Describe the significance of each of the following features of a dicotyledonous leaf in terms of the process named: the distribution of chloroplasts in the process of photosynthesis

Mark scheme

Marking points from the official mark scheme (May/June 2015). The mark or mark type is shown in brackets.

1. [max 4] in palisade ;
2. [max 4] spongy;
3. [max 4] ref. more in palisade ;
4. [max 4] none in epidermis / xylem / phloem / vein / transparent epidermis ;
5. [max 4] near leaf surface / (sun)light / to absorb more or most sunlight ; A exposed to
6. [max 4] rapid AW rate of photosynthesis ; A with ref. either distribution or number
7. [max 4] guard cells;
8. [max 4] controlling stomata ;
9. [max 3] CO2 ;
10. [max 3] O2 ;
11. [max 3] correct ref. to photosynthesis or respiration;
12. [max 3] diffusion;
13. [max 3] (stomata): allow water vapour out/transpiration ;
14. [max 3] (mesophyll cells): moist surface ;
15. [max 3] large surface area ;
16. [max 3] xylem + phloem ;
17. [max 3] around edge of stem ;
18. [max 3] centre of root/description of arrangement ;
19. [max 3] many xylem (stem) + one xylem (root) ;
20. [max 3] phloem and xylem paired in stem/unpaired in root ; A in vascular bundles in stem