Agar cubes may be used to show how altering the surface area to volume ratio affects diffusion. Three different agar cubes, made with a dilute acid, were placed in an indicator solution that moved into the cubes. When the indicator made contact with the acid, its colour changed. The cubes had sizes of $1\ \text{cm}^3$, $2\ \text{cm}^3$ and $3\ \text{cm}^3$, and they were left in the indicator solution for 10 minutes. All the other variables were kept unchanged. The results were shown as diagrams. The results for the $2\ \text{cm}^3$ cube are displayed. Which diagrams show the results for the $1\ \text{cm}^3$ and the $3\ \text{cm}^3$ cubes?
Biology 9700 · AS & A Level · Movement into and out of cells