Deck 3: Basic Principles of Heredity

Question 1

While doing field work in Madagascar, you discover a new dragonfly species that has either red (R)or clear (r)wings.Initial crosses indicate that R is dominant to r.You perform three crosses using three different sets of red-winged parents with unknown genotype and observe the following data: Which cross is likely to have at least one parent with the genotype RR?

A)Cross 1
B)Cross 2
C)Cross 3
D)Crosses 1 and 2
E)Crosses 2 and 3

Answer 1

E

Question 2

Freckles are caused by a dominant allele.A man has freckles but one of his parents does not have freckles.The man has fathered a child with a woman that does not have freckles.What is the probability that their child has freckles?

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

Answer 2

C

Question 3

If an organism of genotype Aa is used for a testcross, what is the genotype of the other individual used in the cross?

A)AA
B)Aa
C)aa
D)The genotype cannot be known.
E)Either AA or Aa is correct.

Answer 3

C

Question 4

Which of the following crosses would produce a 1:1 ratio of phenotypes in the next generation?

A)AA × AA
B)AA × aa
C)Aa × Aa
D)Aa × aa
E)aa × aa

Question 5

Which of the following crosses would produce a 3:1 ratio of phenotypes in the next generation?

A)AA × AA
B)AA × aa
C)Aa × Aa
D)Aa × aa
E)aa × aa

Question 6

In Mendel's peas, yellow seeds are dominant to green.A pure-breeding yellow plant is crossed with a pure-breeding green plant.All of the offspring are yellow.If one of these yellow offspring is crossed with a green plant, what will be the expected proportion of plants with green seeds in the next generation?

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

Question 7

In poodles, black fur is dominant to white fur.A black poodle is crossed with a white poodle.In a litter of seven, all of the puppies are black.What is the BEST conclusion?

A)The black poodle is definitely homozygous.
B)The black poodle is probably homozygous.
C)The black poodle is definitely heterozygous.
D)The black poodle is probably heterozygous.
E)The genotype of the black poodle cannot be inferred with this information.

Question 8

In Mendel's peas, purple flower color is dominant to white.From which of the following descriptions can you NOT infer the genotype at this locus completely?

A)Purple
B)White
C)Pure-breeding purple
D)Heterozygous
E)More than one of the above

Question 9

Which of the following was NOT one of Mendel's conclusions based on his monohybrid crosses?

A)Genes are carried on chromosomes.
B)Alleles exist in pairs.
C)Alleles segregate equally into gametes.
D)Alleles behave as particles during inheritance.
E)One allele can mask the expression of the other allele.

Question 10

Honeybees have a haplo-diploid sex determination system where females develop from a fertilized egg (they are diploid, having one allele from the female queen and one allele from the male), and males develop from unfertilized eggs (they are haploid, having only one allele from the queen).Assuming that the queen is heterozygous for a particular gene, what is the probability that a female will inherit the recessive allele from her mother? What is the probability that a male will inherit a recessive allele from his mother?

A)The probability that a daughter will inherit a recessive allele from her mother is 50%; the probability that a son will inherit a recessive allele from his mother is 50%.
B)The probability that a daughter will inherit a recessive allele from her mother is 50%; the probability that a son will inherit a recessive allele from his mother is 100%.
C)The probability that a daughter will inherit a recessive allele from her mother is 100%; the probability that a son will inherit a recessive allele from his mother is 50%.
D)The probability that a daughter will inherit a recessive allele from her mother is 100%; the probability that a son will inherit a recessive allele from his mother is 100%.
E)The probability that a daughter will inherit a recessive allele from her mother is 0%; the probability that a son will inherit a recessive allele from his mother is 100%.

Question 11

In Labrador retrievers, black coat color is dominant to brown.Suppose that a black Lab is mated with a brown one, and the offspring are 4 black puppies and 1 brown.What can you conclude about the genotype of the black parent? (Assume that B is the allele for black and b is the allele for brown.)

A)The genotype must be BB.
B)The genotype must be bb.
C)The genotype must be Bb.
D)The genotype could be either BB or Bb.
E)The genotype cannot be determined from these data.

Question 12

Freckles are caused by a dominant allele.A man has freckles but one of his parents does not have freckles.What is his genotype?

A)Homozygous dominant
B)Homozygous recessive
C)Heterozygous
D)Heterologous
E)Homologous

Question 13

In animals, the inability to make the pigment melanin results in albinism, a recessive condition.Two unaffected parents, who have decided to have three children, have a first child that has albinism (genotype aa).What is the probability that the second and third children will also have albinism?

A)1/4
B)1/2
C)1/16
D)9/16
E)1 (100%)

Question 14

Which of the following statements is TRUE?

A)The probability of a woman giving birth to three girls in a row is 1/8.
B)The chi-square test is used to determine if observed outcomes are consistent with expected outcomes.
C)The probability of two or more independent events occurring together is calculated by multiplying their independent probabilities.
D)Branched diagrams may be used for determining probabilities of various phenotypes or genotypes for genetic crosses involving more than one gene pair.
E)All of these statements are true.

Question 15

Gregor Mendel carried out a cross between two pea plants by taking pollen from a plant that was homozygous for round seeds and dusting the pollen onto the stigma of a plant homozygous for wrinkled seeds.Which of the following would be the reciprocal cross that Mendel had carried out for this experiment?

A)Homozygous round stigma pollinated with pollen from a homozygous wrinkled plant
B)Homozygous round stigma pollinated with pollen from a heterozygous wrinkled plant
C)Heterozygous round stigma pollinated with pollen from a homozygous wrinkled plant
D)Homozygous wrinkled stigma pollinated with pollen from a homozygous round plant
E)Homozygous wrinkled stigma pollinated with pollen from a homozygous wrinkled plant

Question 16

Why was the pea plant an ideal plant for Mendel to use?

A)Generation time that is several years
B)Simple traits that are easy to identify
C)Low numbers of offspring produced
D)Expensive and time-consuming to grow
E)All of the answers are correct.

Question 17

Genes come in different versions called:

A)alleles.
B)loci.
C)genotypes.
D)chromosomes.
E)genomes.

Question 18

A couple has six daughters and is expecting a seventh child.What is the probability that this child will be a boy?

A)1/2
B)1/4
C)1/16
D)1/64
E)1/128

Question 19

Which of the following statements is TRUE?

A)The genotype is the physical appearance of a trait.
B)Alleles, genes, and loci are different names for the same thing.
C)The phenotype of a dominant allele is never seen in the F₁ progeny of a monohybrid cross.
D)A testcross can be used to determine whether an individual is homozygous or heterozygous for a dominant allele.
E)All of these statements are true.

Question 20

In a cross between pure-breeding tall plants with pure-breeding short plants, all of the F₁ are tall.When these plants are allowed to fertilize themselves, the F₂ plants occur in a ratio of 3 tall:1 short.Which of the following is NOT a valid conclusion from these results?

A)The allele that produces the tall condition is dominant to the allele that produces the short condition.
B)The difference between tall and short stature in these lines is controlled by a single gene pair.
C)During production of gametes in F₁ plants, the tall and short alleles segregate from each other equally into the gametes.
D)The tall and short traits assort independently of each other in this cross.
E)Fertilization occurs randomly between gametes carrying the tall and short alleles.

Question 21

Round seeds (R)is dominant to wrinkled seeds (r), and yellow seeds (Y)is dominant to green seeds (y).A true-breeding pea plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds.The F₁ progeny are allowed to self-fertilize.What is the probability of obtaining a yellow seed in the F₂?

A)3/4
B)1/16
C)9/16
D)3/16
E)1/2

Question 22

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b.What is the probability of producing an A_B_ phenotype from a cross aabb × AABB?

A)1/4
B)1/2
C)1/16
D)9/16
E)1 (100%)

Question 23

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b.What is the probability of producing an AB gamete from an AABb individual?

A)1/4
B)1/2
C)1/16
D)9/16
E)1 (100%)

Question 24

The ability to roll the tongue is caused by a dominant allele.A woman is a "roller, " but one of her parents is not.The woman is expecting a child with a man who is a "nonroller." What is the probability that their first child will be a "roller"?

A)1/4
B)0
C)3/4
D)1/2
E)1

Question 25

Round seeds (R)is dominant to wrinkled seeds (r), and yellow seeds (Y)is dominant to green seeds (y).A true-breeding pea plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds.The F₁ progeny are allowed to self-fertilize.What is the probability of obtaining a round, yellow seed in the F₂?

A)3/4
B)1/16
C)9/16
D)3/16
E)1/2

Question 26

Round seeds (R)is dominant to wrinkled seeds (r), and yellow seeds (Y)is dominant to green seeds (y).A true-breeding pea plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds.The F₁ progeny are allowed to self-fertilize.What is the probability of obtaining a wrinkled, green seed in the F₂?

A)3/4
B)1/16
C)9/16
D)3/16
E)1/2

Question 27

Cystic fibrosis is a human recessive autosomal condition.If two heterozygous parents have two children, what is the probability that they will be born in the order: normal boy and affected girl?

A)3/64
B)3/512
C)9/512
D)9/256
E)3/16

Question 28

Round seeds (R)is dominant to wrinkled seeds (r), and yellow seeds (Y)is dominant to green seeds (y).A plant of unknown genotype is testcrossed to a true-breeding plant with wrinkled and green seeds.The offspring produced were 53 round and yellow, 49 round and green, 44 wrinkled and yellow, 51 wrinkled and green.What is the likely genotype of the parent in question?

A)RRYY
B)RrYY
C)RRYy
D)RrYy
E)rryy

Question 29

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b.What is the probability of producing an AB gamete from an AaBb individual?

A)1/4
B)1/2
C)1/16
D)9/16
E)1 (100%)

Question 30

In a cross between AABbCcDD and AaBbccdd, what proportion of the offspring would be expected to be A_B_C_D_? (A_ means AA or Aa.)

A)3/256
B)3/32
C)3/16
D)3/8
E)3/4

Question 31

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b.What is the probability of producing an AaBb zygote from a cross AaBb × AABB?

A)1/4
B)1/2
C)1/16
D)9/16
E)1 (100%)

Question 32

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b.What is the probability of producing an AABB zygote from a cross AaBb × AaBb?

A)1/4
B)1/2
C)1/16
D)9/16
E)1 (100%)

Question 33

In dogs, black coat color (B)is dominant over brown (b), and solid coat color (S)is dominant over white spotted coat (s).A cross between a black, solid female and a black, solid male produces puppies with only black, solid coats.This same female was then mated with a brown, spotted male.Half of the offspring from this cross were black and solid, and half of the offspring were black and spotted.Which of the following could be the genotype of the black, solid male?

A)BBSs
B)BBss
C)BbSS
D)BbSs
E)Bbss

Question 34

Round seeds (R)is dominant to wrinkled seeds (r), and yellow seeds (Y)is dominant to green seeds (y).A true-breeding plant with round and yellow seeds is crossed to a true-breeding plant with wrinkled and green seeds.What is the genotype of the F₁ progeny?

A)RRYY
B)RrYY
C)RRYy
D)RrYy
E)rryy

Question 35

Two gene loci, A and B, assort independently, and alleles A and B are dominant over alleles a and b.What is the probability of producing an A_B_ phenotype from a cross AaBb × AaBb?

A)1/4
B)1/2
C)1/16
D)9/16
E)1 (100%)

Question 36

In dogs, black coat color (B)is dominant over brown (b), and solid coat color (S)is dominant over white spotted coat (s).A cross between a black, solid female and a black, solid male produces puppies with only black, solid coats.This same female was then mated with a brown, spotted male.Half of the offspring from this cross were black and solid, and half of the offspring were black and spotted.What is the genotype of the female?

A)BBSS
B)BbSS
C)BBSs
D)BbSs
E)bbss

Question 37

The ability to curl one's tongue into a U-shape is a genetic trait.Curlers always have at least one curler parent but noncurlers can have one or both parents who are curlers.Using C and c to symbolize the alleles that control this trait, what is the genotype of a noncurler?

A)CC
B)Cc
C)cc
D)Cc or CC
E)Any of the answers could be correct.

Question 38

In a cross between AaBbCcDdEe and AaBbccDdee, what proportion of the offspring would be expected to be A_bbC_ddE_? (A_ means AA or Aa.)

A)3/256
B)3/32
C)3/16
D)3/8
E)3/4

Question 39

In a cross between AaBbCc and AaBbcc, what proportion of the offspring would be expected to be A_bbcc? (A_ means AA or Aa.)

A)3/256
B)3/32
C)3/16
D)3/8
E)3/4

Question 40

The ability to roll the tongue is caused by a dominant allele.A woman is a "roller, " but one of her parents is not.What is the woman's genotype?

A)Homozygous dominant
B)Heterozygous
C)Homozygous recessive
D)Either homozygous recessive or homozygous dominant
E)Cannot be determined from this information

Question 41

How did Sutton's chromosome theory of inheritance link Mendel's work with a more mechanistic understanding of heredity?

Question 42

Compare and contrast Mendel's principle of segregation and the principle of independent assortment.

Question 43

What is the difference between a backcross and a testcross?

Question 44

The pedigree below shows the segregation of an autosomal recessive trait in humans.Unless there is evidence to the contrary, assume that individuals who marry into the family do not carry the recessive allele.If IV-1 and IV-2 marry, what is the probability that their first child will have this trait?

A)1/16
B)1/6
C)3/64
D)1/9
E)1/24

Question 45

Could the characteristic followed in the pedigree be caused by an autosomal dominant disease? Why or why not?

A)Yes, all individuals fit the autosomal dominant inheritance pattern.
B)No, the offspring of I-1 and I-2 contradict an autosomal dominant inheritance.
C)No, the offspring of I-3 and I-4 contradict an autosomal dominant inheritance.
D)No, the offspring of II-3 and II-4 contradict an autosomal dominant inheritance.
E)Yes, the offspring of I-1 and I-2 are consistent with an autosomal dominant inheritance pattern.

Question 46

If the characteristic followed in the pedigree is autosomal recessive, what is III-1's genotype?

A)Either homozygous dominant or heterozygous
B)Definitely heterozygous
C)Definitely homozygous dominant
D)Must be homozygous recessive
E)Homozygous dominant since he is a male but a female would be heterozygous

Question 47

A pedigree for a particular autosomal recessive human trait is shown below: What is the probability that if III-3 and III-4 marry, their first child will be affected with this trait?

A)1/4
B)1/16
C)3/16
D)1/12
E)1/6

Question 48

What conclusions did Mendel make from his monohybrid crosses?

Question 49

A pedigree shows that two parents are phenotypically normal, but one of their four biological children has a typical autosomal recessive trait.The other three children are phenotypically normal.It is very likely that:

A)the affected child is a girl.
B)the affected child is a boy.
C)the trait was expressed by one of the grandparents of the children.
D)the parents are both heterozygous for the trait.
E)if the affected child eventually marries a phenotypically normal spouse, all of the their children will have the trait.

Question 50

In peas, tall (T)is dominant to short (t).A homozygous tall plant is crossed with a short plant.The F₁ are self-fertilized to produce the F₂.Both tall and short plants appear in the F₂.If the short F₂ are self-fertilized, what types of offspring and proportions will be produced?

Question 51

In pedigree analysis, consanguinity refers to:

A)mating between two heterozygous carrier parents.
B)the realization that phenotypes between children and grandparents are often more closely related than between children and parents.
C)mating between two closely related parents.
D)a situation where the children of two parents are adopted.
E)a situation where only one individual in the entire pedigree is affected with the trait or disorder.

Question 52

A chi-square test was performed and indicated that the observed numbers of offspring were significantly different from the expected.Which of the following P-values would support this conclusion?

A)0)995
B)0)536
C)0)004
D)0)752
E)0)159

Question 53

In pedigree analysis, the proband is:

A)the individual having the trait or disorder from whom the pedigree is initiated.
B)the medical geneticist who analyzes the pedigree to find the mode of inheritance for the disorder.
C)the parents of the first child in the family to show the trait or disorder.
D)one of the grandparents or great grandparents who are in the first generation of the pedigree.
E)the most common software package that geneticists use to analyze pedigrees.

Question 54

Use the following information to answer Questions 44 and 45.A space capsule crashes to Earth with an alien life-form aboard.Two creatures emerge from the capsule, one with green skin and one with yellow skin.The yellow creature soon gives birth to offspring fathered by the green creature, producing 12 green and 8 yellow offspring.Green skin in these diploid creatures is dominant to yellow skin.You are curious to find out if the number of offspring is significantly different from expected Mendelian ratios, so you perform a chi-square test.What is the chi-square value for this cross?

A)0)2
B)0)4
C)0)8
D)1)2
E)1)6

Question 55

Which term refers to mating between closely related people?

A)Consanguinity
B)Probanding
C)Congenital
D)Concordance
E)Discordance

Question 56

In dogs, black coat color (B)is dominant over brown (b), and solid coat color (S)is dominant over white spotted coat (s).A cross between a black, solid female and a black, solid male produces puppies with only black, solid coats.This same female was then mated with a brown, spotted male.Half of the offspring from this cross were black and solid, and half of the offspring were black and spotted.What is the genotype of the brown, spotted male?

A)BBSS
B)BbSS
C)BBSs
D)BbSs
E)bbss

Question 57

In sesame, the one-pod condition (P)is dominant to three-pod (p), and normal leaf (W)is dominant to wrinkled (w).These characteristics assort independently.A one-pod, wrinkled leaf × one-pod, normal leaf cross gave a progeny of 654 one-pod, normal leaf plants and 224 three-pod, normal leaf plants.What are the likely genotypes of the parents in this cross?

A)Pp ww × Pp Ww
B)Pp Ww × Pp Ww
C)Pp ww × Pp WW
D)PP Ww × Pp ww
E)PP ww × PpWw

Question 58

If the pedigree is for an autosomal recessive characteristic, which individuals are definitely heterozygous?

A)I-1, I-2, II-2, II-4, and II-5
B)I-1, I-2, I-4, III-1
C)I-1, I-2, II-4, II-5, III-1
D)II-2, II-4, II-5, II-3
E)II-2, II-4, II-5, III-1

Question 59

Which of the following is NOT a typical characteristic of human traits that follow an autosomal recessive inheritance pattern?

A)They often "skip" generations.
B)They appear equally in males and females.
C)Parents of affected children are often phenotypically normal themselves.
D)When affected individuals marry phenotypically normal individuals, their children are often phenotypically normal.
E)All of these are characteristic of autosomal recessive inheritance.

Question 60

In deer mice, red eyes (r)is recessive to normal black eyes (R).Two mice with black eyes are crossed.They produce two offspring, one with red eyes and one with black eyes.Give the genotypes of parents and offspring of this cross.

Question 61

A man has either an AaBB or AABb genotype with equal probability.Assume these genes assort independently.What is the probability of the man producing an AB gamete?

Question 62

Two pea plants with purple flowers are crossed.Among the offspring, 63 have purple flowers, and 17 have white flowers.With a chi-square test, compare the observed numbers with a 3:1 ratio and determine if the difference between observed and expected could be a result of chance.

Question 63

A man has either an AaBB or AABb genotype with equal probability.Assume these genes assort independently.What is the overall probability that the man will produce an Ab gamete?

Question 64

The following cross produced 125 progeny: aaBbCcDd × AaBbccDD.Assume all the genes assort independently and that the uppercase letters represent dominant alleles.
a.How many offspring are expected to express the phenotype ABCD?
b.How many offspring are expected to have the genotype aaBBccDd?
c.How many offspring are expected to have the genotype AaBbCcDd?

Question 65

For a particular plant, red flowers (A)are dominant over yellow flowers (a).An initial cross was made between a plant that was true-breeding for red flowers, and another plant true-breeding for yellow flowers.F₁ progeny, all having red flowers, were allowed to form seeds, which were then planted to generate F₂ progeny.Pollen from all the resulting F₂ plants was pooled and used to fertilize true-breeding yellow plants.What proportion of the progeny resulting from this cross would be expected to have yellow flowers?