Citric acid was produced in a fermenter using the pulp of cassava (Manihot esculenta) and the fungus Aspergillus niger. This process was carried out at room temperature for 6 days and citric acid was then collected. The apparatus was cleaned and set up for a new fermentation. The process is shown in the diagram. 
State in which numbered part of the process you would find the probes to detect changes in pH.
a. pH decreased by citric acid; b. (pH lowered by) production of produced (by the fungus) in respiration; c. (pH lowered by) production of carbonic acid by dissolving in water;
Explain the possible causes of these changes in pH.
batch fermentation because the citric acid is collected at the end of the fermentation OR batch fermentation because the process was carried out over 6 days then re-set up OR diagram does not show constant supply of nutrients so it must be a batch;
Suggest, with a reason, whether this is a batch or a continuous fermentation.
batch fermentation because the citric acid is collected at the end of the fermentation OR batch fermentation because the process was carried out over 6 days then re-set up OR diagram does not show constant supply of nutrients so it must be a batch;
