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
5-3-8-calculating-productivity-and-efficiency
Calculating productivity and efficiency of energy transfer
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It is possible to calculate the:
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net productivity of producers or consumers
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efficiency of energy transfers within ecosystems
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Calculating net productivity
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While it is important to understand the distinction between net production and net productivity, it is possible to use the equations for production in calculations involving productivity
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The difference is that productivity is a rate, so will include time in the units
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Net productivity of producers can therefore be calculated using the formula for net primary production:
NPP = GPP – R
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Where:
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NPP = net primary production, or productivity
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GPP = gross primary production, or productivity
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R = respiratory losses
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Worked Example
The wheat crop growing in a farmer’s field has a gross primary productivity of 10 000 kJ m-2 yr-1. The wheat crop loses 5500 kJ m-2 yr-1 as heat from respiration.
Calculate the net primary productivity of the wheat crop.
Answer:
Step 1: write out the equation and substitute in the known values
NPP = GPP – R
NPP = 10 000 – 5500
Step 2: calculate the net primary productivity and give appropriate units
NPP = 4500 kJ m-2 yr-1
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The net productivity of consumers can be calculated using the equation for net production of consumers:
N = I – (F + R)
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Where:
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I = the chemical energy store in ingested food
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F = the chemical energy lost to the environment in faeces and urine
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R = the respiratory losses to the environment
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Worked Example
In a grassland ecosystem the net productivity of rabbits is 2400 kJ m-2 yr-1. These rabbits ingest 18 900 kJ m-2 of grass per year.
Calculate the total energy loss of the rabbits.
Step 1: rearrange the equation to find the total energy loss (F + R)
N = I – (F + R)
(F + R) = I – N
Step 2: substitute in the known values
(F + R) = I – N
(F + R) = 18 900 – 2400
Step 3: calculate the total energy loss and give appropriate units
total energy loss = 16 500 kJ m-2 yr-1
Calculating efficiency of energy transfer
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The efficiency of energy transfer is the percentage of energy that is transferred between trophic levels
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Transfer efficiency can be calculated as follows:
% efficiency = 
x 100
Worked Example
The total solar energy received by an area of heather is 6 × 105 kJ m-2 yr-1. The gross primary productivity of the heather is 4.25 × 103 kJ m-2 yr-1.
Calculate the percentage of solar energy converted into chemical energy by photosynthesis.
Step 1: write out the equation and substitute in the known values
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