Biology · May / June 2025 · Paper 41 · Question 2

any four from:

1

(overall) there are more rods than cones / ora ;

2

(number of) cones, peaks / are greater, at fovea / at 0 arbitrary units ; 3

idea that (number of) rods peak either side or are increasing going towards the fovea / 0 arbitrary units ;

4

no rods present at, fovea / 0 arbitrary units ;

5

idea that (number of) cones outside of fovea are (approximately), equal / constant ;

6

(number of) rods greater on left hand-side of fovea ;

more rod (cells) / greater proportion of rod cells / AW ;

ref. to (greater sensitivity) for, night vision / low light conditions / AW ; OR

fewer cones ;

colour vision less important / AW ;

pupil reflex ;

circular muscle (of the iris) ;

antagonistic ;

A – vesicle ;

B – receptor (protein) ;

C – (named) neurotransmitters ;

diffusion ;

by random movement of particles

OR

from higher concentration to lower concentration / down concentration gradient ;