Describe the path taken by a molecule of carbon dioxide, and the processes in which it is involved, from the moment it leaves the atmosphere until it forms part of a starch molecule in a leaf.

Mark scheme

Marking points from the official mark scheme (Oct/Nov 2014). The mark or mark type is shown in brackets.

1. [max. 7] between guard cells / through stoma ;
2. [max. 7] into intercellular/air space ;
3. [max. 7] dissolving in water (film);
4. [max. 7] diffusion;
5. [max. 7] through cell wall ;
6. [max. 7] of mesophyll cell (or named) ;
7. [max. 7] to chloroplast ;
8. [max. 7] during photosynthesis ;
9. [max. 7] links with water molecule ;
10. [max. 7] glucose + forms starch ;
11. [max. 3] little magnesium absorbed ;
12. [max. 3] deficiency in chlorophyll ;
13. [max. 3] less light energy trapped ;
14. [max. 3] photosynthesis inhibited / limiting factor / AW ;
15. [max. 3] less glucose/starch/carbohydrate formed ;