BIO325 Final Exam Questions with Verified
Correct Answers
Two short-haired cats mate and produce six short-haired and two long-haired kittens. What
does this information suggest about the inheritance of hair length?
Select all that apply.
-Two short-haired cats that mated can each produce two genetically different gamete types
-Two long-haired kittens are pure-breeding
In corn, having ligules (L) is dominant to liguleless (l), and green leaves (G) is dominant to
white leaves (g).
If a pure-breeding plant that is liguleless and has green leaves is crossed to a pure-breeding
plant with ligules and white leaves, their F1 offspring would have the genotype of Ll Gg and
the phenotype of green and ligules .
-LlGg
-green and ligules
If the parents of a family already have two boys, what is the probability that the next two
offspring will be a girl and a boy? Assume that boys and girls are equally likely.
0.5
Why do scientists think that all forms of life on earth have a common origin?
-All living organisms use the same genetic code
-Proteins from different organisms have similar amino acid sequences
-Genes from different organisms have similar nucleotide sequences
-Different organisms have related genes that carry out similar function
In corn, having ligules (L) is dominant to liguleless (l), and green leaves (G) is dominant to
white leaves (g).
If a testcross is performed with a dihybrid plant (i.e. heterozygous for two genes), what
proportion of the progeny would be green and liguleless?
1/4
,For an individual who has 10 gene pairs on 10 different chromosomes, how many genetically
distinct gametes can form if four of the gene pairs are homozygous and the remaining six gene
pairs are heterozygous?
64
Sickle cell anemia is a recessive disease in humans. Two carriers of the sickle cell allele (but
without the disease) marry and have three children. What is the probability that all three
children will be normal?
27/64
Sickle cell anemia is a recessive disease in humans. Two carriers of the sickle cell allele (but
without the disease) marry and have three children. What is the probability that at least one
child will be normal?
(Hint: An easier way to approach this problem is to first think about the probability of NOT
having any normal child and consider the sum of all probabilities.)
63/64
In some genetically engineered corn plants, a Bt gene was added to a chromosome. The Bt
gene specifies a protein called Bt that is lethal to certain flying insect pests that eat the corn
plants.
How would the amount of Bt protein in a corn plant homozygous for the Bt gene compare to
that in a hybrid (heterozygote with just one copy of the Bt gene)?
The homozygous transgenic plant is expected to have more Bt protein than the hybrid
In some genetically engineered corn plants, a Bt gene was added to a chromosome. The Bt
gene specifies a protein called Bt that is lethal to certain flying insect pests that eat the corn
plants.
If a corn plant is heterozygous for the Bt gene (one homolog has the introduced Bt gene and
the other does not), what proportion of its pollen (sperm) would carry the Bt gene?
50%
Achondroplasia is a form of dwarfism in humans. It is caused by a mutant allele of the
fibroblast growth factor receptor (FGFR) gene that produces an overactive protein. Having one
copy of the mutant allele results in dwarfism. Having two copies of the mutant allele results
in stillbirth. (Infant dies in the womb.)
Which allele, the mutant allele or the wild-type allele, is dominant with respect to viability?
Wild-type allele
, If two people with achondroplasia have a child together, what is the probability that their
child will also have achondroplasia?
2/3
Two alleles of gene C control hair color in horses: C¹ and C². Horses homozygous for C¹ allele
are red, heterozygotes are yellow, and C² homozygotes are cream.
Assuming C¹ makes an enzyme that produces red pigment, and C² makes a nonfunctional
enzyme, what is a plausible molecular explanation for the inheritance of hair color in horses?
The amount of functional red-producing enzyme made in heterozygotes is not enough to make
them red
In the offspring of mating between a red horse and a yellow horse, what phenotypic ratio is
expected?
1 red: 1 yellow
Part II (Do Part I first): Below is a pedigree of a human genetic disease in which solid color
indicates affected individuals. Assume that the disease is caused by a gene that has two
different alleles A and a, and the disease allele is rare.
In generations II and III combined, how many individuals are heterozygotes for sure (100%
chance)?
4
Based on this pedigree, the most likely mode of inheritance of the disease is __________, and
the genotype of the female 4 is _________
dominant; Aa
If the female 4 marries an affected man (exhibiting the disease) whose parents are both
heterozygotes, what is the probability that they will have a normal child?
1/6
When a pure-breeding, homozygous black rat was crossed to a homozygous albino, all of the
F1 rats were black. When the F1 rats were crossed to each other, the F2 consisted of 161 rats:
93 black, 30 cream, and 38 albino.
What is the genotype of the albino parent?
bbpp
Correct Answers
Two short-haired cats mate and produce six short-haired and two long-haired kittens. What
does this information suggest about the inheritance of hair length?
Select all that apply.
-Two short-haired cats that mated can each produce two genetically different gamete types
-Two long-haired kittens are pure-breeding
In corn, having ligules (L) is dominant to liguleless (l), and green leaves (G) is dominant to
white leaves (g).
If a pure-breeding plant that is liguleless and has green leaves is crossed to a pure-breeding
plant with ligules and white leaves, their F1 offspring would have the genotype of Ll Gg and
the phenotype of green and ligules .
-LlGg
-green and ligules
If the parents of a family already have two boys, what is the probability that the next two
offspring will be a girl and a boy? Assume that boys and girls are equally likely.
0.5
Why do scientists think that all forms of life on earth have a common origin?
-All living organisms use the same genetic code
-Proteins from different organisms have similar amino acid sequences
-Genes from different organisms have similar nucleotide sequences
-Different organisms have related genes that carry out similar function
In corn, having ligules (L) is dominant to liguleless (l), and green leaves (G) is dominant to
white leaves (g).
If a testcross is performed with a dihybrid plant (i.e. heterozygous for two genes), what
proportion of the progeny would be green and liguleless?
1/4
,For an individual who has 10 gene pairs on 10 different chromosomes, how many genetically
distinct gametes can form if four of the gene pairs are homozygous and the remaining six gene
pairs are heterozygous?
64
Sickle cell anemia is a recessive disease in humans. Two carriers of the sickle cell allele (but
without the disease) marry and have three children. What is the probability that all three
children will be normal?
27/64
Sickle cell anemia is a recessive disease in humans. Two carriers of the sickle cell allele (but
without the disease) marry and have three children. What is the probability that at least one
child will be normal?
(Hint: An easier way to approach this problem is to first think about the probability of NOT
having any normal child and consider the sum of all probabilities.)
63/64
In some genetically engineered corn plants, a Bt gene was added to a chromosome. The Bt
gene specifies a protein called Bt that is lethal to certain flying insect pests that eat the corn
plants.
How would the amount of Bt protein in a corn plant homozygous for the Bt gene compare to
that in a hybrid (heterozygote with just one copy of the Bt gene)?
The homozygous transgenic plant is expected to have more Bt protein than the hybrid
In some genetically engineered corn plants, a Bt gene was added to a chromosome. The Bt
gene specifies a protein called Bt that is lethal to certain flying insect pests that eat the corn
plants.
If a corn plant is heterozygous for the Bt gene (one homolog has the introduced Bt gene and
the other does not), what proportion of its pollen (sperm) would carry the Bt gene?
50%
Achondroplasia is a form of dwarfism in humans. It is caused by a mutant allele of the
fibroblast growth factor receptor (FGFR) gene that produces an overactive protein. Having one
copy of the mutant allele results in dwarfism. Having two copies of the mutant allele results
in stillbirth. (Infant dies in the womb.)
Which allele, the mutant allele or the wild-type allele, is dominant with respect to viability?
Wild-type allele
, If two people with achondroplasia have a child together, what is the probability that their
child will also have achondroplasia?
2/3
Two alleles of gene C control hair color in horses: C¹ and C². Horses homozygous for C¹ allele
are red, heterozygotes are yellow, and C² homozygotes are cream.
Assuming C¹ makes an enzyme that produces red pigment, and C² makes a nonfunctional
enzyme, what is a plausible molecular explanation for the inheritance of hair color in horses?
The amount of functional red-producing enzyme made in heterozygotes is not enough to make
them red
In the offspring of mating between a red horse and a yellow horse, what phenotypic ratio is
expected?
1 red: 1 yellow
Part II (Do Part I first): Below is a pedigree of a human genetic disease in which solid color
indicates affected individuals. Assume that the disease is caused by a gene that has two
different alleles A and a, and the disease allele is rare.
In generations II and III combined, how many individuals are heterozygotes for sure (100%
chance)?
4
Based on this pedigree, the most likely mode of inheritance of the disease is __________, and
the genotype of the female 4 is _________
dominant; Aa
If the female 4 marries an affected man (exhibiting the disease) whose parents are both
heterozygotes, what is the probability that they will have a normal child?
1/6
When a pure-breeding, homozygous black rat was crossed to a homozygous albino, all of the
F1 rats were black. When the F1 rats were crossed to each other, the F2 consisted of 161 rats:
93 black, 30 cream, and 38 albino.
What is the genotype of the albino parent?
bbpp
