Biology AS AQA
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1-1-biological-molecules-carbohydrates11 主题
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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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2-1-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-transport9 主题
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2-4-1-the-structure-of-cell-membranes
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2-4-3-the-cell-surface-membrane
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2-4-4-diffusion
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2-4-5-osmosis
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2-4-7-osmosis-in-animal-cells
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2-4-9-required-practical-investigating-water-potential
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2-4-10-active-transport-and-co-transport
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2-4-11-adaptations-for-rapid-transport
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2-4-13-required-practical-factors-affecting-membrane-permeability
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2-4-1-the-structure-of-cell-membranes
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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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3-1-adaptations-for-gas-exchange6 主题
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3-2-human-gas-exchange14 主题
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3-2-5-the-alveolar-epithelium
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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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3-5-5-investigating-heart-rate
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3-5-6-blood-vessels
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3-5-7-capillaries-and-tissue-fluid
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3-5-8-cardiovascular-disease-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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3-2-6-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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3-2-5-the-alveolar-epithelium
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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-animals4 主题
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3-6-mass-transport-in-plants6 主题
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4-1-dna-genes-and-chromosomes10 主题
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4-2-dna-and-protein-synthesis3 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
3-5-2-the-human-heart
Exam code:7401
Mammalian heart structure
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The human heart is divided into four chambers
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The two top chambers are the left and right atria (singular atrium)
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The bottom two chambers are the left and right ventricles
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The left and right sides of the heart are separated by a wall of muscular tissue called the septum that ensures that blood from the left and right sides of the heart doesn’t mix
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The left side of the heart contains oxygenated blood
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The right side of the heart contains deoxygenated blood
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The heart contains valves to ensure that blood flows forward in the right direction
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The right atrium and ventricle are separated by the right atrioventricular valve, also known as the tricuspid valve
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The left atrium and ventricle are separated by the left atrioventricular valve, also known as the bicuspid valve
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The right ventricle and pulmonary artery are separated by right semilunar valve, or the pulmonary valve
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The left ventricle and aorta are separated by left semilunar valve, or the aortic valve
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Two blood vessels bring blood to the heart
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The vena cava brings blood from the body
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The pulmonary vein brings blood from the lungs
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Two blood vessels take blood away from the hear
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The pulmonary artery transports blood to the lungs
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The aorta transports blood to the body
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Examiner Tips and Tricks
When looking at the heart, remember that the right side of the heart will appear on the page as being on the left. This is because the heart is labelled as if it were in your body and facing forward.
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The thickness of the muscle walls in the heart differs depending on the amount of pressure that they need to generate
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The muscular walls of the atria are thinner than those of the ventricles because the atria pump blood over a much shorter distance
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The muscle of the left ventricle is thicker than that of the right ventricle because the blood leaving the right ventricle travels less distance than blood leaving the left ventricle
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Worked Example
The graph below shows pressure changes in different chambers of the heart.
Explain the difference in pressure between the two chambers shown in the graph
[2]
Answer:
The difference in pressure between the two chambers shown in the graph can be explained as follows:
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The muscle wall of the left atrium is thinner than that of the left ventricle so the contraction is weaker OR the muscle wall of the left ventricle is thicker than that of the left atrium so the contraction is stronger; [1 mark]
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The left atrium only needs to pump blood a short distance / from the atrium to the ventricle WHILE the left ventricle needs to pump blood all around the body; [1 mark]
Responses