(a) Describe and explain how a nitrate ion in the soil becomes part of a stored molecule in the seed of a plant.

Mark scheme

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

1. [1] in solution / dissolved;
2. [1] absorbed / taken up (by plant);
3. [1] by root hair;
4. [1] active transport / diffusion;
5. [1] correct description of concentration gradient;
6. [1] (nitrate ion) carried in xylem ;
7. [1] to make amino acid;
8. [1] (amino acid) carried in phloem ;
9. [1] to make proteins;
10. [1] fruit / ovary;
11. [1] cotyledon / endosperm ;
12. [1] solvent;
13. [1] activates enzymes ;
14. [1] for conversion of stored materials to provide energy for growth ;
15. [1] softening the seed coat (testa) ;
16. [1] for transport AW ;