Biology · Oct / Nov 2023 · Paper 41 · Question 3

any two from:

eggs laid in / larvae live in, water and adults live on land / AW ;

two stage life cycle / AW ;

gas exchange occurs through skin (and lungs) ;

larva have gills and adults have lungs ;

moist skin (described) ;

AVP ;

G cornea ;

H lens ;

K (cell) membrane ;

L cytoplasm ;

M nucleus ;

brain and spinal cord ;

P draw on the graph in the fovea (area on the graph where there is the highest number of cone cells and no rod cells) ;

Q draw on the graph in the blind spot (area on the graph where there are no cone cells or rod cells) ;

any five from:

describe:

1

more rod cells than cone cells ;

2

(number of) cone cells peak, in the middle / at the fovea ;

3

there are no rod cells where the number of cone cells is highest ; 4

ref. to uneven distribution of rod cells, either side of the,

middle / fovea ;

5

no rod cells and no cone cells at blind spot ;

explanation:

6

light absorbed (by a pigment) ;

7

rods detect low light (intensity) ;

8

(rods) do not detect colour ;

9

(rods) provide night vision / AW ;

10 (cones) detect high light (intensity) ;

11 (cones) detect colour ;

12 any detail, e.g. three different types of cone ;

13 (no rods and cones at blind spot) because of optic nerve ;

more rods present and no / fewer cones present ;

rods at the fovea / rods mainly at periphery ;