Category: Resources

Planarian Regeneration Activity

Flatworms – Observation of a Live Planarian

click here for background

 

You will receive a small petri dish with a flatworm inside it.  The flatworm is the freshwater planarian, also known as Dugesia.

 

1.  List 3 characteristics of flatworms.

 

 

 

2.  What type of symmetry does this worm have?


3.  Where do planarians live?

 

 

4.  Observe your worm, using a microscope or hand lens. Sketch the planarian below. Label the eyespots. Label the anterior and posterior ends. 

 

 

 

 

 

 

5.  Measure your planarian.  This operation is best performed by removing some of the water from the dish and waiting for the worm to stretch out.   Measure the length of the worm in millimeters.  (Always replace the water; you can use the dish lid to transfer water to and from the planarian environment.)

 

 Length of Planarian  _______mm

 

Write your length on the board and when all the lengths are down, determine the average planarian size.

 

 Average    ____________ mm

 

6.  Observe the planarian for five minutes. Does the planarian seem active or passive?  How does it move?  Does it swim or creep?   Where in the dish does it spend most of its time? Make a current in the water with a pipette.  How does the planarian react?  Fill out the table below.

  Description
Movement   
Worm location  
Reaction to current  

  

7.  Planarians actually display a “handedness” being right or left handed.   You can discover whether your worm is right or left handed by flipping the planarian over on its dorsal (back) and seeing which way it recovers.   If it rolls to the right, it is right handed, if it rolls to the left, it is left-handed.    Do five trials to determine the handedness of your planarian. 

 Fill out the data table:

  Which way does it turn (left or right)
Trial 1  
Trial 2  
Trial 3  
Trial 4  
Trial 5  

 

Based on your data, is your planarian right or left handed?   ____________

 

8.   Design an experiment to test the planarians reaction to light and dark.  You will have flashlights and the room will be darkened for this part of the lab. Describe your experiment.

 

 

   

Conduct your experiment to determine whether the planarian prefers light or dark.   Construct a data table

 

 

     

Write your conclusions.  Make sure you answer the question:  Does the planarian prefer a light or dark environment and include your reasoning.

 

   

 

9.  Drop a piece of food into the petri dish with the planarian.  Observe the planarian’s reactions.  It may take a few minutes.   How does it eat the food?   Where is its mouth?  Use the space below to write your observations.

 

Reaction to food _______________________________________________________

 

How does it feed?

 

 

Where is the mouth located?

 

What is the name of the tube used for feeding in the planarian?

 

Planarian Reproduction –Make sure your planarian has finished eating entirely and its pharynx is withdrawn, if it gets too close to the end of the hour, ask your teacher for a different planarian

 

Planarians are hermaphrodites.  Define hermaphrodite

 

   

Planarians can also reproduce by regeneration. Define regeneration.

 

   

Is this method of reproduction sexual or asexual?

 

Pour out some of the water, so that the planarian is mostly un-submerged.  When it stretches out, use a razor blade to cut it cleanly in half. Replace the water and put the lid on it. Observe the two pieces of the planarian under the microscope.  

Fill out the table below.

 

Movement (observations) Sketch
Anterior end  

 

 

     

Posterior end

 

 

Label the lid with your NAME and HOUR.

 

Make a prediction:  How long do you think (in days) will it take for your planarian to completely regenerate?

 

 

Potato Osmosis Bi Lab

 

Potato Osmosis

 

Introduction:

A shipwrecked sailor is stranded on a small desert island with no fresh water to drink. She knows she could last without food for up to a month, but if she didn’t have water to drink she would be dead within a week. Hoping to postpone the inevitable, her thirst drove her to drink the salty seawater. She was dead in two days. Why do you think drinking seawater killed the sailor faster than not drinking any water at all? Today we explore the cause of the sailor’s death. We’ll prepare solutions of salt water to represent the sea, and we’ll cut up slices of potato to represent the sailor. Potatoes are made of cells, as is the sailor!

Objective:

The concentration of solute in a solution will affect the movement of water across potato cell membranes.

Materials:

potato, corer, 3 plastic cups, marker, salt, sugar, distilled water, paper, pencil, electronic balance, clock with second hand or timer, metric ruler, small ziplock plastic bag, foil or plastic wrap

Procedure:

Day 1

  1. Use a knife to square off the ends of your potato. Your potato’s cells will act like the sailor’s cells.
  2. Stand your potato on end & use your cork borers to bore 3 vertical holes.

  1. Remove the potato cylinders from the cork borer & measure their length in centimeters.
  2. Cut the 3 potato cylinders to the same length (about 4 -5 centimeters long).
  3. Record the length & turgidity of the potato cylinders in your data table (day 1).
  4. Place the 3 potato cylinders in a small ziplock bag to prevent them from dehydrating before they’re used.
  5. Take 3 plastic cups and label them with the solution that will be placed in each one — sugar, salt, distilled water.
  6. Prepare a saturated solution of salt by mixing as much salt as you can with water.
  7. Repeat this step by making a saturated sugar solution.
  8. Now fill each cup 2/3’s full of the correct solution —- sugar water, salt water, or distilled water.
  9. Mass each of the potato cylinders & record this mass in grams on your data table.
  10. Place one of your potato cylinders into each cup and cover the top of the cup with foil or plastic.
  11. Leave the potato cylinders in the solution for 24 hours.

Day 2

  1. Carefully remove the potato cylinder from the distilled water solution & pat it dry on a paper towel.
  2. Measure the length of the potato cylinder & record this length & the appearance of the cylinder on your data table. (day 2)
  3. Measure & record the mass of this cylinder.
  4. Repeat steps 13-15 for the potato cylinders in the salt solution & the sugar solution.
  5. Clean up your equipment & area and return materials to their proper place.

Data:

 

Results of Osmosis in Potato Cells
Solution Initial length
cm
(day1)		 Final length
cm
(day2)		 Change in length
cm		 Initial Mass
g
(day1)		 Final Mass
g
(day2)		 Change in mass
g		 Initial Turgidity
(flaccid or crisp)		 Final Turgidity
(flaccid or crisp)		 Tonicity of Solution
(iso-, hypo-, or hpertonic)
Distilled water
Salt Solution
Sugar Solution

 

Results & Conclusions:

1. Did any of the potato cylinders change in their turgidity (flexibility), and if so, which ones changed?

 

2. Explain why the flexibility of the potato slices changed.

 

3. Define isotonic, hypotonic, & hypertonic solutions.

 

4. If potato slices changed in length or turgidity, what process was responsible for this?

 

5. Make a sketch of your potato cylinder in the distilled water and use arrows to show the direction of water movement across the potato cell membranes.

 

 

6. What type of solutions were the salt & sugar solutions. Explain how you know this.

 

7. Which solution served as the control for this experiment & why?

 

8. In which solutions was their a greater solute concentration outside of the cells?

 

9. In which direction did water move through these cell membranes?

 

10. In what type of solution do plant cells do best & why?

 

11. Using the information you’ve discovered from this experiment, explain why the sailor died that drank saltwater.

 


BACK

Pedigree Lab

Constructing a Pedigree

Introduction

A pedigree is a special chart or family tree that uses a particular set of standardized symbols. Pedigrees are used to show the history of inherited traits through a family. In a pedigree, males are represented by squares and females by circles . An individual who exhibits the trait in question, for example, someone who suffers from hemophilia, is represented by a filled symbol or . A horizontal line between two symbols represents a mating . The offspring are connected to each other by a horizontal line above the symbols and to the parents by vertical lines. Roman numerals (I, II, III, etc.) symbolize generations. Arabic numerals (1,2,3, etc.) symbolize birth order within each generation. In this way, any individual within the pedigree can be identified by the combination of two numbers (i.e., individual II3).

Objective

Inherited traits can be traced through a family’s history by constructing a pedigree chart.

Materials

Large sheet of paper or poster board
Markers
Ruler
Protractor

Procedure
Part 1

1.      Examine Figure 1 that traces the ability to roll your tongue through three generations in a family. Remember: Blackened circles show the trait and circles are females and squares are male.

2.    Determine which parents and which offspring would be able to roll their tongue.  

FIGURE 1

 

Part 2

3.    Read the Passage 1 about the Smith family and their inherited trait of dimples.

4.    After reading the passage, construct a pedigree showing all family members in each generation that does and does NOT have dimples.

5.    Once the pedigree is constructed, write the correct genotype by each person in the family.

 

Passage 1

Grandfather and Grandmother Smith smiled a lot and showed off their dimples each time. They had a son named John, who had dimples, and daughter named Julie, who did not. Julie died at an early age, but her brother John Smith met and married Mary Jones because she had the most beautiful dimples when she smiled. They had 5 children, 2 boys and 3 girls. Only one of their sons, Tom, had dimples, but both girls, Judy and Kay, had dimpled smiles. Their sister June lacked dimples. After college, Tom met and married Jane Kennedy who also had dimples. They had 3 children, all girls, who shared their parent’s dimpled smile. Tom’s sister Kay married a lawyer named James who seldom smiled and didn’t have dimples. Their only son Matthew was like his mother when he smiled. Judy never married. Tom’s sister, June, married a doctor and had 5 children. Three of the children were boys, Jay, Fred, and Mike. Mike and Fred had dimples like dad, but Jay’s smile was like his mom’s lacking dimples. One sister, Susan, had dimples, but the other, Katherine, didn’t.

 

Questions

1.      What type of information does a pedigree contain?

2.    How do you show the presence of a trait in a pedigree?

3.    How do you denote males & females in a pedigree?

4.    From your pedigree, is the presence of dimples a dominant or recessive trait?

5.     How could examining a family pedigree be helpful to a couple wanting to have children?

 

 

Perch Dissection 2

 

Perch Dissection

 

Introduction:

The fish in the class Osteichthyes have bony skeletons. There are three groups of the bony fish — ray-finned fish, lobe-finned fish, and the lung fish. The perch is an example of a ray-finned fish. Its fins have spiny rays of cartilage &/or bone to support them. Fins help the perch to move quickly through the water  and steer without rolling. The perch also has a streamline body shape that makes it well adapted for movement in the water. All ray-finned fish have a swim bladder that gives the fish buoyancy allowing them to sink or rise in the water. The swim bladder also regulates the concentration of gases in the blood of the fish. Perch have powerful jaws and strong teeth for catching and eating prey. Yellow perch are primarily bottom feeders with a slow deliberate bite. They eat almost anything, but prefer minnows, insect larvae, plankton, and worms.  Perch move about in schools, often numbering in the hundreds.

The scientific name for the yellow perch, most often used in dissection, is Perca flavescens (Perca means “dusky”; flavescens means “becoming gold colored”). The sides of the yellow perch are golden yellow to brassy green with six to eight dark vertical saddles and a white to yellow belly. Yellow perch have many small teeth, but no large canines. Yellow perch spawn from mid-April to early May by depositing their eggs over vegetation or the water bottom, with no care given. The eggs are laid in large gelatinous adhesive masses.

Prelab Questions (Click Here)

Materials:

Preserved perch, dissecting pan, scalpel, scissors, forceps, magnifying glass, dissecting pins, apron, gloves, eye cover, tape measure

Procedure (External Anatomy):

  1. Obtain a perch & rinse off the excess preservative. Place the perch in your dissecting pan.
  2. Label the anterior, posterior, dorsal, and ventral sides of the perch on Figure 1.
  3. Use your tape measure to determine the total length, fork length, and girth of your fish. Record  this in Table 1.

Table 1 – Fish Measurements (inches)

 

Total Length
Fork Length
Girth

 

  1. Locate the 3 body regions of the perch — head, trunk, and tail. Label these on Figure 1.
  2. Open the perch’s mouth and observe its bony jaws. Locate and label the upper jaw or maxilla and the lower jaw or mandible.
  3. Feel the inside of the mouth for the teeth. Locate & label the tongue & teeth on Figure 1.
  4. Open the mouth wider and use a probe to reach back to the gill chamber.
  5. Locate the nostrils and label on Figure 1.
  6. Locate and note the location of the eyes. Label on Figure 1.
  7. Find the bony covering on each side of the fish’s head called the operculum. The opercula cover & protect the gills. Label these on Figure 1.

Figure 1 – External Perch anatomy

  1. Use a probe to lift the operculum and observe the gills. Note their color.
  2. Use a scissors to cut away one operculum to view the gills. Find the gill slits or spaces between the gills.
  3. Use your scalpel to carefully cut out one gill. Find the cartilage support called the gill arch and the soft gill filaments that make up each gill. Label the parts of the gill in Figure 2.

Figure 2 – Gill Structure

  1. Observe the different fins on the perch. Locate the pectoral, dorsal, pelvic, anal, and caudal fins. Note whether the fin has spines. Label these on Figure 1 and complete Table 2 on fins.

Table 2 – Fins

 

Name of Fin Spines
(yes or no)		 Number of Fins Location Function
 

 
 

 
 

 
 

 
 

 

 

  1. Locate the anus on the perch anterior to the anal fin. In the female, the anus is in front of the genital pore, and the urinary pore is located behind the genital pore. The male has only one pore (urogenital pore) behind the anus. Determine the sex of your perch.
  2. Find the lateral line on the side of your perch. Label this line on Figure 1.
  3. Use forceps to remove a few scales from your fish. Observe the scales under the magnifying glass. Sketch a scale on Figure 3.

Figure 3 – Structure of a Scale

 

 

  1. Count the growth rings on your scale to tell the age of your fish. (Hint: each ring represents one year’s growth.)

 

Procedure (Internal Anatomy):

  1. Use dissecting pins to secure the fish to the dissecting pan. Use scissors to make the cuts through skin and muscle shown in Figure 4.

Figure 4 – Cut Lines for Internal dissection

  1. After making the cuts, carefully lift off the flap of skin and muscle to expose the internal organs in the body cavity.
  2. Locate the cream colored liver in the front of the body cavity. Also locate the gall bladder between the lobes of the liver. Label these on Figure 5.
  3. Remove the gall bladder & liver to observe the short esophagus attached to the stomach. Label the stomach on Figure 5
  4. At the posterior end of the stomach are the coiled intestines. Locate and then label these on Figure 5.
  5. Find the small reddish brown spleen near the stomach and label this on Figure 5.
  6. Below the operculum, are the bony gill rakers. Locate these & them label them on Figure 5.
  7. In front of the liver & behind the gill rakers is the pericardial cavity containing the heart. The heart of a fish only has 2 chambers — an atrium & and a ventricle. Locate the heart & label it on Figure 5.
  8. In the upper part of the body below the lateral line is the swim bladder. This sac has a thin wall and gives the fish buoyancy. Label the swim bladder on Figure 5.
  9. Below the swim bladder are the gonads, testes or ovaries. In a female, these may be filled with eggs. Label the gonads on Figure 5.
  10. Find the 2 long, dark kidneys in the posterior end of the perch. These filter wastes from the blood. Label the kidneys in Figure 5.
  11. Wastes exit the body through the vent located on the ventral side of the perch. Label this structure on figure 5.

Figure 5 – Internal Perch Anatomy

Questions & Observations:

1. Are both jaws of the fish equally movable? Explain your answer.

 

2. Does the perch have eyelids?

3. How many gills are located on each side of the perch? What covering protects them?

4. What is the function of the gill rakers?

5. Explain how gas exchange occurs at the gills.

 

6. Which fin was the largest? What other difference do you notice in this fin when it was compared to the others?

 

7. What was the sex of your fish?

8. What is the function of the lateral line?

 

9. Describe how the scales are arranged on the trunk & tail of your fish.

 

10. Explain how the swim bladder controls buoyancy.