DP Biology (first assessment 2025)

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Question 19M.1B.SL.TZ1.2a.i

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.1B.SL.TZ1.2a.i
Level SL Paper 1B Time zone TZ1
Command term Outline Question number a.i Adapted from N/A
a.i.
[Maximum mark: 2]
19M.1B.SL.TZ1.2a.i
(a.i)

Outline how O2 consumption is measured using a respirometer.

[2]

Markscheme

a. a CO2 absorber/KOH is added ✔

b. a bubble/starting water level is measured ✔ 

c. «the rate of» movement of the bubble/pressure reduction is a measure of O2 consumption ✔

Examiners report

Very few candidates achieved a mark. Some confused a respirometer with a spirometer; others mentioned data logging probes. Credit was given for mention of a water column. Only the highest scoring candidates understood that a carbon dioxide absorber is required to allow pressure changes to be measured.

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