Describe the pathway of water molecules from the soil, through a plant and into the atmosphere.

Mark scheme

Marking points from the official mark scheme (May/June 2019). The mark or mark type is shown in brackets.

1. [7] root hair;
2. [7] cell wall;
3. [7] membrane;
4. [7] partially AW + permeable ;
5. [7] osmosis / diffusion ;
6. [7] stem;
7. [7] xylem;
8. [7] leaf / mesophyll ;
9. [7] water film;
10. [7] air / intercellular AW + spaces ;
11. [7] out of / through + stomata / guard cells ;
12. [7] transpiration / evaporation / water vapour ;
13. [3] (factor: temperature / heat) variation: high / higher AW; explanation: increased AW + evaporation / water vapour
14. [3] (factor: wind / air movement) variation: fast / faster AW; explanation: fewer water molecules outside / increased concentration gradient
15. [3] (factor: light) variation: high / higher AW; explanation: stomata / guard cells + open
16. [3] (factor: humidity / moisture in air) variation: low / lower AW; explanation: fewer water molecules outside / increased concentration gradient