SB2 The Eye

Question 1

What are the parts of the eye?

Answer 1

• cornea
• iris
• pupil
• lens
• retina
• optic nerve

Question 2

What is the function of the cornea?

Answer 2

Transparent lens that refracts light as it enters the eye

Question 3

What is the function of the iris?

Answer 3

Controls how much light enters the eye

Question 4

What is the function of the lens?

Answer 4

Transparent disc that can change shape to focus light onto the retina

Question 5

What is the function of the retina?

Answer 5

Contains light receptor cells

Question 6

What is the function of the optic nerve?

Answer 6

Sensory neurone that carries impulses between the brain and the eye

Question 7

What is the function of the pupil?

Answer 7

Hole that allows light into the eye

Question 8

What is the function of the ciliary muscles?

Answer 8

A ring of muscle that contracts and relaxes to change the shape of the lens

Question 9

What is the aqueous humour and where is it located?

Answer 9

The watery liquid between the cornea and the lens

Question 10

What is the vitreous humour and where is it located?

Answer 10

Jelly-like substance filling the eyeball (behind the lens)

Question 11

What are the two types of light receptors within the retina and what do they do?

Answer 11

• Cones: can detect colour
• rods: can detect light

Question 12

How does the lens move?

Answer 12

Through the contraction and relaxation of the ciliary muscles

Question 13

What happens if the lens wants to focus on a nearby object?

Answer 13

• ciliary muscles contract
• causing the lens to become fatter
• light is refracted more

Question 14

What happens if you want to focus on a far-away object?

Answer 14

• ciliary muscles relax
• causing the lens to become thinner
• light is refracted less

Question 15

What is the pupil reflex action and why is it carried out?

Answer 15

Reflex action carried out to protect the retina from damage

Question 16

What happens to the pupil in dim light?

Answer 16

It dilates

Question 17

What happens to the pupil in bright light?

Answer 17

It constricts

Question 18

What is the effect of short-sightedness?

Answer 18

Distant objects blurry but closer objects clear

Question 19

What causes short-sightedness?

Answer 19

• lens more curved than normal
• eyeball too long

Question 19

What happens in short-sightedness?

Answer 19

• light is refracted too much
• causing the focal point to fall in front of the retina rather than on the retina

Question 19

How is short-sightedness treated?

Answer 19

• using glasses with a concave lens

Question 19

What are the effects of long-sightedness?

Answer 19

Close objects appear blurry but far away objects look fine

Question 19

What are the causes of long-sightedness?

Answer 19

• lens less curved than normal
• eyeball too short

Question 20

What happens in long sightedness?

Answer 20

• light isn’t refracted enough
• focal point falls behind the retina

Question 21

How can long sightedness be treated?

Answer 21

Using convex lenses

Question 21

What is the impact of colour-blindness?

Answer 21

Not all colours are seen

Question 22

What is the cause of colourblindness?

Answer 22

Cones don’t work properly

Question 23

What is cataract?

Answer 23

A condition that causes the build up of a lot of protein, clouding the lens

Question 24

What is the effect of having cataract?

Answer 24

• light is dispersed throughout the lens
• or absorbed by the lens
• rather than focussing the light on one sharp point

Question 25

How is cataract treated?

Answer 25

Replace the real lens with an artificial one