Chapter 5 Flashcards
The R locus determines flower color in a new plant species. Plants that are genotype RR have red flowers, and plants that are rr have white flowers. However, Rr plants have pink flowers. What type of inheritance does this demonstrate for flower color in these plants?
a. Complete dominance
b. Incomplete dominance
c. Codominance
d. Complementation
e. Lethal alleles
b. Incomplete dominance
Interactions among the human ABO blood group alleles involve _______ and ________.
a. co-dominance; complete dominance
b. codominance; incomplete dominance
c. complete dominance; incomplete dominance
d. epistasis; complementation
e. continuous variation; environmental variation
a. co-dominance; complete dominance
In the endangered African watchamakallit, the offspring of a true-breeding black parent and a true-breeding white parent are all gray. When the gray offspring are crossed among themselves, their offspring occur in a ratio of 1 black:2 gray:1 white. Upon close examination of the coats, each hair of a gray animal is gray. What is the mode of inheritance?
a. One gene pair with black dominant to white
b. One gene pair with codominance
c. One gene pair with incomplete dominance
d. Two gene pairs with recessive epistasis
e. Two gene pairs with duplicate genes
c. One gene pair with incomplete dominance
Suppose that extra fingers and toes are caused by a recessive trait, but it appears in only 60% of homozygous recessive individuals. Two heterozygotes conceive a child. What is the probability that this child will have extra fingers and toes?
a. 0.05
b. 0.10
c. 0.15
d. 0.25
e. 0.33
c. 0.15
Polydactyly is the condition of having extra fingers or toes. Some polydactylous persons possess extra fingers or toes that are fully functional, whereas others possess only a small tag of extra skin. This is an example of
a. variable expressivity.
b. complete dominance.
c. independent assortment.
d. complementation.
e. cytoplasmic inheritance.
a. variable expressivity.
Achondroplasia is a common cause of dwarfism in humans. All individuals with achondroplasia are thought to be heterozygous at the locus that controls this trait. When two individuals with achondroplasia mate, the offspring occur in a ratio of 2 achondroplasia:1 normal. What is the most likely explanation for these observations?
a. Achondroplasia is incompletely dominant to the normal condition.
b. Achondroplasia is codominant to the normal condition.
c. The allele that causes achondroplasia is a dominant lethal allele.
d. The allele that causes achondroplasia is a recessive lethal allele.
e. The allele that causes achondroplasia is a late-onset lethal allele.
d. The allele that causes achondroplasia is a recessive lethal allele.
Crossing two yellow mice results in 2/3 yellow offspring and 1/3 nonyellow offspring. What percentage of offspring would you expect to be nonyellow if you crossed two nonyellow mice?
a. 25%
b. 33%
c. 66%
d. 75%
e. 100%
e. 100%
In humans, blood types A and B are codominant to each other and each is dominant to O. What blood types are possible among the offspring of a couple of blood types AB and A?
a. A, B, AB, and O
b. A, B, and AB only
c. A and B only
d. A, B, and O only
e. A and AB only
b. A, B, and AB only
A mother of blood type A gives birth to a child with blood type O. Which of the following could NOT be the blood type of the father?
a. A
b. B
c. O
d. AB
e. Any of the above is a possible blood type of the father.
d. AB
You are studying body color in an African spider and have found that it is controlled by a single gene with four alleles: B (brown), br (red), bg (green), and by (yellow). B is dominant to all the other alleles, and by is recessive to all the other alleles. The bg allele is dominant to by but recessive to br. You cross a pure-breeding brown spider with a pure-breeding green spider. Predict the genotype of the progeny.
a. B/bg
b. Br/bg
c. br/by
d. by/bg
e. B/by
a. B/bg
You are studying body color in an African spider and have found that it is controlled by a single gene with four alleles: B (brown), br (red), bg (green), and by (yellow). B is dominant to all the other alleles, and by is recessive to all the other alleles. The bg allele is dominant to by but recessive to br. You cross a pure-breeding brown spider with a pure-breeding green spider. Predict the phenotype of the progeny.
a. Half brown, half green
b. Three-fourths brown, one-fourth green
c. All brown
d. All green
e. All yellow
c. All brown
In rabbits, an allelic series helps to determine coat color: C (full color), cch (chinchilla; gray color), ch (Himalayan; white with black extremities), and c (albino; all white). The C allele is dominant to all others, cch is dominant to ch and c, ch is dominant to c, and c is recessive to all the other alleles. This dominance hierarchy can be summarized as C > cch > ch > c. Indicate the phenotypic ratios expected if rabbits with the cross Ccch Cch.
a. 1 full color:1 chinchilla
b. 1 full color:1 Himalayan
c. 1 chinchilla:1 Himalayan
d. 3 full color:1 chinchilla
e. 2 full color:1 Himalayan:1 albino
d. 3 full color:1 chinchilla
In rabbits, an allelic series helps to determine coat color: C (full color), cch (chinchilla; gray color), ch (Himalayan; white with black extremities), and c (albino; all white). The C allele is dominant to all others, cch is dominant to ch and c, ch is dominant to c, and c is recessive to all the other alleles. This dominance hierarchy can be summarized as C > cch > ch > c. Indicate the phenotypic ratios expected if rabbits with the cross Cch chc.
a. 1 full color:1 chinchilla
b. 1 full color:1 Himalayan
c. 1 chinchilla:1 Himalayan
d. 3 full color:1 chinchilla
e. 2 full color:1 Himalayan:1 albino
b. 1 full color:1 Himalayan
In rabbits, an allelic series helps to determine coat color: C (full color), cch (chinchilla; gray color), ch (Himalayan; white with black extremities), and c (albino; all white). The C allele is dominant to all others, cch is dominant to ch and c, ch is dominant to c, and c is recessive to all the other alleles. This dominance hierarchy can be summarized as C > cch > ch > c. Indicate the phenotypic ratios expected if rabbits with the cross Cch cc.
a. 1 full color:1 chinchilla
b. 1 full color:1 Himalayan
c. 1 chinchilla:1 Himalayan
d. 3 full color:1 chinchilla
e. 2 full color:1 Himalayan:1 albino
b. 1 full color:1 Himalayan
In rabbits, an allelic series helps to determine coat color: C (full color), cch (chinchilla; gray color), ch (Himalayan; white with black extremities), and c (albino; all white). The C allele is dominant to all others, cch is dominant to ch and c, ch is dominant to c, and c is recessive to all the other alleles. This dominance hierarchy can be summarized as C > cch > ch > c. Indicate the phenotypic ratios expected if rabbits with the cross cchch chc.
a. 1 full color:1 chinchilla
b. 1 full color:1 Himalayan
c. 1 chinchilla:1 Himalayan
d. 3 full color:1 chinchilla
e. 2 full color:1 Himalayan:1 albino
c. 1 chinchilla:1 Himalayan
In rabbits, an allelic series helps to determine coat color: C (full color), cch (chinchilla; gray color), ch (Himalayan; white with black extremities), and c (albino; all white). The C allele is dominant to all others, cch is dominant to ch and c, ch is dominant to c, and c is recessive to all the other alleles. This dominance hierarchy can be summarized as C > cch > ch > c. Indicate the phenotypic ratios expected if rabbits with the cross Cc chc.
a. 1 full color:1 chinchilla
b. 1 full color:1 Himalayan
c. 1 chinchilla:1 Himalayan
d. 3 full color:1 chinchilla
e. 2 full color:1 Himalayan:1 albino
e. 2 full color:1 Himalayan:1 albino
A mother with blood type A has a child with blood type A. Give all possible blood types for the father of this child.
a. O
b. B, AB
c. A, AB
d. A, B, O
e. A, B, AB, O
e. A, B, AB, O
A mother with blood type B has a child with blood type O. Give all possible blood types for the father of this child.
a. O
b. B, AB
c. A, AB
d. A, B, O
e. A, B, AB, O
d. A, B, O
A mother with blood type A has a child with blood type AB. Give all possible blood types for the father of this child.
a. O
b. B, AB
c. A, AB
d. A, B, O
e. A, B, AB, O
b. B, AB
A mother with blood type AB has a child with blood type B. Give all possible blood types for the father of this child.
a. O
b. B, AB
c. A, AB
d. A, B, O
e. A, B, AB, O
e. A, B, AB, O
You are studying a gene that controls ossicone (horn) length in giraffes. The wild-type long-ossicone allele (L) is dominant to the mutant short-ossicone (l) allele. However the L allele is only 60% penetrant. You cross two heterozygous giraffes. What proportion of offspring would you expect to exhibit the long ossicone phenotype? Assume the penetrance of L applies equally to both homozygotes and heterozygotes.
a. 0.40
b. 0.45
c. 0.55
d. 0.60
e. 0.75
b. 0.45
You are studying a gene that controls ossicone (horn) length in giraffes. The wild-type long-ossicone allele (L) is dominant to the mutant short-ossicone (l) allele. However, the L allele is only 60% penetrant. You cross two heterozygous giraffes. What proportion of offspring would you expect to exhibit the short ossicone phenotype? Assume the penetrance of L applies equally to both homozygotes and heterozygotes.
a. 0.25
b. 0.40
c. 0.45
d. 0.55
e. 0.60
d. 0.55
Hair color is determined in Labrador retrievers by alleles at the B and E loci. A dominant allele B encodes black pigment, whereas a recessive allele b encodes brown pigment. Alleles at a second locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark pigment (black or brown) to be deposited, whereas recessive allele e prevents the deposition of dark pigment, causing the hair to be yellow. What type of gene interaction does this represent?
a. Recessive epistasis
b. Dominant epistasis
c. Duplicate recessive epistasis
d. Duplicate dominant epistasis
e. Dominant and recessive epistasis
a. Recessive epistasis
Hair color is determined in Labrador retrievers by alleles at the B and E loci. A dominant allele B encodes black pigment, whereas a recessive allele b encodes brown pigment. Alleles at a second locus affect the deposition of the pigment in the shaft of the hair; dominant allele E allows dark pigment (black or brown) to be deposited, whereas recessive allele e prevents the deposition of dark pigment, causing the hair to be yellow. A black female Labrador retriever was mated with a yellow male. Half of the puppies were black and half were yellow. If the genotype of the black female parent was Bb Ee, then what was the genotype of the other parent?
a. bb ee
b. bb EE
c. Bb ee
d. BB ee
e. BB EE
d. BB ee