Deck 12: Inheritance, Genes, and Chromosomes

Question 1

Mendel's crossing of spherical-seeded pea plants with wrinkled-seeded pea plants resulted in progeny that all had spherical seeds. This indicates that the wrinkled-seed trait is

A) codominant.
B) dominant.
C) recessive.
D) Both a and b
E) Both a and c

Answer 1

C

Question 2

In Kölreuter's studies, reciprocal crosses

A) always gave identical results.
B) only involved heterozygous individuals.
C) supported the blending hypothesis of inheritance.
D) could be done only with homozygous individuals.
E) consisted of an F₁ and an F₂ generation.

Answer 2

A

Question 3

Which statement about a test cross is not true?

A) It tests whether an unknown individual is homozygous or heterozygous.
B) The test individual is crossed with a homozygous recessive individual.
C) If the test individual is heterozygous, the progeny will have a 1:1 ratio.
D) If the test individual is homozygous, the progeny will have a 3:1 ratio.
E) Test cross results are consistent with Mendel's model of inheritance for unlinked genes.

Answer 3

D

Question 4

In humans, spotted teeth are caused by a dominant sex-linked gene. A man with spotted teeth whose father had normal teeth marries a woman with normal teeth. Therefore,

A) all of their daughters will have normal teeth.
B) all of their daughters will have spotted teeth.
C) all of their children will have spotted teeth.
D) half of their sons will have spotted teeth.
E) all of their sons will have spotted teeth.

Question 5

The phenotype of an individual

A) depends at least in part on the genotype.
B) is either homozygous or heterozygous.
C) determines the genotype.
D) is the genetic constitution of the organism.
E) is either monohybrid or dihybrid.

Question 6

Use the following to answer questions:
Two different groups of imaginary schmoos live in geographically separated locations and rarely interbreed. On one occasion, a big-footed white schmoo does mate with a small-footed brown schmoo. Three offspring result: one big-footed brown schmoo and two small-footed brown schmoos.
Which statement about the inheritance of color in schmoos is most likely to be correct?

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

Question 7

During what year did Gregor Mendel orally present his genetics project?

A) 1565
B) 1665
C) 1765
D) 1865
E) 1965

Question 8

Which statement about an individual that is homozygous for an allele is not true?

A) Each of its cells possesses two copies of that allele.
B) Each of its gametes contains one copy of that allele.
C) It is true-breeding with respect to that allele.
D) Its parents were necessarily homozygous for that allele.
E) It can pass that allele to its offspring.

Question 9

In epistasis

A) nothing changes from generation to generation.
B) one gene alters the effect of another.
C) a portion of a chromosome is deleted.
D) a portion of a chromosome is inverted.
E) the behavior of two genes is entirely independent.

Question 10

The genetic sex of a human is determined by

A) ploidy, with the male being haploid.
B) the Y chromosome.
C) X and Y chromosomes, the male being XX.
D) the number of X chromosomes, the male being XO.
E) Z and W chromosomes, the male being ZZ.

Question 11

Which of the following is not a characteristic that makes an organism suitable for genetic studies?

A) A small number of chromosomes
B) A short generation time
C) Ease of cultivation
D) The ability to control crosses
E) The availability of a variation for traits

Question 12

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 13

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

A) reproduce asexually.
B) have small numbers of offspring.
C) do not have observable phenotypes.
D) do not have genotypes.
E) do not have autosomes.

Question 14

Mendel's research was rediscovered in the published studies of

A) de Vries.
B) Correns.
C) von Tschermak.
D) All of the above
E) None of the above

Question 15

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 16

Which of the following methods 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) Microscopy
D) Production of hybrid plants
E) Quantitative analysis of results

Question 17

In a simple Mendelian monohybrid cross, true-breeding tall plants are crossed with short plants, and the F₁ plants, which are all tall, are allowed to self-pollinate. What fraction of the F₂ generation are both tall and heterozygous?

A) 1/8
B) 1/4
C) 1/3
D) 2/3
E) 1/2

Question 18

Linked genes

A) must be immediately adjacent to one another on a chromosome.
B) have alleles that assort independently of one another.
C) never show crossing over.
D) are on the same chromosome.
E) always have multiple alleles.

Question 19

In the F₂ generation of a dihybrid cross

A) four phenotypes appear in the ratio 9:3:3:1 if the loci are linked.
B) four phenotypes appear in the ratio 9:3:3:1 if the loci are unlinked.
C) two phenotypes appear in the ratio 3:1 if the loci are unlinked.
D) three phenotypes appear in the ratio 1:2:1 if the loci are unlinked.
E) two phenotypes appear in the ratio 1:1 whether or not the loci are linked.

Question 20

A key factor that allowed Mendel to interpret the results of his breeding experiments was that

A) the varieties of peas he used were "true-breeding."
B) peas naturally self-pollinate.
C) peas can reproduce asexually.
D) pollination could be controlled.
E) Both a and d

Question 21

Use the following to answer questions:
Two different groups of imaginary schmoos live in geographically separated locations and rarely interbreed. On one occasion, a big-footed white schmoo does mate with a small-footed brown schmoo. Three offspring result: one big-footed brown schmoo and two small-footed brown schmoos.
Which statement about the inheritance of footedness in schmoos is most likely to be correct?

A) Big is dominant to small.
B) Small is dominant to big.
C) Big and small are codominant.
D) Both a and c
E) This cannot be answered without more information.

Question 22

Separation of the alleles of a single gene into different gametes is called

A) synapsis.
B) segregation.
C) independent assortment.
D) heterozygous separation.
E) recombination.

Question 23

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

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

Question 24

It has been found that at a certain locus of the human genome, 200 different alleles exist in the population. Each person has at most _______ alleles.

A) 1
B) 2
C) 100
D) 200
E) 400

Question 25

Use the following to answer questions:
Two different groups of imaginary schmoos live in geographically separated locations and rarely interbreed. On one occasion, a big-footed white schmoo does mate with a small-footed brown schmoo. Three offspring result: one big-footed brown schmoo and two small-footed brown schmoos.
If big feet (B) in schmoos is dominant to small feet (b), the genotype of the big-footed white parent schmoo with respect to the foot gene can

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

Question 26

Which of the following statements about Mendelian genetics is false?

A) Alternative forms of genes are called alleles.
B) A locus is a gene's location on its chromosome.
C) Only two alleles can exist for a given gene.
D) A genotype is a description of the alleles that represent an individual's genes.
E) Individuals with the same phenotype can have different genotypes.

Question 27

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(n)

A) gene.
B) character.
C) allele.
D) transcription factor.
E) None of the above

Question 28

Segregation of alleles occurs

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

Question 29

Mendel's dihybrid crosses

A) resulted in four different phenotypes.
B) produced recombinant phenotypes.
C) led to the formation of the law of independent assortment.
D) involved unlinked genes.
E) All of the above

Question 30

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

Question 31

A dihybrid cross

A) results in a genotypic ratio of 2:1.
B) involves genes located on the sex chromosomes.
C) results in offspring of lower quality than that of the parents.
D) results in two different phenotypes in the F₂ generation.
E) is a cross between identical double heterozygotes.

Question 32

In a(n) _______ cross, genes for two different characters separate.

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

Question 33

A pea plant with red flowers is test crossed, and one-half of the resulting progeny have red flowers, while the other half has white flowers. Therefore, the genotype of the test-crossed parent was

A) RR.
B) Rr.
C) rr.
D) either RR or Rr.
E) This cannot be answered without more information.

Question 34

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

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

Question 35

If a trait not expressed in the F₁ generation reappears in the F₂ generation, the inheritance of the trait in question is an example of

A) codominance.
B) dominance and recessiveness.
C) incomplete dominance.
D) epistasis.
E) a sex-linked trait.

Question 36

The physical appearance of a character is called

A) the genotype.
B) the phenotype.
C) an allele.
D) a trait.
E) a gene.

Question 37

Classical albinism results from a recessive allele. Which of the following is the expected ratio for the progeny when a normally pigmented male with an albino father has children with an albino woman?

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

Question 38

A particular genetic cross in which the individual in question is crossed with an individual known to be homozygous for a recessive trait is referred to as a

A) parental cross.
B) dihybrid cross.
C) filial generation mating.
D) reciprocal cross.
E) test cross.

Question 39

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

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

Question 40

Different forms of a gene are called

A) traits.
B) phenotypes.
C) genotypes.
D) alleles.
E) None of the above

Question 41

Epistasis refers to

A) a group of genes that are close together.
B) the equal interaction of two genes so that a new phenotype is produced.
C) the expression of two genes in the same individual.
D) the linear order of genes on a chromosome.
E) the expression of one gene masking the expression of another.

Question 42

When a given trait is the result of multigene action, one of the genes may mask the expression of one or all other genes. This phenomenon is termed

A) epistasis.
B) epigenesis.
C) dominance.
D) incomplete dominance.
E) None of the above

Question 43

Use the following to answer questions:
Agouti is a type of coat color pattern in mouse that cannot be expressed in albinos (white mice). A non-albino, 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). Non-albino mice without the dominant agouti allele (AAbb and Aabb) are black.
What percent of the progeny do you expect to be albino?

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

Question 44

Genetic mutations are

A) rare.
B) stable.
C) inherited changes in DNA.
D) random.
E) All of the above

Question 45

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

A) ¹/₄
B) ¹/₃
C) ¹/₂
D) ²/₃
E) ³/₄

Question 46

Use the following to answer questions:
Agouti is a type of coat color pattern in mouse that cannot be expressed in albinos (white mice). A non-albino, 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). Non-albino mice without the dominant agouti allele (AAbb and Aabb) are black.
What percent of the progeny do you expect to be agouti?

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

Question 47

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

A) the use of statistics and 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 combine or blend together.

Question 48

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 short fingers and a widow's peak, one has long fingers and a widow's peak, and one has long fingers and a continuous hairline. 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) None of the above

Question 49

Tall pea plants are crossed to short, and the progeny are medium height. The F₁ plants are crossed together, but the progeny observed among the F₂ have nine different size classes. This result is best explained by

A) the existence of pleiotropic alleles.
B) incomplete dominance.
C) codominance.
D) an increased number of phenotypes due to multiple alleles.
E) epistasis.

Question 50

Use the following to answer questions:
Agouti is a type of coat color pattern in mouse that cannot be expressed in albinos (white mice). A non-albino, 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). Non-albino mice without the dominant agouti allele (AAbb and Aabb) are black.
What percent of the progeny do you expect to be black?

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

Question 51

Mendel performed a cross between individuals heterozygous for three different traits: yellow versus green seeds (green is dominant), red versus white flowers (red is dominant), and green versus yellow pods (green is dominant). What fraction of the offspring would have been expected to have green seeds, red flowers, and green pods?

A) ²⁷/₆₄
B) ¹²/₆₄
C) ⁹/₆₄
D) ⁶/₆₄
E) ³/₆₄

Question 52

In the ABO blood type system,

A) A, B, and O are codominant.
B) A, B, and O are incompletely dominant.
C) A and B are codominant.
D) O is incompletely dominant to A and B.
E) A is dominant to B, and B is dominant to O.

Question 53

In Mendel's experiments, if the allele for tall (T) plants was incompletely dominant over the allele for short (t) plants, what offspring would have resulted from crossing two Tt plants?

A) ¹/₄ tall; ¹/₂ intermediate height; ¹/₄ short
B) ¹/₂ tall; ¹/₄ intermediate height; ¹/₄ short
C) ¹/₄ tall; ¹/₄ intermediate height; ¹/₂ short
D) All tall offspring
E) All intermediate height offspring

Question 54

The genetic disease blue sclera is determined by an autosomal dominant allele. The eyes of individuals with this allele have bluish sclera. These same individuals may also suffer from fragile bones and deafness. This is an example of

A) incomplete dominance.
B) pleiotropy.
C) epistasis.
D) codominance.
E) linkage.

Question 55

A mutation at a single locus causes a change in many different characters. This an example of a(n) _______ effect.

A) polygene
B) epigenetic
C) cytoplasmic
D) multiple negativity
E) pleiotropic

Question 56

In the garden peas used in Mendel's experiments, the spherical seed character (SS) is completely dominant over the wrinkled seed character (ss). If the characters for height were incompletely dominant, such that TT was tall, Tt was intermediate, and tt was short, what would have resulted from crossing a spherical-seeded, short (SStt) plant to a wrinkled-seeded, tall (ssTT) plant?

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

Question 57

In dogs, phenotype A (erect ears and barking while following a scent) is caused by dominant alleles; phenotype B (droopy ears and silent while following a scent) is caused by recessive alleles. A dog that is homozygous for both traits of phenotype A is mated to a dog with phenotype B. If the genes for the two traits are unlinked, which of the following is (are) the expected F₁ phenotypic ratio(s)?

A) 9:3:3:1
B) 1:1
C) 16:0
D) 1:2:1
E) None of the above

Question 58

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

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

Question 59

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) ³/₄

Question 60

The ABO blood groups in humans are determined by a multiple allelic system in which I^A and I^B are codominant and are dominant to i^O. If an infant born to a type O mother also is type O, possible genotypes for the father are

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

Question 61

It is predictable that half of the human babies born will be male and half will be female because

A) of the segregation of the X and Y chromosomes during male meiosis.
B) of the segregation of the X chromosomes during female meiosis.
C) all eggs contain an X chromosome.
D) Both a and b
E) Both a and c

Question 62

Use the following to answer questions:
Cleft chin is an X-linked dominant trait. Assume that a man with a cleft chin marries a woman with a round chin.
What percent of their male progeny will show the cleft chin trait?

A) 0
B) 25
C) 50
D) 75
E) 100

Question 63

The blue sclera allele has 90 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) 22
B) 40
C) 60
D) 90
E) None of the above

Question 64

How many autosomes do humans have?

A) 23 pairs
B) 22 pairs
C) 1 pair
D) 45
E) 16

Question 65

A dominant allele K is necessary for normal hearing. A dominant allele M on a different 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) 75
E) None of the above

Question 66

In tomatoes, tall is dominant to short, and smooth fruits are dominant to hairy fruits. A plant homozygous for both dominant traits is crossed with a plant homozygous for both recessive traits. The F₁ progeny are tested and crossed with 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 67

White eyes is a recessive sex-linked trait in fruit flies. If a white-eyed female fruit fly is mated to a red-eyed male, their offspring should be

A) 50 percent red-eyed and 50 percent white-eyed for both sexes.
B) all white-eyed for both sexes.
C) all white-eyed males and all red-eyed females.
D) all white-eyed females and all red-eyed males.
E) 50 percent red-eyed males and 50 percent white-eyed males and all red-eyed females.

Question 68

Despite the law of independent assortment, when two loci are on the same chromosome, the phenotypes of the progeny sometimes do not fit the predicted phenotypes due to

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

Question 69

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

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

Question 70

The complete phenotype of an organism is dependent on

A) genotype.
B) penetrance.
C) expressivity.
D) polygenes.
E) All of the above

Question 71

In guppies, fan tail is dominant to flesh tail, and rainbow color is dominant to pink. F₁ female guppies are crossed with flesh-tailed, pink-colored males, and the following progeny are observed: 401 fan-tailed, pink-colored; 399 flesh-tailed, rainbow-colored; 98 flesh-tailed, pink-colored; and 102 fan-tailed, rainbow-colored guppies. Assuming that the F₁ female guppies have both dominant alleles on one chromosome, the map distance between these two genes is

A) 80 cM.
B) 25 cM.
C) 0.8 cM.
D) 20 cM.
E) None of the above

Question 72

Use the following to answer questions:
Cleft chin is an X-linked dominant trait. Assume that a man with a cleft chin marries a woman with a round chin.
What percent of their female progeny will show the cleft chin trait?

A) 0
B) 25
C) 50
D) 75
E) 100

Question 73

Very few genes have been located on the Y chromosomes. Y-linked genes include a gene called testis-specific protein Y. A male with this gene will

A) usually pass it to his sons, but occasionally also to a daughter.
B) only pass the gene to his sons.
C) only pass the gene to his daughters.
D) only pass the gene to his grandsons.
E) pass the gene to all of his children if the mother is a carrier.

Question 74

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 75

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.

Question 76

If Mendel's crosses between spherical-seeded tall plants and wrinkled-seeded short plants had produced many more than ¹/₁₆ wrinkled-seeded short plants in the F₂ generation, he might have concluded that

A) the spherical seed and tall traits are linked.
B) the wrinkled seed and short traits are unlinked.
C) all traits in peas assort independently.
D) all traits in peas are linked.
E) None of the above

Question 77

Which of the following observations support the idea that the gene controlling maleness is located on the Y chromosome?

A) XO individuals are usually sterile, normal intelligence, female, with slight physical abnormalities.
B) XXY individuals are sterile males with long limbs.
C) XXX individuals are normal females.
D) Some men are XX but have a small piece of the Y attached to another chromosome.
E) All of the above are observations suggesting that the gene controlling maleness is on the Y chromosomes.

Question 78

When a dihybrid black, straight-winged fly is crossed to 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.

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

Question 79

A linkage group corresponds to

A) a group of genes on different chromosomes.
B) the linear order of centromeres on a chromosome.
C) the length of a chromosome.
D) a group of genes on the same chromosome.
E) None of the above

Question 80

When reciprocal crosses produce identical results, the trait is

A) sex-linked.
B) not sex-linked.
C) not autosomally inherited.
D) Both a and c
E) Both b and c