Biology_A-level_Aqa
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1-biological-molecules
1-1-biological-molecules-carbohydrates11 主题-
1-1-1-biological-molecules-key-terms
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1-1-2-biological-molecules-reactions
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1-1-3-monosaccharides
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1-1-4-glucose
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1-1-5-the-glycosidic-bond
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1-1-6-chromatography-monosaccharides
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1-1-7-disaccharides
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1-1-8-starch-and-glycogen
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1-1-9-cellulose
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1-1-10-biochemical-tests-sugars-and-starch
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1-1-11-finding-the-concentration-of-glucose
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1-1-1-biological-molecules-key-terms
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1-2-biological-molecules-lipids3 主题
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1-3-biological-molecules-proteins5 主题
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1-4-proteins-enzymes12 主题
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1-4-1-many-proteins-are-enzymes
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1-4-2-enzyme-specificity
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1-4-3-how-enzymes-work
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1-4-4-required-practical-measuring-enzyme-activity
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1-4-5-drawing-a-graph-for-enzyme-rate-experiments
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1-4-6-using-a-tangent-to-find-initial-rate-of-reaction
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1-4-7-limiting-factors-affecting-enzymes-temperature
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1-4-8-limiting-factors-affecting-enzymes-ph
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1-4-10-limiting-factors-affecting-enzymes-enzyme-concentration
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1-4-11-limiting-factors-affecting-enzymes-substrate-concentration
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1-4-12-limiting-factors-affecting-enzymes-inhibitors
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1-4-14-control-of-variables-and-uncertainty
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1-4-1-many-proteins-are-enzymes
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1-5-nucleic-acids-structure-and-dna-replication8 主题
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1-5-2-nucleotide-structure-and-the-phosphodiester-bond
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1-5-3-dna-structure-and-function
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1-5-4-rna-structure-and-function
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1-5-5-ribosomes
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1-5-6-the-origins-of-research-on-the-genetic-code
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1-5-8-the-process-of-semi-conservative-replication
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1-5-9-calculating-the-frequency-of-nucleotide-bases
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1-5-10-the-watson-crick-model
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1-5-2-nucleotide-structure-and-the-phosphodiester-bond
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1-6-atp-water-and-inorganic-ions4 主题
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2-cell-structure2-1-cell-structure7 主题
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2-2-the-microscope-in-cell-studies4 主题
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2-3-cell-division-in-eukaryotic-and-prokaryotic-cells8 主题
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2-4-cell-membranes-and-transport7 主题
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2-5-cell-recognition-and-the-immune-system7 主题
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2-6-vaccines-disease-and-monoclonal-antibodies6 主题
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3-exchange-and-transport3-1-adaptations-for-gas-exchange6 主题
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3-2-human-gas-exchange10 主题
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3-2-1-the-human-gas-exchange-system
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3-2-2-dissecting-the-gas-exchange-system
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3-2-3-microscopy-and-gas-exchange-surfaces
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3-2-4-investigating-gas-exchange
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3-2-5-the-alveolar-epithelium
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3-2-6-ventilation-and-gas-exchange
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3-2-8-the-effects-of-lung-disease
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3-2-9-pollution-and-smoking-data
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3-2-10-risk-factor-data
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3-2-11-correlations-and-causal-relationships
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3-2-1-the-human-gas-exchange-system
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3-3-digestion-and-absorption5 主题
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3-4-mass-transport-in-animals6 主题
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3-5-the-circulatory-system-in-animals8 主题
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3-6-mass-transport-in-plants6 主题
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4-genetics-variation-and-interdependence4-1-dna-genes-and-chromosomes7 主题
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4-2-dna-and-protein-synthesis6 主题
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4-3-genetic-diversity-mutations-and-meiosis7 主题
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4-4-genetic-diversity-and-adaptation6 主题
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4-5-species-and-taxonomy4 主题
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4-6-biodiversity9 主题
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5-energy-transfers-in-and-between-organisms-a-level-only5-1-photosynthesis-a-level-only5 主题
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5-2-respiration-a-level-only7 主题
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5-3-energy-and-ecosystems-a-level-only9 主题
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5-4-nutrient-cycles-a-level-only4 主题
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6-organisms-respond-to-changes-in-their-environments-a-level-only6-1-response-to-stimuli-a-level-only12 主题
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6-1-1-survival-and-response
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6-1-2-growth-factors-in-flowering-plants
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6-1-3-indoleacetic-acid-iaa
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6-1-4-taxes-and-kinesis
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6-1-5-reflex-arcs
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6-1-6-required-practical-investigating-animal-movement
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6-1-7-the-pacinian-corpuscle
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6-1-8-pacinian-corpuscles-generator-potential
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6-1-9-investigating-touch-and-temperature-receptors
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6-1-10-the-human-retina
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6-1-11-myogenic-stimulation-of-the-heart
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6-1-13-heart-rate
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6-1-1-survival-and-response
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6-2-nervous-coordination-a-level-only10 主题
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6-3-skeletal-muscles-a-level-only6 主题
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6-4-homeostasis-a-level-only11 主题
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6-4-1-principles-of-homeostasis
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6-4-2-negative-feedback
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6-4-3-glucose-concentration-and-insulin
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6-4-4-glucose-regulation-glucagon
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6-4-5-glucose-regulation-adrenaline
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6-4-6-glucose-regulation-the-liver
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6-4-7-diabetes
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6-4-8-required-practical-determining-the-concentration-of-glucose-in-urine
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6-4-9-nephron-structure
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6-4-10-nephron-function
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6-4-11-control-of-blood-water-potential
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6-4-1-principles-of-homeostasis
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7-genetics-populations-evolution-and-ecosystems-a-level-only7-1-inheritance-a-level-only6 主题
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7-2-populations-a-level-only3 主题
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7-3-evolution-a-level-only5 主题
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7-4-populations-in-ecosystems-a-level-only7 主题
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8-the-control-of-gene-expression-a-level-only8-1-genetic-mutations-a-level-only2 主题
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8-2-regulation-of-gene-expression-a-level-only11 主题
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8-2-1-totipotent-cells
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8-2-2-stem-cells
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8-2-3-the-use-of-stem-cells
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8-2-4-producing-tissue-cultures-of-explants
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8-2-5-regulation-of-transcription
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8-2-6-evaluating-data-about-genetic-expression
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8-2-7-epigenetics
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8-2-8-epigenetics-and-disease
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8-2-9-rna-interference
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8-2-10-two-types-of-tumours
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8-2-11-tumour-development
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8-2-1-totipotent-cells
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8-3-using-genome-projects-a-level-only4 主题
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8-4-gene-technologies-a-level-only13 主题
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8-4-1-recombinant-dna-technology
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8-4-2-producing-fragments-of-dna
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8-4-3-investigating-the-specificity-of-restriction-enzymes
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8-4-4-polymerase-chain-reaction
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8-4-5-culture-of-transformed-host-cells
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8-4-6-uses-of-recombinant-dna-technology
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8-4-7-dna-probes-and-dna-hybridisation
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8-4-8-screening-patients
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8-4-9-genetic-counselling-and-personalised-medicine
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8-4-10-variable-number-tandem-repeats
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8-4-11-gel-electrophoresis
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8-4-12-genetic-fingerprinting
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8-4-13-uses-of-genetic-fingerprinting
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8-4-1-recombinant-dna-technology
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exam-guidance-and-skillsessay-guidance3 主题
1-4-11-limiting-factors-affecting-enzymes-substrate-concentration
The effect of substrate concentration
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The greater the substrate concentration, the higher the rate of reaction:
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As the number of substrate molecules increases, the likelihood of enzyme-substrate complex formation increases
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If the enzyme concentration remains fixed but the amount of substrate is increased past a certain point, however, all available active sites eventually become saturated, and any further increase in substrate concentration will not increase the reaction rate
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When the active sites of the enzymes are all full, any substrate molecules that are added have nowhere to bind to form an enzyme-substrate complex
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In the graph below, there is a linear increase in reaction rate as substrate is added, which then plateaus when all active sites become occupied

Examiner Tips and Tricks
As substrate concentration increases with constant enzyme concentration, a point is reached where all active sites are occupied. The enzyme is then working at its maximum rate, called Vmax (maximum velocity), and substrate molecules must wait for active sites to become available.