2003 Bio Al

Paper 1 Section A

|Terms with *, mark deduction for spelling error. | |Marks |
|1 | |D→E→B→C→A |(2) |
| | |(1) (1) | |
|2 |(a) |During the favourable season more secondary xylem cells are formed and they are larger with thin|(3) |
| | |wall (1) / larger lumen. | |
| | |In the unfavourable season, less secondary xylem cells are formed and they are smaller with | |
| | |thick wall (1) / smaller lumen. | |
| | |The former gives a lighter / wider colour and the latter gives a darker / narrower colour which | |
| | |appear as rings(1) | |
| | |(Accept alternative but correct account of the ring morphology.) | |
| | | | |
| |(b) |(ii) 2 (½) |(3) |
| | |(iii) narrow / closely packed growth rings (1) | |
| | |(iv) presence of burn scar (1) / damaged growth ring, 5(½) | |

Page total = 8

|3 |(a) |any two: (accept correct alternatives) |(2) |
| | |help dispersal (1)