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Please fully answer the following problems: 1, 2, 4, 6, and 9 that uploaded below. If you can do the rest I will appreciate it.
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Explanation & Answer

Kindly see attached file with the step by step solution of the genetic problems
Practice Genetics Problems
1) Jack and Jill are both heterozygous for albinism, a recessive trait. What proportion of their
offspring will be albino? What proportion will have a heterozygous genotype?
Let Aa be the heterozygous genotype for albinism, we can build the following Punnett square to
determine the proportion of albino offspring of Jack and Jill:
A
a
A
AA
Aa
A
Aa
aa
According to this Punnett square, we see that 1/4 of the offspring has the genotype aa, which
corresponds to albino people. Taking this into account, we find that the proportion of albino offspring
resulting from the cross between two heterozygous for albinism like Jack and Jill will be of 1/4 or 25%.
2) A breeder crosses a heterozygous guinea pig with a white one. A) If black is dominant,
predict the phenotypic ratio of the offspring. B) What would be the phenotypic ratio if a
homozygous black guinea pig mated with a white guinea pig?
A) Let B denote the dominant black color and b the recessive white color of guinea pigs. Taking this into
account, we can build the following Punnett square for a cross between a black heterozygous guinea pig
with a white one:
b
b
B
Bb (black)
Bb (black)
b
bb (white)
bb (white)
According to this Punnett square, the offspring is formed by 2 black and 2 white guinea pigs such that
the phenotypic ratio is 1(black)/1(white).
B) Let B denote the dominant black color and b the recessive white color of guinea pigs. Taking this into
account, we can build the following Punnett square for a cross between a black homozygous guinea pig
with a white one:
2
b
b
B
Bb (black)
Bb (black)
B
Bb (black)
Bb (black)
According to this Punnett square, the offspring is formed by 4 black and 0 white guinea pigs such that
the phenotypic ratio is 4(black)/0(white).
3) In snapdragons, neither the red allele nor the white allele for flower color is dominant.
The heterozygote is pink in color. What would be the phenotypic and genotypic ratios if a
pink flower is crossed with a white flower?
Let R denote the codominant red color and W the codominant white color of snapdragons. Taking this
into account, we can build the following Punnett square for a cross between a pink and a white flower:
R
W
W
RW (pink)
WW (white)
W
RW (pink)
WW (white)
According to this Punnett square, the offspring is formed by 2 pink (RW) and 2 white (WW) flowers the
phenotypic ratio is 1(pink)/1(white) and the genotypic ratio is 1(RW)/1(WW).
4) Myopia (nearsightedness) and PKU, a chemical disorder leading to mental retardation, are
both inherited as recessive traits occurring on separate chromosome pairs. A man who is a
carrier for both traits marries a woman with an identical genotype. What is the chance their
first child will be myopic? What is the chance that a child will have PKU? What is the chance
that a child will inherit both myopia and PKU simultaneously? What is the likelihood that a
child will have neither PKU nor myopia.
Let m denote the recessive allele for myopia and p the recessive allele for PKU, such that the
corresponding dominant alleles are M and P. Taking this into account, the genotype of
somebody who is a carrier for both recessive traits would be MmPp. The Punnett square for the
cross between two MmPp would be:
3
MP
Mp
mP
mp
MP
MMPP
MMPp
MmPP
MmPp
Mp
MMPp
MMpp
MmPp
Mmpp
(PKU)
mP
mp
MmPP
MmPp
MmPp
(PKU)
mmPP
mmPp
(myopia)
(myopia)
Mmpp
mmPp
mmpp
(PKU)
(myopia)
...
