The Eye

Question 1

what are the parts of the eye?

Answer 1

iris
cornea
pupil
lens
ciliary muscle
optic nerve
retina
rods cones

Question 2

what does the iris do?

Answer 2

controls how much light enters the pupil

Question 3

what does the cornea do?

Answer 3

refracts light into the eye

Question 4

what does the pupil do?

Answer 4

the hole in the middle

Question 5

what does the lens do?

Answer 5

the light sensitive part and its covered in receptor cells which detect light

Question 6

what do rods do?

Answer 6

more sensitive in dim light but can’t sense colour

Question 7

what do cones do?

Answer 7

sensitive to different colours but not so good in dim light

Question 8

what happens to the information from light?

Answer 8

converted into electrical impulses

Question 9

what does the optic nerve do?

Answer 9

information from light is converted into electrical impulses

-it carries impulses from the receptors to the brain

Question 10

why is the lens elastic and flexible?

Answer 10

so the ye can focus light onto the retina by changing the shape of the lens

Question 11

how does the eye look at distant objects?

Answer 11

• the ciliary muscle relaxes, which allows suspensory ligaments to pull tight
• pulls the lens into a less rounded shape so light is refracted less

Question 12

how does the eye look at close objects?

Answer 12

• the ciliary muscle contracts, which slackens the suspensory ligaments
• the lens becomes a more rounded shape, so light is refracted more

Question 13

what are long-sighted people?

Answer 13

unable to focus on near objects

Question 14

what are short-sighted people?

Answer 14

unable to focus on distant objects

Question 15

how does long-sightedness occur?

Answer 15

• when the lens is the wrong shape and doesn’t bend light enough or the eyeball is too short
• light from near objects is brought into focus behind the retina

Question 16

how does short-sightedness occur?

Answer 16

• when the lens is the wrong shape and bends the light too much or the eyeball is too long
• light from distant objects is brought into focus in front of the retina

Question 17

how can you correct long-sightedness?

Answer 17

glasses or contact lenses with a convex lens

Question 18

how can you correct short-sightedness?

Answer 18

glasses or contact lenses with a concave lens

Question 19

what is colour blindness?

Answer 19

when people can tell the difference between certain colours

Question 20

how is red-green colour blindness caused?

Answer 20

when red or green cones in the retina are not working properly

Question 21

why is there no cure for colour blindness?

Answer 21

the cone cells cannot be replaced

Question 22

what is a cataract?

Answer 22

• where protein build up inside and makes a cloudy patch on the lens
• stops light from being able to enter the eye normally

Question 23

what may people with a cataract experience?

Answer 23

• likely to have blurred vision
• colours looking less vivid
• difficulty in seeing bright light

Question 24

how can a cataract be treated?

Answer 24

by replacing the faulty lens with an artificial plastic one

Question 25

what properties should an artificial lens have?

Answer 25

• flexible to be squashed and stretched
• clear/transparent so light rays can pass easily through it
• colourless (colours can’t be changed)