Deck 11: Patterns of Inheritance

Question 1

What is the ratio of phenotypes in the offspring produced by the cross Aa × Aa? Assume complete dominance for the trait.

A) 100% dominance
B) 50% dominant:50% recessive
C) 75% dominant:25% recessive
D) 25% dominant:75% recessive
E) 100% recessive

Answer 1

C

Question 2

If we cross two pea plants, each heterozygous for yellow seed color genes, the expected ratio of yellow:green among the offspring will be

A) 25% yellow:75% green.
B) 50% yellow:50% green.
C) 100% yellow.
D) 100% green.
E) 75% yellow:25% green.

Answer 2

E

Question 3

Round pea shape (R) is dominant over wrinkled pea shape (r). If a round pea has a wrinkled parent, the round pea is

A) RR.
B) rr.
C) recessive.
D) Rr.
E) haploid.

Answer 3

D

Question 4

Which of the following statements about genotypes and phenotypes is TRUE?

A) Matings between individuals with recessive phenotypes produce offspring with dominant phenotypes.
B) Individuals with the same phenotype might have different genotypes.
C) Individuals with the same genotype might have different phenotypes.
D) Matings between individuals with dominant phenotypes cannot produce offspring with recessive phenotypes.

Question 5

When alleles on a pair of homologous chromosomes move into different gametes during meiosis, this demonstrates

A) dominance.
B) segregation.
C) crossing over.
D) fertilization.
E) recessive inheritance.

Question 6

If the allele for inflated pea pods (I) is dominant to the allele for constricted pods (i), then the cross Ii xii is expected to produce

A) half with inflated and half with constricted pods.
B) 3/4 with inflated and 1/4 with constricted pods.
C) all peas with constricted pods.
D) 3/4 with constricted and 1/4 with inflated pods.
E) all peas with inflated pods.

Question 7

The results of a test cross reveal that all the offspring resemble the parent being tested. This parent must be

A) self-pollinated.
B) recessive.
C) haploid.
D) homozygous.
E) heterozygous.

Question 8

Mendelʹs law of segregation states that

A) genes in the same chromosome must stay together.
B) genes end up in their respective gametes by chance.
C) members of a pair of alleles on homologous chromosomes move away from each other during gamete formation.
D) each gamete receives a full complement of chromosomes.
E) there may be alternative forms of the same gene.

Question 9

Peas were a good organism of choice for Mendel because

A) he could study one trait at a time.
B) they cannot cross-fertilize.
C) they cannot self-fertilize.
D) the traits were difficult to visualize.

Question 10

According to the law of segregation, in an organism with the genotype Aa

A) one-half of the gametes get the A allele and one-half get the a allele.
B) three-quarters of the gametes get the A allele and one-quarter get the a allele.
C) one-quarter of the gametes get the A allele and three-quarters get the a allele.
D) all of the gametes get the a allele.
E) all of the gametes get the A allele.

Question 11

What type of allele produces its effects in only homozygous individuals?

A) Haploid
B) Recessive
C) Diploid
D) Dominant

Question 12

Gregor Mendel concluded that each pea has two units for each trait, and each gamete contains one unit. Mendelʹs ʺunitsʺ are now called

A) transcription factors.
B) genes.
C) characters.
D) chromosomes.

Question 13

The genetic makeup of an individual is the

A) mutation.
B) gene pool.
C) phenotype.
D) genotype.
E) sex cell.

Question 14

According to the law of segregation

A) pairs of alleles on homologous chromosomes separate during the formation of gametes.
B) there is an independent assortment of nonhomologous chromosomes during meiosis.
C) each individual carries a single copy of each ʺfactor.ʺ
D) the sex chromosomes of males and females differ.
E) pairs of alleles fuse during the formation of gametes.

Question 15

When Mendel used true-breeding white flowers and true-breeding purple flowers as the parental generation, what were the results? (Purple flower is dominant over white.)

A) Three-quarters of the flowers produced were white and one-quarter were purple.
B) All of the offspring had purple flowers.
C) All of the offspring had white flowers.
D) One-half of the flowers produced were white and one-half were purple.
E) Three-quarters of the flowers produced were purple and one-quarter were white.

Question 16

A recessive allele is one

A) that is not expressed as strongly as a dominant allele.
B) that appears only in a heterozygote.
C) that must be lethal in the homozygous condition.
D) that produces no effect when present in the homozygous condition.
E) whose effect is masked when paired with a dominant allele.

Question 17

When the two gametes that fuse to form a zygote contain different alleles of a given gene, the offspring is

A) heterozygous.
B) haploid.
C) homozygous.
D) abnormal.
E) a new species.

Question 18

A Mendelian test cross is used to determine whether

A) segregation or independent assortment is occurring.
B) an allele is dominant or recessive.
C) the genotype or phenotype is more important.
D) the flowers are purple or white.
E) an individual is homozygous or heterozygous.

Question 19

If, in a heterozygous individual, only one allele is expressed in the phenotype, that allele is

A) potent.
B) dominant.
C) haploid.
D) recessive.
E) normal.

Question 20

The physical manifestation of an organismʹs genes is its

A) environment.
B) genotype.
C) phenotype.
D) number of chromosomes.
E) genetic code.

Question 21

What would be TRUE if linkage of two genes was complete?

A) All possible combinations of alleles in the offspring would be produced.
B) The genes would assort independently.
C) All possible combinations of alleles in the gametes would be produced.
D) Crossing over between the two genes would rarely occur.

Question 22

Albinism results from a recessive allele. Which of the following describes the expected offspring from a normally pigmented male (who had an albino father) and an albino wife?

A) All normal
B) 75% albino; 25% normal
C) 75% normal; 25% albino
D) All albino
E) 50% normal; 50% albino

Question 23

In crossing a homozygous recessive with a heterozygote, what is the chance of getting a homozygous recessive phenotype in the F1 generation?

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

Question 24

If you cross pea plants that are both heterozygous for purple flowers and yellow seeds ( PpYy), and you examine 800 offspring for flower and seed color, about how many do you expect to have white flowers and green seeds?
A) 450

A) All of them (800)
B) 50
D) 150
E) None of them

Question 25

What is the genotype of a dominant individual if, when selfed, some of its offspring show the recessive phenotype?

A) Either DD or Dd
B) DD
C) dd
D) Dd

Question 26

When genes are linked, a few of the recombinant genotypes still occur in the offspring because of

A) linkage.
B) independent assortment.
C) crossing over.
D) natural selection.
E) mutation.

Question 27

Crossing smooth-seeded pea plants with wrinkled-seeded pea plants resulted in progeny that all had smooth seeds. This indicates that the wrinkled-seed trait is

A) codominant and dominant.
B) recessive only.
C) codominant and recessive.
D) dominant only.
E) codominant only.

Question 28

31) Imagine that a newly discovered species of fish normally has three eyes ( E), but the rare mutation
(e) causes ?diopthalmic? fish with two eyes to be born. In addition, eye color in these fish is inherited similarly to humans, with black eyes (B) being dominant to blue (b). Assuming these two genes are carried on separate chromosomes, what must the genotypes of two black -eyed,
three-eyed parents be if they have a blue-eyed, diopthalmic son?

A) eeBB and EEbb
B) Both EeBb
C) Both eebb
D) EEBB and eebb

Question 29

In garden peas, the allele for tall plants is dominant over the allele for short plants. Imagine that a true-breeding tall plant is crossed with a short plant. Then one of their offspring is test crossed. Out of 20 offspring resulting from the test cross, about how many should be tall?

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

Question 30

In a test cross, what percentage of the offspring will have the same phenotype as the tested parent if the parent to be tested is homozygous?

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

Question 31

Imagine you do a test cross between a purple -flowered pea plant having serrated leaves (both dominant traits) and a white-flowered pea plant having smooth edges. If the purple -flowered plant is heterozygous for both traits, the expected ratio in the offspring is 1 purple -serrated:1 purple-smooth:1 white-serrated:1 white-smooth. Instead, you see 7 purple-serrated:1 purple-smooth:1 white-serrated:7 white-smooth. What is the explanation of this ratio?

A) The genes are linked.
B) There is incomplete dominance.
C) The genes are sex-linked and inherited by incomplete dominance.
D) There has been a mutation during the cross.

Question 32

Suppose you cross a pea plant with yellow, smooth seeds with one that has green, wrinkled seeds. You examine the seeds of 967 offspring and find that some have yellow, smooth seeds and some have yellow, wrinkled seeds, but no green seeds of either type show up. What is the genotype of the yellow-seeded parent? (Y = yellow, y = green; S = smooth, s = wrinkled)

A) YYSs
B) YYss
C) YYSS
D) YySS
E) YySs

Question 33

All of the following combinations are possible in the gametes of an organism that is AaBb EXCEPT

A) aa.
B) AB.
C) ab.
D) aB.
E) Ab.

Question 34

Although the law of independent assortment is generally applicable, when two loci are located physically close to each other on the same chromosome, the phenotypes of the offspring sometimes do not fit the phenotypes predicted. This is due to

A) linkage.
B) inversions.
C) translation.
D) chromosome exchange.
E) chromatid abnormalities.

Question 35

A pea plant with red flowers is test crossed; half of the resulting progeny have red flowers, whereas the other half have white flowers. The genotype of the test -crossed parent was

A) rr.
B) either RR or Rr.
C) Rr.
D) RR.

Question 36

If two parents are carriers of albinism (an autosomal recessive trait), what is the chance that their fourth child will have a homozygous dominant genotype?

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

Question 37

Which of the following is TRUE of genes that are physically located close to each other on the same chromosome?

A) They are not linked.
B) They tend to not be inherited together.
C) They are linked and tend to be inherited together.
D) They will be expressed differently in males than in females.

Question 38

Imagine that you self-pollinate heterozygous purple-flowered, long-pollened pea plants and get mostly purple-flowered, long-pollened plants and white-flowered, short-pollened plants, with a few purple-flowered, short-pollened or white-flowered, long-pollened plants. What is the most likely explanation?

A) The genes for flower color and pollen length are linked.
B) The gene for flower color is on a sex chromosome.
C) Long pollen is often lethal, so few plants with long pollen survive to adulthood.
D) The purple allele influences pollen to become shorter.
E) This is a normal random variation from the expected ratio for independent assortment.

Question 39

In pea plants, tall plants are dominant over short, and green pods are dominant over yellow. If you crossed true-breeding tall, green-podded plants with true-breeding short, yellow-podded plants, and then crossed the F1 individuals among themselves, what proportion of the F2 offspring would you expect to be tall and yellow-podded?

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

Question 40

Yellow-seeded pea plants may be homozygous or heterozygous. To find out which, cross the plants with

A) heterozygous yellow-seeded plants.
B) true-breeding yellow-seeded plants.
C) heterozygous green-seeded plants.
D) true-breeding green-seeded plants.
E) the same genotype.

Question 41

In Mendel?s experiments, if the gene for tall (T₁) plants was incompletely dominant over the gene for short (T₂) plants, what would be the result of crossing two T₁T₂ plants?

A) 25% tall, 25% intermediate, and 50% short
B) 50% tall, 25% intermediate, and 25% short
C) All the offspring would be tall.
D) All the offspring would be intermediate.
E) 25% tall, 50% intermediate, and 25% short

Question 42

A recessive allele on the X chromosome causes color deficiency. A color-deficient boy has a mother with normal vision and a color-deficient father. From which parent did he get the color-deficiency gene?

A) Either mother or father
B) Mother
C) Father

Question 43

A type of muscular dystrophy shows sex-linked recessive inheritance. Affected persons usually die by the age of 20. Suppose that a boy with the disease lives long enough to marry a woman heterozygous for the trait. If they have a son, what is the probability that he will have the disease?

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

Question 44

A recessive allele on the X chromosome causes color deficiency. A noncolor-deficient woman (whose father is color deficient) marries a color-deficient man. If they have a son, what is the chance that he will be color deficient?

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

Question 45

If an individual who is homozygous for type B blood marries a heterozygous type A individual, what is the chance that their first child will have type AB blood?

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

Question 46

Blood typing is often used as evidence in paternity cases in court. In one case, the mother had blood type B and the child had blood type O. Which of the following blood types could the father NOT have?

A) O
B) A
C) B
D) AB

Question 47

In humans, the sex of the offspring is determined by the

A) cytoplasm carried by the egg cell.
B) autosomes carried by the sperm cell.
C) autosomes carried by the egg cell.
D) sex chromosome carried by the sperm cell.
E) sex chromosome carried by the egg cell.

Question 48

Codominance occurs when

A) offspring exhibit several different phenotypic expressions of a single trait.
B) both of the alleles in a heterozygote are equally expressed phenotypically in an individual.
C) expression of two different alleles alternates from one generation to the next.
D) a heterozygote expresses an intermediate phenotype.

Question 49

A human sperm cell possesses autosomes and

A) an X chromosome always.
B) exactly the same genetic information as a body cell.
C) either an X or a Y chromosome.
D) a Y chromosome always.
E) both an X and a Y chromosome.

Question 50

Human eye color is the result of

A) sex-linked recessive inheritance.
B) codominance.
C) polygenic inheritance.
D) genes and environmental effects.
E) simple dominance.

Question 51

Hemophilia is a sex-linked recessive gene that causes a blood disorder. What are the chances that the daughter of a normal man and a heterozygous woman will have hemophilia?

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

Question 52

Imagine that smurfs live in widely separated groups and rarely interbreed, so geneticists know very little about them. On one occasion, two smurfs from different groups did mate. A big -footed, white smurf mated with a small-footed, blue smurf. Three offspring resulted: one big-footed and blue and two small-footed and blue. Which statement about the inheritance of color in smurfs is most likely to be correct?

A) White is dominant to blue.
B) White and blue are codominant.
C) Blue is dominant to white.

Question 53

A man who carries a harmful sex-linked (on the X chromosome) gene will pass the gene on to

A) all of his daughters.
B) half of his daughters.
C) all of his sons.
D) half of his sons.
E) all of his sons and daughters.

Question 54

Traits controlled by sex-linked recessive genes are expressed more often in males because

A) males always carry two copies of these genes.
B) all male offspring of a female carrier get the gene.
C) males inherit these genes from their fathers more often than their mothers.
D) the male has only one gene for the trait.
E) males get more doses of the recessive gene than do females.

Question 55

Two parents with normal vision have two sons, one color deficient and one with normal vision. If this couple then has six daughters, can you predict what percentage of the daughters will have normal color vision?

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

Question 56

When the expression of a trait is influenced by the action of many genes, the pattern of inheritance is called

A) incomplete dominance.
B) multiple alleles.
C) polygenic inheritance.
D) discontinuous variation.
E) complete dominance.

Question 57

An individual who is a carrier for a sex-linked trait such as hemophilia

A) cannot pass the gene on to his or her daughters.
B) is homozygous for the recessive condition.
C) is always female.
D) shows the dominant phenotype.

Question 58

Human skin color is the result of

A) simple dominance.
B) codominance.
C) sex-linked recessive inheritance.
D) one pair of genes showing incomplete dominance.
E) polygenic inheritance.

Question 59

Which of the following is a sex-linked recessive condition?

A) Down syndrome
B) Albinism
C) Hemophilia
D) Cystic fibrosis
E) Sickle-cell anemia

Question 60

Color deficiency is more common in men than in women because

A) women cannot inherit the gene from their fathers.
B) the gene is located on the Y chromosome.
C) men get more copies of the gene than do women.
D) crossing over occurs only in women.
E) men have only one X chromosome.

Question 61

Which of the following is the most common chromosome disorder among live -born infants?

A) Down syndrome
B) Klinefelter syndrome
C) Turner syndrome
D) Trisomy X

Question 62

Which of the following conditions may cause infertility in a human?

A) XXY
B) XY
C) XX
D) XYY
E) XXX

Question 63

What is the reason for the prevalence of the sickle-cell allele in African populations?

A) Sickled cells are better able to clot blood.
B) African populations tend to be at higher altitudes, and sickled cells better bind oxygen in these environments.
C) Heterozygotes have some resistance to the parasite that causes malaria.
D) Sickled cells help prevent vitamin A deficiency among African populations.

Question 64

Yellow pea color is dominant over green pea color, despite the observation that most store-bought, edible peas are green.

Question 65

Which disorder is the most common chromosome anomaly among newborns?

A) Turner syndrome
B) Klinefelter syndrome
C) Trisomy X
D) XYY syndrome
E) Down syndrome

Question 66

Which disorder is characterized by an abnormal number of autosomes?

A) Turner syndrome
B) Klinefelter syndrome
C) Trisomy X
D) XYY syndrome
E) Down syndrome

Question 67

Only males can express sex-linked traits.

Question 68

Females always inherit sex-linked traits from their mothers.

Question 69

Sickle-cell anemia is caused by a recessive mutation in the hemoglobin gene. However, heterozygote individuals also show a small percentage of sickled red blood cells. What type of inheritance pattern is this an example of?

A) Polygenic inheritance
B) Sex linked
C) Chromosomal nondisjunction
D) Incomplete dominance

Question 70

The failure of chromosomes to segregate properly during meiosis is called

A) inversion.
B) translocation.
C) replication.
D) independent assortment.
E) nondisjunction.

Question 71

For which disorder can those affected be male or female?

A) Turner syndrome
B) Klinefelter syndrome
C) Trisomy X
D) XYY syndrome
E) Down syndrome

Question 72

Autosomal nondisjunction can result in

A) Down syndrome.
B) XYY males.
C) trisomy X.
D) Klinefelter syndrome.
E) Turner syndrome.

Question 73

What is the difference between phenotype and genotype?

A) Phenotype is when both alleles are the same and genotype is when the alleles are different.
B) Genotype is the physical expression of a trait and phenotype is the combination of alleles carried by the organism.
C) Phenotype is the physical expression of a trait and genotype is the combination of alleles carried by the organism.
D) Phenotype is the alleles that are hidden and genotype is the alleles that are expressed.

Question 74

Sickle-cell anemia is caused by a

A) recessive autosomal gene.
B) recessive sex-linked gene.
C) dominant autosomal gene.
D) combined interaction of several genes.
E) simple dominant gene.

Question 75

Which disorder is characterized by the individual having a normal number of sex chromosomes?

A) Turner syndrome
B) Klinefelter syndrome
C) Trisomy X
D) XYY syndrome
E) Down syndrome

Question 76

All of the following are true regarding pedigree analysis EXCEPT that it

A) documents the transmission of a genetic characteristic over two or more generations.
B) can incorporate molecular biology techniques.
C) is exclusively used to study the patterns of inheritance in dogs.
D) reveals whether a trait is dominant or recessive.

Question 77

A child is born with dwarfism (tt). His parents are of normal height. Which of the following must be TRUE of the parents?

A) They are both homozygous recessive dwarf.
B) They are both heterozygous tall.
C) They are both heterozygous dwarf.
D) They are both homozygous dominant tall.

Question 78

A disorder caused by nondisjunction of chromosome 21, resulting in a trisomy 21 child, is

A) color deficiency.
B) Down syndrome.
C) cystic fibrosis.
D) hemophilia.

Question 79

A woman with blood type AB and a man with blood type O have three children, one of whom is adopted. The blood types of the children are A, B, and O. What is the blood type of the adopted child?

A) A
B) O
C) B
D) Not enough information is provided to answer this question.

Question 80

Which disorder is more common among the babies of older mothers?

A) Turner syndrome
B) Klinefelter syndrome
C) Trisomy X
D) XYY syndrome
E) Down syndrome