O-LevelBiologyRespiration5090/22 · Oct/Nov 2019 · Q710 Marks

Respiration in the muscle cells of a human may take place when oxygen is available and when oxygen is not available.

(a)Name the type of respiration that takes place when oxygen is available.[1]
(b)A person is running in a race. Outline the advantages to the person of the type of respiration in (a) compared with the type of respiration that takes place when oxygen is not available.[4]
(c)The oxygen required for the type of respiration in (a) is provided to the muscle cells from the air. Describe the events that must take place in a person's body so that a muscle cell can be provided with molecules of oxygen from the air.[5]

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2019). The mark or mark type is shown in brackets.

[1] aerobic;
[4] A each point if stated correctly for either aerobic / oxygen available or anaerobic / oxygen unavailable reference to amount of energy ; reference to speed / distance / endurance / amount of muscle activity AW; reference to lactic acid; reference to oxygen debt; reference to pain / cramp / fatigue ;
[5] oxygen / air + breathed in / inhaled / inspired / into lungs ; diaphragm + contracts / moves down / flattens; external + intercostal muscles contract; alveoli / air sacs; dissolve / solution; mucus / moist lining; diffusion; blood / red blood cell / erythrocyte / haemoglobin / oxyhaemoglobin ; heart / atrium / ventricle + contracts / beats / pumps ; across AW + membrane ; Ig any point if given with ref. to CO2 Ig RBC

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