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.


Bacteria Virus Worksheet Bl


Bacteria Worksheet   




Bacterial Cell Evolution

1. Bacteria are microscopic _____________.

2. Fossils evidence shows bacteria are about __________ years old, while eukaryotes are about __________ years old.

3. Discuss where bacteria can be found.


4. Ribosomal differences have put bacteria into what two kingdoms? Which is the older group?


5. What is absent in the cell wall of Archaebacteria? Describe this substance.



6. Describe the environments in which you would find Archaebacteria.



7. Compare & contrast these tree groups of Archaebacteria — methanogens, extreme halophiles, and thermoacidophiles.





8. Most bacteria are found in what kingdom?

9. Name & describe the three shapes of Eubacteria.



10. Are Eubacteria aerobic or anaerobic? Explain.


11. Eubacteria may be heterotrophic or photosynthetic. Explain what this means & give an example of each type.



12. What type of staining is used to group Eubacteria?

13. Describe the appearance of gram-positive and gram-negative bacteria under a microscope.


14. Explain why Eubacteria do not all stain the same color during Gram staining.


15. Describe, in detail, cyanobacteria.



16. Cyanobacteria, also known as ______________ bacteria lack a membrane bound __________ & _____________.

17. How are heterocysts helpful to cyanobacteria?


18. What is eutrophication?


19. Explain the role of cyanobacteria in eutrophication.



20. What bacterium causes syphilis? Describe this bacteria.


21. Streptococci bacteria causing strep throat are in what group?

22. Why are actinomycete bacteria important?


23. Compare & contrast these three groups of Proteobacteria — enteric bacteria, chemoautotrophs, and nitrogen-fixing bacteria.





24.Name a genus of nitrogen-fixing bacteria found on the roots of soybeans in our area.


Characteristics of Bacteria

25. Name the three main parts of all bacteria.


26. Describe the cell wall of bacteria. How does this differ from a plant cell wall?



27. Compare & contrast the cell membrane of Eubacteria with that of other eukaryotes.



28.Are Gram positive or negative bacteria more protected against antibiotics & why?


29. Where does cell respiration take place in eukaryotes? in bacteria?

30. Describe how the cell membrane of photosynthetic bacteria are adapted for this process. Where does this process take place in plants?



31. Compare & contrast the cytoplasm of bacteria with that of eukaryotes.



32. Describe the DNA (hereditary material) found in bacteria. Make a sketch of what you think this would look like.




33. Where is the capsule of a bacteria, what is it made of, and give two ways it helps a bacterium?



34. Where is the glycoclayx of a bacteria, what is it made of, and how does it help a bacterium?


35. How do pili help the bacteria that have them?


36. How do Gram positive bacteria protect themselves against harsh environments?


37. Describe two methods of locomotion in bacteria.



38. Compare & contrast saprophytic and photoautotrophic bacterial nutrition.



39. Distinguish among these three bacteria & give an example of each — obligate anaerobes, facultative anaerobes, & obligate aerobes.





40. Compare & contrast these three methods of bacterial reproduction — transformation, conjugation, and transduction.




Bacteria and Humans

41. What does a pathologist do for a living?


42. Compare & contrast the two types of toxins bacteria produce.



43. Besides injuring the body by releasing toxins, how else do bacteria hurt the body?


44. Describe four antibiotics against bacteria.




45. Explain how antibiotic resistance occurs.



46. Name two  bacterial diseases carried by ticks.

47. name two bacterial diseases caused by eating contaminated food.

48. Name a sexually transmitted bacterial disease.

49. Name a bacterium that can cause disease whenever it gets into deep wounds.

50. Name a bacterium that is transmitted by coughing & infects the lungs.

51. Describe, in detail, how bacteria can be useful to humans.



Evaluation Webquest Classification


Students will be evaluated as a group in the areas listed in the rubric.









Classify plants and animals according to internal and external features using a developed classification systems, organized using a flow chart. Classification of a total of 6 out of 10 living organisms (that includes the created living things) correctly with 6 flow charts.Classification of a total of 7 out of 10 living organisms (that includes the created living organisms) correctly with 6 legible and easy to follow flow charts. Classification of a total of 8 out of 10 living organisms (that includes the created living organisms) correctly with 6 legible and easy to follow flow charts and 1 flow chart that combines all 6 flow charts. Classification of a total of 9 or 10 living organisms correctly with 6 flow charts that are easy to follow  and 1 flowchart that combines all 6 flow charts and is easy to follow.
Poster of new living thing that communicates what the new living thing looks like.
Poster that includes:  

1)a picture of an original living thing
2)a description of five characteristics listed

A poster that includes:  

1) a picture of an original living thing

2)a  description of six  characteristics listed in an organized fashion

3)few spelling errors

A poster that includes

1)a picture of an original living thing

2) a  description of six or more characteristics listed in an organized fashion

3) no spelling errors.

4)easy to read
A poster that includes:

1) a picture of an original living thing2) a description of six or more characteristics listed in an organized fashion

3) no spelling errors.

4) good artistic design.

Presentation of classification findings and new living thing

 1)Information presented relevant and in a logical order

2)One media used for presentation effectively

1)Information presented relevant and in a logical order

2)Two media forms used for presentation excluding video effectively.

1)Information presented relevant and in a logical order

2)Video used for presentation media effectively.


1)Information presented relevant and in a logical order

2)Two media forms used for presentation including video effectively.
in a group


co-operatively using information technology skillsOR

2)Demonstrate ability to collaborate to develop a group display.

1)Work co-operatively using information technology skills


2)Demonstrate ability to collaborate to develop a group display with satisfactory results

1)Work co-operatively using information technology skills


2)Demonstrate ability to collaborate to develop a group display
with average results

1)Work co-operatively using information technology skills


2)Demonstrate ability to collaborate to develop a group display with  above average results



Worked together though some problems
(had disagreements)
Worked together with a few problems
(only minor disagreements)
Worked together and every one had input into decisions though a few problemsWorked well together, no problems and everyone had input into decisions.



Cell Respiration


Cell Respiration

In this experiment, you will work with seeds that are living but dormant. A seed contains an embryo plant and a food supply surrounded by a seed coat. When the necessary conditions are met, germination occurs, and the rate of cellular respiration greatly increases. In this experiment you will measure oxygen consumption during germination. You will measure the change in gas volume in respirometers containing either germinating or non-germinating pea seeds. In addition, you will measure the rate of respiration of these peas at two different temperatures.

Before doing this laboratory you should understand:

  • how a respirometer works in terms of the gas laws; and
  • the general processes of metabolism in living organisms.

After doing this laboratory you should be able to:

  • calculate the rate of cell respiration from experimental data.
  • relate gas production to respiration rate; and
  • test the effect of temperature on the rate of cell respiration in ungerminated versus germinated seeds in a controlled experiment.

Cellular respiration is the release of energy from organic compounds by metabolic chemical oxidation in the mitochondria within each cell. Cellular respiration involves a series of enzyme-mediated reactions. The equation below shows the complete oxidation of glucose. Oxygen is required for this energy-releasing process to occur.

C6H12O6 + 6O2 —–> 6 CO2 + 6 H2O + 686 kilocalories of energy / mole of glucose oxidized

By studying the equation above, you will notice there are three ways cellular respiration could be measured. One could measure the:

1. Consumption of O2 ( How many moles of oxygen are consumed in cellular respiration?)

2. Production of CO2 ( How many moles of carbon dioxide are produced by cellular respiration?)

3. Release of energy during cellular respiration.

In this experiment, the relative volume of O2 consumed by germinating and non-germinating (dry) peas at two different temperatures will be measured.

Background Information:
A number of physical laws relating to gases are important to the understanding of how the apparatus that you will use in this exercise works. The laws are summarized in the general gas law that states:

PV = nRT


P is the pressure of the gas,

V is the volume of the gas,

n is the number of molecules of gas,

R is the gas constant ( its value is fixed), and

T is the temperature of the gas (in K0).

This law implies the following important concepts about gases:

1. If temperature and pressure are kept constant, then the volume of the gas is directly proportional to the number of molecules of gas.

2. If the temperature and volume remain constant, then the pressure of the gas changes in direct proportion to the number of molecules of gas present.

3. If the number of gas molecules and the temperature remain constant, then the pressure is inversely proportional to the volume.

4. If the temperature changes and the number of gas molecules is kept constant, then either pressure or volume ( or both ) will change in direct proportion to the temperature.

It is also important to remember that gases and fluids flow from regions of high pressure to regions of low pressure.

In this experiment, the CO2 produced during cellular respiration will be removed by potassium hydroxide (KOH) and will form solid potassium carbonate (K2CO3) according to the following reaction.

CO2 + 2 KOH —-> K2CO3 + H2O

Since the carbon dioxide is being removed, the change in the volume of gas in the respirometer will be directly related to the amount of oxygen consumed. In the experimental apparatus if water temperature and volume remain constant, the water will move toward the region of lower pressure. During respiration, oxygen will be consumed. Its volume will be reduced, because the carbon dioxide produced is being converted to a solid. The net result is a decrease in gas volume within the tube, and a related decrease in pressure in the tube. The vial with glass beads alone will permit detection of any changes in volume due to atmospheric pressure changes or temperature changes. The amount of oxygen consumed will be measured over a period of time. Six respirometers should be set up as follows:

1RoomGerminating seeds
2RoomDry Seeds and Beads
4100CGerminating Seeds
5100CDry Seeds and Beans

 1.Prepare a room-temperature bath (approx. 25 degrees Celsius) and a cold-water bath (approx. 10 degrees Celsius).

2.Find the volume of 25 germinating peas by filling a 100mL graduated cylinder 50mL and measuring the displaced water.

3.Fill the graduated cylinder with 50mL water again and drop 25 non-germinating peas and add enough glass beads to attain an equal volume to the germinating peas.

4.Using the same procedure as in the previous two steps, find out how many glass beads are required to attain the same volume as the 25 germinating peas.

5.Repeat steps 2-4. These will go into the 10-degree bath.

6.To assemble 6 respirometers, obtain 6 vials, each with an attached stopper and pipette. Number the vials. Place a small wad of absorbent cotton in the bottom of each vial and, using a dropper, saturate the cotton with 15% KOH (potassium hydroxide). It is important that the same amount of KOH be used for each respirometer.

7.Place a small wad of dry, nonabsorbent cotton on top of the saturated cotton.

8.Place the first set of germinating peas, dry peas & beads, and glass beads in the first three vials, respectively. Place the next set of germinating peas, dry peas & beads, and glass beads in vials 4, 4, and 6, respectively. Insert the stopper with the calibrated pipette. Seal the set-up with silicone or petroleum jelly. Place a weighted collar on each end of the vial. Several washers around the pipette make good weights.

9.Make a sling of masking tape attached to each side of the water baths. This will hold the ends of the pipettes out of the water during an equilibration period of 7 minutes. Vials 1, 2, and 3 should be in the room temperature bath, and the other three should be in the 10 degree bath.

10.After 7 min., put all six set-ups entirely into the water. A little water should enter the pipettes and then stop. If the water continues to enter the pipette, check for leaks in the respirometer.

11.Allow the respirometers to equilibrate for 3 more minutes and then record the initial position of the water in each pipette to the nearest 0.01mL (time 0). Check the temperature in both baths and record. Record the water level in the six pipettes every 5 minutes for 20 minutes.

Table 5.1: Measurement of O2 Consumption by Soaked and Dry Pea Seeds at Room Temperature (250C) and 100C Using Volumetric Methods.

Beads AloneGerminating Peas

Dry Peas and Beans

Reading at time XDiff*Reading at time XDiff*Corrected Diff. ^Reading at time XDiff*Corrected diff ^
Initial – 0
5- 10
10 -15
Initial – 0
5- 10
10 -15

* difference = ( initial reading at time 0) – ( reading at time X )

^ corrected difference = ( initial pea seed reading at time 0 – pea seed reading at time X) – ( initial bead reading at time X).

Analysis of Results:
1. In this investigation, you are investigating both the effect of germination versus non-germination and warm temperature versus cold temperature on respiration rate. Identify the hypothesis being tested in this activity.



2. This activity uses a number of controls. Identify at least three of the control, and describe the purpose of each control.







3. Graph the results from the corrected difference column for the germinating peas and dry peas at both room temperature and 100C.

a. What is the independent variable? ____________________________________________________

b. What is the dependent variable? ______________________________________________________

Graph Title: _____________________________________________________________________

Graph 5.1


4. Describe and explain the relationship between the amount of oxygen consumed and time.





5. From the slope of the four lines on the graph, determine the rate of oxygen consumption of germinating and dry peas during the experiments at room temperature and 100C. Recall that rate = delta Y/delta X.

Table 5.2

ConditionShow Calculations HereRate in ml.O2 / min
Germinating Peas/100C 




Germinating peas /Room Temperature 





Dry peas/100C 




Dry Peas /Room Temperature 





6. Why is it necessary to correct the readings from the peas with the readings from the beads?





7. Explain the effect of germination ( versus non-germination) on peas seed respiration.





8. What is the purpose of KOH in this experiment?





9. Why did the vial have to be completely sealed around the stopper?





10. If you used the same experimental design to compare the rates of respiration of a 25 g. reptile and a 25 g. mammal, at 100C, what results would you expect/ Explain your reasoning.







11. If respiration in a small mammal were studied at both room temperature (210C) and 100C, what results would you predict? Explain your reasoning.





12. Explain why water moved into the respirometer pipettes.