The Eye

Question 1

what is the eye

Answer 1

highly specialised sense organ containing receptor cells that allow us to detect the stimulus of light

Question 2

what are the two receptors in the eye called and what are their functions

Answer 2

Receptor cells that are sensitive to light, known as rods, and receptor cells that can detect colour, known as cones

Question 3

what is the cornea

Answer 3

TRANSPARENT LENS THAT REFRACTS (BENDS) LIGHT

ASIT ENTERS THE EYE

Question 4

what is the function of the IRIS

Answer 4

CONTROLS HOW MUCH LIGHT ENTERS THE PUPIL

Question 5

what is the function of the lens

Answer 5

TRANSPARENT DISC THAT CAN CHANGF SHAPF TO

FOCUS LIGHT ONTO THE RETINA

Question 6

what is the function of the retina

Answer 6

CONTAINS LIGHT RECEPTOR CELLS

- RODS (DETECT LIGHT INTENSITY) AND CONES (DETECT COLOUR)

Question 7

what is the optic nerve

Answer 7

the sensory neurone that carries the electrical impulses from the eye to the brain

Question 8

why is the lens able to focus on distant and close up objects

Answer 8

The lens is elastic and its shape can be changed when the suspensory ligaments attached to it become tight or loose

Question 9

how does the eye focus on distant objects

Answer 9

The ciliary muscles relax (the ring of muscle increases in diameter)
This causes the suspensory ligaments to tighten
The suspensory ligaments pull on the lens, causing it to become thinner
Light is refracted less

Question 10

how does the eye focus on distant objects

Answer 10

The ciliary muscles contract (the ring of muscle decreases in diameter)
This causes the suspensory ligaments to loosen
This stops the suspensory ligaments from pulling on the lens, which allows the lens to become fatter
Light is refracted more

Question 11

explain the pupil reflex

Answer 11

reflex action carried out to protect the retina from damage

Question 12

what happens when there is a-lot of light

Answer 12

In bright light, the pupil constricts (narrows) in order to prevent too much light from entering the eye and damaging the retina

Question 13

what happens when dim light

Answer 13

In dim light, the pupil dilates (widens) in order to allow as much light into the eye as possible to improve vision

Question 14

what is shortsightedness

Answer 14

when the lens is more curved than normal or the eyeball is too long which means the light is refracted too much and so the focal point falls in front of the retina (rather than on the retina)
This means that distant objects appear blurry

Question 15

how can short sightedness be cured

Answer 15

concave lens

Question 16

what is longsightedness

Answer 16

It happens when the lens is less curved than normal or the eyeball is too short which means the light is not refracted enough and so the focal point falls behind the retina (rather than on the retina)
This means that close objects appear blurry

Question 17

how can longsightednesses be cured

Answer 17

using a convex lens

Question 18

what colour blindness and why

Answer 18

People who suffer from colour blindness cannot distinguish between certain colours and in rare cases, cannot see colours at all
This happens because the cones in the retina do not work properly or are absent

Question 19

what is Cataracts

Answer 19

clouding of the lens
A cloudy lens means that the light is dispersed throughout the eye or absorbed by the lens, rather than being sharply focussed to one particular point
This often leads to blurred vision
Eventually, if left untreated, cataracts can lead to blindness

Question 20

how can u cure cataracts

Answer 20

Cataracts can be corrected by replacing the cloudy lens with an artificial one