell Cycle and Mitosis: Root Tip Squash and Mitotic IndexMeiosis: Meiosis I and Meiosis II, crossing over and independent assortmentMeiosis: differences from mitosis
All Organisms Are Related Through Their Evolutionary History
Topic overviewClassification: Hierarchical Groups, Need and Tentative NatureClassification: Three Domains and Five KingdomsAssessing RelatednessSpecies Concept and Binomial SystemBiodiversity and Its Assessment: Habitat LevelBiodiversity and Its Assessment: Genetic Level and Molecular LevelNatural Selection as the Source of Biodiversity and Anatomical, Physiological and Behavioural Adaptations
Adaptations for Gas Exchange
Topic overviewSurface Area to Volume Ratio and Gas Exchange in Small Organisms: AmoebaSurface Area to Volume Ratio and Gas Exchange in Small Organisms: Flatworm and EarthwormSpecialised Respiratory Surfaces and Ventilation in Bony Fish: Counter-currentSpecialised Respiratory Surfaces and Ventilation in Bony Fish: Parallel FlowGas Exchange in Terrestrial Animals: Human Breathing SystemGas Exchange in Terrestrial Animals: VentilationGas Exchange in Terrestrial Animals: the Insect Tracheal SystemThe Angiosperm Leaf: StructureThe Angiosperm Leaf: Photosynthetic RoleThe Angiosperm Leaf: Stomatal Control of Gas Exchange
Adaptations for Transport
Topic overviewVascular Systems Across Animal Groups: Earthworm and InsectVascular Systems Across Animal Groups: Fish and MammalThe Mammalian Heart and Circulation: Blood Vessels and Cardiac CycleThe Mammalian Heart and Circulation: Sino-atrial Node, Purkyne Fibres and ElectrocardiogramsBlood and the Transport of Respiratory Gases: Erythrocytes, Plasma and Dissociation CurvesBlood and the Transport of Respiratory Gases: Bohr Effect and Chloride ShiftTransport of Nutrients, Hormones, Excretory Products and HeatTissue Fluid, Lymph and OedemaWater Uptake and Movement Through the Root: Dicotyledon Root Structure and ApoplastWater Uptake and Movement Through the Root: Symplast, Vacuolar Pathways and EndodermisXylem, the Transpiration Stream and Plant Water Adaptations: Cohesion-Tension TheoryXylem, the Transpiration Stream and Plant Water Adaptations: Hydrophytes and XerophytesPhloem Structure and Translocation from Source to Sink: Mass Flow ModelsPhloem Structure and Translocation from Source to Sink: Experimental Evidence
Adaptations for Nutrition
Topic overviewModes of Nutrition: Autotrophic, Heterotrophic and HolozoicModes of Nutrition: Parasitic, and Digestion in Amoeba and Hydra to Tube GutsThe Human Gut: Adaptations to an Omnivorous DietThe Human Gut: EnzymesThe Human Gut: ConditionsHerbivore, Carnivore and Parasite Adaptations: Guts and DentitionHerbivore, Carnivore and Parasite Adaptations: Ruminants, Taenia and Pediculus
Working Scientifically: Practical Skills
Topic overviewThe A2 Unit 5 Practical Examination Tasks: Experimental TaskThe A2 Unit 5 Practical Examination Tasks: Practical Analysis TaskIndependent Thinking and Use of Scientific Methods and Practices: Solving Problems in Practical ContextsIndependent Thinking and Use of Scientific Methods and Practices: Identifying and Following InstructionsIndependent Thinking and Use of Scientific Methods and Practices: Making and Keeping RecordsIndependent Thinking and Use of Scientific Methods and Practices: Presenting DataNumeracy in Practical Contexts, Research and Referencing: Plotting, Interpreting Graphs and ProcessingNumeracy in Practical Contexts, Research and Referencing: Analysing Data, Margins of Error and AccuracyNumeracy in Practical Contexts, Research and Referencing: Precision and OnlineNumeracy in Practical Contexts, Research and Referencing: Offline Research Skills
Use of Apparatus and Techniques
Topic overviewMeasurement and Laboratory Technique: Quantitative ApparatusMeasurement and Laboratory Technique: InstrumentationMeasurement and Laboratory Technique: Glassware Including Serial DilutionsMicroscopy, Scientific Drawing and Separation and Identification Techniques: Light MicroscopeMicroscopy, Scientific Drawing and Separation and Identification Techniques: Annotated Drawings and Food TestsMicroscopy, Scientific Drawing and Separation and Identification Techniques: ChromatographyWorking with Organisms and Aseptic TechniqueViable Counts, Dissection and Fieldwork SamplingMark-Release-Recapture, Quadrats and ICT for Data Collection
Mathematical Requirements (Appendix C)
Topic overviewArithmetic and Numerical Computation: Appropriate Units, Decimal and Standard FormArithmetic and Numerical Computation: Ratios, Percentages and Estimating ResultsArithmetic and Numerical Computation: Power, Exponential and Logarithmic FunctionsHandling Data: Significant Figures, Arithmetic Means and MeanHandling Data: Median, Frequency Tables and HistogramsHandling Data: Scatter DiagramsProbability, Sampling, Statistical Tests and Uncertainty: Simple Probability and SelectingProbability, Sampling, Statistical Tests and Uncertainty: Using the Chi-squared TestProbability, Sampling, Statistical Tests and Uncertainty: Correlation CoefficientProbability, Sampling, Statistical Tests and Uncertainty: Standard DeviationAlgebra and Magnification: Mathematical Symbols and Changing the Subject of an EquationAlgebra and Magnification: Substituting Values, Solving Equations and Using LogarithmsGraphs: Translating Between Graphical, Plotting Two Variables and Linear RelationshipsGraphs: Intercepts, Rate of Change and Slope of a Tangent to a CurveGeometry: Circumferences, Surface Areas and Volumes of Regular Shapes
How Science Works (Appendix D)
Topic overviewDeveloping and Communicating Scientific Explanations: Using Theories, Models and IdeasDeveloping and Communicating Scientific Explanations: Posing Scientific QuestionsScientific Methodology, Evidence and Evaluation: Appropriate Methodology Including ICTScientific Methodology, Evidence and Evaluation: Analysing and Conflicting DataScience, Society and Ethics: How Scientific Knowledge Develops Over TimeScience, Society and Ethics: Risks, Ethical Treatment of Humans and Other OrganismsScience, Society and Ethics: Environment and How Society Uses Science
Adaptations for Gas Exchange
- 10 subtopics
- 29 things to know
- AS Unit 2
What Adaptations for Gas Exchange covers
Adaptations for Gas Exchange is examined on AS Unit 2 of WJEC Biology, Biodiversity and Physiology of Body Systems. 105 recall questions across 10 subtopics.
Where it is assessed
AS Unit 2
Biodiversity and Physiology of Body Systems.
Check the WJEC specification ↗The 10 subtopics
Each one has its own page. WJEC AS Biology students sit this topic in the first year.
- Surface Area to Volume Ratio and Gas Exchange in Small Organisms: AmoebaRecall questions on Amoeba.Open →
- Surface Area to Volume Ratio and Gas Exchange in Small Organisms: Flatworm and EarthwormRecall questions on Flatworm and Earthworm.Open →
- Specialised Respiratory Surfaces and Ventilation in Bony Fish: Counter-currentRecall questions on Counter-current.Open →
- Specialised Respiratory Surfaces and Ventilation in Bony Fish: Parallel FlowRecall questions on Parallel Flow.Open →
- Gas Exchange in Terrestrial Animals: Human Breathing SystemRecall questions on Human Breathing System.Open →
- Gas Exchange in Terrestrial Animals: VentilationRecall questions on Ventilation.Open →
- Gas Exchange in Terrestrial Animals: the Insect Tracheal SystemHow concentration gradients are kept up at the alveoli, then the insect tracheal system: spiracles and water loss, tracheae and tracheoles, the fluid at the tracheole ends, and how active insects ventilate.Open →
- The Angiosperm Leaf: StructureRecall questions on Structure.Open →
- The Angiosperm Leaf: Photosynthetic RoleRecall questions on Photosynthetic Role.Open →
- The Angiosperm Leaf: Stomatal Control of Gas ExchangeRecall questions on Stomatal Control of Gas Exchange.Open →
What you need to know
Answer each one before you reveal it.
Your recallNot started
Process
Compare the walls of the trachea, a bronchiole and an alveolus.
Evaluation
What conflict does a plant face in keeping its stomata open?
Key term
What would happen to a flatworm's ability to exchange gases if its body kept the same volume but became cylindrical?
Key term
Across which surface does an earthworm exchange gases?
Key term
Why must the pressure in the buccal cavity remain higher than that in the opercular cavity?
Key term
Why do the gills appear bright red?
Key term
Which muscles are used during forced expiration?
Key term
What maintains the concentration gradients across the alveolar wall?
Key term
Why are the tracheae of an insect strengthened by spiral bands of chitin?
Key term
Name the two transport tissues in a leaf vein and state what each carries.
Key term
What happens to the surface area to volume ratio of an organism as it becomes larger?
Numbers
A cube has sides of 1 cm. Calculate its surface area to volume ratio.
Key term
Why must a respiratory surface be moist?
Key term
Why is the trachea supported by rings of cartilage?
Key term
Why is the diffusion distance between alveolar air and the blood so short?
Key term
Why must the walls of the mesophyll cells be moist?
Key term
Give two ways in which a guard cell differs from an ordinary epidermal cell.
Key term
Give three precautions needed to make a comparison of stomatal density between two species valid.
Key term
Why must several fields of view be counted and a mean taken?
Key term
Besides a falling surface area to volume ratio, what other problem does increasing size cause for gas exchange?
Key term
Why does an earthworm have a smaller surface area to volume ratio than a flatworm of similar mass?
Key term
Compare the oxygen content of air and of water.
Process
Why does a fish need a ventilation mechanism at all?
Key term
Why are the cartilage rings of the trachea incomplete at the back?
Key term
Which muscles contract during inspiration?
Key term
How does the insect tracheal system differ in principle from a mammalian lung?
Key term
Which ions move, and in which direction, when a stoma begins to open?
Key term
Name the tissues that should be labelled on a low-power plan of a leaf section, working from the top downwards
Take Adaptations for Gas Exchange further
The same content, four other ways.
Questions from this topic
Each one with the model answer underneath.
- 1
What happens to the surface area to volume ratio of an organism as it becomes larger?
Model answer
The ratio falls, because volume increases more rapidly than surface area.
- 2
A cube has sides of 1 cm. Calculate its surface area to volume ratio.
Model answer
The surface area is 6 cm² and the volume is 1 cm³, so the ratio is 6:1.
- 3
Calculate the ratio for a cube of side 3 cm and compare it with that of a cube of side 1 cm.
Model answer
The surface area is 54 cm² and the volume 27 cm³, giving a ratio of 2:1, which is one third of the ratio of the smaller cube.
- 4
Why does a falling surface area to volume ratio create a problem for gas exchange?
Model answer
There is less body surface available to supply each unit of tissue with oxygen and to carry away its carbon dioxide.
- 5
Besides the ratio itself, what other problem does increasing size cause?
Model answer
The distance from the surface to the innermost cells becomes too great for diffusion alone to supply them quickly enough.
- 6
What relationship links the rate of diffusion to surface area, concentration difference and thickness?
Model answer
The rate of diffusion is proportional to the surface area multiplied by the difference in concentration and divided by the thickness of the exchange surface.
What is inside Levo
Six ways to work the same material.
Adaptations for Gas Exchange revision questions
- Is Adaptations for Gas Exchange examined at AS in WJEC Biology?
- Yes. It sits in AS Unit 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 Adaptations for Gas Exchange cover in WJEC AS-Level Biology?
- 10 subtopics: surface area to volume ratio and gas exchange in small organisms: amoeba, surface area to volume ratio and gas exchange in small organisms: flatworm and earthworm, specialised respiratory surfaces and ventilation in bony fish: counter-current, specialised respiratory surfaces and ventilation in bony fish: parallel flow, gas exchange in terrestrial animals: human breathing system, gas exchange in terrestrial animals: ventilation, gas exchange in terrestrial animals: the insect tracheal system, the angiosperm leaf: structure, the angiosperm leaf: photosynthetic role and the angiosperm leaf: stomatal control of gas exchange. Each one has its own page with questions and model answers.
- How is Adaptations for Gas Exchange organised?
- By the WJEC 601-5290-0 specification, subtopic by subtopic, so it matches the order you are taught it in.
Every question in Adaptations for Gas Exchange, 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.
Or £46 a year, about £3.83 a month. Cancel anytime.