Question 23M.1.HL.TZ1.3
| Date | May 2023 | Marks available | [Maximum mark: 1] | Reference code | 23M.1.HL.TZ1.3 |
| Level | HL | Paper | 1 | Time zone | TZ1 |
| Command term | Question number | 3 | Adapted from | N/A |
Onion (Allium cepa) epidermis was placed in pure water and observed with a light microscope using high magnification.
What would happen to these cells if they were transferred to a hypertonic solution?
A. Cells would gain mass.
B. Cells would take in water by osmosis and swell.
C. Cells would burst open, releasing their content.
D. Cell membranes would detach from walls at some points.
[1]
D
SL:
About 20% of candidates answered this question correctly, making it the hardest on the paper. It was also a poorly-answered question on the HL paper, where it was question 3. Further comments on it are given in the report for that paper.
HL:
Only 30% of candidates answered this correctly. Many candidates thought that onion cells would take in water by osmosis and swell after being transferred from pure water to a hypertonic solution. The terms hypertonic and hypotonic are included in Practical 2 (in 1.4 of the core on membrane transport), so students are expected to understand them.