CAIE A Level Biology 9700 · Cell membranes and transport
A biologist examines the cell surface membrane of a deep-sea bacterium that lives at 80 °C and high pressure. Its membrane contains a high proportion of saturated fatty acids and cholesterol-like molecules (hopanoids).
Outline the fluid mosaic model of membrane structure, describing how hydrophobic interactions between phospholipids maintain the bilayer and how the arrangement of cholesterol and proteins influences membrane stability, fluidity, and function.
5 marks, so the mark scheme is looking for about 5 separate creditworthy points. Making the same point twice in different words earns it once.
Outline means: Give the main points briefly. Less detail than describe, but every key step has to be there. One short line per step, in order. The marks are for coverage, not depth.
Written by Markquill to follow the Cambridge International syllabus. Markquill is independent and is not affiliated with or endorsed by Cambridge International.