CAIE A Level Biology 9700 · Cell membranes and transport
A biologist places cylinders of potato (plant tissue) and a sample of red blood cells into a beaker of concentrated sucrose solution. The solution has a lower water potential than the cytoplasm of both the potato cells and the red blood cells.
After 30 minutes, the biologist examines the cells.
Compare the expected changes in the plant cells and the animal cells, and explain the reasons for the differences in their responses.
7 marks, so the mark scheme is looking for about 7 separate creditworthy points. Making the same point twice in different words earns it once.
Compare means: Give similarities or differences between two things, and say which side each point belongs to. Write each point as a pair, for example: A is X, whereas B is Y. Two separate descriptions rarely earn the marks.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.