A2 Biology - Respiration? Watch

thenextchemist
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Hi guys, I don't understand the mark scheme to this question:
Why would aerobic respiration release less volume of gas than anaerobic?



Question:
If aerobic respiration had been investigated rather than anaerobic respiration, how
would you expect the volumes of gas collected at 30°C to differ from these results?

Mark Scheme:
Volume(s) less/ no gas evolved;
Glucose has RQ of 1.0;
So (volume) CO2 evolved = (volume of) O2 taken in;
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RMNDK
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(Original post by Bloom77)
Hi guys, I don't understand the mark scheme to this question:
Why would aerobic respiration release less volume of gas than anaerobic?



Question:
If aerobic respiration had been investigated rather than anaerobic respiration, how
would you expect the volumes of gas collected at 30°C to differ from these results?

Mark Scheme:
Volume(s) less/ no gas evolved;
Glucose has RQ of 1.0;
So (volume) CO2 evolved = (volume of) O2 taken in;
Anaerobic respiration produces less (if not none) CO2 because the Krebs Cycle and the Electron Transport Chain cannot take place (because oxygen acts as a final electron acceptor and FAD+ and NAD+ are integral in Krebs). Thus, only anaerobic glycolysis takes place which produces less CO2.

RQ means respiratory coefficient calculated as Vol CO2/Vol O2.
Glucose has a RQ of 1.0. If you remember from the equation of respiration you have a 1:1 ratio of CO2 to O2. I guess this is mentioned to reinforce the point that since oxygen is absent, no CO2 will evolve.
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