O-LevelBiologyEcology & Environment5090/21 · Oct/Nov 2017 · Q710 Marks

Fig. 7.1 shows a fermenter used for the production of an antibiotic. [Figure 7.1]

(a)(i)Identify what enters or leaves through each of W, X, Y and Z in Fig. 7.1. W X Y Z[4]
(a)(ii)Explain the importance of the substance entering through Y in the production of the antibiotic.[2]
(b)Explain why it is important to detect and to control the pH and temperature of the contents of the fermenter.[3]
(c)Suggest one advantage of the motor being located outside, rather than inside, the reaction vessel of the fermenter.[1]

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Mark scheme

Marking points from the official mark scheme (Oct/Nov 2017). The mark or mark type is shown in brackets.

[4] (a)(i) (W) fungus / microorganism / bacteria / nutrient / yeast / water; (X) carbon dioxide; (Y) oxygen; (Z) antibiotic / named antibiotic ;
[2] (a)(ii) respiration; aerobic; reference to increased yield ; sparger/bubbles / more surface area; growth;
[3] (b) detect changes ; enzymes; denature; reduce rate of reaction / product formed; kill microorganisms or named ; maintain optimum / best conditions ;
[1] (c) heat production / temperature ; ease of maintenance; prevents water damage to motor ; doesn't take up space (in fermentation vessel) AW ;

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