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
Nucleic Acids and Their Functions
Extracting DNA from living material
- 3 things to know
- Component 1
Overview
Recall questions on breaking up the tissue, why detergent and salt are added, the brief warming and rapid cooling, filtering, the ice-cold ethanol layered on top, why the DNA precipitates at the boundary, and why the product is not pure.
What you need to know
Answer each one before you reveal it.
Your recallNot started
Key term
When DNA is extracted, why is the mixture sometimes warmed to about 60 degrees Celsius?
Key term
In DNA extraction, why must the warmed mixture then be cooled quickly in ice?
Questions from this subtopic
Each one with the model answer underneath.
- 1
Why is a plant material such as onion or kiwi fruit used for a simple DNA extraction?
Model answer
It is cheap, easy to break up, and its cells yield a large quantity of DNA without specialist equipment.
- 2
What is the first step in extracting DNA from living material?
Model answer
Breaking up the tissue, by chopping or blending, to separate the cells from each other.
- 3
Why is detergent added to the mixture?
Model answer
It breaks down the phospholipid membranes of the cell and the nucleus, releasing the DNA into solution.
- 4
Why is salt added?
Model answer
The sodium ions neutralise the negative charge on the phosphate groups of the DNA, so the strands clump together instead of repelling one another.
- 5
Why is the mixture sometimes warmed to about 60 degrees Celsius?
Model answer
Warming helps the detergent break down the membranes and inactivates enzymes that would otherwise digest the DNA.
- 6
Why must the mixture then be cooled quickly in ice?
Model answer
Prolonged warming would begin to break the DNA itself, so the temperature is dropped once the membranes have been disrupted.
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