Fig. 3.1 shows a young tomato plant growing near a window. Cells from two positions in the stem are also shown. [Figure 3.1] The cells at X divide constantly. They then increase in size and some form mature cells like the one shown from position Y.

Mark scheme

Marking points from the official mark scheme (May/June 2023). The mark or mark type is shown in brackets.

1. [1] cell at Y has chloroplasts / cell at X has no chloroplasts ;
2. [1] cell at Y has a (sap) vacuole / cell at X has no vacuole ;
3. [1] cell at Y has more cytoplasm / cell at X has less cytoplasm ;
4. [1] osmosis ;
5. [1] (movement of water molecules) from high to low water potential ; A down a water potential gradient References to concentration must specify solute or water
6. [1] water source, e.g. soil / surrounding cells across a partially / selectively permeable (cell) membrane ;
7. [1] increases volume of sap / cytoplasm ;
8. [1] until equilibrium reached / no net movement / pressure from cell wall prevents further expansion ;
9. [1] phototropism ;
10. [1] auxin produced in shoot tip / cells at X ;
11. [1] diffuses down stem / shoot ;
12. [1] more on shaded side / less on side exposed to light ; R auxin destroyed on light side Ig uneven distribution unless qualified
13. [1] promotes / stimulates AW + cell elongation ;
14. [1] cells on shaded side elongate more than those on light side ;
15. [1] bends/grows towards light ;
16. [1] 24 ;
17. [1] cells at X dividing by mitosis ; A references to the production of genetically identical cells / cells at Y are not gametes