SB2h The Eye

Question 1

Identify the main parts of the eye.

Answer 1

Cornea: refracts light, bends it as it enters the eye
Iris:controls how much light enters the pupil
Lens: focuses light onto the retina
Retina:contains the light receptors
Optic nerve:carries impulses between the eye and the brain

Question 2

Explain how receptor cells allow full colour

vision in bright light.

Answer 2

Rods work well in dim light, where cones work in bright light, this is why our colour vision is better in bright light.

Question 3

Describe common eye defects (cataracts)

Answer 3

A cataract is a cloudiness in the lens, caused by a build up of protein inside the lens.
Cataracts can be treated by removing the lens and replacing with a plastic lens.

Question 4

Describe common eye defects

long-sightedness,

Answer 4

unable focus near objects:
does not bend enough light, 
light from near objects is brought into focus behind retina. 
convex lenses to correct it 
lens is fat

Question 5

Describe common eye defects (colour blindness).

Answer 5

can not tell difference between certain colours, most common is red-green, red or green cones in retina not working, no cure at moment, as can not get replaced

Question 6

Describe common eye defects. (short-sightedness.)

Answer 6

unable to focus on distant objects
light from distant objects brought into focus in front of retina,
use concave lens
lens is short,