Deck 12: Inheritance, Genes, and Chromosomes

Question 1

The physical appearance of an organism is called its

A) genotype.
B) allele.
C) merotype.
D) phenotype.
E) gene.

Answer 1

D

Question 2

One of the major contributions of Mendel to the study of genetics was

A) the use of probability to analyze data.
B) a complete description of the process of meiosis.
C) the understanding that phenotypes are affected by the environment.
D) the discovery that dominance is always complete.
E) the finding that heritable traits blend together.

Answer 2

A

Question 3

Which statement about haploid organisms is true?

A) They must be heterozygous for all genes.
B) They must be homozygous for all genes.
C) They can have only one allele for any particular gene.
D) They are missing a certain number of genes.
E) They have excess alleles for certain genes.

Answer 3

C

Question 4

If two strains of true-breeding plants that have different alleles for a certain character are crossed, their progeny are called

A) the P generation.
B) the F₁ generation.
C) the F₂ generation.
D) F₁ crosses.
E) F₂ progeny.

Question 5

Geneticists have discovered the existence of meiotic drive genes, which have alleles that, when present in a heterozygous state, are able to become incorporated into much more than 50 percent of the gametes.As a result, the offspring ratios are not what Mendel would have predicted.Which statement about these meiotic drive genes is true?

A) They violate the law of independent assortment.
B) They violate the law of equal segregation.
C) They alter dominance relationships.
D) They alter phenotypes.
E) They are an example of blending inheritance.

Question 6

Which method was not used by Mendel in his study of the genetics of the garden pea?

A) Maintenance of true-breeding lines
B) Cross pollination
C) Production of hybrid plants
D) Quantitative analysis of results
E) Tracking of chromosomal movements

Question 7

Suppose on the hypothetical planet Trantor, a plantlike creature called a zork exhibits the characteristics of blending inheritance.Red zorks that are crossed with other red zorks produce only red offspring.White zorks that are crossed with other white zorks produce only white offspring.White zorks that are crossed with red zorks yield pink offspring.If pink offspring were backcrossed to their white parents, which would be the most likely result?

A) All red individuals
B) All white individuals
C) 3/4 white individuals, 1/4 red individuals
D) 1/2 white individuals, 1/2 red individuals
E) 1/2 white individuals, 1/2 pink individuals

Question 8

The parents of individuals in the F₂ generation are members of the _______ generation.

A) P
B) F₁
C) F₂
D) F₃
E) M

Question 9

If Mendel had performed experiments on cattle rather than on peas, the patterns of inheritance would not have been easily detectable, because cattle

A) have only dominant traits.
B) have small numbers of offspring.
C) do not have observable phenotypes.
D) are animals.
E) are diploid.

Question 10

Suppose Mendel had an assistant who sometimes forgot to emasculate the short plants before placing pollen from the homozygous tall plants on the pistils of the short plant flowers.As a result, about 2/3 of the pollen that fertilized the short flowers came from short plants.What fraction of the progeny from this cross would have been tall? (Recall that the trait of tall is dominant to short.)

A) 1/3
B) 1/2
C) 2/3
D) 3/4
E) All of the progeny from this cross would have been tall.

Question 11

Suppose that a genetics researcher concludes that the probability of obtaining a double dominant phenotype in an F₂ cross is 9/16.This conclusion can be valid only if one or more assumptions are true.Which assumption is necessary?

A) Alleles have an unequal probability of separating into gametes.
B) The two genes assort independently.
C) The sample size is small.
D) The two genes are linked.
E) The gene exhibits incomplete dominance.

Question 12

The genotype of an organism that expresses a dominant trait can be determined by

A) crossing the organism with a homozygous recessive organism.
B) crossing the organism with a heterozygous dominant organism.
C) crossing the organism with a homozygous dominant organism.
D) observing the phenotype of the progeny from any cross.
E) observing the genotype of the progeny from any cross.

Question 13

Classical albinism results from a recessive allele.What are the expected probabilities for the progeny of an albino female and a fully pigmented male with an albino father?

A) All normal
B) 1/2 normal, 1/2 albino
C) 3/4 normal, 1/4 albino
D) 3/4 albino, 1/4 normal
E) All albino

Question 14

Which statement about the theories of blending inheritance and particulate inheritance is correct?

A) Genes remain stable across generations according to the theory of blending inheritance, but not according to particulate inheritance.
B) Genes remain stable across generations according to the theory of particulate inheritance, but not according to blending inheritance.
C) Gametes fuse during fertilization according to the theory of blending inheritance, but not according to particulate inheritance.
D) Gametes fuse during fertilization according to the theory of particulate inheritance, but not according to blending inheritance.
E) The theory of blending inheritance applies to diploid organisms, whereas the theory of particulate inheritance applies to haploid organisms.

Question 15

If white-eyed flies are crossed with other white-eyed flies from the same strain, the offspring will all have white eyes.This trait can thus be said to be

A) dominant.
B) recessive.
C) filial.
D) true breeding.
E) heterozygous.

Question 16

Segregation of alleles occurs

A) during meiosis.
B) at fertilization.
C) during mitosis.
D) during the random combination of gametes to produce the F₂ generation.
E) only in monohybrid crosses.

Question 17

Mendel's results demonstrated that

A) phenotype is responsible for establishing genotype.
B) genotype is responsible for establishing phenotype.
C) diploid organisms have phenotypes, whereas haploid organisms have genotypes.
D) haploid organisms have phenotypes, whereas diploid organisms have genotypes.
E) phenotype is independent of genotype.

Question 18

In a species of mice, short hair is dominant to long hair.If a short-haired individual is crossed with a long-haired individual and both long- and short-haired offspring result, one can conclude that

A) the short-haired individual is homozygous.
B) the long-haired individual is heterozygous.
C) the long-haired individual is homozygous.
D) the short-haired individual is heterozygous.
E) This cannot be answered without more information.

Question 19

Curly wing is recessive to straight wing in Drosophila.In a cross between true-breeding curly- and straight-winged parental flies, there are 480 flies in the F₂ generation.How many F₂ progeny should have curly wings?

A) 25
B) 75
C) 120
D) 240
E) 360

Question 20

Mendel concluded that each pea has two units for each character, and each gamete contains one unit.Mendel's "unit" is now referred to as a

A) gene.
B) character.
C) trait.
D) genotype.
E) phenotype.

Question 21

Which number cannot be a value for a probability?

A) 0
B) 0.56
C) 0.794
D) 0.96543
E) 1.13

Question 22

A(n) _______ cross involves two different unlinked genes, each affecting a different character.

A) monohybrid
B) dihybrid
C) trihybrid
D) F₁
E) F₂

Question 23

Refer to the table.In Drosophila, white (w), eosin (w^e), and wild-type red (w⁺) are multiple alleles at a single locus for eye color.This locus is on the X chromosome.A female that has eosin (pale orange) eyes is crossed with a male that has wild-type (red) eyes.All the female progeny are red-eyed; about half the male progeny have eosin eyes, and about half have white eyes.Assume the female has two X chromosomes and the male has one X and one Y. What is the order of dominance of these alleles?

A) w > w^e > w⁺
B) w^e > w > w⁺
C) w⁺ > w > w^e
D) w > w⁺ > w^e
E) w⁺ > w^e > w

Question 24

In garden peas, the allele for tall plants is dominant over the allele for short plants.Suppose that a true-breeding tall plant is crossed with a short plant, and one of their offspring is crossed with a short plant.Out of 20 offspring resulting from the cross, about _______ should be tall.

A) 0
B) 5
C) 10
D) 15
E) 20

Question 25

Geneticists have discovered the existence of meiotic drive genes, which have alleles that, when present in a heterozygous state, are able to become incorporated into much more than 50 percent of the gametes.As a result, the offspring ratios are not what Mendel would have predicted.Suppose that the short allele is a meiotic drive gene, and 80 percent of the gametes from a heterozygous individual with tall and short alleles contain short alleles.If tall is dominant to short, what percent of individuals from a cross between a heterozygous tall individual and a homozygous recessive individual will be tall?

A) 20 percent
B) 40 percent
C) 50 percent
D) 60 percent
E) 80 percent

Question 26

In Drosophila, the genes for body coloration and eye size are on different chromosomes.Normal-colored bodies are dominant to ebony-colored (very dark) bodies, and normal-sized eyes are dominant to eyelessness.Line A is true breeding for normal bodies and normal eyes, whereas line B is true breeding for ebony bodies and eyelessness.From an F₂ cross between lines A and B, 800 flies are scored.How many F₂ flies are expected to have both normal body color and normal eyes?

A) 3
B) 50
C) 150
D) 450
E) 600

Question 27

If big feet (B) in schmoos is dominant to small feet (b), the genotype of a big-footed schmoo with respect to the foot gene can

A) only be bb.
B) only be BB.
C) either be Bb or BB.
D) either be bb or BB.
E) either be bb and Bb.

Question 28

In Drosophila, the recessive allele p, when homozygous, determines pink eyes.Pp or PP results in wild-type eye color.On the same chromosome of Drosophila that carries the p (pink eyes) locus there is another locus that affects the wings.Homozygous recessives, byby, have blistery wings, while the dominant allele By produces wild-type wings.The P and By loci are very close together on the chromosome; that is, the two loci are tightly linked.Assume that no crossing over occurs, and that the F₂ generation is produced by interbreeding the F₁ progeny.For the cross PPbyby * ppByBy, what is the phenotype ratio of the F₂ generation?

A) 1 wild-type eyes/blistery wings : 2 wild-type eyes/wild-type wings : 1 pink eyes/wild-type wings
B) 1 wild-type eyes/wild-type wings : 2 wild-type eyes/blistery wings : 1 pink eyes/wild-type wings
C) 1 pink eyes/wild-type wings : 2 pink eyes/blistery wings : 1 wild-type eyes/blistery wings
D) 1 wild-type eyes/blistery wings : 2 pink eyes/blistery wings : 1 pink eyes/wild-type wings
E) 1 pink eyes/blistery wings : 2 wild-type eyes/blistery wings : 1 wild-type eyes/wild-type wings

Question 29

The site on the chromosome occupied by a gene is called a(n)

A) allele.
B) region.
C) locus.
D) type.
E) phenotype.

Question 30

In cocker spaniels, black color (B) is dominant over red (b), and solid color (S) is dominant over spotted (s).If the genes are unlinked and the offspring of BBss and bbss individuals are mated with each other, what fraction of their offspring will be black and spotted?

A) 1/16
B) 9/16
C) 1/9
D) 3/16
E) 16/16

Question 31

Suppose that in a certain population of lizards, the probability of the birth of a male is 0.6.Assume that the sex of each individual is independently determined.What is the probability that a clutch of three will be all male?

A) 0.064
B) 0.125
C) 0.216
D) 0.25
E) 0.36

Question 32

Mendel performed a cross between two individuals, each heterozygous for three different traits that are unlinked: Round versus wrinkled seeds (round is dominant), purple versus white flowers (purple is dominant), and tall versus dwarf stems (tall is dominant).Of the 64 offspring, how many had wrinkled seeds, purple flowers, and dwarf stems?

A) 3
B) 6
C) 9
D) 12
E) 27

Question 33

In humans, a widow's peak is caused by a dominant allele (W), and a continuous hairline is caused by a recessive allele (w).Short fingers are caused by a dominant allele (S), and long fingers are caused by a recessive allele (s).Suppose a woman with a continuous hairline and short fingers and a man with a widow's peak and long fingers have three children.One child has a widow's peak and short fingers, one has a widow's peak and long fingers, and one has a continuous hairline and long fingers.What are the genotypes of the parents?

A) Female wwSS; male WWss
B) Female wwSs; male Wwss
C) Female wwSs; male WWss
D) Female WwSs; male WwSs
E) Female WwSs; male WWss

Question 34

Human pedigrees do not show the clear patterns that Mendel found in his peas because

A) there are no dominant traits in humans.
B) there are no recessive traits in humans.
C) Punnett squares cannot be constructed for humans.
D) human meiosis does not result in segregation of alleles into gametes.
E) humans do not produce large numbers of offspring.

Question 35

Nearly all male wasps in natural populations of the species Nasonia vitripenis have small wings.The trait of small wings in this species is thus considered

A) polymorphic.
B) dominant.
C) codominant.
D) a genotype.
E) the wild type.

Question 36

Which observed phenotypic pattern in a pedigree would make it more likely that an inherited trait is recessive rather than dominant?

A) Every affected individual has an affected parent.
B) About half of the offspring of an affected parent are also affected.
C) Some affected individuals have unaffected parents.
D) The family size is small.
E) The family size is large.

Question 37

Suppose that in a certain population of lizards, the probability of the birth of a male is 0.6.Assume that the sex of each individual is independently determined.What is the probability that a clutch of three will have exactly two females? (Note that there are three ways to arrive at this outcome when calculating the probabilities of each egg's sex.)

A) 0.096
B) 0.125
C) 0.196
D) 0.288
E) 0.375

Question 38

In Drosophila, the recessive allele p, when homozygous, determines pink eyes.Pp or PP results in wild-type eye color.On the same chromosome of Drosophila that carries the p (pink eyes) locus there is another locus that affects the wings.Homozygous recessives, byby, have blistery wings, whereas the dominant allele By produces wild-type wings.The P and By loci are very close together on the chromosome; that is, the two loci are tightly linked.Assume that no crossing over occurs, and that the F₂ generation is produced by interbreeding the F₁ progeny.For the cross PPByBy * ppbyby, what is the genotype ratio of the F₂ generation?

A) 3 PPByBy : 1 ppbyby
B) 1 PPByBy : 3 ppbyby
C) 1 PPByBy : 2 PpByby: 1 ppbyby
D) 3 PpByby : 1 ppbyby
E) 1 PpByby : 3 PPByBy

Question 39

Mendel performed a cross between two individuals, each heterozygous for three different traits controlled by unlinked genes: Green versus yellow seeds (green is dominant), red versus white flowers (red is dominant), and green versus yellow pods (green is dominant).Of the 64 offspring, how many had green seeds, red flowers, and green pods?

A) 3
B) 6
C) 9
D) 12
E) 27

Question 40

In Drosophila, the genes for body coloration and eye size are on different chromosomes.Normal-colored bodies are dominant to ebony-colored (very dark) bodies, and normal-sized eyes are dominant to eyelessness.Line A is true breeding for normal bodies and normal eyes, whereas line B is true breeding for ebony bodies and eyelessness.From an F₂ cross between lines A and B, 800 flies are scored.How many F₂ flies are expected to have normal body color and to be eyeless?

A) 3
B) 50
C) 150
D) 450
E) 600

Question 41

If the same allele has two or more phenotypic effects, it is said to be

A) codominant.
B) a marker.
C) linked.
D) hemizygous.
E) pleiotropic.

Question 42

Epistasis refers to

A) a group of genes that are close together.
B) intermediate dominance.
C) the expression of two alleles of the same gene in an individual.
D) the linear order of genes on a chromosome.
E) the expression of one gene affecting the expression of another.

Question 43

Agouti is a type of coat color pattern in mice that cannot be expressed in albinos (white mice).A nonalbino agouti mouse that is heterozygous at the albino (A) and agouti (B) loci (AaBb) is mated to an albino mouse that is heterozygous at the agouti locus (aaBb).Nonalbino mice without the dominant agouti allele (AAbb and Aabb) are black.What percent of the progeny would you expect to be albino?

A) 0 percent
B) 12.5 percent
C) 37.5 percent
D) 50 percent
E) 100 percent

Question 44

In Netherlands dwarf rabbits, a gene showing incomplete dominance produces three phenotypes.Rabbits that are homozygous for one allele are small; individuals that are homozygous for the other allele are deformed and die; individuals that are heterozygous are dwarf.If two dwarf rabbits are mated, what proportion of their surviving offspring are likely to be dwarf?

A) 1/4
B) 1/3
C) 1/2
D) 2/3
E) 3/4

Question 45

Suppose that in a plant the smooth seed character (SS) is completely dominant over the wrinkled seed character (ss).If the characters for height are incompletely dominant-such that TT is tall, Tt is intermediate, and tt is short-what will result from crossing a smooth-seeded short plant (SStt) with a wrinkled-seeded tall plant (ssTT)?

A) One-half will be smooth-seeded and intermediate in height; one-half will be smooth-seeded and tall.
B) All the progeny will be smooth-seeded and tall.
C) All the progeny will be smooth-seeded and short.
D) All the progeny will be smooth-seeded and intermediate in height.
E) This cannot be answered without more information.

Question 46

Suppose that two different groups of schmoos (an imaginary animal) live in geographically separated locations and rarely interbreed.On one occasion, a big-footed white-haired schmoo does mate with a small-footed brown-haired schmoo.Six offspring result: two big-footed schmoos with light brown hair and four small-footed schmoos with light brown hair.Which statement about the inheritance of hair color in schmoos is most likely correct?

A) There is incomplete dominance.
B) Brown is dominant to white.
C) White is dominant to brown.
D) White and brown are codominant.
E) This cannot be answered without more information.

Question 47

The ABO blood groups in humans are determined by a multiple-allele system in which I^A and I^B are codominant and are both dominant to I^O.If an infant born to a mother with blood type O is also type O, the father's blood type can be

A) only O or A.
B) only A or B.
C) only O.
D) O, A, or B.
E) impossible to determine.

Question 48

In a particular plant species, two alleles control flower color, which can be yellow, blue, or white.Crosses of these plants produce the offspring shown in the table. What will be the phenotype, and ratio, of the offspring of a cross of blue *blue?

A) Blue, yellow, and white in a 1:2:1 ratio
B) White and yellow in a 1:1 ratio
C) Yellow and white in a 3:1 ratio
D) Blue and white in a 3:1 ratio
E) Yellow, blue, and white in a 1:2:1 ratio

Question 49

Which phenomenon is the best evidence against genetic determinism?

A) Pleiotropy
B) Independent assortment
C) Variable expressivity
D) Codominance
E) Epistasis

Question 50

The blue sclera allele has 75 percent penetrance for producing blue sclera, 60 percent penetrance for fragile bones, and 40 percent penetrance for deafness.If these probabilities of penetrance are independent, _______ percent of individuals with the blue sclera allele will have deafness, blue sclera, and fragile bones.

A) 18
B) 24
C) 45
D) 54
E) 82

Question 51

Suppose members of a true-breeding strain of salamanders with yellow stripes are crossed with a true-breeding strain with red stripes.Red and yellow are two alleles of the same gene.The resulting offspring have both yellow stripes and red stripes.Which dominance pattern is most likely?

A) Red stripes are dominant to yellow stripes.
B) Yellow stripes are dominant to red stripes.
C) Red and yellow stripes exhibit incomplete dominance.
D) Red and yellow stripes exhibit overdominance.
E) Red and yellow stripes exhibit codominance.

Question 52

Refer to the table.In Drosophila, white (w), eosin (w^e), and wild-type red (w⁺) are multiple alleles at a single locus for eye color.This locus is on the X chromosome.A female that has eosin (pale orange) eyes is crossed with a male that has wild-type (red) eyes.All the female progeny are red-eyed; about half the male progeny have eosin eyes, and about half have white eyes.Assume the female has two X chromosomes and the male has one X and one Y. What are the genotypes of the parents?

A) w^ew^e and wY
B) w^ew and wY
C) w^ew⁺ and wY
D) w^ew and w⁺Y
E) w^ew^e and w⁺Y

Question 53

The ABO blood groups in humans are determined by a multiple-allele system in which I^A and I^B are codominant and are both dominant to I^O.A newborn infant is type A.The mother is type O.Possible phenotypes of the father are

A) A, B, or AB.
B) A, B, or O.
C) O only.
D) A or AB.
E) A or O.

Question 54

Agouti is a type of coat color pattern in mice that cannot be expressed in albinos (white mice).A nonalbino agouti mouse that is heterozygous at the albino (A) and agouti (B) loci (AaBb) is mated to an albino mouse that is heterozygous at the agouti locus (aaBb).Nonalbino mice without the dominant agouti allele (AAbb and Aabb) are black.What percent of the progeny would you expect to be agouti?

A) 0 percent
B) 12.5 percent
C) 37.5 percent
D) 50 percent
E) 100 percent

Question 55

Suppose members of a true-breeding strain of salamanders with yellow stripes are crossed with a true-breeding strain with red stripes.Red and yellow are two alleles of the same gene.The resulting offspring have both yellow stripes and red stripes.What pattern would you expect in the F₂ generation?

A) Half will have yellow stripes, and half will have red stripes.
B) Half will have both yellow and red stripes, one-quarter will have just yellow stripes, and one-quarter will have just red stripes.
C) One-third will have both yellow and red stripes, one-third will have just yellow stripes, and one-third will have just red stripes.
D) Half will have both yellow and red stripes, and half will be stripeless.
E) One-quarter will have both yellow and red stripes, half will have just yellow stripes, and one-quarter will have just red stripes.

Question 56

A dominant allele (K) is necessary for normal hearing.A dominant allele (M) at a different, unlinked locus results in deafness no matter which other alleles are present.If a kkMm individual is crossed with a Kkmm individual, _______ percent of the offspring will be deaf.

A) 0
B) 25
C) 50
D) 67
E) 75

Question 57

The blue sclera allele has 75 percent penetrance for producing blue sclera, 60 percent penetrance for fragile bones, and 40 percent penetrance for deafness.If these probabilities of penetrance are independent, _______ percent of individuals with the blue sclera allele will be unaffected.

A) 0
B) 6
C) 24
D) 54
E) 82

Question 58

Agouti is a type of coat color pattern in mice that cannot be expressed in albinos (white mice).A nonalbino agouti mouse that is heterozygous at the albino (A) and agouti (B) loci (AaBb) is mated to an albino mouse that is heterozygous at the agouti locus (aaBb).Nonalbino mice without the dominant agouti allele (AAbb and Aabb) are black.What percent of the progeny would you expect to be black?

A) 0 percent
B) 12.5 percent
C) 37.5 percent
D) 50 percent
E) 100 percent

Question 59

Suppose that two different groups of schmoos (an imaginary animal) live in geographically separated locations and rarely interbreed.On one occasion, a big-footed white-haired schmoo does mate with a small-footed brown-haired schmoo.Six offspring result: two big-footed schmoos with light brown hair and four small-footed schmoos with light brown hair.Which statement about the inheritance of footedness in schmoos is most likely correct?

A) Big is dominant to small.
B) Small is dominant to big.
C) Big and small are codominant.
D) There is intermediate dominance.
E) This cannot be answered without more information about whether the parents are true-breeding.

Question 60

Suppose that in corn some alleles result in higher yield, but only in the heterozygous state (Aa has higher yield than either AA or aa).If different homozygous strains of corn each have different deleterious alleles, hybrids will likely to exhibit _______, as explained by the _______ hypothesis.

A) epistasis; dominance
B) epistasis; overdominance
C) heterosis; dominance
D) heterosis; overdominance
E) codominance; dominance

Question 61

Sometimes scientists get lucky.Consider Mendel's dihybrid cross shown in the figure. Peas have a haploid number of seven chromosomes, so many of their genes are linked.What would Mendel's results have been if the genes for seed color and seed shape were linked with a map distance of 14 units?

A) 14% recombinant, approximately 7% round green and 7% wrinkled yellow
B) 14% recombinant, approximately 7% round yellow and 7% wrinkled green
C) 50% recombinant, approximately 25% round yellow and 25% wrinkled green
D) 90% recombinant, approximately 45% round green and 45% wrinkled yellow
E) 90% recombinant, approximately 45% round yellow and 45% wrinkled green

Question 62

Suppose that tall plants are crossed with short, and the progeny are medium height.The F₁ plants are then crossed, and the progeny among the F₂ have many more size classes (9) than what is typically seen in crosses involving a single gene (fewer than 4).Which is the best explanation for this outcome?

A) The existence of pleiotropic alleles
B) Incomplete dominance
C) Codominance
D) Epistasis
E) Multiple alleles

Question 63

Suppose you are an advisor to a wildlife agency that has asked you to evaluate a population of deer in which antler size has shrunk considerably in the course of about three generations.The animals mate more or less randomly and are not being targeted by hunters.Which effect best accounts for the change in antler size?

A) Environmental effects
B) Overdominance
C) Heterosis
D) Pleiotropy
E) Epistasis

Question 64

In Drosophila, the recessive allele p, when homozygous, determines pink eyes.Pp or PP results in wild-type eye color.On the same chromosome of Drosophila that carries the p (pink eyes) locus there is another locus that affects the wings.Homozygous recessives, byby, have blistery wings, whereas the dominant allele By produces wild-type wings.The P and By loci are very close together on the chromosome; that is, the two loci are tightly linked.For the cross PPbyby * ppByBy, what phenotype(s) would appear in the F₂ generation if crossing over occurred?

A) Wild-type eyes/blistery wings and pink eyes/wild-type wings
B) Wild-type eyes/wild-type wings and pink eyes/blistery wings
C) Wild-type eyes/wild-type wings, wild-type eyes/blistery wings, and pink eyes/wild-type wings
D) Pink eyes/blistery wings, pink eyes/wild-type wings, and wild-type eyes/blistery wings
E) Wild-type eyes/wild-type wings, wild-type eyes/blistery wings, pink eyes/wild-type wings, and pink eyes/blistery wings

Question 65

In Drosophila, three autosomal genes have alleles as follows: Normal bristles (Sb) is dominant over stubble bristles (sb); straight wings (C) is dominant over curly wings (c); and red eye (Se) is dominant over sepia (se).Two test crosses were performed, with the results shown in the table. What linkage can you determine from these crosses?

A) Only Se and Sb are linked, with a distance of 32.2 units.
B) Only Sb and C are linked, with a distance of 48.7 units.
C) Only Se and C are linked, with a distance of 40.7 units.
D) None of the genes are linked.
E) All of the genes are on the same chromosome, Se and Sb are 32.2 units apart, and Sb and C are 48.7 units apart.

Question 66

Which observation would not support the hypothesis that the gene controlling maleness is located on the Y chromosome?

A) XO individuals are usually sterile females, with slight physical abnormalities.
B) XXY individuals are sterile males with long limbs.
C) XXX individuals are normal males.
D) Some men are XX but have a small piece of the Y attached to another chromosome.
E) XYY individuals are males.

Question 67

Sex in humans is determined by

A) a gene called SRY found on the Y chromosome.
B) a gene called SRY found on the X chromosome.
C) a gene called SDG found on an autosomal chromosome.
D) the simple presence or absence of a Y chromosome.
E) a gene called SDG found on the Y chromosome.

Question 68

When two loci are on the same chromosome, progeny sometimes do not exhibit the phenotypes that would be predicted by the law of independent assortment.This outcome can be explained by the phenomenon of

A) translocation.
B) inversions.
C) chromatid affinities.
D) linkage.
E) reciprocal chromosomal exchanges.

Question 69

Egg and Fluffy are two linked bird genes that are 16 map units apart.The E allele of Egg produces large eggs, and the e allele produces small eggs (E is dominant).The F allele produces fluffy feathers, and the f allele produces nonfluffy feathers (F is dominant).If EEFF is crossed with eeff, what proportion of the offspring should be birds that produce large eggs and fluffy feathers?

A) 8 percent
B) 16 percent
C) 42 percent
D) 84 percent
E) 100 percent

Question 70

In Drosophila, three autosomal genes have alleles as follows: Straight bristles (Hk) is dominant over hooked bristles (hk); straight wings (A) is dominant over arc wings (a); and red eye (Bw) is dominant over brown eye (bw).Two test crosses were performed, with the results shown in the table. What linkage can you determine from these crosses?

A) Only Hk and A are linked, with a distance of 45.3 units.
B) Only A and Bw are linked, with a distance of 5.3 units.
C) Only Hk and Bw are linked, with a distance of 40.0 units.
D) None of the genes are linked.
E) All of the genes are on the same chromosome; Hk and A are 45.3 units apart, and A and Bw are 5.3 units apart.

Question 71

In tomatoes, tall is dominant to dwarf, and smooth fruits are dominant to hairy fruits.A plant that is homozygous for both dominant traits is crossed with a plant that is homozygous for both recessive traits.Crosses of the F₁ progeny yield the following results: 78 tall smooth fruits, 82 dwarf hairy fruits, 22 tall hairy fruits, and 18 dwarf smooth fruits.These data indicate that the genes are

A) on different chromosomes.
B) linked, but do not cross over.
C) linked and show 10 percent recombination.
D) linked and show 20 percent recombination.
E) linked and show 40 percent recombination.

Question 72

When a dihybrid black straight-winged fly is crossed with a double-recessive brown curly-winged fly, the frequency at which black curly-winged and brown straight-winged flies are seen in the progeny is called the _______ frequency.(Note: The two genes are linked.)

A) mutation
B) mitotic
C) meiotic
D) allele
E) recombinant

Question 73

Humans have _______ pairs of autosomes.

A) 22
B) 23
C) 45
D) 46
E) None

Question 74

In humans, red-green color blindness is determined by an X-linked recessive allele (a), whereas eye color is determined by an autosomal gene, where brown (B) is dominant over blue (b).What gametes can be formed with respect to these genes by a heterozygous, brown-eyed, color-blind male?

A) BX^a, BY
B) bX^a, bY
C) BX^a, bY
D) BX, BY, bX, bY
E) BX^a, BY, bX^a, bY

Question 75

Egg and Fluffy are two linked bird genes that are 16 map units apart.The E allele of Egg produces large eggs, and the e allele produces small eggs (E is dominant).The F allele produces fluffy feathers, and the f allele produces nonfluffy feathers (F is dominant).If EeFf is crossed with eeff, what proportion of the offspring should be birds that produce small eggs and fluffy feathers? (Note: Assume that the parents of EeFf were EEFF and eeff.)

A) 8 percent
B) 16 percent
C) 42 percent
D) 84 percent
E) 100 percent

Question 76

Allelic variation at the insulin growth factor-1 gene is one of several variables that affect body size in dogs.Based on this information, one can say that this gene

A) displays heterosis.
B) is a quantitative trait locus.
C) is a pleiotropic gene.
D) is a quantitative trait locus and displays heterosis.
E) is a quantitative trait locus and is pleiotropic.

Question 77

Egg and Fluffy are two linked bird genes that are 16 map units apart.The E allele of Egg produces large eggs, and the e allele produces small eggs (E is dominant).The F allele produces fluffy feathers, and the f allele produces nonfluffy feathers (F is dominant).If EeFf is crossed with eeff, what proportion of the offspring should be birds that produce small eggs and nonfluffy feathers? (Note: Assume that the parents of EeFf were EEFF and eeff.)

A) 8 percent
B) 16 percent
C) 42 percent
D) 84 percent
E) 100 percent

Question 78

When analyzing Drosophila offspring of test crosses to determine gene linkage, what value for recombination frequency would tell you that two genes are probably not linked?

A) 0.00
B) 0.25
C) 0.50
D) 1.00
E) 1.50

Question 79

A human male carrying an allele for a trait on the X chromosome is

A) heterozygous.
B) homozygous.
C) holozygous.
D) monozygous.
E) hemizygous.

Question 80

An organism that produces either male gametes or female gametes, but not both, is called

A) monoecious.
B) dioecious.
C) heterozygous.
D) homozygous.
E) parthenogenic.