Download Dr. Mo Elkerdany

Dr. Mo Elkerdany
GENETICS..practice PROBLEMS
1. For each of the following GENOTYPES, give all possible GAMETES.
a. WW
b. WWSs
c. Tt
d. Ttgg
e. AaBb
f. LLFf
2. For each of the following, indicate whether it represents a GENOTYPE or a
GAMETE.
a. D
b. Ll
c. Pw
d. LlGg
e. BbHH
3. If freckles are dominant to no freckles, and a man and a woman are
both HETEROZYGOUS for freckles; what are the possible
GENOTYPES and PHENOTYPES for their offspring? What is the
probability that their first child will have freckles? What is the
probability to have 2 children in a row with NO freckles?
4. Short fingers are DOMINANT over long fingers. A woman is
HOMOZYGOUS dominant for short fingers. Will any of her
children have long fingers?
5. Free earlobes are dominant over attached earlobes. Both you and
your sister have attached earlobes, but your parents have free
earlobes. Show the genotypes for all!!
6. Dimples are dominant over no dimples. If a man has dimples and a
woman does NOT have dimples, and all of their children have
dimples; show the genotypes for all!
7. If blue eyes are RECESSIVE to brown eyes; show the expected
genotypes and phenotypes of the children of a marriage between a
blue-eyed woman and a brown-eyed man who had a blue-eyed
mother. What is the probability of this couple to have 2 blue-eyed
daughters in a row!!
8. In humans, the gene for the ability to taste phenylthiocarbamide
(PTC) is dominant over that for inability to taste PTC. The gene for
brown eyes is dominant over that for blue eyes. WHAT [proportion
of offspring of two parents, each is HETEROZYGOUS for both
traits would be expected to be blue-eyed tasters of PTC? WHAT
proportion of the offspring would be blue-eyed and non-tasters of
PTC?
9. The gene for astigmatism is inherited as dominant. Two
heterozygous for astigmatism marry. What is the probability that
they will have 2 normal children in a row?
10. WHAT is the probability for a couple to have 2 boys in a row? And
3 boys in a row?!
11. Two brown-eyed parents have a blue-eyed child. What is the
probability that their next child will be blue-eyed?
12. Albinism is autosomal recessive trait. A homozygous woman with
normal pigmented skin married an albino man. What is the
probability for this couple to have an albino child?
13. A man who has dimples and freckles marries a woman who does
not have dimples or freckles. This couple produced a child that does
NOT have dimples or freckles. Give the genotypes of all the
individuals mentioned.
14. If this child (in question #13) marries someone who is heterozygous
for both traits; what is the probability that they will have a child with
the same GENOTYPE as its grandmother?!
15. Achondoplasia (dowarfism) is inherited as autosomal dominant
trait. If a heterozygous man for the trait (dwarf) married a normal
woman, what is their probability to have a normal height boy?
16. If two heterozygous (2 dwarfs) for the same trait (achondoplasia)
married, what is their probability to have two normal children in a
row?
17. From the following blood types; determine which baby belongs to
which parents:
Mrs. Doe—blood type A
Mr. Dow—blood type A
Mrs. Jones—blood type A
Mr. Jones—blood type AB
Baby 1 -- blood type O
Baby 2—blood type B
Doe’s baby is ______________ Jones’ baby is ________________
18. Show that a child does NOT have to have the blood type of either
parent by indicating that blood types might be possible when a
person with blood type “A” reproduces with a person with blood type
“B”.
19.A man with blood type “AB” has children with a woman with blood
type “O”. What are the chances that a child they will conceive will
have blood type “A”? Blood type “B”? Blood type “AB”? Or blood
type “O”?
20. David is heterozygous for widow peak and dimples. Both widow’s
peak and dimples are dominant traits. His wife is heterozygous for
widow’s peak. She has NO dimples. What is the genotype of both?