Question 21M.1.HL.TZ1.3
| Date | May 2021 | Marks available | [Maximum mark: 1] | Reference code | 21M.1.HL.TZ1.3 |
| Level | HL | Paper | 1 | Time zone | TZ1 |
| Command term | Question number | 3 | Adapted from | N/A |
The images show samples of red blood cells that were placed in different concentrations of salt solutions.
Which solution has the highest salt concentration?
A. The original solution
B. Solution 1
C. Solution 2
D. Solution 3
[1]
B
Three quarters of candidates answered this question correctly so it was not difficult, but the discrimination index was only moderate suggesting that some well-prepared candidates answered incorrectly. The most popular wrong answer showed a cell bursting in the way that would have happened in a hypotonic solution. Either candidates muddled up hypo- and hypertonic or they did not think carefully enough about the direction of water movement in osmosis. It is always worth double checking in one's mind to make sure that a chosen answer is not the opposite of what it should be.
