Biology · May / June 2026 · Paper 41 · Question 1

active transport ;

as surface area (to volume ratio) decreases, the time taken (for the cube to turn completely red / for the acid to move through the cube) increases / ora ; correct ref. to diffusion ;

idea that (smaller surface area / bigger cube) there is a greater distance for acid (particles) to move through, (to reach the centre) / ora ;

any three from:

the time taken for (all) cubes to turn red decreases ;

increasing temperature increases the kinetic energy (of the particles / AW) ; increasing (the rate of) diffusion ;

idea that the same relationship between time and surface area : volume ratio still applies ;

any six from:

1

ref. to osmosis ;

2

water moves (into / out of cells), across / through, a partially / AW, permeable membrane ;

cells in the highly concentrated salt solution

3

idea that cells have a higher water potential than the salt solution / ora ; 4

cells / vacuole / cell sap / cytoplasm, decreases in volume / turgor pressure decreases ;

5

become, flaccid / plasmolysed OR cell membrane, pulls away / AW, from cell wall ;

cells in distilled water

6

idea that cells have a lower water potential than distilled water / ora ; 7

cells / vacuole / cell sap / cytoplasm, increase in volume / turgor pressure increases ;

8

become turgid / cell contents push against cell wall ;