Genetics Problems
ppt Questions
Independent Assortment
1. How many different kinds of gametes could the following
Remember the formula 2n where
n equals the number of heterozygotes.
individuals produce?
a. aaBb
b. CCDdee
c. AABbCcDD
d. MmNnOoPpQq
e. UUVVWWXXYYZz
P1, F1, and F2 Monohybrid Crosses
2. In dogs, wire-haired is due to a dominant gene (W), smoothhaired is due to its recessive allele (w). Show the results of
crossing a homozygous wire-haired dog with a smooth-haired
dog.
3. What kind of cross is this?
4. What was the genotype of all of the puppies? the phenotype?
5. The puppies belong to the _________ generation.
6. How would you write the F1 cross for this trait?
7. Show the results of working the F1 cross for this trait.
6. What phenotypic ratio did you get from this F1 cross?
7. What genotypic ratio did you get from this F1 cross?
8. Two wire-haired dogs are mated. Among the offspring of
their first litter is a smooth-haired pup. If these two dogs
mate again, what are the chances of them having another
smooth-haired pup?
9. What are the chances that the pup will be wire-haired?
10. A Wire-haired male is mated with a smooth-haired female.
The mother of the wire-haired male was smooth-haired. What
are the phenotypes and genotypes of the pups they could
produce? Show how you got your results.
Incomplete Dominance
11. In snapdragons, red flower color (R) is
incompletely
dominant
over white flower color (r). The hybrids or
heterozygous plants (Rr) are pink in color. Show the genotype
for a white flower and for a red flower.
12. If a red-flowered plant is crossed with a white-flowered
plant, what are the genotypes and phenotypes of the F1
generation plants? Show your work.
13. What is the phenotype of the flowers? what is their
genotype?
14. What genotypes and phenotypes will be produced in the F2
generation? Show your work.
15. How did the genotypic and phenotypic ratio compare to each
other in this incomplete dominance cross?
16. What would the phenotypic ratio have been if this had been
complete dominance?
17. What kind of offspring can be produced if a red-flowered
plant is crossed with a pink-flowered plant? Show your work.
18. What kind of offspring is/are produced if a pink-flowered
plant is crossed with a white-flowered plant? Show your work.
Sex-linked Traits
19. What is the genotype for female? for male?
20. In humans, colorblindness (Xc) is a recessive sex-linked
trait. Two people with normal color vision (XC) have a colorblind
son. What are the genotypes of the parents?
21. What are the genotypes and phenotypes possible among
their other children? Show your work.
22. A couple has a colorblind daughter. What are the possible
genotypes and phenotypes of the parents and the daughter?
Dihybrid Crosses
23. In humans, the presence of freckles is due to a dominant
gene (F) and the non-freckled condition is due to its recessive
allele (f). Dimpled cheeks (D) are dominant to non-dimpled
cheeks (d). Two persons with freckles and dimpled cheeks have
two children. One child has freckles but no dimples. The other
child has dimples but no freckles. What is the genotypes of the
parents? the children?
24. What are the possible phenotypes and genotypes of the
children that they could produce? Show all your work.
25. What phenotypic ratio did you get?
26. What genotypic ratio did you get?
27. What are the chances that they would have a child whom
lacks both freckles and dimples? What would be the child's
genotype?
28. A person with freckles and dimples whose mother lacked
both freckles and dimples marries a person with freckles but no
dimples whose father did not have freckles or dimples. What
are the chances that they would have a child whom lacks both
freckles and dimples? Show the genotypes of the parents and all
the offspring.
29. In dogs, the inheritance of hair color involves a gene (B) for
black hair and a gene (b) for brown hair. A dominant (C) is also
involved. It must be present for the color to be synthesized
(made). If this gene is NOT present, a blond condition results.
Complete the following table:
BB or Bb
bb
Color
Deposition
gene
CC or Cc
CC or Cc
BB or Bb
bb
cc
cc
Genotype
Phenotype
30. A brown-haired male, whose father was a blond, is mated
with a black-haired female ,whose mother was brown-haired and
her father was blond. What is the genotype of the man and
woman? Show the genotypes and phenotypes of all of their
offspring.
Population Genetics or Hardy-Weinberg Law
Sixteen percent (16%) of the human population is known to be
able to wiggle their ears. This trait is determined to be a
recessive gene. Use the following equations to answer this
population genetics problem:
1 = p2 + 2pq + q2
then use 1 = p + q
p2 - frequency of homozygous dominants
2pq - frequency of heterozygotes
q2 - frequency of homozygous recessives
p - frequency of dominant allele
q - frequency of recessive allele
31. What percent of the population is homozygous dominant for
this trait? Show your work.
32. What percent of the population is heterozygous for this
trait? Show your work.
Multiple Alleles
-
ABO Blood Type
33. Henry Anonymous, a film star, was involved in a paternity
case. The woman bringing the suit had two children. One child
had blood type A and the other child had blood type B. Her
blood type was O, the same as Henry's. The judge in the case
awarded damages to the woman, saying that Henry had to be
the father of at least one of her children. was the judge
correct in his decision? Show how you got your answer.