Mammals produce ATP by anaerobic and aerobic respiration. The effect of exercise intensity on the lactate concentration in human blood was investigated. - An athlete and a non-athlete performed the same exercise at the same intensity for three minutes. - Their blood lactate concentrations were measured as soon as they finished exercising. - This was repeated for different intensities of exercise. *(ii) The table and graph show some of the results of this investigation. Stroke volume is the volume of blood that leaves each ventricle during ventricular systole. The graph shows the stroke volumes of the athlete and the non-athlete at different heart rates. Explain the results of this investigation. Use the information in the graph and the table and your own knowledge to support your answer. (6) ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................ ................................................................................................................................................................................................................................................................................
Exam No：wbi15-01-que-20240608 Year：2024 Question No：6(a)(ii)
Answer:
Answers will be credited according to candidate's deployment of knowledge and understanding of the material in relation to the qualities and skills outlined in the generic mark scheme.
The indicative content below is not prescriptive and candidates are not required to include all the material indicated as relevant. Additional content included in the response must be scientific and relevant.
- blood lactate increases with increasing intensity of exercise
- stroke volume increases with increasing heart rate
- positive correlation between heart rate and stroke volume for athlete / little change in stroke volume for non-athlete as heart rate increases/ stroke volume always higher in athlete than non-athlete
- non athletes started at a higher lactate concentration than athletes/ converse / athletes lactate always lower in non-athletes
- any use of data from lactate concentration table
- any use of data from stroke volume graph
- blood lactate levels increase because there is anaerobic respiration occurring / insufficient oxygen available for aerobic respiration / oxygen stores used up
- anaerobic respiration produces lactate / lactate converted to pyruvate / glucose \(\rightarrow\) lactic acid + energy / \{anaerobic respiration / lactate\}causes blood pH to drop / less anaerobic respiration gives less lactate
- stroke volume increases more in athlete due to \{(more / stronger) \{heart / cardiac\} muscle present/ greater ventricular contraction force/ increased contraction of cardiac muscle\} /converse
- (increase in stroke volume) supplying more (oxygen / glucose) to respiring cells
- athletes have larger lung capacity \{for oxygen exchange due to training/ more effective gas exchange /to respire aerobically for longer\} / converse.
- endurance athletes have more \{slow twitch muscles /stores of myoglobin / mitochondria\} / sprinters will have more fast twitch muscle fibres / non athlete have \{greater proportion of / less\} fast twitch muscles in their musculature / accept a correct comment about slow / fast muscle fibres
- in non-athletes (because stroke volume doesn't increase) less oxygen being delivered to the respiring muscle cells than in athlete / accept converse
- non athletes develop larger oxygen debt than athletes (because lactate levels are higher)
- drop in blood pH detected by chemoreceptors which start chain of events leading to increase in \{ventilation /breathing / heart\} rate
The indicative content below is not prescriptive and candidates are not required to include all the material indicated as relevant. Additional content included in the response must be scientific and relevant.
- blood lactate increases with increasing intensity of exercise
- stroke volume increases with increasing heart rate
- positive correlation between heart rate and stroke volume for athlete / little change in stroke volume for non-athlete as heart rate increases/ stroke volume always higher in athlete than non-athlete
- non athletes started at a higher lactate concentration than athletes/ converse / athletes lactate always lower in non-athletes
- any use of data from lactate concentration table
- any use of data from stroke volume graph
- blood lactate levels increase because there is anaerobic respiration occurring / insufficient oxygen available for aerobic respiration / oxygen stores used up
- anaerobic respiration produces lactate / lactate converted to pyruvate / glucose \(\rightarrow\) lactic acid + energy / \{anaerobic respiration / lactate\}causes blood pH to drop / less anaerobic respiration gives less lactate
- stroke volume increases more in athlete due to \{(more / stronger) \{heart / cardiac\} muscle present/ greater ventricular contraction force/ increased contraction of cardiac muscle\} /converse
- (increase in stroke volume) supplying more (oxygen / glucose) to respiring cells
- athletes have larger lung capacity \{for oxygen exchange due to training/ more effective gas exchange /to respire aerobically for longer\} / converse.
- endurance athletes have more \{slow twitch muscles /stores of myoglobin / mitochondria\} / sprinters will have more fast twitch muscle fibres / non athlete have \{greater proportion of / less\} fast twitch muscles in their musculature / accept a correct comment about slow / fast muscle fibres
- in non-athletes (because stroke volume doesn't increase) less oxygen being delivered to the respiring muscle cells than in athlete / accept converse
- non athletes develop larger oxygen debt than athletes (because lactate levels are higher)
- drop in blood pH detected by chemoreceptors which start chain of events leading to increase in \{ventilation /breathing / heart\} rate
Knowledge points:
CH7 – Respiration, Muscles and the Internal Environment
Solution:
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