DP Biology (first assessment 2025)

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Question 21M.2.SL.TZ1.7a

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Date May 2021 Marks available [Maximum mark: 4] Reference code 21M.2.SL.TZ1.7a
Level SL Paper 2 Time zone TZ1
Command term Outline Question number a Adapted from N/A
a.
[Maximum mark: 4]
21M.2.SL.TZ1.7a
(a)

Outline the process of inhalation.

[4]

Markscheme

a. diaphragm contracts / moves downwards/flattens ✔

b. external intercostal muscles contract ✔

c. (muscle contraction) moves the rib cage upwards and outwards ✔

d. increases volume of the thorax / lungs ✔

e. difference in pressure/decreasing pressure causes air to flow into lungs / lungs inflate ✔

Examiners report

This question was attempted by approximately 56 % of candidates.

Done well by many. Diaphragm contraction and external intercostal muscle contraction was commonly known along with the idea that the rib cage moves upwards and outwards. Further understanding of the consequent pressure changes in the thorax was not clear.

Syllabus sections