Download Genetics Study Guide 16

Name: ______________________________________________________ Date: _________________
Genetics Study Guide 2016
1. If a blue-eyed (recessive) woman had children with a homozygous brown-eyed man, what is the
chance of any of their children having blue eyes. Show the Punnett Square.
2. If a blue-eyed woman had children with a heterozygous brown-eyed man, what is the chance of any
of their children having blue eyes. Show the Punnett Square.
3. If 2 heterozygous brown-eyed parents had children, what is the chance of any of their children
having blue eyes. Show the Punnett Square.
4. In purple people eaters, one-horn is dominant and no horns is recessive. Draw a Punnett Square
showing the cross of a purple people eater that is heterozygous for horns with a purple people eater
that does not have horns. Summarize the genotypes & phenotypes of the possible offspring.
5. Sickle cell anemia is a real recessive disease of the blood. It causes your red blood cells to be
crescent-shaped instead of round which means they can’t do their job of carrying oxygen in your
blood. Since it is a recessive disease that means you need two copies of the sickle cell gene to
show the disease. If instead you are a heterozygote- you have one good copy of the gene and one
sickle cell copy of the gene — you don’t show the disease. But you are carrying the one bad copy of
the gene and can pass it on to your children. Therefore, a heterozygote is also called a “carrier”.
Let’s consider a situation where two carriers marry and have children. Draw a Punnett Square
showing the cross and summarize the genotypes & phenotypes of the possible children. Say
whether the children have normal blood, are carriers, or have the sickle cell disease.
GENETICS PRACTICE 2: NON-MENDELIAN GENETICS
1. In radishes, the gene that controls color exhibits incomplete dominance. Pure-breeding red
radishes crossed with pure-breeding white radishes make purple radishes. What are the
genotypic and phenotypic ratios when you cross a purple radish with a white radish?
2. Crosses between a yellow rat and a yellow rat always produce yellow rats. Crosses between a
white rat and a white rat always produce white rats. But crosses of a white with a yellow produce a
cream rat. What are the genotype and phenotype ratios if you cross two creams?
3. In humans, the allele for albinism (lack of pigment) is recessive to the allele for normal skin
pigmentation. If two heterozygous parents have children what is the chance that a child will be
albino?
4. If normal parents have an albino child, what is the probability that their next child will be normal for
pigment?
5. Achondroplasia (dwarfism) is caused by a dominant gene. A woman and a man both with dwarfism
marry. If homozygous achondroplasia results in death of embryos, list the genotypes and
phenotypes of all potential live-birth offspring.
6. The genes for hemophilia are located on the X chromosome. It is a recessive disorder. List the
possible genotypes and phenotypes of the children from a man normal for blood clotting and a
woman who is a carrier. (HINT: You have to keep track of what sex the children are!)
7. Answer the following questions based on human blood group genetics.
The father of a child has type AB blood. The mother has type A. Which blood types can their children
NOT have? Show the Punnett Square.
8. A woman with type A blood and a man with type B blood could potentially have offspring with what
blood types?
9. The mother has type A blood. Her husband has type B blood. Their child has type O blood.
The father claims the child can’t be his. Is he right? Explain.
10. The mother has type B blood. Her husband has type AB blood. Their child has type O blood.
The father claims the child can’t be his. Is he right? Explain.
11. The mother has type AB blood. The father has type B blood. His mother has type O blood. What
are all the possibilities of blood type for their children?
GENETICS PRACTICE : Pedigrees and Vocabulary
1. An allele is: ______________________________________________________________
2. What is the difference between a genotype and a phenotype? Give an example of each.
3. In traditional inheritance, if the genotype consists of a dominant and recessive allele, the
phenotype will show which allele? Give an example.
4. Assuming that both parent plants in the diagram above are homozygous, why
would all of the f1 generation have yellow phenotypes?
5. When two traits are inherited together, and both show in the phenotype, not
as a mixture, this is called: ______________________________ when the
phenotype shows both traits as a mixture, this is
called___________________. Give one example of each of these types of
inheritance.
1. Traits that have MANY different versions, like human eye color are
called ____________________ traits. Give 2 more examples.
7. In the diagram above, what accounts for the green pea seed in the f2
generation?
8. For each of the genotypes below, determine the phenotype, assume traditional
inheritance.
Purple flowers are dominant to white flowers
PP ___________________________
Pp ___________________________
pp ___________________________
Brown eyes are dominant to blue eyes
BB ___________________________
Bb ___________________________
bb ___________________________
9. For each phenotype, list the genotypes. Choose the letter you would like to use.
Straight hair is dominant to curly.
____________ straight
____________ straight
____________ curly
Pointed heads are dominant to round heads.
____________ pointed
____________ pointed
____________ round
10. A black eyed, long haired male is crossed with a short haired,
brown eyed female. One of the offspring has short hair and black
eyes.
What is the father’s genotype? Phenotype?
What is the mother’s genotype? Phenotype?
What are the possible offspring’s genotypes?
Dominant
White Fur (F)
Tail (T)
Brown Eyes (B)
Long Hair (H)
Brown Nose (N)
Coarse Hair (D)
Round Ears (R)
Recessive
Brown Fur (f)
No tail (t)
Black Eyes (b)
Short Hair (h)
Pink Nose (n)
Fine Hair (d)
Pointed Ears (r)