Key term
Eduqas A-Level Biology A400QS
Biological Molecules
Cell Structure and Organisation
Cell Membranes and Transport
Enzymes
Nucleic Acids and Their Functions
Importance of ATP
Photosynthesis
Respiration
Microbiology
Population Size and Ecosystems
Topic overviewPopulation growth and its measurementThe population growth curve and carrying capacityDensity dependent and density independent factorsSampling abundance and distributionEcosystems, habitats and communitiesEnergy transfer and pyramids of biomassSuccessionDecomposition and the carbon cycleThe nitrogen cycle and human interventionEutrophication and the effects of drainage
Human Impact on the Environment
Classification and Biodiversity
Topic overviewThe need for classification and the taxonomic hierarchyThe three domain and five kingdom systemsCharacteristic features of the five kingdomsAssessing relatedness by physical features and biochemistryThe species concept and the binomial systemBiodiversity, adaptation and natural selectionMeasuring biodiversity in a habitatGenetic and molecular measures of biodiversity
Mitosis and Meiosis
Sexual Reproduction in Humans
Sexual Reproduction in Plants
Inheritance
Variation and Evolution
Application of Reproduction and Genetics
Topic overviewThe Human Genome Project, other sequenced genomes and genomics in healthcareScreening embryos, stem cells and the ethical issuesGenetic fingerprinting, PCR and electrophoresis in forensic workRecombinant DNA and the production of human insulinGenetically modified crops and gene therapy
Adaptations for Gas Exchange
Topic overviewSurface area to volume ratio and gas exchange in small organismsSpecialised respiratory surfaces and the need for ventilationGills and counter current flow in bony fishThe human breathing system and its histologyVentilation and gas exchange in humansThe insect tracheal systemThe angiosperm leaf, stomata and gas exchange
Adaptations for Transport
Topic overviewVascular systems compared across animal groupsThe mammalian heart and blood vesselsThe cardiac cycle and its controlBlood, haemoglobin and dissociation curvesThe Bohr effect, chloride shift and tissue fluidThe root and the uptake of waterThe endodermis and the entry to the xylemXylem, transpiration and cohesion-tensionThe potometer and xerophytes and hydrophytesPhloem and translocation
Adaptations for Nutrition
Homeostasis and the Kidney
The Nervous System
Immunology and Disease: Disease and Its TransmissionImmunology
Immunology and Disease: AntibioticsImmunology
Immunology and Disease: The Immune ResponseImmunology
Human Musculoskeletal Anatomy: Skeletal TissuesMusculoskeletal
Topic overviewCartilage and its three typesThe composition and functions of compact boneBone remodelling and the Haversian systemRickets, osteomalacia, osteoporosis and brittle bone diseaseThe structure of skeletal muscleThe sliding filament theoryFast and slow twitch fibres, and energy for contraction
Human Musculoskeletal Anatomy: Structure and Function of the SkeletonMusculoskeletal
Human Musculoskeletal Anatomy: JointsMusculoskeletal
Neurobiology and Behaviour: The BrainNeurobiology
Neurobiology and Behaviour: NeuroscienceNeurobiology
Cell Membranes and Transport
The fluid-mosaic model
- 3 things to know
- Component 1
Overview
Recall questions on the phospholipid bilayer and why it forms, what fluid and mosaic each describe, intrinsic and extrinsic proteins, cholesterol and glycoproteins, which molecules cross the bilayer directly, and why the membrane is only partially permeable.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
Why do phospholipids form a bilayer in water?
Key term
What does the word fluid describe in the fluid-mosaic model?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Name the principal components of a plasma membrane.
Model answer
A phospholipid bilayer, proteins, cholesterol, glycoproteins and glycolipids.
- 2
Why do phospholipids form a bilayer in water?
Model answer
Each has a hydrophilic phosphate head and two hydrophobic fatty acid tails, so the heads face the water on each side and the tails face inwards away from it.
- 3
What does the word fluid describe in the fluid-mosaic model?
Model answer
The phospholipids and many of the proteins move laterally within the layer, so the membrane is not a fixed structure.
- 4
What does the word mosaic describe?
Model answer
The proteins are scattered through the bilayer in an irregular pattern, like the tiles of a mosaic.
- 5
Distinguish an intrinsic from an extrinsic membrane protein.
Model answer
An intrinsic protein spans the bilayer, while an extrinsic protein sits on one surface of it.
- 6
Give two functions of intrinsic proteins.
Model answer
They form channels and carriers for substances that cannot cross the bilayer, and they act as pumps in active transport.
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