Science 8
Name __________________
Date _______________ Blk _
Dissecting a Sheep Eye
Purpose:
A sheep eye and a human eye have many things in common-as well as a few
important differences. In this activity, you will examine a sheep eye in order to better
understand how your own eyes function.
Materials:
o preserved sheep eye
o scissors
o prod
o dissection tray
o gloves
o paper towel
Procedure:
Read the entire procedure carefully on pages 212-213 of your textbook.
Data and Observations:
BEFORE YOU CUT THE EYEBALL:
 Examine the outside of the sheep eye.
1) Describe the fat around the eye.
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2) What is the function of the fat?
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3) Count how many muscles are attached to they eye. How many are there?
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4) What is the function of the muscles attached to the eye?
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 Use scissors to trim away the excess fat and muscle.
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5) Look at the front of the eye and note the outer layer, called the cornea. Why
is the cornea curved?
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6) Note that an opaque layer, the sclera, covers the eye. Explain why the sclera
has a dark layer.
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 Locate the optic nerve.
7) What is the function of the optic nerve?
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8) Why do you think that the optic nerve is so large?
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9) What interprets all the information that the optic nerve carries?
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 Use the prod to poke a hole in the eye halfway between the cornea and the optic
nerve.
 Use scissors to cut all the way around the eye, separating it into front and back
halves.
 Separate the eye into two halves.
10) Taking the front half of the eye, try to look through it. If you can see an
image through the eye, note whether it appears upright or upside down.
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 Use the prod again to poke a hole at the junction of the cornea and the sclera.
 Use the scissors to cut a circle around the cornea in order to remove it.
11) Describe the cornea.
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12) Describe the jelly-like substance under the cornea.
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13) What is the jelly-like substance called? What is its function?
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14) Describe the iris of the eye.
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15) How is the iris different in a human compared to a sheep?
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16) Locate the hole in the iris. What is this hole called? ______________________
 Remove the lens from the eye and wipe all the jelly from it.
17) Describe the appearance, colour, shape, and feel of the lens.
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18) Can you see an image through the lens? _______________________________

Examine the inside of the back half of the eye.
19) Where is the sheep’s blind spot?
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20) Do humans have a similar blind spot? _________________________________
21) Describe the retina.
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22) Describe the appearance of the back of the sheep eye.
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23) What is the purpose of the shiny layer under the retina of the sheep eye?
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24) What colour is the layer under the retina of a human eye? Why?
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25) Make a labelled diagram of a cross section of the sheep eye that includes all of
the structures you studied.
 Clean up according to your teacher’s instructions!
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Discussion:
1) List FOUR differences between the anatomy of a sheep eye and a human eye.
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2) List the path that light takes as it passes through the eye until it reaches the
brain.
a) CORNEA
b) ____________________
c) ____________________
d) ____________________
e) ____________________
f) ____________________
g) ____________________
h) BRAIN
3) Label the diagram of the eye shown below.
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