Chapter 5 Test Bank
E
A 24-year-old woman with myotonic dystrophy, a genetic disorder caused by a dominant mutant allele, has significant muscle weakness and wasting. She has a 1-year-old son with very poor muscle tone, severe weakness, and significant developmental delay. Her affected 55-year-old father has minor cataracts but no muscle weakness. Which of the following terms BEST describes this situation? A) codominance B) complementation C) multiple alleles D) compound heterozygote E) anticipation
B
A deletion of a small region on the long arm of chromosome 15 causes a developmental disorder in children called Prader-Willi syndrome when the deletion is inherited from the father. However, the deletion of this same region of chromosome 15 can also be inherited from the mother, but this inheritance results in a completely different set of symptoms, called Angelman syndrome. What type of genetic phenomenon does this represent? A) sex-influenced B) genomic imprinting C) cytoplasmic inheritance D) maternal effect E) paternal effect
D
Assume that a polygenic character in Drosophila is produce through the activity of five genes, each with two alleles. Two individuals who are both heterozygous for all five genes are crossed. How many different genotypes are expected in the offspring? A) 9 B) 27 C) 81 D) 243 E) 729
B
Coat color is determined by two loci in large cats. Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white. What kind of gene interaction is this? A) recessive epistasis B) dominant epistasis C) duplicate recessive epistasis D) duplicate dominant epistasis E) dominant and recessive epistasis
C
Coat color is determined by two loci, A and B, in large cats. Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white. What is the genotype of the black progeny? A) A_B_ B) A_BB C) aa B_ D) aa bb E) A_ B_ and A_ bb
E
Coat color is determined by two loci, A and B, in large cats. Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white. What is the genotype of the pink progeny? A) A_B_ B) A_bb C) aa B_ D) aa bb E) A_ B_ and A_ bb
D
Coat color is determined by two loci, A and B, in large cats. Two pink panthers fall in love and produce a large litter of baby panthers with the following phenotypic ratios: 12/16 pink; 3/16 black; and 1/16 white. What is the genotype of the white progeny? A) A_B_ B) A_bb C) aa B_ D) aa bb E) A_ B_ and A_ bb
B
Deafness is often inherited in humans as an autosomal recessive trait. Assume that this is the case here. Two severely deaf people meet and marry. They have four children and all of them have normal hearing. What is the MOST reasonable explanation for this outcome? A) The mutant allele for deafness shows variable expressivity and the normal children may have some hearing loss that is difficult to detect. B) Complementation has occurred in the children, indicating that the deafness mutations in the parents involved different genes. C) Deafness in this family shows a genetic maternal effect with the condition being determined by the genotype of the mother. D) Deafness in this family is most likely caused by an epigenetic change such as the addition of methyl groups to the DNA. E) The mutant allele for deafness shows anticipation and becomes more weakly expressed in succeeding generations.
D
Hair color is determined in Labrador retrievers by alleles at the B & 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) bbee B) bbEE C) Bbee D) BBee E) BBEE
A
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
C & D
Huntington's disease tends to strike earlier and lead to a more rapid progression of symptoms as it moves from generation to generation. Also, it tends to strike earlier and progress more rapidly when it is passed from the father to his children rather than from the mother. Which genetic phenomenon (or phenomena) is/are likely operating here? (Select all that apply.) A) incomplete penetrance B) sex-limited inheritance C) genetic anticipation D) parental imprinting E) epistasis
C
In a certain species of plant, flowers occur in three colors: blue, pink, and white. A pure-breeding pink plant is mated with a pure-breeding white plant. All of the F1 are blue. When the blue F1 plants are selfed, the F2 plants occur in the ratio 9 blue : 3 pink : 4 white. How many gene pairs control the flower color phenotype? A) 0 B) 1 C) 2 D) 3 E) 4
C
In a certain species of plant, flowers occur in three colors: blue, pink, and white. A pure-breeding pink plant is mated with a pure-breeding white plant. All of the F1 are blue. When the blue F1 plants are selfed, the F2 plants occur in the ratio 9 blue : 3 pink : 4 white. The genotype that produces white is ww. The presence of one W allele allows pink or blue color to occur. The alleles at the hypostatic locus are B (blue) and b (pink). What is the genotype of the F1 plants? A) bbWW B) bbWw C) BbWw D) Bbww E) BBww
A
In a certain species of plant, flowers occur in three colors: blue, pink, and white. A pure-breeding pink plant is mated with a pure-breeding white plant. All of the F1 are blue. When the blue F1 plants are selfed, the F2 plants occur in the ratio 9 blue : 3 pink : 4 white. The genotype that produces white is ww. The presence of one W allele allows pink or blue color to occur. The alleles at the hypostatic locus are B (blue) and b (pink). What is the genotype of the pink parent? A) bbWW B) bbWw C) BbWw D) Bbww E) BBww
E
In a certain species of plant, flowers occur in three colors: blue, pink, and white. A pure-breeding pink plant is mated with a pure-breeding white plant. All of the F1 are blue. When the blue F1 plants are selfed, the F2 plants occur in the ratio 9 blue : 3 pink : 4 white. The genotype that produces white is ww. The presence of one W allele allows pink or blue color to occur. The alleles at the hypostatic locus are B (blue) and b (pink). What is the genotype of the white parent? A) bbWW B) bbWw C) BbWw D) Bbww E) BBww
A
In a certain species of plant, flowers occur in three colors: blue, pink, and white. A pure-breeding pink plant is mated with a pure-breeding white plant. All of the F1 are blue. When the blue F1 plants are selfed, the F2 plants occur in the ratio 9 blue : 3 pink : 4 white. What is the name for this type of interaction? A) recessive epistasis B) dominant epistasis C) duplicate recessive epistasis D) duplicate dominant epistasis E) dominant and recessive epistasis
E
In chickens, comb shape is determined by genes at two loci (R, r and P, p). A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_). A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp). A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_). If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced. Give genotypes for comb shape of the parents in the following cross: Pea crossed with single produces 1 single offspring. A) rrPP×rrpp B) RRPp×rrpp C) Rr PP × rr pp D) Rr Pp × rr pp E) rrPp×rrpp
C
In purple people eaters, purple is dominant to white. A true-breeding white mutant is mated with a different true-breeding white mutant. All of the F1 are purple. When the purple F1 offspring mate with each other, their offspring occur in the ratio of 9 purple : 7 white. Which phenomenon explains the purple F1 offspring? A) recessive epistasis B) dominant epistasis C) complementation D) mutation E) suppression
A
In chickens, comb shape is determined by genes at two loci (R, r and P, p). A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_). A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp). A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_). If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced. Give genotypes for comb shape of the parents in the following cross: Rose crossed with pea produces 20 walnut offspring. A) RRpp×rrPP B) Rr pp × rr Pp C) Rr pp × rr PP D) RRpp×rrPp E) Rr pp × Rr Pp
E
In chickens, comb shape is determined by genes at two loci (R, r and P, p). A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_). A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp). A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_). If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced. Give genotypes for comb shape of the parents in the following cross: Rose crossed with single produces 10 rose and 11 single offspring. A) RRPP×rrpp B) RRPp×rrpp C) Rr PP × rr pp D) Rr Pp × rr pp E) Rr pp × rr pp
B
In chickens, comb shape is determined by genes at two loci (R, r and P, p). A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_). A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp). A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_). If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced. Give genotypes for comb shape of the parents in the following cross: Rose crossed with single produces 31 rose offspring A) RRPP×rrpp B) RRpp×rrpp C) Rr PP × rr pp D) Rr Pp × rr pp E) Rr pp × rr pp
E
In chickens, comb shape is determined by genes at two loci (R, r and P, p). A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_). A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp). A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_). If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced. Give genotypes for comb shape of the parents in the following cross: Rose crossed with walnut produces 6 walnut, 6 rose, 2 single, and 2 pea offspring. A) RRpp×rrPP B) Rr pp × rr Pp C) Rr pp × rr PP D) RRpp×rrPp E) Rr pp × Rr Pp
D
In chickens, comb shape is determined by genes at two loci (R, r and P, p). A walnut comb is produced when at least one dominant gene R is present at one locus and at least one dominant gene P is present at a second locus (genotype R_ P_). A rose comb is produced when at least one dominant gene is present at the first locus and two recessive genes are present at the second locus (genotype R_ pp). A pea comb is produced when two recessive genes are present at the first locus and at least one dominant gene is present at the second (genotype rr P_). If two recessive genes are present at the first and the second locus (rr pp), a single comb is produced. Give genotypes for comb shape of the parents in the following cross: Walnut crossed with single produces 1 walnut, 1 rose, 1 pea, and 1 single offspring. A) RRPP×rrpp B) RRPp×rrpp C) Rr PP × rr pp D) Rr Pp × rr pp E) Rr pp × rr pp
D
In domestic chickens, some males display a plumage pattern called cock feathering. Other males and all females display a pattern called hen feathering. Cock feathering is an autosomal recessive trait that is exhibited in males only. Two birds heterozygous for cock feathering are mated. What are the phenotypes of the parents? A) male with cock feathering, female with hen feathering B) male with hen feathering, female with cock feathering C) male with cock feathering, female with cock feathering D) male with hen feathering, female with hen feathering E) cannot be determined from the information given
A
In domestic chickens, some males display a plumage pattern called cock feathering. Other males and all females display a pattern called hen feathering. Cock feathering is an autosomal recessive trait that is exhibited in males only. Two heterozygous birds are mated. What fraction of the female offspring is expected to exhibit cock feathering? A) 0 B) 1/8 C) 1/4 D) 1/2 E) 3/4
C
In domestic chickens, some males display a plumage pattern called cock feathering. Other males and all females display a pattern called hen feathering. Cock feathering is an autosomal recessive trait that is exhibited in males only. Two heterozygous birds are mated. What fraction of the male offspring is expected to exhibit cock feathering? A) 0 B) 1/8 C) 1/4 D) 1/2 E) 3/4
B
In domestic chickens, some males display a plumage pattern called cock feathering. Other males and all females display a pattern called hen feathering. Cock feathering is an autosomal recessive trait that is exhibited in males only. Two heterozygous birds are mated. What fraction of the total offspring is expected to exhibit cock feathering? A) 0 B) 1/8 C) 1/4 D) 1/2 E) 3/4
B
In domestic chickens, some males display a plumage pattern called cock feathering. Other males and all females display a pattern called hen feathering. Cock feathering is an autosomal recessive trait that is exhibited in males only. What type of inheritance is exhibited by this trait? A) sex-linked B) sex-limited C) sex-influenced D) autosomal recessive E) autosomal dominant
C
In order to determine if mutations from different organisms in the same species that exhibit the same phenotype are allelic, which test would you perform? A) testcross B) epistasis test C) complementation test D) allelic series test E) biochemical test
D
In the yawncat (a rare hypothetical animal), the dominant allele R causes solid tail color, and the recessive allele r results in white spots on a colored background. The black coat color allele B is dominant to the brown allele b, but the B and b alleles can only be expressed if the animal has an mm genotype at a third gene locus. Animals that are M_ are yellow regardless of which allele from the B locus is present. A mating between a solid yellow-tailed male yawncat and a solid brown-tailed female yawncat produces 16 offspring with the following tail phenotypes: six solid yellow, two spotted yellow, three solid black, one spotted black, three solid brown, and one spotted brown. What is the MOST likely genotype of the female parent? A) mm bb rr B) Mm bb rr C) mmBbrr D) mm bb Rr E) mmBbRr
E
In the yawncat (a rare hypothetical animal), the dominant allele R causes solid tail color, and the recessive allele r results in white spots on a colored background. The black coat color allele B is dominant to the brown allele b, but the B and b alleles can only be expressed if the animal has an mm genotype at a third gene locus. Animals that are M_ are yellow regardless of which allele from the B locus is present. A mating between a solid yellow-tailed male yawncat and a solid brown-tailed female yawncat produces 16 offspring with the following tail phenotypes: six solid yellow, two spotted yellow, three solid black, one spotted black, three solid brown, and one spotted brown. What is the MOST likely genotype of the male parent? A) MMBBRR B) MM Bb RR C) Mm Bb RR D) MmBBRr E) Mm Bb Rr
D
In the yawncat (a rare hypothetical animal), the dominant allele R causes solid tail color, and the recessive allele r results in white spots on a colored background. The black coat color allele B is dominant to the brown allele b, but the B and b alleles can only be expressed if the animal has an mm genotype at a third gene locus. Animals that are M_ are yellow regardless of which allele from the B locus is present. A mating between a solid yellow-tailed male yawncat and a solid brown-tailed female yawncat produces 16 offspring with the following tail phenotypes: six solid yellow, two spotted yellow, three solid black, one spotted black, three solid brown, and one spotted brown. What is the probability of the next offspring from these same two parents having a spotted brown tail? A) 1/2 B) 3/16 C) 1/4 D) 1/16 E) 9/16
D
Leber hereditary optic neuropathy (LHON) is a human disease that exhibits cytoplasmic inheritance. It is characterized by rapid loss of vision in both eyes, resulting from the death of cells in the optic nerve. A teenager loses vision in both eyes and is later diagnosed with LHON. How did this individual MOST likely inherit the mutant DNA responsible for this condition? A) a nuclear gene from the father B) a nuclear gene from the mother C) a mitochondrial gene from the father D) a mitochondrial gene from the mother E) Any of these answers is possible.
C
Male-limited precocious puberty results from a rare autosomal allele (P) that is dominant over the allele for normal puberty (p) and is expressed only in males. A male and female that both went through normal puberty have two sons. The first son undergoes precocious puberty but the second undergoes normal puberty. What is the genotype of the father? A) PP B) Pp C) pp D) PP or Pp E) Pp or pp
B
Male-limited precocious puberty results from a rare autosomal allele (P) that is dominant over the allele for normal puberty (p) and is expressed only in males. A male and female that both went through normal puberty have two sons. The first son undergoes precocious puberty but the second undergoes normal puberty. What is the genotype of the mother? A) PP B) Pp C) pp D) PP or Pp E) Pp or pp
E
Multifactorial traits are influenced by _____ and _____. A) dominance; codominance B) epistasis; pleiotropy C) age; sex D) genetic imprinting; reduced penetrance E) multiple genes; environment
C
Suppose that the "fabulous" phenotype is controlled by two genes, A and B, as shown in the following diagram. Allele A produces enough enzyme 1 to convert "plain" to "smashing." Allele a produces no enzyme 1. Allele B produces enough enzyme 2 to convert "smashing" to "fabulous." Allele b produces no enzyme 2. The A and B genes are both autosomal and assort independently. What will be the phenotype(s) of the F1 offspring of a true-breeding "fabulous" father and a true-breeding "plain" mother (aa bb)? A) all "plain" B) all "smashing" C) all "fabulous" D) "plain" females and "fabulous" males E) "fabulous" females and "smashing" males
C
Suppose that the "fabulous" phenotype is controlled by two genes, A and B, as shown in the following diagram. Allele A produces enough enzyme 1 to convert "plain" to "smashing." Allele a produces no enzyme 1. Allele B produces enough enzyme 2 to convert "smashing" to "fabulous." Allele b produces no enzyme 2. The A and B genes are both autosomal and assort independently. What will be the phenotype(s) of the F2 offspring of a true-breeding "fabulous" father and a true-breeding "plain" mother (aa bb)? A) 9 "fabulous" : 7 "plain" B) 13 "fabulous" : 3 "plain" C) 9 "fabulous" : 3 "smashing" : 4 "plain" D) 12 "plain" : 3 "fabulous" : 1 "smashing" E) 15 "fabulous" : 1 "smashing"
E
The SRY gene is located on the Y chromosome. This single gene encodes a protein called a transcription factor that binds to DNA and stimulates the transcription of other genes that lead to the development of male sex characteristics, including physical, biochemical, and behavioral phenotypes. What concept in genetics BEST describes this example? A) dominance B) discontinuous characteristic C) polygenic characteristic D) phenocopy E) pleiotropy
D
The bicoid mutation (bcd-) in fruit flies is inherited as a maternal effect recessive allele. What is the expected ratio of phenotypes in the offspring of a cross between a bcd+/bcd- female and a bcd+/bcd- male? A) 1 normal : 1 mutant B) 3 normal : 1 mutant C) 3 mutant : 1 normal D) all normal E) all mutant
B
The cross of CcDd × CcDd results in a 12:3:1 phenotypic ratio. What is the expected phenotypic ratio when a CcDd × ccdd testcross is made involving the same two genes? (They are assorting independently.) A) 1:1:1:1 B) 2:1:1 C) 3:1 D) 9:3:3:1 E) 1:1
E
The himalayan allele in rabbits produces dark fur at the extremities of the body—on the nose, ears, and feet. The dark pigment develops, however, only when a rabbit is reared at a temperature of 25°C or lower; if a Himalayan rabbit is reared at 30°C, no dark patches develop. What does this exemplify? A) dominance B) discontinuous characteristic C) genetic imprinting D) phenocopy E) temperature-sensitive allele
C
The phenomenon in which a gene's expression is determined by its parental origin is called: A) sex-influenced. B) sex-limited. C) genomic imprinting. D) maternal effect. E) paternal effect.
C
The presence of a beard on some goats is determined by an autosomal gene that is dominant in males and recessive in females. Heterozygous males are bearded, while heterozygous females are beardless. What type of inheritance is exhibited by this trait? A) sex-linked B) sex-limited C) sex-influenced D) autosomal recessive E) autosomal dominant
B
The red kernel color in wheat is caused by the presence of at least one dominant allele in each of two independently segregating gene pairs (e.g., R_B_). Wheat plants with rrbb genotypes have white kernels, and plants with genotypes R_bb and rrB_ have yellow kernels. You cross a plant homozygous for red kernels (RR BB) with a plant homozygous for white kernels. What are the relative proportions of the phenotypic classes expected in the F2 progeny after selfing the F1 progeny? A) 9 red; 3 white; 4 yellow B) 9 red; 6 yellow; 1 white C) 9 yellow; 4 red; 1 white D) 9 red; 3 yellow; 4 white E) 12 red; 3 yellow; 1 white
E
The very rare Bombay blood phenotype in humans (first discovered in Bombay, India) results in blood type O because of the lack of both the A and B antigens in individuals who are of hh genotype. This genotype results in blood type O regardless of the genotype at the unlinked I locus. If two parents are both of IA IB Hh genotype (type AB blood), what is the probability that their first child will also have type blood B? A) 3/8 B) 2/3 C) 1/16 D) 1/4 E) 3/16
C
Two loci control body color in beetles. In a cross between a black beetle and a white beetle you obtain a ratio of 9 black to 7 white beetles. What kind of gene interaction is this? A) recessive epistasis B) dominant epistasis C) duplicate recessive epistasis D) duplicate dominant epistasis E) dominant and recessive epistasis
D
What phenomenon describes a genetic trait that is expressed more strongly or earlier in development with each generation? A) epigenetics B) maternally determined progeny phenotypes C) epistasis D) anticipation E) genomic imprinting
E
Which of the following is a characteristic exhibited by cytoplasmically inherited traits? A) present in both males and females B) usually inherited from one parent, typically the maternal parent C) reciprocal crosses that give different results D) extensive phenotypic variation exhibited, even within a single family E) All of the answers are correct.
C
Which organelle in an animal cell, in addition to the nucleus, contains genes? A) lysosome B) ribosome C) mitochondrion D) Golgi body E) vesicle
