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Biology 101 – Exercise 13 – Connecting Meiosis and Genetics
Name
For all the problems, show your work!
1.
Phenylketonuria is a somewhat common disease in which the affected individual cannot
break down the amino acid phenylalanine. The disease is a recessive condition where the body’s cells
cannot make the protein involved in phenylalanine metabolism. Suppose a man who was
homozygous dominant (PP) for the PKU allele had a child with a woman who was heterozygous (Pp)
for the PKU allele.
a. Is it genetically possible for this child to have PKU? (5 points)
b. Would it be theoretically possible for this child’s children to be homozygous dominant
for the allele? (5 points)
No, it is not possible for this child to have PKU. He would have to be recessive for the PKU allele
(pp) and this is not possible since his father is homozygous dominant. The child will be either
homozygous dominant or heterozygous.
It is theoretically possible for this child to eventually have children who are homozygous dominant.
Since the kid has at least one dominant allele, as long as he does not marry a woman with PKU, his
child could have the PP genotype.
2.
Define the term diploid. (4 points)
Diploid = describes a cell or an organism that has two copies of each chromosome, i.e., twice the
haploid number
3.
TRUE or FALSE:
(2 points)
The number of chromosomes in a single sperm cell plus the
number of chromosomes in a single egg cell is greater than the
number of chromosomes in a single fertilized egg
4.
Label all the appropriate structures on this drawing with the following terms: centromere,
sister chromatids, non-sister chromatids. (4 points)
Centromere
Centromere
Sister chromatids
Nonsister chromatids
5.
Guess what phase of Meiosis I, this cell is in!!!! (4 points)
Metaphase I
6.
Centuries ago, males were sometimes castrated (testicles were removed) prior to puberty, so
that their voices would not change and they would be able to sing in a certain way. Would
such individuals still perform meiosis? Why?/Why not? (5 points)
No! In males, meiosis occurs for sperm formation which takes place in the seminiferous tubules of
the testes. No testes  No meiosis
7.
Take a look at cute little baby Harvey:
His paternal grandfather has type O blood. His paternal grandmother has type A blood.
His mom has type B blood. Is it possible for Harvey to have Type O blood? Show your
work/reasoning. (6 points)
Harvey’s father’s blood type could be IAi or ii. Thus it is theoretically possible for Harvey to receive
the i allele from his father. Harvey’s mom could have blood type I Bi, so it is possible that Harvey
could receive the i allele from her. Thus, it’s possible that Harvey could have type O blood.
8.
If 2n=14,
a.
b.
How many chromosomes will be present in somatic cells? (2pts)
How many chromosomes will be found in gametes? (2pts)
If n=14,
9.
a.
How many chromosomes will be found in diploid somatic cells? (2pts)
b.
How many sets of homologous chromosomes will be found in gametes?
(2pts)
A tall pea plant (tallness is dominant) is crossed with a recessive dwarf pea plant. What will
the phenotypic and genotypic ratio of offspring be?
a.
If the tall plant is TT? (4pts)
b.
If the tall plant is Tt? (4pts)