Mrs. Keadle JH Science
The Genetics of Garden Peas
Introduction
Inheritance of genes explains all of the traits expressed in organisms, from the colors in
pea plant flowers to patterns of baldness in adult humans. The work of Gregor Mendel
(1822-1884) paved the way toward understanding dominant and recessive traits, and
helped geneticists analyze the influence of genes on health, appearance and sex.
You can check your answers by going to this web site:
http://library.thinkquest.org/17109/game.htm
Materials
8 Index Cards
Lab Sheet
Procedure
1. In this lab, you will play the role of a plant breeder. Index cards will represent your
plants. Divide your cards into 2 stacks, 1 with all P and one with all p. Each stack of
cards represents pure breeding stock. These are your Parental Generation or the
original mother and father.
2. In pea plants, P is dominant and it represents a tall, purple flowering pea plant with
round peas.
the letter p is recessive and it represent a short, white flowering pea plant with wrinkled
peas.
3. Turn both stacks of cards face down.
4. Draw one card from each stack, pair them up and set them aside face down. The first
pair will be parent 1. Repeat again and the second pair will be parent 2.
5. Next, separate the 8 cards into two stacks with 2 P and 2 p cards in each stack. Shuffle
these two stacks and place them face down.
6. Take one card from each stack and pair them up. This will be parent 1. Repeat to get
the genotype for parent 2.
7. Place the parents genotypes in the Punnett Square and fill in the offspring’s genotypes.
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The Genetics of Garden Peas
Mrs. Keadle JH Science
More interactive punnett square links. Visit these if you have extra class time.
http://vital.cs.ohiou.edu/steamwebsite/downloads/FurryFamily.swf
http://glencoe.mcgraw-hill.com/sites/dl/free/0078759864/383934/BL_05.html
http://www.tcet.unt.edu/tegs/chapter2/fires.swf
http://genetics.gsk.com/kids/heredity01.htm
http://www2.edc.org/weblabs/WebLabDirectory1.html
(Mendel’s Peas)
http://www.neok12.com/Genetics.htm
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The Genetics of Garden Peas
Mrs. Keadle JH Science
Name__________________________________ period _____
date assigned_____________ date due ______________ date returned _____________
The Genetics of Garden Peas
Follow instructions 1-4.
Cross 1. Place the parents genotypes in the Punnett Square and fill in the offspring’s
genotypes.
Parent 2
Parent 1
Results of Cross
Genotype
Phenotype
Was parent 1 homozygous or heterozygous?
______________________________________
Was parent 2 homozygous or heterozygous?
_______________________________________
What percent of the offspring were homozygous
dominant?____________________
What percent of the offspring were homozygous
recessive? ______________
What percent of the offspring were
heterozygous?_____________
What percent of the offspring were purple, tall
and round?___________________
The Genetics of Garden Peas
What percent of the offspring were white, short, 3
and wrinkled? _____________
Mrs. Keadle JH Science
Cross 2: Follow instructions 5-7.
Parent 2
Results of Cross
Genotype
Phenotype
Parent 1
Was parent 1 homozygous or heterozygous?_____________________________________
Was parent 2 homozygous or heterozygous?______________________________________
What percent of the offspring were homozygous dominant?____________________
What percent of the offspring were homozygous recessive? ______________
What percent of the offspring were heterozygous?_____________
What percent of the offspring were purple, tall and round?___________________
What percent of the offspring were white, short, and wrinkled? _____________
Cross 3: Repeat the process.
Parent 2
Results of Cross
Genotype
Phenotype
Parent 1
Was parent 1 homozygous or heterozygous?_____________________________________
Was parent 2 homozygous or heterozygous?______________________________________
What percent of the offspring were homozygous dominant?____________________
What percent of the offspring were homozygous recessive? ______________
What percent of the offspring were heterozygous?_____________
What percent of the offspring were purple, tall and round?___________________
What percent of the offspring were white, short, and wrinkled? _____________
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The Genetics of Garden Peas
Mrs. Keadle JH Science
Cross 4: Repeat the process.
Parent 2
Results of Cross
Genotype
Phenotype
Parent 1
Was parent 1 homozygous or heterozygous?_____________________________________
Was parent 2 homozygous or heterozygous?______________________________________
What percent of the offspring were homozygous dominant?____________________
What percent of the offspring were homozygous recessive? ______________
What percent of the offspring were heterozygous?_____________
What percent of the offspring were purple, tall and round?___________________
What percent of the offspring were white, short, and wrinkled? _____________
37. What genotypes would the parents need to have to produce ONLY purple, tall and
round? _________________________________________
38. What genotypes would the parents need to have to produce ONLY white, short and
wrinkled? _________________________________________
39 The work of Gregor Mendel was based on
his discovery that hereditary information
for two different forms of a trait can
coexist in one individual. He recognized
that one form of the trait can mask the
expression of the other. This principle is
known as -
40 What percentage of offspring from a
Tt x Tt cross would be tt?
A 25%
B 50%
C 100%
A the law of genotypes
D 0%
B the law of dominance
C the law of separation
D the law of sorting
The Genetics of Garden Peas
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Mrs. Keadle JH Science
USE THE FOLLOWING INFORMATION TO ANSWER THE QUESTIONS ON THIS PAGE.
In humans, eye color and hair color are controlled by several genes. Assume for the following
questions that each is controlled by only one. For eye color, brown (B) is dominant over blue (b)
and for hair color, black (H) is dominant over blonde (h).
A male with blue eyes produces offspring with a female that has brown eyes.
41 Which of the following represents
possible parental genotypes for eye
color?
43 The genotypes for hair color for the
parents are: Father hh Mother Hh
B Father: bb, Mother: Bb
Which of the following Punnett squares
correctly represents the possible
genotypes for hair color for the
offspring?
C Father: BB, Mother: Bb
A
HH
HH
HH
HH
B
Hh
Hh
hh
hh
C
Hh
Hh
hh
hh
D
HH
HH
Hh
Hh
A Father: bb, Mother: bb
D Father: Bb, Mother: BB
42 What is NOT a possible genotype for
eye color for the offspring?
A Bb
B BB
C bb
D There is not enough information
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The Genetics of Garden Peas
Mrs. Keadle JH Science
A dog breeder has begun to raise Labrador retrievers. So far, she hasn’t been able to predict
the color of the puppies that she breeds. She does not know that dark fur (D) is dominant over
yellow fur (d).
When the breeder crossed a yellow Lab female with a dark furred male, she expected half of
the puppies to be yellow and half to be dark. However, in a litter of eight puppies, all had dark
fur. The breeder next crossed the same yellow female with a different dark male. This time,
half the puppies were yellow and half were dark.
44 Which letters represent the most probable genotype of the second male?
A Dd
B DD
C DO
D dd
45 How can the woman breed a litter of all yellow puppies?
A By making sure that either the mother or the father is yellow
B By making sure that both the mother and father are yellow
C By making sure that at least one of the grandparents are yellow
D She cannot breed for a yellow litter because yellow fur is recessive.
46 The breeder is going to cross two dark Labs. One is homozygous and the other is
heterozygous. Predict what percentage of the puppies will be yellow.
A 0%
B 25%
C 50%
D 75%
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The Genetics of Garden Peas