Topic 2:The Eye

Question 1

Retina

Answer 1

-receptor cells are found

Question 2

Cones

Answer 2

• receptor cells are sensitive to light
• generates impulses in sensory neurones which leads into the brain through the optic nerve
• only work in bright light

Question 3

Rods

Answer 3

• receptor cells detect differences in light intensity

- works well in dim light

Question 4

Pupil

Answer 4

-dark area in the middle of the eye

Question 5

Iris

Answer 5

-amount of light entering the eye is controlled by muscles - it can constrict and dilate

Question 6

Cornea

Answer 6

-most focusing - bends light rays to bring them togethar

Question 7

Lens

Answer 7

-fine tunes the focusing

Question 8

Ciliary muscles

Answer 8

• makes the lens fatter to focus light from near objects

- thinner to focus light from distant objects

Question 9

Short sight

Answer 9

• cannot focus on distant objects - light ray focuses on point in front of retina
• eyeball too long or cornea curved too sharply
• corrected by diverging lens

Question 10

Long sight

Answer 10

• cannot focus on near objects - light ray focused to a point behind the retina
• eyeball too short
• corrected by converging lens

Question 11

Describe laser eye sugery

Answer 11

-laser can be used to cut away the cornea and reshape it

Question 12

Cataract

Answer 12

• protein builds up inside the lens and makes it cloudy

- replace the clouded lens with a plastic one

Question 13

Colour blindness

Answer 13

• some cones do not work properly; so have difficulty in seeing some colour
• cannot be corrected