Chapter 9: Genes and Inheritance

Question 1

Mary, who has type O blood, is expecting a child with her husband, who has type B blood. Mary’s husband’s father has type A blood. What is the probability that the child will have type O blood?

1. 75%
2. 0%
3. 25%
4. 100%
5. 50%

Answer 1

50%

Question 2

In humans, X-linked traits:

1. occur on the X chromosome.
2. are passed from fathers to their sons.
3. are more common than autosomal traits.
4. occur more frequently in females.
5. All of the above are correct.

Answer 2

occur on the X chromosome

Question 3

Which of the following will likely be true because of the law of independent assortment?

1. an individual will get most of their alleles from one parent
2. monozygotic twins will have about 50% of their alleles in common
3. two typical siblings will have about 50% of their alleles in common
4. Both A and C are correct.

Answer 3

two typical siblings will have about 50% of their alleles in common

Question 4

The phenotype of an organism can best be determined by:

1. inbreeding.
2. outbreeding.
3. sequencing its genes.
4. observing the organism.
5. a reciprocal cross.

Answer 4

observing the organism

Question 5

Phenylketonuria (PKU) is a disease characterized by the buildup of phenylalanine. The enzyme phenylalanine hydroxylase, which catalyzes the conversion of _________ to __________, is mutated and non-functional.

1. arginine; phenylalanine
2. phenylalanine; arginine
3. tyrosine; phenylalanine
4. phenylalanine; tyrosine
5. None of the above is correct.

Answer 5

phenylalanine; tyrosine

Question 6

What is the relationship between a gene and an allele?

1. An allele can consist of several genes.
2. A gene is the same thing as an allele.
3. Alleles are different forms of a gene.
4. A human can have only 23 alleles and 46 genes.

Answer 6

Alleles are different forms of a gene

Question 7

How can an individual whose parents did not have the “fish odor syndrome” trait inherit that trait?

1. The “fish odor syndrome” trait is inherited extra-genetically.
2. If each parent were a silent carrier of the “fish odor syndrome,” then their offspring would have a 50% chance of having the syndrome.
3. If each parent were a silent carrier of the “fish odor syndrome,” then their offspring would have a 100% chance of having the syndrome.
4. Under the circumstances outlined above, the “fish odor syndrome” cannot be inherited.
5. If each parent were a silent carrier of the “fish odor syndrome,” then their offspring would have a 25% chance of having the syndrome.

Answer 7

If each parent were a silent carrier of the “fish odor syndrome,” then their offspring would have a 25% chance of having the syndrome

Question 8

In snapdragons, flower color is inherited as a trait with incomplete dominance. There is an allele, CW, that produces no pigment, and an allele, CR, that produces red pigment. A plant with the CWCR genotype will produce _________________ flowers.

1. no
2. pink
3. white
4. two kinds of
5. red

Answer 8

pink

Question 9

Ignoring crossing over, segregation of alleles occurs when which of the following happens?

1. homologous chromosomes separate during meiosis
2. homologous chromosomes separate during mitosis
3. sister chromatids separate during meiosis II
4. sister chromatids separate during mitosis II

Answer 9

homologous chromosomes separate during meiosis

Question 10

Gregor Mendel performed his famous experiments on:

1. hawkweed.
2. humans.
3. pigeons.
4. garden peas.
5. Darwin’s finches.

Answer 10

garden peas

Question 11

The test-cross:

a. makes it possible to determine the genotype of an individual of unknown genotype who exhibits the dominant version of a trait.
b. is a cross of an individual whose genotype for a trait is not known with an individual homozygous-recessive for the trait.
c. requires the production of multiple offspring in order to reveal the genotype of an individual whose genotype is unknown.
d. a) and b) are both correct.
e. a), b), and c) are correct.

Answer 11

a), b), and c) are correct

Question 12

People whose hairline makes a V-shape in the middle of the forehead are said to have a “widow’s peak”. The characteristic is controlled by one gene and is due to a dominant allele. Lucius Malfoy has a widow’s peak. What is his genotype for the trait, based only on this information?

1. He is homozygous dominant.
2. He is homozygous recessive.
3. He is heterozygous.
4. He may be either homozygous dominant or heterozygous.

Answer 12

He may be either homozygous dominant or heterozygous

Question 13

A woman with type B blood and a man with type A blood could have children with which of the following phenotypes?

1. A, B, AB, or O
2. A, B, or O
3. AB only
4. AB or O
5. O only

Answer 13

A, B, AB, or O

Question 14

If a true-breeding, blue-flowered plant was crossed with a true-breeding white-flowered plant, what phenotypic ratio would we observe in the progeny resulting from this cross? Assume the white-flowered trait is completely dominant.

1. 75% blue, 25% white
2. 100% blue
3. 100% light blue
4. 100% white
5. There is not enough information to answer this question.

Answer 14

100% white

Question 15

The sickle-cell allele is considered to be pleiotropic because:

1. it is involved in a continuously varying trait: the amount of oxygen delivery.
2. it has at least two effects: disrupting oxygen delivery and protecting against malaria.
3. it is involved in a continuously varying trait: the amount of resistance to malaria.
4. it is codominant, in that heterozygotes have both circular and sickled red blood cells.
5. it has at least two effects: promoting oxygen delivery and protecting against malaria.

Answer 15

it is codominant, in that heterozygotes have both circular and sickled red blood cells

Question 16

Most genes come in alternative forms called:

1. chromosomes.
2. gametes.
3. recessives.
4. alleles.
5. dominants.

Answer 16

alleles

Question 17

Which of the following genotypes is homozygous?

a. Rr
b. RR
c. rr
d. both b and c

Answer 17

both b and c

Question 18

Phenylketonuria is a genetic disorder that:

1. causes the inability to convert phenylalanine to tyrosine.
2. causes too many copies of phenylalanine to be added to protein chains.
3. causes the build up of tyrosine in the system.
4. causes the inability to convert tyrosine to phenylalanine.
5. causes too few copies of tyrosine to be added to protein chains.

Answer 18

causes the inability to convert phenylalanine to tyrosine

Question 19

The failure of a seedling to turn green if grown in the dark is an example of:

1. the environment affecting gene expression.
2. incomplete dominance.
3. an interaction between codominant alleles.
4. pleiotropy.
5. continuous variation.

Answer 19

the environment affecting gene expression

Question 20

In many species of birds, males are XX and females are XZ. With birds like this, who is most likely to display a sex-linked recessive trait?

1. There is no Y chromosome so they are not affected by sex-linked recessive traits.
2. Males and females are equally likely to display a sex-linked recessive trait.
3. The gender that is incubated at a higher temperature.
4. females
5. males

Answer 20

females