Z The Human E

The diagram shows a section through the human eye. 
Which structure regulates the amount of light entering the eye?

• A
• B
• C
• D

Which part of the eye prevents mechanical injury?

• cornea
• pupil
• sclera
• iris

What is the function of the conjunctiva?

• secretes mucus to keep the eyeball moist
• refracts light 
• prevents excessive entry of light
• contains a pigment that gives the eye its colour

In a brightly lit environment, the radial muscles will __________, and the circular muscle will ___________.

• contract, relax
• relax, relax
• relax, contract
• contract, contract

State the function of the cornea.

• protects the iris and pupil against mechanical injury
• jelly layer that keeps the eye moist
• it refracts light rays into the eye
• contains muscles that control the size of the pupil

Which of the following is responsible for colored vision?

• rod

• cone

• retina

• fovea

Which layer of the eye are black pigmented and prevent the internal reflection of light?

• sclera

• retina

• choroid

• fovea

What substance need to be produce in order for us to see in dim light?

• visual C

• visual purple

• visual color

• vitamin D

Which of the following contain the highest concentration of cones?

• blind spot

• fovea

• optic nerve

• ciliary body

Which of the following does not refract light?

• vitreous humour

• cornea

• conjuctiva

• lens