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
Enzymes
Temperature, pH and buffers
- 3 things to know
- Component 1
Overview
What happens to an enzyme above its optimum temperature, optimum temperature of an enzyme and buffer solution.
What you need to know
Answer each one before you reveal it.
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Key term
Describe an investigation into the effect of temperature on the activity of amylase.
Key term
Describe and explain the effect on the rate of an enzyme reaction of raising the temperature from 0 °C towards the optimum.
Questions from this subtopic
Each one with the model answer underneath.
- 1
Describe and explain the effect on the rate of an enzyme reaction of raising the temperature from 0 °C towards the optimum.
Model answer
The rate rises, because both enzyme and substrate molecules gain kinetic energy and collide more often and with more energy, so more enzyme–substrate complexes form each second.
- 2
What is the temperature coefficient Q₁₀ for a typical enzyme reaction below the optimum?
Model answer
About 2, meaning the rate roughly doubles for each 10 °C rise in temperature.
- 3
Explain what happens to an enzyme above its optimum temperature.
Model answer
The molecule vibrates so strongly that hydrogen and ionic bonds holding the tertiary structure break, the active site loses its shape and the enzyme is denatured.
- 4
Why is denaturation by heat usually permanent?
Model answer
When the chain refolds the bonds re-form in a different arrangement, so the original shape of the active site is not recovered on cooling.
- 5
Define the optimum temperature of an enzyme.
Model answer
The temperature at which the enzyme catalyses its reaction at the greatest rate.
- 6
Why is the optimum temperature of most human enzymes around 40 °C rather than higher?
Model answer
Above that temperature the rate of denaturation rises steeply, so any gain from faster molecular movement is lost as active sites are destroyed.
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