Question 22N.1A.SL.TZ0.5
| Date | November 2022 | Marks available | [Maximum mark: 1] | Reference code | 22N.1A.SL.TZ0.5 |
| Level | SL | Paper | 1A | Time zone | TZ0 |
| Command term | Question number | 5 | Adapted from | N/A |
In 1925, Gorter and Grendel carried out an experiment to study the structure of cell membranes in different mammals. The total surface area of red blood cells was measured in a sample and compared to the surface area formed by a single layer of lipid extracted from cell membranes and floated on water.
Which diagram best illustrates Gorter and Grendel’s conclusion drawn from this experiment?
[Source: Gorter, E. and Grendel, F., 1925. On bimolecular layers of lipoids on the chromocytes of the blood. Journal of Experimental Medicine 41(4), pp. 439–443.]
[1]
C
This question was on the work of Gorter and Grendel in determining the structure of the cell membrane. The data shows that the surface area of membrane in red blood cells is half the surface area of extracted lipids suggesting there is a lipid bilayer making response C correct. It was commented that this was beyond the scope of the syllabus but in setting the question it was considered that there was enough evidence in the data for students to conclude a bilayer was present. No conclusion could be drawn from the data about proteins, ruling out answers A and D. The question discriminated rather poorly with most students opting for response A.
