CAIE IGCSE Biology 21.2.7 Controlling Conditions in Fermenters

Practise explaining how temperature, pH, oxygen, nutrients, mixing and waste are controlled during fermentation.

Exam points

explain how a water jacket and pH monitoring maintain optimum enzyme conditions
link aeration and stirring to oxygen supply and even distribution of nutrients and heat
use nutrient or product graphs to identify depletion, waste build-up or the best harvest point

[Maximum number: 5]

Bacteria are useful in biotechnology and genetic engineering.
Fig. 6.1 shows a photomicrograph of a bacterium.

Fig. 6.1

(a)

Genetically modified bacteria are often grown in fermenters.

[ 5 ]

(i)

Suggest why steam is used to clean fermenters.

[ 2 ]

(ii)

State three conditions inside a fermenter that are measured and controlled.

1

2

3

[ 3 ]

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