Eye Dissection


Cow Eye Dissection

How do we see? The eye processes the light through photoreceptors located in the eye that send signals to the brain and tells us what we are seeing. There are two types of photoreceptors, rods and cones. These photoreceptors are sensitive to the light. Rods are the most sensitive to light and therefore provide gray vision at night. Cones are mainly active in bright light and enable you to see color. There are 100 million rods compared to the 3 million cones located in your retina. The photoreceptors help you adjust to night and day. For example, if you walk inside from the sun, you can not initially see anything. This is due to the activity of the cones and the lack of activity of the rods. The rods become activated and adapted to the dim light, resulting in gray images formed in the dark. The same thing happens when you leave a dark movie theatre during the day. The rods are mainly activated and the cones have to adjust to sunlight when you leave the theatre.

By dissecting the eye of a cow, which is similar to the eyes of all mammals including humans, you will gain an understanding of the structure and function of the parts of the eye.

Cow eye, dissecting pan, dissecting kit, safety glasses, lab apron, and gloves

Procedure (External Structure):

  1. Obtain a cow eye, place it in your dissecting pan, & rinse the eye with water.
  2. Rotate the eye until the larger bulge or tear gland is on the top of the eye. The eye is now in the position it would be in a body as you face the body.
  3. On the outside of the eye, locate the following parts:
  • fat– surrounds the eye & cushions it from shock
  • tear or lacrimal gland – forms a bulge on the top outer area of the eye & produces tears to wash the surface of the eye
  • tear ducts – tubes to carry the tears from the gland to the eye
  • optic nerve – a white cord on the back of the eye about 3mm thick just toward the nasal side; carries messages between the eye & brain
  • muscles – reddish, flat muscles found around the eye to raise, lower, & turn (right & left) the eye
  1. Turn the eye so that it is facing you & examine these structures on the front surface of the eye:
  • eyelids – two moveable covers that protect the eye from dust, bright light, and impact
  • sclera – this is the tough, white outer coat of the eye that extends completely around the back & sides of the eye
  • cornea – a clear covering over the front of the eye that allows light to come into the eye (preservative often makes this appear cloudy)
  • iris – round black tissue through the cornea that controls the amount of light that enters the inner part of the eye (may be colored in humans)
  • pupil – the round opening in the center of the eye that allows light to enter and whose size is controlled by the iris

Click here for labeled eye model

Procedure (Internal Structure):

  1. Place the eye in the dissecting pan so it is again facing you. Using your scalpel, pierce the white part of the eye or sclera just behind the edge of the cornea. Make a hole large enough for your scissors.
  2. Using your scissors, carefully cut around the eye using the edge of the cornea as a guide. Lift the eye & turn it as needed to make the cut and be careful not to squeeze the liquid out of the eye.
  3. After completing the cut, carefully remove the front of the eye and lay it in your dissecting pan.
  4. Place the back part of the eye in the pan with the inner part facing upward.
  5. Locate the following internal structures of the eye:
  • cornea – observe the tough tissue of the removed cornea; cut across the cornea with your scalpel to note its thickness
  • aqueous humor – fluid in front the eye that runs out when the eye is cut
  • iris – black tissue of the eye that contains curved muscle fibers
  • ciliary body – located on the back of the iris that has muscle fibers to change the shape of the lens
  • lens – can be seen through the pupil; use your scalpel & dissecting needle to carefully lift & work around the edges of the lens to remove it
  • vitreous humor – fluid inside the back cavity of the eye behind the lens
  • retina – tissue in the back of the eye where light is focused; connects to the optic nerve; use forceps to separate the retina from the back of the eye & see the dark layer below it

10. Answer the worksheet questions on the cow eye dissection.

Click here for eye dissection questions

  1. Dispose of the eye as your teacher advises and rinse and return all equipment to the supply cart. Wash your hands thoroughly.

Introduction to Animals Study Guide


Introduction to Animals Study Guide

How are most animals classified?
What are the main characteristics of chordates?
How are vertebrates classified?
What are heterotrophs & give some examples.
In what ways do animals differ from plants?
What are tissues?
What determines an animal’s body plan?
In what habitat do you find most species of animals?
What is bilateral symmetry?
What does bipedal mean?
Where are the dorsal & ventral surfaces on a bipedal organism?
What is radial symmetry?
Name invertebrates that are asymmetrical, radial symmetry, & bilateral symmetry.
What does cephalization mean?
What invertebrate group was first to show cephalization?
Describe the “surfaces” of animals with radial symmetry.
Why is cephalization an advantage for animals?
What is a postanal tail & give examples of adult chordates with this characteristic?
Describe the “skeletal” support found in roundworms.
What is segmentation, & what animals exhibit this characteristic?
What is the function of kidneys, and what organisms have these organs?
How do closed & open circulatory systems differ?
How are terrestrial animals protected against water loss?
What structures show segmentation in vertebrates?
What is the advantage of having a long intestinal tract?
How are nutrients moved through a cnidarian’s body?
Describe how spiral cleavage occurs.
describe the embryo at the start of gastrulation.
What forms from endoderm in cnidarians.


1st Semester Test Review 2004-05


First Semester Review  2004-05      


What are the smallest units that can carry on life functions called?
Living things are composed of ______________.
Give an example of a scientific observation.
What is a hypothesis?
What 3 things compose an atom?
Matter is made of ________________.
When atoms gain energy, what happens to electrons?
Do  cells contain a few or thousands of different kinds of enzymes?
__________________ reactions are important in organisms because they allow the passage of energy from one molecule to another.
What is a polar molecule?
Water molecules break up other polar substances. Give an example of such a polar molecule.
What happens to ionic compounds in water?
Which is not a carbohydrate —– glycogen, steroids, cellulose, or sugars?
Amino acids are the monomers for making ________________.
Is ice an example of an organic molecule?
The type & order of the amino acids determines the ___________ of a protein.
Very active cells need more of which organelle?
What organelle is the packaging & distribution center of the cell?
What membrane surrounds the nucleus?
What is the function of mitochondria. Sketch their shape.
Where is chlorophyll found in plants?
Diffusion takes place from ________________ concentration to ___________.
If a cell has a high water content, will it lose or gain water?
Ink dispersing in a beaker is an example of ________________.
Very large molecules enter cells by a process called ________________.
Endocytosis and exocytosis occur in ______________ directions across a cell membrane.
What is photosynthesis?
Where do the dark reactions of photosynthesis take place?
When chlorophyll absorbs light energy ATP is made and what other energy carrying molecule?
When chlorophyll absorbs light energy, what happens to its electrons?
_______________ molecules are responsible for the photosystems.
Electrons that have absorbed energy & moved to a higher energy level enter what chain?
When cells break down food molecules, energy is temporarily stored in what molecule?
When muscles do not get enough oxygen, what acid forms during exercise?
If you are growing bacteria in a culture and lactic acids starts to form, the bacteria are not getting enough of what gas?
The 2 stages of cellular respiration are _____________ & oxidative respiration.
Citric acid forms in which cycle during cellular respiration?
ATP molecules are formed inside what cellular organelle?
What is the study of life called?


2006 1st Semester Test Guide

First Semester Test 2006 Study Guide


1. What is the study of life called?

2. Instructions for traits passed from parent to offspring?

3. Keeping things stable or the same in cells?

4. Smallest units that can carry on life?

5. All living things require _________ for metabolism.

6. All living things are made of __________.

7. Salamanders with curved tails in polluted water are an example of which part of the scientific method?

8. The smallest part of carbon with all the same properties is called?

9. Where are electrons found in an atom & what is their charge?


10. When electrons gain energy they move to _____________________.

11. How many covalent bonds can carbon form?

12. Compounds may form from the transfer or __________ of electrons.

13. What happens to ionic compounds when placed in water?


14. Ionic bonds form from the ____________ of electrons.

15. Covalent bonds form from the ___________ of electrons.

16. What element do all organic compounds contain?

17. Give several examples of carbohydrates.



18. In what from do animals store glucose?

19. What are the monomers for proteins?

20. Is the following model a carbohydrate, lipid, or protein?

21. Sketch a fatty acid chain found in lipids.

22. What type of fatty acids contains double bonds?

23. Name the 2 nucleic acids.

24. When the volume of a cell increases, what happens to the surface area?



25. How does a prokaryotic cell differ from a eukaryotic cell?



26. What’s the job of the plasma membrane?


27. Parts of cells performing specific functions are called?

28. The ER sends proteins & lipids it makes to the __________ to be modified.

29. The Golgi ships & receives cell products in transport ___________.

30. In what organelle is ATP produced?

31. Ribosomes make ____________.

32. All eukaryotic cells have a ___________ containing the genetic material.

33. Diffusion occurs in what direction?

34. What is osmosis?

35. Ink dissolving in water is an example of _____________.

36. Riding of cell wastes in sacs is called _____________.

37. What is the effect of placing a plant into a hypertonic solution?


38. What is the ultimate energy for life on Earth?

39. Grana are suspended in the _________ of chloroplasts.

40. ____________ absorbs light energy for plants.

41. What happens to chlorophyll’s electrons when they absorb sunlight?

42. What is the source of oxygen in photosynthesis?

43. What gas is a byproduct of photosynthesis?

44. What type of skeleton do insects have?

45. The Calvin cycle occurs in what process?

46. The breaking down of food to release energy is called?

47. __________ builds up in heavily exercised muscles.

48. Name the 3 parts of cellular respiration.


49. How many chromosomes are in a human egg or sperm cell?

50. DNA compacts itself by wrapping around ____________.

51. How do insects help crops?


Writing Lab Notebook Reports



General Instructions:

  1. All labs must be written in pencil and be submitted to the teacher in a spiral notebook.
  2. Always use third person (NO personal pronouns — me, I, you, we, etc.) when writing all parts of a lab report. (USE HE, SHE, THEY, THEIR, THEM, ETC.
  3. The following things should be written clearly in marker on the front cover — “Subject” Lab Notebook, teacher name, student name, period.
  4. Number each page of the spiral notebook in the lower right hand corner.
  5. On Page 1, write the subject, year, student name, class period, and teacher name.
  6. Page 2 should have “Table of Contents” written at the top and two columns, one for “Page” and the other for “Lab Title”.
  7. Begin writing the first lab on page 3 of you notebook. DO NOT WRITE ON THE BACK OF YOUR PAPER!
  9. TITLE and UNDERLINE each section & then begin writing on the NEXT LINE!

Your lab report should be written using the following format: (Be sure to left align & underline headings)

Title (center on top line; on the right of line 2, put date & lab #)
The title should indicate clearly & concisely the subject and scope of the report.

Introduction – 20 points (PARAGRAPH FORM)

  • The introduction should give background information about the experiment.
  • It should also state the purpose of the investigation.
  • This section will be two or more paragraphs in length.

Hypothesis – 20 points (SINGLE SENTENCE)

  • The hypothesis should be a single statement telling the exact thing you are trying to prove in your experiment.
  • NEVER write this statement using “first person”. Write the hypothesis in past tense (third person.)

Materials – 5 points (SINGLE SENTENCE)

  • This section should be written in sentence form and name all of the materials and equipment used.
  • Be sure to include specific amounts and concentrations of chemicals used.
  • Start the statement, “The materials used include _____, _____, etc.”

Methods (Procedure)- 5 points (STEPS; NUMBER)

  • This section includes the step-by-step procedures used.
  • The procedure should be so thorough that someone else could use your listed materials and procedures to conduct the same experiment and get the same results.

Results (Data & Questions) – 20 points

  • All data should be collected and organized in a logical order. Results should be illustrated as charts, tables, graphs, &/or diagrams. All graphs should include a title, the independent variable labeled on the horizontal axis, and the dependent variable labeled on the vertical axis.
  • All lab questions and answers should be included also with this section. ( NUMBER & UNDERLINE the questions & then write, but DON’T UNDERLINE the answers)

Error Analysis

  • Include any important factors that you think may have actually affected your results.

Discussion and Conclusion – 30 points

Discussion is the most important part of your report, because here, you show that you understand the experiment beyond the simple level of completing it.!!

  • This is where you give a detailed account of what happened in the experiment.
  • Explain all observations and results in your experiment.
  • Analyze and interpret why these results were obtained.
  • Be sure to tell the significance or meaning of the results.
  • Restate the original hypothesis and explain whether the experiment succeeded. If the hypothesis was not correct, you should analyze why the results were not as predicted.
  • Explain experimental errors that appear in the results.


Additional help with Conclusions


Click here for Notebook paper Layout of Lab