DP Biology (first assessment 2025)

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Question 19M.2.HL.TZ2.c

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Date May 2019 Marks available [Maximum mark: 2] Reference code 19M.2.HL.TZ2.c
Level HL Paper 2 Time zone TZ2
Command term Distinguish Question number c Adapted from N/A
c.
[Maximum mark: 2]
19M.2.HL.TZ2.c

Distinguish between the different phases of the cardiac cycle in the atria and in the ventricular muscle.

[2]

Markscheme

a. action potential of atrium precedes the ventricle
OR
the phases happen later in ventricle
OR
atrium contracts before the ventricle ✔

b. atrium has a shorter phase 2/longer phase 2 in ventricle
OR
atrium falls abruptly in phase 2/ventricle shows a plateau in phase 2 ✔

c. phase 3 is more distinct/falls more abruptly in ventricular action potential ✔

d. ventricular phase is overall longer than atrial phase ✔

Examiners report

Part (c) confused many candidates and they did not realise they had to refer to the graphs in their answers. Most scored one mark for stating ventricular contraction occurs after atrial contraction.

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