Download Frog Dissection Lab Packet

FROG DISSECTION LAB
100 points possible
Purpose: The purpose of this lab is to enhance lab performance skills, develop dissection techniques, and compare and contrast the
digestive system of a frog to that of a human.
Materials:
1 Preserved frog, 1 dissection tray, 1 goggles, dissection kit (scalpel, forceps, scissors, pins, probe), 2 pairs of gloves (nonlatex),
apron/lab coat, paper towels, plastic bag, plastic container, microscope, microscope slide, 1 straw, ruler
Procedures
PART 1 – EXTERNAL OBSERVATIONS
1.
Clear desk then gather materials. Put on apron/lab coat, gloves, goggles.
2.
Follow instructions on the Frog External Anatomy Sheet to make observations.
PART 2 – INITIAL DISSECTION (See images below)
3.
Place the frog on dissection tray (with belly facing up).
4.
Pin each of the four limbs on dissection tray.
5.
Use the forceps to lift the skin midway between the rear legs of the frog. Then, using the scalpel, make a small cut through the lifted
skin.
6.
Now, using the scissors, continue the incision up the midline all the way to the frog’s neck. Do not cut too deeply. When you reach
the frog’s neck, stop.
7.
Using the scissors, make horizontal incisions through the skin between the front legs. Repeat for the rear legs.
8.
Separate the skin flaps from the muscles below it. Pick up flaps of skin with forceps and use scalpel to help separate the skin from the
muscle. Then pin skin flaps to the dissection tray.
9.
Use the forceps to lift the muscle midway between the rear legs of the frog.
10. Use the scalpel to start the incision in the direction of the chin. Then, using the scissors, continue the incision up the midline all the
way to the frog’s neck. Do not cut too deeply. The muscle is thin and you don’t want to damage any organs.
11. VERY IMPORTANT: When you reach the point just below the front legs, turn the scissor blades sideways to cut through the bones
in the chest. This will prevent damage to the organs.
12. Using the scissors, make horizontal incisions through the muscle between the front legs the repeat for the back legs.
13. Open the abdominal area by pulling back the muscle flaps with the forceps then use the scalpel to separate the muscle from the tissue.
14. Once the muscle flaps have been separated, pin them back.
15. Use Frog Organ Sheet to observe, identify, and record the frog’s internal organs.
16. Remove a microscopic piece of tissues from different organs to view under the microscope. Make observations and drawings.
GO TO PART 3 (OPTIONAL) OR PART 4 FOR POST LAB
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PART 3 – ADVANCED DISSECTION (Optional)
17. Try inflating the lungs by putting a straw in the frog’s Eustachian tube and blowing. Be careful. Make observations.
18. Take a microscopic piece of any tissue and view it under the microscope. Make observations and drawings.
19. Continue to part 4.
PART 4 – POST LAB
20. Clean-up: Place all parts of frog back in plastic bag. Wash and dry all equipment and instruments. Return all materials to proper
place, clean table. Wash your hands. Trash gloves.
21. Post Lab Reflection – Answer the questions on the “Frog Dissection Reflection” sheet
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Frog External Anatomy Sheet
1. Observe the dorsal and ventral sides of the frog. Dorsal side color ___________ Ventral side color ____________
2. Examine the hind legs. How many toes are present on each foot? ________
Are the toes webbed? ______
3. Examine the forelegs.
How many toes are present? _________Are the toes webbed? _______
4. Use a ruler to measure your frog, measure from the tip of the head to the end of the frog's backbone (do not include the
legs in your measurement). Compare the length of your frog to other frogs
Your Frog (cm) Frog 2 Frog 3 Frog 4 Frog 5 Average Length
5. Feel the frog's skin. Is it scaley or is it slimey? ____________
6. Other observations:
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Frog Organ Sheet
Locate each of the organs below. Put a check in the circle for each organ you find.
o
Liver—The large structure of the body cavity. This brown colored organ is composed of three parts, or
lobes.
o Heart - at the top of the liver, the heart is a triangular structure.
o Lungs - Locate the lungs by looking underneath and behind the heart and liver. They are two spongy
organs.
o Gall bladder--Lift the lobes of the liver, there will be a small green sac under the liver.
o Stomach--Curving from underneath the liver is the stomach. The stomach is the first major site of
chemical digestion. Follow the stomach to where it turns into the small intestine.
o Small Intestine--Leading from the stomach.
o Large Intestine--As you follow the small intestine down, it will widen into the large intestine. The large
intestine is also known as the cloaca in the frog.
o Spleen--Return to the folds of the mesentery, this dark red spherical object serves as a holding area for
blood.
o Esophagus--Return to the stomach and follow it upward, where it gets smaller is the beginning of the
esophagus.
STOP! If you have not located each of the organs above, do not continue on to the next
sections!
Removal of the Stomach:
Cut the stomach out of the frog and open it up. You may find what remains of the frog's last meal in
there. Look at the texture of the stomach on the inside. What did you find in the stomach?
Measuring the Small intestine: Remove the small intestine from the body cavity and carefully separate
the mesentery from it. Stretch the small intestine out and measure it. Now measure your frog. Record
the measurements below in centimeters.
Frog length: _______ cm Intestine length ________ cm
Kidneys - flattened bean shaped organs located at the lower back of the frog, near the spine. They are often a dark
color. The kidneys filter wastes from the blood.
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Testes - in male frogs, these organs are located at the top of the kidneys, they are pale colored and roundish.
Oviducts - Oviducts are where eggs are produced.
Bladder - An empty sac located at the lowest part of the body cavity. The bladder stores urine.
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FROG DISSECTION DIAGRAM
Directions: Accurately draw, color, and label all organs observed.
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Frog Dissection Lab Scoring Guide
50 points possible
Team Name: __________________________________ Score: ________
Name: _______________________________
Name: _______________________________
Name: _______________________________
Name: _______________________________
Grade of a “C”
Satisfactory behavior/Cooperation.
Demonstrated adequate lab skills (mostly everyone preformed their own job to complete the lab).
Followed written/verbal directions most of the time.
Acceptable clean up. But can use improvement.
Grade of a “B”
Group consistently showed good behavior/Cooperation.
Followed written/verbal directions the majority of the time.
Very good clean up.
Grade of an “A”
Excellent behavior/Cooperation (ex: NEVER played around/Always got along/helped others without asking, etc.)
Followed all written/verbal directions at all times (does not ask teacher to repeat already given/printed instructions,
proactive and takes initiative)
Excellent clean up (ex: leaves desk spotless, resupplies materials for next class, etc).
Group exceeded all expectations.
Comments:
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Frog Dissection Reflection
25 points possible
Directions: Answer the following questions thoroughly and in complete
sentences.
1. Why did you do a frog dissection? 2. What was your job during the frog dissection? 3. Describe in detail what it was like when the frog was being dissected. 4. What did you find surprising or interesting about the frog? 5. What did you specifically learn by doing the frog dissection? 6. Explain what you would do differently to have the lab be more successful. 8
FROG/HUMAN DIGESTIVE SYSTEM OBSERVATIONS
25 points possible
Directions: As you complete the frog dissection, draw (in detail) the digestive system of both the human and the
frog. Then write a summary comparing and contrasting the digestive system of both. Be thorough and clear.
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