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
5-4-3-microorganisms-and-recycling-minerals
The role of microorganisms in mineral cycling
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Microorganisms play a vital role in recycling chemical elements, such as phosphorus and nitrogen, in ecosystems; examples include:
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saprobionts in decomposition
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mycorrhizae in plant roots
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Saprobionts
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Saprobionts are:
organisms that decompose dead and waste organic matter
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Examples include fungi and bacteria
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Decomposition by saprobionts releases chemical elements, such as phosphorus and nitrogen, from within dead and waste material
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The process of decomposition by saprobionts is as follows:
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enzymes are secreted onto a food source
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extracellular digestion occurs
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nutrients are absorbed
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Importantly, not all of the products of extracellular digestion are absorbed by saprobionts; some mineral ions remain in the soil where they can be absorbed by plants
Examiner Tips and Tricks
When answering questions about saprobionts, it is not enough to describe their role as ‘decomposition’; you need to say that they release mineral ions, such as nitrates and phosphates.
Mycorrhizae
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Mycorrhizae are:
symbiotic relationships between fungi and the roots of plants
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Fungi form long, thin filaments known as hyphae, which connect with plant roots
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The hyphae effectively increase the surface area of the root systems of the plants, increasing absorption of water and inorganic ions
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In return the fungi receive carbon compounds, e.g. glucose, from the plant
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Microorganisms |
Role in mineral cycling |
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Saprobionts |
Decompose dead and waste matter via extracellular digestion, making inorganic ions available to other organisms |
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Nitrogen-fixing bacteria |
Convert atmospheric nitrogen gas into nitrogen-containing compounds, such as ammonia |
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Nitrifying bacteria |
Convert ammonium ions in soil into nitrates |
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Denitrifying bacteria |
Use nitrates during respiration, releasing nitrogen gas in the process |
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Mycorrhizal fungi |
Increase surface area of root systems, helping plants to absorb water and mineral ions from soil |