An amoeba is a single-celled organism. A mouse is a multicellular organism with a much greater volume. Why does the mouse need a transport system, but the amoeba does not?
The mouse has a larger surface area to volume ratio, so diffusion alone can supply all of its cells.
The mouse has a larger surface area to volume ratio, so diffusion alone is too slow to supply all of its cells.
The mouse has a smaller surface area to volume ratio, so diffusion alone can supply all of its cells.
The mouse has a smaller surface area to volume ratio, so diffusion alone is too slow to supply all of its cells.
58 exam-style questions on AQA GCSE Biology 1.3 Transport in cells, covering 1.3.1 Diffusion, 1.3.2 Osmosis, and 1.3.3 Active transport. Each one has a worked solution and a mark scheme showing where the marks go.