B3.1.3 The Eye

Question 1

Describe cornea and it’s function

Answer 1

Transparent coating on the front of the eye
Protects eye by refracting light entering

Question 2

Describe pupil and its function

Answer 2

Central hole in the iris
Allows light to enter the eye

Question 3

Describe iris and it’s function

Answer 3

Coloured ring of muscle tissue
Alters pupil size by contracting or relaxing

Question 4

Describe lens and it’s function

Answer 4

Transparent biconvex lens
Focuses light clearly onto the retina

Question 5

Describe ciliary body and it’s function

Answer 5

Ring of muscle tissue
Alters shape of lens

Question 6

Describe suspenseful ligaments and their function

Answer 6

Ligament tissue
Connects the ciliary muscle to the lens

Question 7

Describe optic nerve and it’s function

Answer 7

Nervous tissue
Carries nerve impulses to the brain

Question 8

Describe how images are formed

Answer 8

Cornea refracts incoming light rays
Providing most of the focus to incoming light
The light then passes through the pupil and is further refracted by lens
Creates a sharp image on the retina
Photoreceptors in retina produce nervous impulse when exposed to light
Impulse travels down optic nerve to brain which interprets impulses as a visual image

Question 9

When ciliary muscle contracts…

Answer 9

Lens becomes more convex (fatter)
You can focus on nearby objects

Question 10

When ciliary muscles relax

Answer 10

Lens becomes less convex (thinner)
You can focus on distant objects

Question 11

What causes short sightedness?

Answer 11

A persons lens being too strong or the eyeball too big

Question 12

What causes long sightedness

Answer 12

A persons lens too weak or eyeball too short

Question 13

Concave lenses

Answer 13

Correct short sightedness
Bend light rays outwards before entering eye

Question 14

Convex lenses

Answer 14

Correct long sightedness
Bend light rays inward before entering the eye

Question 15

Two types of photoreceptor cells in retina

Answer 15

Rods- respond to light, allow you to see in low light levels
Cones- respond to different colours. Diff cone cells respond to red blue and green light

Question 16

Explain the changes in the eye that occur as you look from a book to the front of a classroom.

Answer 16

Iris contracts so pupil is smaller to reduce the amount of light entering is eye, as the classroom environment typically has brighter
The ciliary muscles surrounding the lens contract, causing the lens to become more convex, enabling clear focus on the front of classroom