Date | May 2022 | Marks available | 1 | Reference code | 22M.1.SL.TZ2.3 |
Level | Standard level | Paper | Paper 1 | Time zone | Time zone 2 |
Command term | Question number | 3 | Adapted from | N/A |
Question
In an experiment on osmosis, red blood cells were immersed in a salt solution for two hours. The micrographs show the appearance of these cells before and after immersion in the salt solution.
[Source: Ed Uthman, Acanthocytes, from peripheral blood [image online] Available at:
https://en.wikipedia.org/wiki/Acanthocyte#/media/File:Acanthocytes,_Peripheral_Blood_(3884092551).jpg
This file is licensed under the Creative Commons Attribution 2.0 Generic (CC BY 2.0) https://creativecommons.org/licenses/by/2.0/ Source adapted.]
What explains the observed changes?
A. The salt solution was hypertonic and entered the red blood cells.
B. The salt solution was hypotonic and disrupted the membranes of the red blood cells.
C. The salt solution was hypertonic and water moved into it from the red blood cells.
D. The salt solution was hypotonic and mineral salts were lost from the red blood cells.
Markscheme
C
Examiners report
This question performed well in terms in terms of difficulty and in having the highest discrimination index on the paper.