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Question 18N.3.HL.TZ0.10

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Date November 2018 Marks available [Maximum mark: 8] Reference code 18N.3.HL.TZ0.10
Level HL Paper 3 Time zone TZ0
Command term Deduce, List, Outline, State Question number 10 Adapted from N/A
10.
[Maximum mark: 8]
18N.3.HL.TZ0.10

The diagram shows an overview of the Henriksdal wastewater treatment process in Stockholm, Sweden.

(a)

State a group of organisms that will be active in the fermenter labelled X. 

[1]

Markscheme

bacteria
OR
archaeans
OR
methanogens ✔

Accept a named bacterium

(b)

Deduce, with a reason, whether X is a continuous fermenter or a batch fermenter.

[1]

Markscheme

continuous because there is a constant input of raw materials ✔

(c)

Probes are used to monitor significant variables within the fermenter. List three significant variables that should be monitored in the fermenter.

[3]

Markscheme

a. pH/acidity/alkalinity ✔

b. foam ✔

c. metabolites ✔

d. substrate ✔

e. oxygen ✔

f. carbon dioxide ✔

g. temperature ✔

h. pressure ✔

Accept other valid condition

(d)

State the main component of biogas.

[1]

Markscheme

methane ✔

(e)

Inside Y there are rotating paddles. Outline two reasons for these paddles being needed.

[2]

Markscheme

a. mixing substrate to increase contact with bacteria
OR
preventing sedimentation ✔

b. avoids formation of biofilms ✔

c. aeration for aerobic bacteria ✔

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