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Question 19N.3.SL.TZ0.8c

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Date November 2019 Marks available [Maximum mark: 2] Reference code 19N.3.SL.TZ0.8c
Level SL Paper 3 Time zone TZ0
Command term Distinguish Question number c Adapted from N/A
c.
[Maximum mark: 2]
19N.3.SL.TZ0.8c

The diagram below represents a small-scale biogas fermenter.

[Source: © Science in Society. http://www.i-sis.org.uk/BiogasChina.php]

(c)

Distinguish between batch and continuous culture fermentation.

[2]

Markscheme

a. in batch culture product is withdrawn at the end of the «organisms» growth phases whereas in continuous culture product is withdrawn while the organism is growing / OWTTE ✔

b. in batch culture all of the growth medium/nutrients are added at the beginning whereas in continuous culture, growth medium/nutrients are added at a constant rate / OWTTE ✔

c. batch culture is carried out in large scale fermenters whereas continuous culture could be in small scale ✔

d. continuous can run for a longer time than batch ✔

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