Category: My Classroom Material

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?

 

 

Percents, Fractions, Decimals

 

Decimals, Fractions and Percentages

Decimals, Fractions and Percentages are just different ways of showing the same value:

A Half can be written…
As a fraction:
1/2
As a decimal:
0.5
As a percentage:
50%

 

A Quarter can be written…
As a fraction:
1/4
As a decimal:
0.25
As a percentage:
25%

Example Values

Here is a table of commonly occurring values shown in Percent, Decimal and Fraction form:

PERCENT DECIMAL FRACTION
1% 0.01 1/100
5% 0.05 1/20
10% 0.1 1/10
12½% 0.125 1/8
20% 0.2 1/5
25% 0.25 1/4
331/3% 0.333… 1/3
50% 0.5 1/2
75% 0.75 3/4
80% 0.8 4/5
90% 0.9 9/10
99% 0.99 99/100
100% 1 100/100
125% 1.25 5/4
150% 1.5 3/2
200% 2 4/2

 

Conversions

From Percent to Decimal

To convert from percent to decimal: divide by 100, and remove the “%” sign.

The easiest way to divide by 100 is to move the decimal point 2 places to the left. So:

From Percent To Decimal
move the decimal point 2 places to the left, and remove the “%” sign.

 

From Decimal to Percent

To convert from decimal to percent: multiply by 100, and add a “%” sign.

The easiest way to multiply by 100 is to move the decimal point 2 places to the right. So:

From Decimal To Percent
move the decimal point 2 places to the right, and add the “%” sign.

 

From Fraction to Decimal

The easiest way to convert a fraction to a decimal is to divide the top number by the bottom number (divide the numerator by the denominator in mathematical language)

Example: Convert 2/5 to a decimal

Divide 2 by 5: 2 ÷ 5 = 0.4

Answer: 2/5 = 0.4

 

From Decimal to Fraction

To convert a decimal to a fraction needs a little more work.

Example: To convert 0.75 to a fraction

STEPS EXAMPLE
First, write down the decimal “over” the number 1 0.75 / 1
Then multiply top and bottom by 10 for every number after the decimal point (10 for 1 number, 100 for 2 numbers, etc) 0.75 × 100 / 1 × 100
(This makes it a correctly formed fraction) = 75 / 100
Then Simplify the fraction 3 / 4

 

From Fraction to Percentage

The easiest way to convert a fraction to a percentage is to divide the top number by the bottom number. then multiply the result by 100, and add the “%” sign.

Example: Convert 3/8 to a percentage

First divide 3 by 8: 3 ÷ 8 = 0.375,
Then multiply by 100: 0.375 x 100 = 37.5
Add the “%” sign: 37.5%

Answer: 3/8 = 37.5%

 

From Percentage to Fraction

To convert a percentage to a fraction, first convert to a decimal (divide by 100), then use the steps for converting decimal to fractions (like above).

Example: To convert 80% to a fraction

STEPS EXAMPLE
Convert 80% to a decimal (=80/100): 0.8
Write down the decimal “over” the number 1 0.8 / 1
Then multiply top and bottom by 10 for every number after the decimal point (10 for 1 number, 100 for 2 numbers, etc) 0.8 × 10 / 1 × 10
(This makes it a correctly formed fraction) = 8 / 10
Then Simplify the fraction 4 / 5

Adapted from MATH IS FUN!

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.

Perch Prelab

 

 

Perch Dissection Prelab

 

1. Perch belong to what class of bony fish?

2. Are perch ray-finned or lobe-finned fish? Explain.

 

3. Name the fins found on a perch. What function(s) to the fins serve?

 

 

4. Give the function for the swim bladder.

 

5. Describe the external appearance of a yellow perch.

 

6. What is the scientific name for the yellow perch?

7. Describe spawning of yellow perch.

 

8. Name several organs that belong to the digestive system of the perch.

 

9. Describe the heart of a perch & explain blood flow through this organ.

 

10. Where is the lateral line found 7 what is its job?