2.91 describe the structure and function of the eye as a receptor

Eye: sense organ that detects light. The eye is essentially a receptor of light, as it has light receptor cells in its retina. These cells turn stimuli into electrical impulses.

Structure	Function
Ciliary muscle	change the shape of the lens in the eye to help with focusing
Iris	contains pigment and controls how much light enters pupil
Lens	transparent disc, focuses light on retina
Pupil	Hole that allows light to enter the eye to be focused on retina
Cornea	transparent convex lens, refracts light
Conjunctiva	a thin, transparent membrane covering the inside of the eyelids and the front of the eye
Suspensory ligaments	hold the lens in position and alter its shape in conjunction with the ciliary muscle
Choroid	thin black middle layer containing the main arteries of the eye. The black pigment in this layer prevents reflection of light within the eyeball
Retina	the inner most layer of the wall of the eye, contains rods that detect black and white and cones that detect light
Fovea	has a large concentration of light sensitive cells and so has the greatest visual ability
Optic nerve	connects the eye to the brain, because of sensory neurones that sends impulses between eye and brain
Blind spot	the point at which the optic nerve leaves the eye. It is so called as there are no light sensitive cells present here
Sclera	tough, white, outer layer which protects the delicate parts inside the eye.

I know this is a lot of information, so don't focus on trying to memorise everything. For the test, the most important bits to know are probably: cornea, iris, lens, retina, optic nerve, pupil and ciliary muscles. Start with learning these first before the others.