The Eye(Complete)

Question 1

What are the general features of the eye?

Answer 1

It is 2.5cm in diameter and is protected by the orbital( bony depressions) in the skull.
6 muscles control the movement of each eye.
There are 120 million light receptors in each eye( rods and cones) and they convert light into nerve impulses which are sent to the cerebrum of the brain to form a visual image.

Question 2

What is the structure of the sclera?

Answer 2

The white part of the eye.
It is the outermost layer of the eye and is opaque.
It forms the cornea at the front of the eye.

Question 3

What are the functions of the sclera?

Answer 3

To protect and give shape to the eyeball.

Question 4

What is the structure of the choroid?

Answer 4

The dark and black middle layer with melanin.

Question 5

What are the functions of the choroid?

Answer 5

To prevent internal reflection by absorbing any light rays that pass beyond the retina.

Question 6

What is the structure of the retina?

Answer 6

The innermost layer of the eye.

Has rods and cones- photoreceptors.

Question 7

What are the functions of the retina?

Answer 7

Converts light into nerve impulses so an image can form on the retina- generates impulses.

Question 8

What is the structure of the fovea?

Answer 8

Part of the retina with cones only.

Question 9

What are the functions of the fovea?

Answer 9

Provides detailed coloured vision in bright light.

Question 10

What is the structure of the photoreceptors?

Answer 10

Sensory cells sensitive to light.
Contains rods and cones.
Contains the pigment rhodopsin which needs vitamin A.

Question 11

What are the functions of the photoreceptors?

Answer 11

Rods:
Provide vision in dim light but only in black and grey.
Cones:
Provide detailed coloured vision in bright light.

Question 12

What is the structure of the cornea?

Answer 12

Transparent front of eye with a curved surface to focus light.

Question 13

What are the functions of the cornea?

Answer 13

To allow light to enter the light and bends it towards the retina.

Question 14

What is the structure of the aqueous humour?

Answer 14

A clear liquid with salt.

Question 15

What are the functions of the aqueous humour?

Answer 15

Contains the nutrients and oxygen for the cornea.

Maintains shape of cornea.

Question 16

What is the structure of the vitreous humour?

Answer 16

Clear gel-like.

Question 17

What are the functions of the vitreous humour?

Answer 17

Maintains the correct shape of the eyeball.

Question 18

What is the structure of the pupil?

Answer 18

Central opening of the iris.

Question 19

What are the functions of the pupil?

Answer 19

Allows light to enter the eyes:
Dilates in dim light to allow more light to enter the eyes.
Constricts in bright light to allow less light to enter the eyes.
Avoids dazzling effect.

Question 20

What is the structure of the iris?

Answer 20

Coloured sheet of muscle with melanin.

Question 21

What are the functions of the iris?

Answer 21

Controls the amount of light entering the eyes as follows:
Iris contracts in response to changing light intensity.
It changes the diameter of the pupil to allow more or less light to enter.

Question 22

What is the structure of the lens?

Answer 22

Transparent curved structure with biconvex shape.

Question 23

What are the functions of the lens?

Answer 23

To focus light onto the retina and carries fine adjustments to produce a sharp image.

Question 24

What is the structure of the ciliary body?

Answer 24

The ring of choroid tissue that contains the colliery muscle.

Question 25

What are the functions of the ciliary body?

Answer 25

Ciliary body:
Secretes the liquid that forms the aqueous humour.

Ciliary muscle:
Controls the curvature and focusing of strength of the lens.

Question 26

What is the structure of the suspensory ligaments?

Answer 26

Fibres that connect the ciliary body to the lens.

Question 27

What are the functions of the suspensory ligaments?

Answer 27

Holds the lens in place and is involved in the changing shape of the lens.

Question 28

What is the structure of the blind spot?

Answer 28

Part of the retina.

Question 29

What are the functions of the blind spot?

Answer 29

Does not generate a visual response as it has no rods or cones.

Question 30

What is the structure of the optic nerve?

Answer 30

Bundles of nerve fibres.

Question 31

What are the functions of the optic nerve?

Answer 31

To carry impulses to the cerebrum of the brain.

Question 32

When is the pupil constricted?

Answer 32

In bright light to allow less light ti enter the eye.

Question 33

When is the pupil dilated?

Answer 33

In dim light to allow more light to enter the eye.

Question 34

What is the fluid that fills the rear chamber of the eye?

Answer 34

The vitreous humour.

Question 35

What is the transparent covering in front of the cornea?

Answer 35

The conjunctiva.

Question 36

What is the function of the conjunctiva?

Answer 36

Protects against infection.

Question 37

What is the advantage of having 2 eyes?

Answer 37

3D vision.

Wider field of vision.

Question 38

The eyes of carnivores are located relatively close together at the front of the skull.
In herbivores they tend to be located to the side of the skull.
Suggest a benefit of either arrangement.

Answer 38

Herbivore- wider field of vision to detect predators.

Carnivore- to allow better judgement of distance.

Question 39

Apart from the eyelid, state one way in which the eye is protected from external damage.

Answer 39

Eyelashes.

Question 40

Name the part of the eye that contains a large amount of blood vessels.

Answer 40

Choroid layer.

Question 41

Where is the aqueous humour located?

Answer 41

Behind the cornea.

In front of the lens.

Question 42

Explain the importance of the eye reacting to bright light.

Answer 42

To prevent damage to the retina.