Download More Practice

Genetics Problems
Name ____________________________
1. A pea plant with green pods is crossed with a plant with yellow pods. All their offspring have green pods.
a. Which allele is dominant? Which allele is recessive?
b. Using letters, what is the genotype of the green parent? The yellow parent?
c. What are the genotypes of the offspring?
2.
A brown mouse is mated with a white mouse. All of their offspring (75) are brown.
a. Which allele is dominant?
b.
What are the genotypes of these mice? Genotype of the offspring (F1 generation)
c.
If two of these brown offspring are mated, what fraction of their offspring will be white?
Freckles (F) is dominant to no freckles (f)
Widows peak (P) is dominant to straight hairline (p)
Free earlobes is (L) dominant to attached earlobes (l)
1.
Fred and Wilma have widow’s peaks. Their daughter Shirley has a straight hairline.
a. What are Fred and Wilma’s genotypes?
b.
2.
What is Shirley’s genotype?
A man and women, both without freckles have four children.
a. What are the genotypes of the parents?
b.
How many would you expect to have freckles
3.
A man and woman both have free earlobes, but their daughter has attached earlobes. What is the probability that their
next child will have attached earlobes?
4.
In dogs, wire hair (S) is dominant to smooth (s).
a. In a cross of homozygous wire-haired dog with a smooth-haired dog, what will be the phenotype of the offspring?
b.
What would be their genotype?
c.
If you allow these offspring to mate, what would be the ratio of wire-haired to smooth-haired dogs in the next
generation? Show your work.
5.
Make a cross between a heterozygous wire-haired dog and a smooth-haired dog. What is the chance of getting a wirehaired dog. Show your work.
6.
A couple is told that they are carrier (that is, heterozygous) for the disease cystic fibrosis.
a. What is the genotype of each parent?
7.
b.
Complete a punnett square for this couple
c.
d.
e.
What is the chance they will have a child with cystic fibrosis _____________
What is a chance that they will have a child who is a carrier?______________
What is the chance they will have a child who has a normal phenotype and has no chance of passing the disease
allele to children of their own? ______________________
If two plants are both heterozygous for flower color (purple is dominant to white). What is the expected phenotypic ratio
of their offspring?
Use this information for questions 8-9
Freckles is dominant to no freckles. Widows peak is dominant to straight hairline. Free earlobes is dominant to attached earlobes
8.
A man is heterozygous for free earlobes and has no freckles. His wife is heterozygous for freckles and heterozygous for
earlobes. They really want their child to have free earlobes and freckles. What is the chance they will get their wish?
9.
A man has no freckles and attached earlobes. His wife has freckles and free earlobes. They have 18 children (I know,
CRAZY). 10 of them have freckles and free earlobes and 8 of them have freckles and attached earlobes. What are the
genotypes of mom, dad, and the kids?
10. In pigs, mule hoof (fused hoof) is dominant while cloven foot is recessive. Belted coat pattern is dominant to solid color.
A cloven foot, heterozygous belted coat pig is mated with a homozygous mule hoof, heterozygous belted coat pig.
What is the chance of getting a solid colored, mule hoof pig?
11. In rabbits, black is dominant to brown, and spotted coat is dominant to solid coat. Give the genotypes of the parents if a
black, spotted male is mated with a brown, solid and all the offspring are black and spotted.
Use the information below for questions 10-16
In mice, the ability to run normally is a dominant trait. Mice with this trait are called running mice (R ), the recessive trait causes
mice to run in circles only. Mice with this trait are called waltzing mice (r ). Hair color is also inherited in mice. Black hair (B) is
dominant over brown hair (b)
12. Cross a heterozygous running, heterozygous black mouse with a homozygous, running heterozygous black mouse.
a. What are the genotypes of the parents?
b. Draw out a Punnett square
c.
What is the probable phenotype ratio?
d.
e.
What is the chance of getting running brown mouse?__________________
What is the chance of getting a running black mouse? _________________
13. Cross a heterozygous running, heterozygous black mouse with a heterozygous running, brown mouse.
a. what are the genotypes of the parents?
b. Draw the Punnett square
c.
d.
e.
What is the probable phenotypic ratio?______________
What is the chance of getting a running brown mouse?__________________
What is the chance of getting a running black mouse? ___________________
14. Cross a waltzing brown mouse with a waltzing brown mouse.
a. What are the genotypes of the parents?_______________________________
b. What is the chance of having a waltzing black mouse?
15. Cross a homozygous running, heterozygous black mouse with a waltzing brown mouse.
a. What are the genotypes of the parents?__________________________
b. Complete a Punnett square
c.
d.
What is the probable phenotype ratio?
What is the chance of getting running, black mouse?
16. A waltzing brown mouse was crossed with a waltzing black mouse. 42 mice were born and all were waltzing black mice. What
are the genotypes of the parents and the offspring?
17. Snapdragons show incomplete dominance. A pink flowered plant is crossed with a white flowered plant. What are the
phenotypic ratios of the offspring?
18. A red snapdragon is crossed with a pink plant. What are the phenotypic ratios of the offspring?
19. A garden enthusiast wants to grow as many pink flowered snapdragons as possible so she crosses two pink snapdragons. Is
this the best option? Is there a better option? Use Punnett squares to support your claim.
20. In cattle coat color shows codominance. When a red cow mates with a white cow the coat has both red and white hairs
and is called roan. What are the percentages of coat colors when two roan cows mate?
21. Mating what types of cows will produce the most roan coats in the offspring?
22. A man with blood type AB marries a woman with blood type O. What are the possible blood types of their children?
23. A man has blood type B. His mother had blood type O. What is his genotype?
24. A woman has blood type B and her child has blood type O. What are the possible blood types of the father?
25. A woman has blood type A. Her mother had type AB blood. She has a child with type O blood. Could this be her child?
Why or why not?
26. A woman is blood type A and has a child that is blood type B. What is the genotypes of the woman, her child, and all the
possible genotypes of the father
`
27. A child is born that has blood type O. A man is suspected of being the father, but he says it isn’t so. He has blood by AB.
Who is right?
Humans can be rh+ or rh- depending on whether or not they have an antigen called the rh factor on their RBCs. Being dominant is
the dominant trait.
28. A woman who is O- gives birth to a daughter who is A+. This daughter gives birth to a son who is AB-. What is the genotype
of
a. mom____________
b. Daughter __________
c. Son (grandson) _____________
d. Possible genotypes of the daughters husband ____________________________________________________
29. A woman is AB + and known to be heterozygous for the rh factor marries a man who is A+ and heterozygous for both the
ABO blood group and the rh factor. What is the possible phenotypic ratio of their offspring?
30. What is the chance the couple above would give birth to an A- child?
31. If a yellow guinea pig is crossed with a white one, the offspring are cream-colored.
What inheritance pattern does this trait follow?
Give the phenotypic ratio of the offspring produced from mating two cream-colored guinea pigs
32. If tall is dominant to dwarf (in plants) and a cross produces 100 plants. 73 of them are tall and 27 of them are dwarf. What
is the genotypes of the parents
33. In fruit flies, red eyes are dominant and white eyes are recessive. The gene for this trait is found on the X chromosome. A
white-eyed female fruit fly is crossed with a red-eyed male.
a.
b.
What are the genotypes of the parents
Draw a punnett square below
c.
What are the expected phenotypes of the offspring? ______________________
34. In a cross between a homozygous, red-eyed female fruit fly and a white-eyed male, what percent of the offspring will have
white eyes? (white eyes are X-linked, recessive)
d.
e.
Genotypes of parents:
Punnett square
f.
Answer the question
35. Hemophilia is a recessive disease in humans is due to an X-chromosome mutation. What will be the results of mating
between a normal (non-carrier) female and a hemophilac male?
g.
Genotypes of parents:
h.
Answer the question
36. A human female "carrier" is heterozygous for the recessive, sex-linked trait causing red-green color blindness. She marries
a normal male. What proportion of their children will have red-green color blindness?
i.
j.
Genotypes of parents:
Answer the question
37. A man who is color blind marries a woman who with normal vision who is homozygous.
k. Genotypes of parent:
l.
what will be true of their daughters?
m. What would be true of their sons?
38. A woman has hemophilia. Her mother did not. What is her genotype and what is the genotype of her parents?