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Genetic Question Set 1 2011
1. Mendel: Who, What, Where and When?
2. He contributed two laws what are they?
3. How do the two laws work?
4. Define P generation and F generation.
a. What is the difference between the two?
Mendel studied pea plants. What characteristics did he study?
Characteristic
Dominant or Recessive
Allele
5. Use the characteristics from above and give an example of true breeding vs something that is
unknown. Use a punnett square.
6. Use the two laws from above to help answer the WHY of following:
a. Where characteristics he studied linked? In other words were yellow peas always
wrinkled? Did green peas always come from tall plants?
b. Give an example of how the two laws work:
i. Law of independent assortment
ii. Law of segregation
Chickens
Chickens that lay brown eggs have a dominant gene (B). Chickens that lay white
eggs are homozygous for the recessive gene (b). You have a brown egg- laying hen
named Henny Penny.
Use Punnett Squares when you can
1. What are Henny Penny’s possible genotypes?
2. If Henny Penny were homozygous for brown, show the possible genotypes,
using a punnet square, of her children if mated with a rooster who is pure
white?
3. What are the possible phenotypes of her children?
4. Let’s say that Henny penny had 5 chicks and later in life two of Henny’s
chicks mate (weird to us but not to chickens). Use the genotypes from #3.
What would be the possible genotypes?
5. What is the genotypic ratio?
6. What is the phenotypic ratio?
7. If Henny Penny were heterozygous, show the possible genotypes of her
children if she were mated with a rooster that is heterozygous for egg
laying.
8. What are the possible phenotypes of her children?
9. What is the genotypic ratio?
10. What is the phenotypic ratio?
Henny Penny has an unknown genotype:
11. If you cross Henny Penny with a rooster who is pure for white eggs and you
get just one white egg-laying hen out of her children, what can you say
about Henny Penn’s genotype?
12. If you cross Henny Penny with a rooster who is pure for white eggs and you
do not get any white egg laying hens, what can you say about Henny
Penny’s genotype.
Final Question:
13.A farmer has a hen house that is filled with 20 chickens and 2 roosters.
Rooster “A” always stays on the right while rooster “B” always stays on the
left. Chickens on the Right always lay brown eggs which is not desirable for
a majority of the population and is only sold to neighbors. The left side
always lays white eggs, which is sold at the local grocery store. One day the
farmer went out and found that the left side had 7 brown eggs. The color
for eggs is determined by one trait and brown has been determined to be
dominant. Explain what happened and explain the genotypes of the
roosters/chickens. How did the left side lay brown eggs?
Peas and other Crosses
1. In peas, yellow color is dominant to green. What will be the color of the offspring when
the following parents are crossed – females are listed first? (show with a punnet square)
a.) Homozygous yellow x green
Genotype ratio:
Phenotype ratio:
b.) Heterozygous yellow x green
Genotype ratio:
Phenotype ratio:
c.) Heterozygous yellow x homozygous yellow
Genotype ratio:
Phenotype ratio:
d.) Heterozygous yellow x heterozygous yellow
Genotype ratio:
Phenotype ratio:
2. Two long- winged fruit flies were mated. The offspring consisted of 76 with long wings
and 24 short wings. Is the short- winged condition dominant or recessive? What are the
genotypes of the parents?
3. The ability to roll the tongue into almost a complete circle is conferred by a dominant
gene, while its recessive allele fails in the ability to do so. A man and a woman can both
roll their tongues and are surprised to find that their son cannot. Explain this by showing
the genotypes of all three persons.
4. A man and a woman are heterozygous for tongue rolling, and have three sons. The
three sons marry women who are not tongue rollers. Assuming that each of the three
sons has a different genotype, show by Punnett Square diagrams what proportion of
their children might have the ability to roll their tongues.
a.) What is the genotype ratio for each of the sons offspring?
5. Suppose that in outer space there exist creature in which purple eyes (P) are dominant
to yellow eyes (p). Two purple- eyed creatures mate and produce six offspring. Four of
the offspring have purple eyes and two of them have yellow eyes.
a.) What are the genotypes of the parents?
b.) What are the genotypes of the offspring?
6. In a certain animal, black fur (B) is dominant to white fur (b). Determine the expected
genotypic and phenotypic ratios using a punnet square resulting from crosses between:
a.) Homozygous black x homozygous white
Genotype ratio:
Phenotype ratio:
b.) Two heterozygous blacks
Genotype ratio:
Phenotype ratio:
c.) Heterozygous black x homozygous white
Genotype ratio:
Phenotype ratio:
7. In humans, brown eyes, B, are dominant to blue eyes, b. A brown-eyed man marries a
blue-eyed woman. They have eight children, all are brown-eyed. What are the possible
genotypes of each person in the family?