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Question 18N.3.SL.TZ0.2b

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Date November 2018 Marks available [Maximum mark: 2] Reference code 18N.3.SL.TZ0.2b
Level SL Paper 3 Time zone TZ0
Command term Explain Question number b Adapted from N/A
b.
[Maximum mark: 2]
18N.3.SL.TZ0.2b

Measurements of the lung capacity of a student were recorded using a spirometer and displayed with a data logger. Initially the student was at rest, then changed to carrying out strenuous exercise. The results are displayed in the graph.

(b)

Explain the changes in ventilation after 35 seconds.

[2]

Markscheme

a. the volume of air per breath increases
OR
the volume of each breath reaches a maximum/levels off
OR
frequency of ventilation/breaths per minute increases ✔

b. exercise increases «rate of cellular» respiration/energy use/blood CO2/acidity ✔

c. exercise causes increased demand for oxygen/removal of carbon dioxide ✔

d. maximum rate/depth of ventilation is determined by the capacity of the student ✔

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