- (a) (i) Complete the following equation, which is a summary of aerobic respiration.
C6H12O6 + 6O2
(ii) Aerobic respiration is a two-stage process. The first stage takes place in the
cytoplasm. Where does the second stage take place?
(b) The apparatus below may be used to demonstrate aerobic respiration. Air is drawn through
the apparatus by attaching it to a vacuum pump at X. Sodium hydroxide is placed in flask 1
to remove carbon dioxide
(i) What is the purpose of removing carbon dioxide?
(ii) Limewat7er is put in flasks 2 and 3. Suggest a reason for putting it in each flask.
(iii) What is the purpose of a control in an experiment? Suggest a suitable control for
this experiment.
(iv) If the animal in the apparatus were replaced by a plant, and the experiment carried
out in daylight, would you expect a similar result? Explain your answer.
(c) The apparatus below may be used to demonstrate anaerobic respiration in yeast.
The water was boiled and cooled before adding the yeast.
(i) Why was the water boiled before adding the yeast?
(ii) Why do you think a layer of oil has been put on top of the water?
(iii) Would the same apparatus containing water and yeast but without sugar be a
suitable control?
Respiration
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