Genetics Test 3 Ch. 4

Question 1

1) Which mode of inheritance produces heterozygotes with phenotypes that differ from either homozygote but typically more closely resembles one homozygous phenotype than the other?<br></br>A) complete dominance<br></br> <br></br>B) incomplete dominance<br></br>C) codominance<br></br>D) epistasis<br></br>E) incomplete penetrance

Answer 1

Answer: B

Question 2

2) Which mode of inheritance results in the phenotype of a heterozygote being indistinguishable from that of an organism homozygous for the dominant allele?<br></br>A) complete dominance<br></br>B) incomplete dominance<br></br>C) codominance<br></br>D) epistasis<br></br>E) incomplete penetrance

Answer 2

Answer: A

Question 3

3) Which mode of inheritance results in both alleles being detected equally in the heterozygous phenotype?<br></br>A) complete dominance<br></br>B) incomplete dominance<br></br>C) codominance<br></br>D) epistasis<br></br>E) incomplete penetrance

Answer 3

Answer: C

Question 4

4) A mutation results in an enzyme that is partially active compared to the wild- type allele. This type of “leaky” mutation is classified as ________.<br></br>A) null/ amorphic<br></br>B) hypomorphic<br></br>C) hypermorphic<br></br>D) neomorphic<br></br>E) dominant negative

Answer 4

Answer: B

Question 5

5) A mutation resulting in an inactive gene product is classified as ________. <br></br>A) null/ amorphic<br></br>B) hypomorphic<br></br>C) hypermorphic<br></br>D) neomorphic<br></br>E) dominant negative

Answer 5

Answer: A

Question 6

6) 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 ________.<br></br>A) null/ amorphic<br></br>B) hypomorphic<br></br>C) hypermorphic<br></br>D) neomorphic<br></br>E) dominant negative

Answer 6

Answer: E

Question 7

7) Many oncogenes result from mutations that cause excessive expression of a protein in cells where it is normally not expressed or is expressed at inappropriate times during development. This type of mutation can be described as ________.<br></br>A) hypomorphic<br></br>B) dominant negative<br></br>C) amorphic<br></br>D) hypermorphic <br></br>E) neomorphic

Answer 7

Answer: D

Question 8

8) 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 ________.<br></br>A) dominant negative<br></br>B) hypermorphic <br></br>C) hypomorphic<br></br>D) amorphic<br></br>E) neomorphic

Answer 8

Answer: E

Question 9

9) Which of the following is correct regarding individuals who are blood type AB?<br></br>A) Their blood cells clump when they receive blood from an individual with the genotype IAi.<br></br>B) They express B- transferase that adds N- acetylgalactosamine to the H antigen.<br></br>C) They do not carry the A or B antigen.<br></br>D) They are the universal recipients.<br></br>E) They carry both the anti- A and anti- B antibodies.

Answer 9

Answer: D

Question 10

10) A man with blood type A (whose mother was blood type O) has children with a woman that has blood type AB. The man and the woman are also heterozygous for the H antigen. What is the probability that they will have a child with blood type A?<br></br> A) 0 B) 1/8 C) 3/4 D) 1/2 E) 3/8

Answer 10

Answer: E

Question 11

12) What type of allele is often detected as a distortion in segregation ratios, where one class of expected progeny is missing?<br></br>A) incompletely penetrant allele <br></br>B) partially dominant allele<br></br>C) dominant negative allele<br></br>D) temperature- sensitive allele<br></br>E) lethal allele

Answer 11

Answer: E

Question 12

13) You discover a new allele of a gene important for tail formation in mice. WT mice have long tails, but mice heterozygous for the allele have short tails. When you cross two heterozygous mice together, you obtain a 2:1 ratio of short- tailed mice to long- tailed mice. None of the short- tailed progeny are homozygous. What type of allele results in short tails?<br></br>A) temperature- sensitive allele<br></br>B) lethal allele<br></br>C) incompletely penetrant allele<br></br>D) partially dominant allele<br></br>E) dominant negative allele

Answer 12

Answer: B

Question 13

14) The amount of enzyme activity in a cell that is homozygous for a mutant allele is 400 units. The amount of enzyme activity in a cell homozygous for the WT allele is 200 units. The amount of enzyme activity in a heterozygote is 300 units. What type of allele is the mutant allele?<br></br>A) hypermorphic<br></br>B) hypomorphic <br></br>C) neomorphic<br></br>D) null/ amorphic<br></br>E) dominant negative

Answer 13

Answer: A

Question 14

15) The amount of enzyme activity in a cell that is homozygous for a mutant allele is 400 units. The amount of enzyme activity in a cell homozygous for the WT allele is 200 units. The amount of enzyme activity in a heterozygote is 300 units. What is the dominance relationship between the WT and mutant allele for the phenotype of amount of enzyme per cell? <br></br>A) The WT and mutant alleles show incomplete dominance.<br></br>B) The mutant allele is dominant.<br></br>C) The WT allele is dominant.<br></br>D) The WT and mutant alleles are codominant.<br></br>E) It is impossible to determine from the information given.

Answer 14

Answer: A

Question 15

16) The amount of enzyme activity in a cell that is homozygous for a mutant allele is 0 units. The amount of enzyme activity in a cell homozygous for the WT allele is 200 units. The amount of enzyme activity in a heterozygote is 0 units. What type of allele is the mutant allele?<br></br>A) neomorphic<br></br>B) hypermorphic<br></br>C) hypomorphic<br></br>D) null/ amorphic<br></br>E) dominant negative

Answer 15

Answer: E

Question 16

17) Which phenomenon explains differences in the inheritance patterns of the appearance of a chin beard between males and females of certain species of goats, even when their genotypes are the same?<br></br>A) sex- limited trait<br></br>B) lethal allele<br></br>C) sex- influenced trait<br></br>D) incomplete penetrance<br></br>E) variable expressivity

Answer 16

Answer: C

Question 17

18) In certain goat breeds, appearance of a chin beard is a sex- influenced trait. Recall that bearding is inherited as an autosomal trait determined by two alleles, B1 and B2, and females must be homozygous for the bearded allele, B2, to have a beard. What genotypes must a bearded billy goat (male) and a beardless female goat have if they have a bearded female offspring?<br></br>A) The bearded billy goat must be heterozygous for the bearded allele, while the beardless female must be homozygous for the bearded allele.<br></br>B) The bearded billy goat could be heterozygous or homozygous for the bearded allele, while the beardless female must be homozygous for the bearded allele.<br></br>C) Both the bearded billy goat and beardless female must be heterozygous for the bearded allele.<br></br>D) The bearded billy goat could be heterozygous or homozygous for the bearded allele, while the beardless female must be heterozygous for the bearded allele.<br></br>E) Both the bearded billy goat and beardless female must be homozygous for the bearded allele.

Answer 17

Answer: D

Question 18

21) King George III of England and other members of the royal family were afflicted with a series of strange, seemingly unrelated symptoms including abdominal pain, rapid pulse, convulsions, and insanity. It has been determined that he likely suffered from porphyria, caused by a mutation in a single allele. What is the genetic term describing the alteration of multiple, distinct traits of an organism by a mutation in a single gene?<br></br>A) incomplete dominance<br></br>B) pleiotropy<br></br>C) epistasis<br></br>D) codominance<br></br>E) incomplete penetrance

Answer 18

Answer: B

Question 19

22) Gene interactions in which an allele of one gene modifies or prevents expression of alleles of another gene is known as ________.<br></br>A) incomplete dominance<br></br>B) codominance<br></br>C) epistasis<br></br>D) incomplete penetrance <br></br>E) pleiotropy

Answer 19

Answer: C

Question 20

23) 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?<br></br>A) 16 purple to 0 white <br></br>B) 7 purple to 9 white<br></br>C) 0 purple to 16 white<br></br>D) 9 purple to 7 white<br></br>E) 8 purple to 8 white

Answer 20

Answer: D

Question 21

24) The 9:6:1 ratio seen in the dihybrid cross of summer squash indicates what genetic relationship between the two genes controlling fruit shape?<br></br>A) recessive epistasis<br></br>B) dominant suppression<br></br>C) complementary gene interaction<br></br>D) dominant epistasis<br></br>E) dominant gene interaction

Answer 21

Answer: E

Question 22

27) Wild- type bacteria can grow on minimal medium. Four mutants that cannot grow on minimal medi but can grow on minimal medium supplemented with the nutrient “H” are isolated. It is suspected th metabolites T, P, and A are in the biochemical pathway for synthesis of H, so each mutant is tested fo ability to grow on minimal medium supplemented with these metabolites: <br></br>A. Mutant 1: can grow on minimal medium supplemented with T, but not P or A<br></br>B. Mutant 2: is unable to grow on minimal medium supplemented with T, P, or A<br></br>C. Mutant 3: is able to grow on minimal medium supplemented with A or T, but not P<br></br> D. Mutant 4: can grow on minimal medium supplemented with T, P, or A.<br></br>Which of the following is NOT consistent with this information?<br></br>A) Mutant 1 will cause a build up of metabolite A<br></br>B) Mutant 4 blocks a step before all the metabolites<br></br>C) Mutant 3 blocks the conversion of metabolite P metabolite A<br></br>D) Mutant 3 will cause a build up of metabolite T<br></br>E) Mutant 2 blocks a step right before metabolite H

Answer 22

Answer: D

Question 23

28) Wild- type bacteria can grow on minimal medium. Four mutants that cannot grow on minimal medi but can grow on minimal medium supplemented with the nutrient “H” are isolated. It is suspected the metabolites T, P, and A are in the biochemical pathway for synthesis of H, so each mutant is tested for<br></br> <br></br>ability to grow on minimal medium supplemented with these metabolites: A<br></br>A Mutant 1: can grow on minimal medium supplemented with T, but not P or A<br></br>B. Mutant 2: is unable to grow on minimal medium supplemented with T, P, or A <br></br>C Mutant 3: is able to grow on minimal medium supplemented with A or T, but not P<br></br> D. Mutant 4: can grow on minimal medium supplemented with T, P, or A.<br></br>Which of the following is NOT consistent with this information?<br></br>A) Mutant 3 blocks the conversion of metabolite P metabolite A <br></br>B) Mutant 4 blocks a step before all the metabolites <br></br>C) Mutant 1 will cause a build up of metabolite A<br></br>D) Mutant 1 blocks the conversion of metabolite T metabolite H <br></br>E) Mutant 2 blocks a step right before metabolite H

Answer 23

Answer: D

Question 24

29) 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?<br></br>A) heterozygotes with a novel phenotype between the dominant and recessive homozygotes<br></br>B) 1/3 of the progeny with the dominant phenotypes and 2/3 recessive<br></br>C) more than four phenotypes<br></br>D) fewer than four phenotypes<br></br>E) no change in the 9:3:3:1 ratio

Answer 24

Answer: D

Question 25

30) 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?
A) The genes are part of two distinct biosynthetic pathways.
B) The allele is pleiotropic.
C) The allele exhibits incomplete dominance.
D) More than one gene is involved in determining the phenotype.
E) The two lines exhibit different mutations in the same gene.

Answer 25

Answer: D

Question 26

31) You are looking at the color of feathers in ducks and find that yellow ducks (Y) are dominant to green ducks (y). However, a second gene, H, controls whether the color will be expressed in the feathers. If the duck is hh, the duck will always be white, because the pigment does not go into feathers. What ratio of phenotypes would you expect following a dihybrid cross?
A) 15:1 B) 12:3:1 C) 9:3:4 D) 9:6:1 E) 13:3

Answer 26

Answer: C

Question 27

32) In sheep, coat color is influenced by two genes. Gene A influences pigment production, while gene B produces black or brown pigment. If two heterozygous white sheep resulted in 12 white sheep, 3 black sheep, and 1 brown sheep, which genotype(s) of the white sheep explain this data?
A) The white sheep could be A_B_ or aabb.
B) The white sheep must all be A_B_.
C) The white sheep could be A_B_ or A_bb.
D) The white sheep must all be aabb.
E) The white sheep could be A_B_ or aaB_.

Answer 27

Answer: C

Question 28

33) A certain species of morning glories produces flowers that are blue, red, or purple. Two pure- breeding purple lines are crossed and produce F1 progeny that all make blue flowers. The F1 a allowed to self and produce 320 F2 progeny with the following distribution: 185 blue, 115 purple, an red.
Which the following is NOT consistent with this information?
A) Blue- flowering plants are either A_bb or aaB_.
B) The pure- breeding parental parents are homozygous recessive for mutations in two different genes.
C) Dominant gene interaction appears to result in a 9:6:1 ratio.
D) Analysis of the F1 and F2 progeny phenotypes suggests epistasis.
E) Red- flowering plants are homozygous recessive for both genes.

Answer 28

Answer: A

Question 29

34) Deafness is caused by recessive mutations in any one of at least five genes. Two deaf individuals have nine children, all of whom have normal hearing. Which of the following can you conclude?
A) The mutations are codominant to the normal allele.
B) The parents have the same mutated protein involved in inner ear development.
C) The parents have mutations in different genes.
D) The mutations are incompletely dominant to the normal allele.
E) The parents have mutations in the same gene.

Answer 29

Answer: C

Question 30

35) In yeast, there are three gene products required to synthesize the amino acid lysine. You cross two haploid lysine auxotrophs to form a diploid. The diploid fails to grow on plates lacking lysine.
Which of the following can you definitively conclude?
A) The haploid strains have identical mutations in the same genes.
B) The haploid strains must belong to the complementation group encoding the first enzyme in the biosynthetic pathway.
C) The haploid strains have identical mutations in different genes.
D) The haploid strains have mutations in the same gene.
E) The haploid strains have mutations in different genes.

Answer 30

Answer: D

Question 31

37) 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?

Answer 31

Answer: D is haplosufficient.

Question 32

42) You cross a pure- breeding white flower with a pure- breeding red flower, and the offspring are all pink. This is an example of what type of inheritance?

Answer 32

Answer: incomplete dominance

Question 33

43) You cross a pure- breeding white flower with a pure- breeding red flower, and the offspring are white with red spots. This is an example of what type of inheritance?

Answer 33

Answer: codominance

Question 34

44) Alleles of the Sbe1 gene, which controls pea shape, can be detected by DNA analysis. In heterozygous plants, two distinct bands of DNA are visible. What is the relationship between the alleles of the heterozygote at the molecular level?

Answer 34

Answer: codominant

Question 35

45) The four different human blood types are caused by how many different alleles? What are the alleles?

Answer 35

Answer: three: IA, IB, and i

Question 36

46) Which antigen, expressed on the surface of all red blood cells, is modified by A- or B- transferases?

Answer 36

Answer: H antigen

Question 37

47) The allele responsible for the Siamese coat- color pattern produces an unstable tyrosinase enzyme. This type of gene product is an example of what type of allele?

Answer 37

Answer: temperature- sensitive

Question 38

48) 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?

Answer 38

Answer: incomplete penetrance

Question 39

49) People with the dominant mutant polydactyly allele can have extra digits on one or both of their hands. What is the genetic explanation for this observation?

Answer 39

Answer: variable expressivity

Question 40

50) To better understand which genes are involved in developmental pathways, geneticists use experimental analyses of mutant phenotypes. What is this analytic approach called?

Answer 40

Answer: genetic dissection

Question 41

51) Mendel studied tall and short pure- breeding lines of pea plants. Inherited genetic 51) variation would dictate that one line would produce tall plants and the other short plants, but the genes and phenotypes are influenced by what external factor?

Answer 41

Answer: environmental influence

Question 42

52) Amorphic, hypomorphic, and dominant negative mutations are ________ mutations, which decrease or eliminate gene activity.

Answer 42

Answer: Loss- of- function

Question 43

53) Hypermorphic and neomorphic mutations are ________ mutations, which cause overexpression or result in new functions.

Answer 43

Answer: Gain- of- function

Question 44

54) Most combinations of different ABO alleles result in complete dominance of one allele. Which combination results in codominance?

Answer 44

Answer: IAIB

Question 45

55) If an organism with a particular genotype fails to produce the corresponding phenotype, the organism is said to be ________ for the trait.

Answer 45

Answer: nonpenetrant

Question 46

56) In Labrador retrievers, coat color is controlled by gene interaction in which homozygosity for a recessive allele can mask the phenotypic expression of a second gene. This genetic interaction is known as ________ and has a characteristic ________ ratio.

Answer 46

Answer: recessive epistasis; 9:3:4