2003 Bio Al

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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) | | | | |give rise to gametophyte (1) / reproduction | | | |(b) |2N (1) / diploid |(1) | | |(c) |any two: (accept correct alternatives) |(2) | | | |D gives rise to C (1) | | | | |D provides C with nutrient (1) / food / water / minerals | | | | |D provides anchorage (1) / support for C | |

Page total = 5

|4 |(a) |(i) nematoblast (1) / nematocyst / stinging cell / one body opening / radial symmetry / a ring|(1) | | | |of tentacles | | | | |(ii) |key running based on the perception of the body covering of the starfish as the |(2) | | | | |exoskeleton: | | | | | |D (1) | | | | | |1b→2a→3a→4b(1) | | | | | |Or | | | | | |key running based of the perception of the body covering of the starfish as not | | | | | |equivalent to the exoskeleton (or the starfish possesses an endoskeleton): | | | | | |G(1)...
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