Genetics Problems, biology homework help

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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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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? 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? 2 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? 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. 3 5) Betsey is color-blind, a condition due to a sex-linked recessive allele. She marries a normal man. What phenotypes will their offspring exhibit? 6) In corn the allele for purple kernels (P) is dominant to the allele for yellow kernels (p), and the allele for smooth kernels (S) is dominant to the allele for wrinkled kernels (s). What would be the genotypic and phenotypic ratios if a heterozygous purple smooth corn plant is crossed with a yellow wrinkled corn plant. 4 7) In humans, hemophilia is sex-linked and is recessive to normal blood clotting. Henry and Sara, both with normal clotting, have three children: 1) a hemophiliac son, Bob, who later has a normal clotting daughter; 2) a normal clotting daughter, Mary, who later has one hemophiliac and one normal clotting son; and 3) a normal clotting daughter, Jill, who later has three sons, all normal clotting What are the probable genotypes of each of the individuals? 8) Alisha has blood type B. Her mother has blood type O. Alisha marries Jared, who has blood type AB. a. What is Alisha’s genotype? b. What is Jared’s genotype? c. Using a Punnett square, determine the probability of the couple having a child with the following: blood type B? blood type O? blood type AB? blood type A? 5 9) Achondroplasia is an autosomal dominant condition that results in short stature or dwarfism due to lack of bone growth. Ndidi has achondroplasia and is concerned about passing it on to her children. Her father was of average height, but her mother had achondroplasia. a. What are the genotypes of Ndidi’s mother and father? b. What is Ndidi’s genotype? c. Ndidi wants to have children with Abubakar who does not have achondroplasia. What is his genotype? d. What is the chance that Ndidi and Abubakar’s children will have achondroplasia?
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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)
...

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