Chapter 4 test bank Questions and
Answers 2023
Which mode of inheritance produces heterozygotes with phenotypes that differ from
either homozygote but more closely resembles one homozygous phenotype than the
other? - -incomplete dominance
-Which mode of inheritance results in the phenotype of a heterozygote being
indistinguishable from that of an organism homozygous for the dominant allele? - -
complete dominance
-Which mode of inheritance results in both alleles being detected equally in the
heterozygous phenotype? - -codominance
-A mutation results in an enzyme that is partially active compared to the wild-type allele.
This type of "leaky" mutation is classified as - -hypomorphic.
-A mutation resulting in an inactive gene product is classified as - -amorphic.
-Two proteins interact to form a multimeric complex. When one of the proteins is
mutated, there is a substantial loss of functional activity in the multimeric protein. This
type of mutation is classified as - -dominant negative.
-Many oncogenes result from mutations that cause a protein to be expressed in cells
where it is normally not expressed or at inappropriate times during development. This
type of mutation can be described as - -hypermorphic.
-A mutation results in a gene product with a novel function that is not normally found in
wild-type organisms. This type of mutation is known as - -neomorphic.
-Most combinations of different ABO alleles result in complete dominance of one allele.
Which combination results in codominance? - -IAIB
-What is the genotype for individuals with blood type O? - -ii
-What type of allele is often detected as a distortion in segregation ratios, where one
class of expected progeny is missing? - -lethal allele
-Most people with the dominant mutant polydactyly allele have extra digits, but at least
25% have the normal number of digits. What is the genetic explanation for this
observation? - -incomplete penetrance
-Gene interactions in which an allele of one gene modifies or prevents expression of
alleles of another gene is known as - -epistasis.
, -Bateson and Punnett crossed two white-flowered lines and saw all purple flowers in the
F1 generation. They concluded this was an example of complementary gene
interactions because a cross of the F1 plants yielded what ratio in the F2 generation? - -
9 purple to 7 white
-If a dominant allele of one gene completely suppresses the phenotypic expression of
alleles of another gene, this is an example of - -dominant suppression.
-The 9:6:1 ratio seen in the dihybrid cross of summer squash indicates what genetic
relationship between the two genes controlling fruit shape? - -dominant interaction
-In the biosynthetic pathway for conversion from homoserine to methionine, you identify
a Neurospora crassa double mutant Met1/Met2. This mutant will grow only if which
supplement(s) are added to the minimal media?
(LOOK AT CHART) - -methionine only
-Which step is catalyzed by the enzyme responsible for the Met 3 mutant? - -cysteine →
cystathionine
-Independent assortment predicts a 9:3:3:1 ratio with four different phenotypes in the F2
progeny. If the alleles are epistatic, what would you predict? - -fewer than four
phenotypes
-Two pure-breeding mutant plants produce white flowers. When they are crossed, all of
the progeny have wild-type purple flowers. What does this genetic complementation tell
you? - -More than one gene is involved in determining the phenotype.
-A metabolic reaction requires 40 units of enzymatic activity to proceed. If a dominant
allele "D" can generate 40 units of enzyme and a mutant allele "d" generates 20 units of
enzyme, what can be said of the dominant wild-type allele? - -D is haplosufficient.
-A metabolic reaction requires 10 units of enzymatic activity to proceed. If a dominant
allele "D" can generate 8 units of enzyme and a recessive allele "d" can generate 2
units of enzyme, what can be said of the dominant wild-type allele? - -D is
haploinsufficient.
-Are loss-of function mutations more likely to be dominant or recessive? - -recessive
-What are the three categories of loss-of-function mutations? - -amorphic (null),
hypomorphic (leaky), dominant negative
-What are the two categories of gain-of-function mutations? - -neomorphic and
hypermorphic
Answers 2023
Which mode of inheritance produces heterozygotes with phenotypes that differ from
either homozygote but more closely resembles one homozygous phenotype than the
other? - -incomplete dominance
-Which mode of inheritance results in the phenotype of a heterozygote being
indistinguishable from that of an organism homozygous for the dominant allele? - -
complete dominance
-Which mode of inheritance results in both alleles being detected equally in the
heterozygous phenotype? - -codominance
-A mutation results in an enzyme that is partially active compared to the wild-type allele.
This type of "leaky" mutation is classified as - -hypomorphic.
-A mutation resulting in an inactive gene product is classified as - -amorphic.
-Two proteins interact to form a multimeric complex. When one of the proteins is
mutated, there is a substantial loss of functional activity in the multimeric protein. This
type of mutation is classified as - -dominant negative.
-Many oncogenes result from mutations that cause a protein to be expressed in cells
where it is normally not expressed or at inappropriate times during development. This
type of mutation can be described as - -hypermorphic.
-A mutation results in a gene product with a novel function that is not normally found in
wild-type organisms. This type of mutation is known as - -neomorphic.
-Most combinations of different ABO alleles result in complete dominance of one allele.
Which combination results in codominance? - -IAIB
-What is the genotype for individuals with blood type O? - -ii
-What type of allele is often detected as a distortion in segregation ratios, where one
class of expected progeny is missing? - -lethal allele
-Most people with the dominant mutant polydactyly allele have extra digits, but at least
25% have the normal number of digits. What is the genetic explanation for this
observation? - -incomplete penetrance
-Gene interactions in which an allele of one gene modifies or prevents expression of
alleles of another gene is known as - -epistasis.
, -Bateson and Punnett crossed two white-flowered lines and saw all purple flowers in the
F1 generation. They concluded this was an example of complementary gene
interactions because a cross of the F1 plants yielded what ratio in the F2 generation? - -
9 purple to 7 white
-If a dominant allele of one gene completely suppresses the phenotypic expression of
alleles of another gene, this is an example of - -dominant suppression.
-The 9:6:1 ratio seen in the dihybrid cross of summer squash indicates what genetic
relationship between the two genes controlling fruit shape? - -dominant interaction
-In the biosynthetic pathway for conversion from homoserine to methionine, you identify
a Neurospora crassa double mutant Met1/Met2. This mutant will grow only if which
supplement(s) are added to the minimal media?
(LOOK AT CHART) - -methionine only
-Which step is catalyzed by the enzyme responsible for the Met 3 mutant? - -cysteine →
cystathionine
-Independent assortment predicts a 9:3:3:1 ratio with four different phenotypes in the F2
progeny. If the alleles are epistatic, what would you predict? - -fewer than four
phenotypes
-Two pure-breeding mutant plants produce white flowers. When they are crossed, all of
the progeny have wild-type purple flowers. What does this genetic complementation tell
you? - -More than one gene is involved in determining the phenotype.
-A metabolic reaction requires 40 units of enzymatic activity to proceed. If a dominant
allele "D" can generate 40 units of enzyme and a mutant allele "d" generates 20 units of
enzyme, what can be said of the dominant wild-type allele? - -D is haplosufficient.
-A metabolic reaction requires 10 units of enzymatic activity to proceed. If a dominant
allele "D" can generate 8 units of enzyme and a recessive allele "d" can generate 2
units of enzyme, what can be said of the dominant wild-type allele? - -D is
haploinsufficient.
-Are loss-of function mutations more likely to be dominant or recessive? - -recessive
-What are the three categories of loss-of-function mutations? - -amorphic (null),
hypomorphic (leaky), dominant negative
-What are the two categories of gain-of-function mutations? - -neomorphic and
hypermorphic
