5.7

Question 1

the eye is a

Answer 1

spherical structure

Question 2

its wall is made up of 3 layers

Answer 2

outer sclera - tough and fibrous
middle choroid layer - blood vessels
inner retina - light sensitive rod and cone cells

Question 3

At the front of the eye the sclera is transparent, forming the part known as the

Answer 3

cornea - allows light to enter the eye

Question 4

The conjunctiva is a membrane that surrounds the cornea it is

Answer 4

lubricated by watery tear fluid

Question 5

the iris is a modification of the choroid layer at the front of the eye, it contains

Answer 5

smooth radial muscle and circular muscles surrounding the hole - pupil

Question 6

contraction and relaxation of the iris muscles changes the pupil size and allows

Answer 6

variable amounts of light to enter the eye

Question 7

light-sensitive receptor cells in the retina (rods and cones) connect to sensory neurones that leave the retina at the blind spot and form the

Answer 7

optic nerve

Question 8

Behind the pupil is the lens, held in place by

Answer 8

suspensory ligaments attached to a ring of ciliary muscle

Question 9

front of lens = Aqueous humour =

Answer 9

clear, watery fluid

Question 10

behind lens = Vitreous humour =

Answer 10

clear, jelly-like fluid

Question 11

When light rays enter the eye they are

Answer 11

refracted

Question 12

the light is first refracted by the

Answer 12

cornea at the front of the eye

Question 13

the light is then refracted by the

Answer 13

lens, which focuses the light so that it forms a clear image on the retina

Question 14

three refracting surfaces:

Answer 14

cornea
front surface of the lens
rear surface of the lens

Question 15

light is refracted to greater or lesser extent depending on

Answer 15

how far the object is from the eye

Question 16

light rays from a distant object are almost parallel and these need a

Answer 16

thin lens to focus them on the retina

Question 17

when looking at a distant object, the ciliary muscles relax

Answer 17

pulling the suspensory ligaments taut

Question 18

the lens, which is made of flexible proteins, is pulled into a

Answer 18

thin shape

Question 19

near object - the light rays enter the eye at a more

Answer 19

acute angle

Question 20

The ciliary muscles contract and the suspensory ligaments loosen, allowing the lens to

Answer 20

return to its natural, round, fat shape - refracts the light rays more so that they are focused on the retina

Question 21

the way in which the ciliary muscles cause the lens to change shape is called

Answer 21

ACCOMODATION