genetics ch.5 part one
What are the chances that a man with type O blood and a woman with type AB blood could have a child with type O blood? a) 75%(Persons with type O blood are homozygous recessive (ii.) Because the woman is type AB (IaIB) none of her offspring will have type O blood.) b) 25%(Persons with type O blood are homozygous recessive (ii.) Because the woman is type AB (IaIB) none of her offspring will have type O blood.) c) 100%(Persons with type O blood are homozygous recessive (ii.) Because the woman is type AB (IaIB) none of her offspring will have type O blood.) d) 50% (Persons with type O blood are homozygous recessive (ii.) Because the woman is type AB (IaIB) none of her offspring will have type O blood.) e) 0%
0%
The most commonly-occurring allele in a population is called the ___-___ allele
wild-type
Coloration of the stripes on snake skin is controlled by two genes. The dominant allele O for one gene leads to orange coloration. The corresponding recessive allele o does not give orange color. The dominant allele B for a separate gene leads to black coloration. The corresponding allele b does not give black color. Snakes that inherit at least one copy of the dominant alleles for both genes have a camouflage phenotype while snakes that are homozygous recessive for both genes have an albino phenotype. Suppose two snakes known to be heterozygous for both the orange and black coloration genes are mated. What fraction of the offspring would be expected to have albino coloration? a) 1/16 b) 3/16 (Albino snakes have the oobb genotype.) c) None of the offspring will have albino coloration. d) 9/16 (Albino snakes have the oobb genotype.)
1/16
Among the children of two parents with the HbA HbS genotype, what fraction is expected to be unaffected by sickle cell anemia and resistant to malaria? a) None of the offspring are expected to be resistant to malaria. b) None of the offspring are expected to be unaffected by sickle cell anemia. c) 1/4 (Heterozygous individuals are unaffected by sickle cell anemia and resistant to malaria.) d) 3/4 e) 1/2
1/2
*Figure 5.7Inheritance of sickle cell disease* Instead of the Mendelian ratio of 3:1, the ratio of phenotypes for offspring from a cross between two individuals who are heterozygous for sickle cell disease is ____:____ : ____
1:2:1
Suppose a man with type A blood and a woman with type B blood have a child with type O blood. What are the chances that they could have a child with type AB blood at a later time? a) 75% b) 25% c) 0% (The parental genotypes are IAi and IBi so a child with IAIB genotype can be produced.) d) 50%
25%
Suppose a man with type A blood and a woman with type B blood have a child with type O blood. What are the chances that they could have a child with type AB blood at a later time? a) 75% b) 25% c) 0% (The parental genotypes are IAi and IBi so a child with IAIB genotype can be produced.) d) 50%
25%
For harebell plants, dominant alleles for two separate genes are needed to produce blue petal color. Suppose Gene 1 has alleles P and p and Gene 2 has alleles B and b. Only plants with at least one P allele and at least one B allele will have blue petals; all other genotypes lead to white petals. For the cross PpBb x PpBb, what fraction of the offspring are expected to have white petals? a) 9/16 (9/16 will have at least one P alele and at least one B allele, for blue petals.) b) 7/16 c) 1/16 (Any genotype that does not contain at least one P allele and at least one B allele will lead to white petals.) d) 3/16 (Any genotype that does not contain at least one P allele and at least one B allele will lead to white petals.) e) All of the offspring will have white petals
7/16
Suppose Gene 1 has alleles P and p and Gene 2 has alleles B and b. Only plants with at least one P allele and at least one B allele will have blue petals; all other genotypes lead to white petals. For the cross PpBb x PpBb, what fraction of the offspring are expected to have white petals? a) All of the offspring will have white petals b) 1/16 (Any genotype that does not contain at least one P allele and at least one B allele will lead to white petals.) c) 9/16 (Any genotype that does not contain at least one P allele and at least one B allele will lead to white petals.) d) 7/16 e) 3/16 (Any genotype that does not contain at least one P allele and at least one B allele will lead to white petals.)
7/16
In fruit flies, dominant alleles for two different genes are required for red eye color. Suppose Gene 1 has alleles R and r and Gene 2 has alleles E and e. Only flies with at least one R allele and at least one E allele will have red eyes; all other genotypes lead to white eyes. For the cross RrEe x RrEe, what fraction of the offspring are expected to have red eyes? a) 9/16 b) 7/16(Only flies with at least one R allele and at least one E allele will have red eyes.) c) All of the offspring will have red eyes d) 3/16 (Only flies with at least one R allele and at least one E allele will have red eyes.) e) None of the offspring will have red eyes
9/16
*Figure 5.5 Incomplete dominance in the four-o'clock plant, Mirabilis jalapa.* Which outcome in this Punnett square shows the effects of incomplete dominance? a) C b) B c) A
B
A mutation occurs in a gene inducing it to be overexpressed, thereby producing abnormally large amounts of the protein. What type of dominant mutation does this describe? a) Haploinsufficiency b) Dominant-negative mutation c) Gain-of-function mutation
Gain-of-function mutation
Suppose that the covering on corn kernels can have a purple color due to the dominant allele P of gene 1. Alleles of gene 2 can mask this color, with the dominant allele C having no effect but genotype cc changing the purple color to colorless. For corn with the genotype Ppcc, what is the effect of gene 2 on gene 1? a) Recessive epistasis b) Complementation c) Dominant epistasis (The masking effect occurs with the cc genotype.)
Recessive epistasis
When more than one wild-type allele occurs in a population, the phenomenon is called ___ ____
genetic polymorphism
A cell with at least one copy of a wild-type allele will typically produce a) none of the protein specified by this allele. b) a functional version of the protein specified by this allele. c) a non-functional version of the protein specified by this allele.
a functional version of the protein specified by this allele.
A dominant mutant allele that changes a gene such that it yields a new or abnormal function is called a) haploinsufficiency. b) a gain-of-function mutation. c) a dominant-negative mutation.
a gain-of-function mutation.
Select the two fundamental laws of inheritance discovered by Mendel a) Law of independent assortment b) Law of genetic transmission c) Law of recombination d) Law of genetic variability e) Law of segregation
a) Law of independent assortment e) Law of segregation
Genes that may differ slightly in sequence but were derived by duplication during evolution are called ____
paralogs
In fruit flies, the para mutation causes a change in a sodium channel necessary for conducting nerve signals. Mutant flies have normal movement at 22oC but become immediately paralyzed at 29oC. The paralysis is reversed when the temperature returns to 22oC. The para mutation is most likely due to a a) gain-of-function mutation. b) codominant allele. c) non-coding allele. d) temperature-sensitive allele. e) incompletely dominant allele.
temperature-sensitive allele.
Individuals with the HbA HbS genotype do not develop malaria because a) they make sufficient amounts of hemoglobin S to avoid sickle cell disease. b) the presence of hemoglobin A prevents the malarial parasite from reproducing within their bodies. (Hemoglobin S prevents the reproduction of the parasite.) c) the presence of hemoglobin S prevents the malarial parasite from reproducing within their bodies. d) they make sufficient amounts of hemoglobin A to avoid sickle cell disease.
the presence of hemoglobin S prevents the malarial parasite from reproducing within their bodies.
*Figure 5.7 Inheritance of sickle cell disease.* Individuals with an HbS HbS genotype suffer from sickle cell anemia because a) they produce hemoglobin A, a variant that causes their red blood cells to form a round, concave shape that clogs body capillaries. b) they produce hemoglobin S, a variant that causes their red blood cells to form a round, concave shape that clogs body capillaries. c) they produce hemoglobin A, a variant that causes their red blood cells to form a crescent shape when oxygen concentration is low. d) they produce hemoglobin S, a variant that causes their red blood cells to form a crescent shape when oxygen concentration is low.
they produce hemoglobin S, a variant that causes their red blood cells to form a crescent shape when oxygen concentration is low.
Suppose a mother with the IAi genotype and a father with the IBi genotype have two children, one with a codominant genotype and one with a genotype demonstrating complete dominance. The children's genotypes can be a) Codominant = IAIB; Complete dominance= IBi b) Codominant = IAi; Complete dominance=IBi c) Codominant = ii; Complete dominance= IAIB d) Codominant = IBi; Complete dominance= IAIB e) Codominant = IAi; Complete dominance=ii
Codominant = IAIB; Complete dominance= IBi
Which of the surface antigens related to blood type would be found on the red blood cells of an individual with the IAIB genotype? a) Each red blood cell would carry both surface antigen A and surface antigen B. b)Half of the red blood cells would carry surface antigen A and the other half would carry surface antigen B. (The phenomenon in which two alleles are both expressed in a heterozygote is called codominance. In this case the RBC will carry both the A and B surface antigens.) c) All of the red blood cells would have surface antigen B and none would have surface antigen A.(The phenomenon in which two alleles are both expressed in a heterozygote is called codominance. In this case the RBC will carry both the A and B surface antigens.) d) All of the red blood cells would have surface antigen A and none would have surface antigen B. (The phenomenon in which two alleles are both expressed in a heterozygote is called codominance. In this case the RBC will carry both the A and B surface antigens.)
Each red blood cell would carry both surface antigen A and surface antigen B.
Suppose loss-of-function mutations in two separate genes do not produce any phenotypic effects but combining the two loss-of-function mutations in one organism shows a difference in phenotype. What is the most likely explanation? a) Gene redundancy b) Epistasis (For epistasis, phenotypic effects would occur with a loss-of function mutation in a single gene.) c) Multiple alleles for each gene d) Complementation (For epistasis, phenotypic effects would occur with a loss-of function mutation in a single gene.)
Gene redundancy
For which of the following genotypes would the effects of codominance be observed in the individual's phenotype? a) IBi b) IBIB c) IAi d) IAIB e) IAIA
IAIB
The ability to prevent the symptoms of phenylketonuria by restricting the diets of patients who inherit the disease is an example of _____ effects on a phenotype.
environmental
*Figure 5.7 Inheritance of sickle cell disease.* A patient with sickle cell disease may experience a painful episode leading to tissue and organ damage because cells carrying hemoglobin S ______. a) bring excess oxygen to the tissues causing cell death b) have a shorter lifespan c) form abnormal crescent shapes that block capillaries, depriving nearby cells of oxygen d) have a longer lifespan
form abnormal crescent shapes that block capillaries, depriving nearby cells of oxygen
The pattern where allelic variants of two different genes affect a single trait is called ____ ___
gene interaction
When one gene can compensate for the loss of function of another gene, the phenomenon is called ___ ___
gene redundancy
A population that contains more than one wild-type allele demonstrates a) genetic recombination. b) genetic diversity. (Genetic diversity relates to variation in both wild-type and mutant alleles.) c) genetic polymorphism.
genetic polymorphism.
The difference between type A and type B blood is produced by a) glycosyl transferase enzymes with different activities. b) an active enzyme for type A blood and an inactive enzyme for type B blood. c) an active enzyme for type B blood and an inactive enzyme for type A blood.
glycosyl transferase enzymes with different activities.
Even though it leads to sickle cell disease in homozygous individuals, the allele HbS is retained in some populations because it confers resistance to _____ for heterozygotes.
malaria
A single gene for white coloring on the coats of dogs has four alleles with a hierarchy of dominance. Various combinations of these alleles can lead to solid coat, Irish-spotting, piebald-spotting and white coats. This inheritance pattern for white coloring is due to the existence of ______ for the gene for coat coloring. a) a single gene b) multiple alleles c) incomplete dominance (Incompletely dominant traits are those in which a heterozygote expresses a trait intermediate to either the homozygous dominant or homozygous recessive trait.)
multiple alleles
Suppose Protein C functions as a homodimer, where the two subunits can be identical (C1C1 or C2C2) or slightly different (C1C2). Further suppose that the C1C2 homodimer is more stable than either homodimer with identical subunits. Heterozygous individuals would then have an advantage due to _____
overdominance
The situation where a heterozygote has a characteristic that makes it more likely than either homozygous individual to reproduce in a given environment is calledThe situation where a heterozygote has a characteristic that makes it more likely than either homozygous individual to reproduce in a given environment is called
overdominance
While causing sickle-cell anemia in homozygous individuals, the product of the HbS allele provides resistance to malaria in individuals with the HbA HbS genotype. This advantage to heterozygotes demonstrates a) incomplete dominance. b) overdominance c) codominance
overdominance
While causing sickle-cell anemia in homozygous individuals, the product of the HbS allele provides resistance to malaria in individuals with the HbA HbS genotype. This advantage to heterozygotes demonstrates a) codominance. b) incomplete dominance. c) overdominance.
overdominance.
One gene can compensate for the loss of function of another gene in cases where a duplicate gene or _____ has arisen over evolutionary time or when the function of another ____can be increased to compensate for the missing protein product of the non-functional gene.
paralog and protein
Human hemoglobin is a complex of four protein chains produced by two different genes, one for for alpha-hemoglobin and one for beta-hemoglobin. These genes have sequence differences but similarities suggest that they were produced by gene duplication earlier in evolutionary time. These genes would be described as a) paralogs. b) duplicate genes. c) orthologs. d) pseudogenes.
paralogs.
In the general population, 1/150 people are carriers for the allele for Tay-Sachs disease. A child with the disease is born to healthy parents who are unaware of their carrier status. The allele that prevents the disease in the parents is a ______ allele and the one that causes the disease is a ______ allele. a) wild-type; codominant b) wild-type; mutant c) codominant; incompletely dominant d) mutant; wild-type e) wild type; incompletely dominant
wild-type; mutant
Brittle Bone Disease is caused by a mutation in a gene that codes for collagen fibers. The product of the mutant allele binds to normal collagen and disrupts proper fiber formation. The mutation can be described as a a) gain-of-function mutation. b) haploinsufficiency mutation. c) dominant-negative mutation.
dominant-negative mutation.
The effect of phenylketonuria, an autosomal recessive disorder in which individuals are unable to metabolize phenylalanine, can be altered by a restricted diet with limited amounts of phenylalanine. This is an example of a) variation in expressivity. b) environmental effects on gene expression. c) incomplete penetrance. d) overdominance in a heterozygote.
environmental effects on gene expression.
When Blue-Eyed Mary plants inherit at least one dominant allele for a gene for flower color, their petals are blue to match their name. If plants are homozygous recessive for a second gene, however, they develop white petals. The effect of the second gene on the first flower color gene is called
epistasis
The enzyme glycosyl transferase is the product of the gene for ABO blood type. In determining the phenotype of individuals inheriting specific alleles of this gene, the product of the i allele is ______ and the products of the IA and IB alleles are ______. a) inactive; inactive b) active; active c) inactive; active d) active; inactive
inactive; active
Suppose a genetic test shows that a woman has inherited the dominant BRCA1 allele that causes breast cancer. If she does not develop breast cancer in her lifetime, the phenomenon is called ___ ____
incomplete penetrance
The pattern observed when a heterozygote does not show the trait associated with the dominant allele is __ ___
incomplete penetrance
In chickens, feather color can be black or splash (white with black spots). If a black rooster is crossed to a splash hen, the offspring show an intermediate blue color. If a splash rooster is crossed to a blue hen, what fraction of the offspring will be expected to have blue feathers? a) 1/4 (In a trait that is incompletely dominant, heterozygotes will exhibit an intermediate phenotype.) b) 1/2 c) 3/4 (In a trait that is incompletely dominant, heterozygotes will exhibit an intermediate phenotype.) d) all of the offspring are expected to have blue feathers (In a trait that is incompletely dominant, heterozygotes will exhibit an intermediate phenotype.)
1/2
In chickens, feather color can be black or splash (white with black spots). If a black rooster is crossed to a splash hen, the offspring show an intermediate blue color. If a blue rooster is crossed to a blue hen, what fraction of the offspring will be expected to have black feathers? a) 1/2 (In a trait that is incompletely dominant, heterozygotes will exhibit an intermediate phenotype.) b) 3/4 (In a trait that is incompletely dominant, heterozygotes will exhibit an intermediate phenotype.) c) All of the offspring are expected to have black feathers. (In a trait that is incompletely dominant, heterozygotes will exhibit an intermediate phenotype.) d) None of the offspring are expected to have black feathers.(In a trait that is incompletely dominant, heterozygotes will exhibit an intermediate phenotype.) e) 1/4
1/4
Suppose that the covering on corn kernels can have a purple color due to the dominant allele P of gene 1. The genotype pp leads to a colorless covering. Alleles of gene 2 can mask the purple color, with the dominant allele C having no effect but genotype cc changing the purple color to colorless. Alleles of gene 2 have no effect on plants with genotype pp for gene 1. For the cross PpCc x PpCc, what fraction of the plants are expected to have colorless covering on their corn kernels? a) 9/16 (This epistatic interaction only produces two phenotypes, in a 9:7 ratio.) b) 12/16 (This epistatic interaction only produces two phenotypes, in a 9:7 ratio.) c) 4/16 d) 7/16 e) 1/16 (This epistatic interaction only produces two phenotypes, in a 9:7 ratio.)
7/16
Suppose a mother with the IAi genotype and a father with the IBi genotype have one child with type A blood and one child with type AB blood. Which is the best description of the observed genetic patterns? a) Codominance is observed for the child with type AB blood while complete dominance is observed for the child with type A blood. b) Complete dominance is observed for both children. c) Codominance is observed for the child with type A blood while complete dominance is observed for the child with type AB blood. (The child with type A blood has a genotype of IAi. In this case the A gene is masking the expression of the i gene. The child with type AB blood is expressing both alleles.) d) Codominance is not observed for either of the children. e) Codominance is observed for both children.
Codominance is observed for the child with type AB blood while complete dominance is observed for the child with type A blood.
Which pattern is shown by a heterozygous individual that has a phenotype that is intermediate between the phenotypes of the dominant and recessive homozygotes? a) Incomplete penetrance b) Codominance (For codominance, the heterozygote has a different phenotype than either homozygote, but it is not intermediate between the two.) c) Incomplete dominance d) Variable expressivity
Incomplete dominance
Which two fundamental laws of inheritance did Mendel discover? a) Law of Genetic Variability and Law of Segregation b) Law of Segregation and Law of Independent Assortment c) Law of Genetic Transmission and Law of Independent Assortment d) Law of Independent Assortment and Law of Genetic Recombination e) Law of Segregation and Law of Genetic Recombination
Law of Segregation and Law of Independent Assortment
What phenomenon is observed in a population when three or more alleles can be found for a single gene? a) Multiple alleles b) Overdominance c) Incomplete dominance d) Environmental effects
Multiple alleles
What is the name for the situation where heterozygotes have greater reproductive success than either of the two homozygotes? a) Incomplete dominance b) Overdominance c) Codominance
Overdominance
Which description matches each pattern of inheritance? a) Incomplete Dominance b) Codominance c) Sex-limited d) Sex-influenced e) incomplete penetrance A) trait is inherited by both sexes but with different dominant/recessive patterns B) heterozygote has intermediate phenotypes C) failure to express a dominant phenotype even though the individual carries the dominant allele for that trait D) heterozygote expresses both alleles simultaneously E) trait occurs in only one of the two sexes
a) Incomplete Dominance-> heterozygote has intermediate phenotypes b) Codominance -> heterozygote expresses both alleles simultaneously c) Sex-limited -> trait occurs in only one of the two sexes d) Sex-influenced-> trait is inherited by both sexes but with different dominant/recessive patterns e) incomplete penetrance-> failure to express a dominant phenotype even though the individual carries the dominant allele for that trait
Which description matches each pattern of inheritance? a) Simple Mendelian Inheritance b) X-linked c) Lethal alleles d) Codominance e) Incomplete dominance A) follows a strict dominant/recessive relationship B) pattern producing an intermediate phenotype in the heterozygote C) traits for which males inherit only one allele while females inherit two alleles D) pattern in which both alleles are expressed in the heterozygote without blending E) alleles that have the potential to cause death
a) Simple Mendelian Inheritance-> follows a strict dominant/recessive relationship b) X-linked -> traits for which males inherit only one allele while females inherit two alleles c) Lethal alleles-> alleles that have the potential to cause death d) Codominance-> pattern in which both alleles are expressed in the heterozygote without blending e) Incomplete dominance -> pattern producing an intermediate phenotype in the heterozygote
Gene redundancy can be demonstrated by a) a gene duplication event where a paralog can carry out the function of a missing gene. b) death of the organism when a loss-of-function mutation occurs in a specific gene. c) change in phenotype when lower enzymatic activity is observed due to a loss-of-function mutation. d) increase in function of one protein to compensate for the loss of function of a similar one.
a) a gene duplication event where a paralog can carry out the function of a missing gene. d) increase in function of one protein to compensate for the loss of function of a similar one.
The type of mutation in which a protein produced by a mutant allele acts against a normal protein is called a _____-_____ mutation.
dominant-negative mutation
For summer squash, the dominant allele for one gene leads to yellow color while the recessive allele for this gene leads to green color. When the genotype of a second gene is either homozygous dominant or heterozygous, neither color is produced and the squash is white. The effect of the second gene on the first one is called a) epistasis. b) complementation. c) codominance. d) complete dominance. e) overdominance.
epistasis.
Corn kernels can have a purple color due to the dominant allele of one gene. When the alleles of a second gene are present in the homozygous recessive genotype, the kernel color is changed to red. This is an example of a) incomplete dominance. ( Incomplete dominance is a pattern observed for alleles of the same gene.) b) overdominance. c) pleiotropy. (Pleiotropy is the result of the action of a single gene.) d) gene interaction.
gene interaction.
Less frequent alleles that have genetic changes making them defective in protein production are called ______ alleles. a) mutant b) wild-type
mutant
When a preexisting allele is changed to a new version that no longer codes for a functional protein, the new allele is called a _____ allele
mutant
When an allele causes a disease in the homozygous recessive genotype but confers resistance to a different disease in heterozygotes, the phenomenon is called a) incomplete dominance. b) overdominance. c) codominance.
overdominance.
For Labrador Retrievers the dominant allele B for gene 1 leads to black coat while the recessive allele b leads to brown coat. Alleles of gene 2 can change this color, with the dominant allele E having no effect but genotype ee changing either black or brown to yellow color. For dogs with the genotype BBee, the effect of gene 2 on gene 1 is a) complementation. b) dominant epistasis. c) recessive epistasis.
recessive epistasis.
Himalayan coloring in rabbits is due to a dominant allele that codes for a tyrosinase enzyme which participates in the production of the dark pigment melanin. In cold temperatures, dark coloring is only found in the ears, nose and feet of the animal. White coloration develops on body areas where blood flow keeps the animal warm. The tyrosinase enzyme is most likely a a) temperature-sensitive enzyme. b) gain-of-function mutation. c) loss-of-function mutation. d) recessive allele.
temperature-sensitive enzyme.
Coloration of the stripes on snake skin is controlled by two genes. The dominant allele O for one gene leads to orange coloration. The corresponding recessive allele o does not give orange color. The dominant allele B for a separate gene leads to black coloration. The corresponding allele b does not give black color. Snakes that inherit at least one copy of the dominant alleles for both genes have a camouflage phenotype while snakes that are homozygous recessive for both genes have an albino phenotype. Suppose two snakes known to be heterozygous for both the orange and black coloration genes are mated. What fraction of the offspring would be expected to have black coloration? a) 9/16 (Snakes with black coloration have either the ooBB or ooBb genotypes.) b) 3/16 c) 1/16 (Snakes with black coloration have either the ooBB or ooBb genotypes.) d) None of the offspring will have black coloration.
3/16
For summer squash, the dominant allele Y for gene 1 leads to yellow color while the recessive allele y leads to green color. Alleles of gene 2 can prevent color formation, with the dominant allele W leading to white squash while the recessive allele w does not interfere with color development. For the cross YyWw x YyWw, what is the fraction of offspring that will be white? a) 3/16 (All offspring with at least one W allele will be white. This will represent more than 3/16 of the offspring.) b) 7/16 (All offspring with at least one W allele will be white. This will represent more than 7/16 of the offspring.) c) 9/16 (All offspring with at least one W allele will be white. This will represent more than 9/16 of the offspring.) d) 12/16
12/16
The following pathway is proposed to explain the inheritance of purple flower color in pea plants: Colorless Precursor→Colorless Intermediate→Purple Pigment. A dominant allele for Gene C provides an enzyme that converts Colorless Precursor→Colorless Intermediate. A dominant allele for Gene P provides an enzyme that converts Colorless Intermediate→Purple Pigment. An explanation of why plants with CCpp and ccPP genotypes have white petals while plants with the CcPp genotype have purple flowers is a) complementation occurs in the purple-petaled plant, showing that the mutations preventing color in the white plants are in the same gene. (Complementation occurs when each recessive allele is complemented by a wild-type allele, indicating the recessive alleles are in different genes. Epistasis occurs when one gene masks the expression of another gene.) b) the dominant allele C exerts epistasis over the recessive allele p and the dominant allele P exerts epistasis over the recessive allele c. (Complementation occurs when each recessive allele is complemented by a wild-type allele, indicating the recessive alleles are in different genes. Epistasis occurs when one gene masks the expression of another gene.) c) complementation occurs in the purple-petaled plant, showing that the mutations preventing color in the white plants are in different genes. d) the dominant allele C exerts epistasis over the recessive allele c and the dominant allele P exerts epistasis over the recessive allele p. (Complementation occurs when each recessive allele is complemented by a wild-type allele, indicating the recessive alleles are in different genes. Epistasis occurs when one gene masks the expression of another gene.)
complementation occurs in the purple-petaled plant, showing that the mutations preventing color in the white plants are in different genes.
In corn plants, the enzyme alcohol dehydrogenase functions as a homodimer, where the two subunits can be identical or slightly different. One type of subunit is stable but somewhat inactive, while another type of subunit is active but somewhat unstable. Homodimers composed of one of each subunit are both stable and active. Heterozygous plants that can produce both types of subunits have an advantage due to a) complete dominance. b) pseudodominance. c) overdominance.
overdominance.
The following pathway is proposed to explain the inheritance of purple flower color in pea plants: Colorless Precursor→Colorless Intermediate→Purple Pigment. A dominant allele for Gene C provides an enzyme that converts Colorless Precursor→Colorless Intermediate. A dominant allele for Gene P provides an enzyme that converts Colorless Intermediate→Purple Pigment. An explanation for why plants with the ccPp genotype have white petals while plants with the CcPp genotype have purple petals is a) the dominant allele C exerts epistasis over the recessive allele c. (Complementation occurs when each recessive allele is complemented by a wild-type allele, indicating the recessive alleles are in different genes. Epistasis occurs when one gene masks the expression of another gene.) b) complementation occurs between the c and P alleles, preventing purple color formation. (Complementation occurs when each recessive allele is complemented by a wild-type allele, indicating the recessive alleles are in different genes. Epistasis occurs when one gene masks the expression of another gene.) c) the dominant allele P exerts epistasis over the recessive allele c. (Complementation occurs when each recessive allele is complemented by a wild-type allele, indicating the recessive alleles are in different genes. Epistasis occurs when one gene masks the expression of another gene. the cc genotype exerts epistasis over the Pp genotype, preventing purple color formation.) d) complementation occurs between the C and p alleles, preventing purple color formation. ( Complementation occurs when each recessive allele is complemented by a wild-type allele, indicating the recessive alleles are in different genes. Epistasis occurs when one gene masks the expression of another gene.)
the cc genotype exerts epistasis over the Pp genotype, preventing purple color formation.
