Question 1

What is the pattern of inheritance for a rare dominant allele?

Accepted Answer

A)  Every affected person has an affected parent. 
B)  Unaffected parents can produce children who are affected. 
C)  Affected parents do not produce affected children. 
D)  Unaffected mothers have affected sons and daughters who are carriers. 
E)  None of the above 
A)  Every affected person has an affected parent. 
B)  Unaffected parents can produce children who are affected. 
C)  Affected parents do not produce affected children. 
D)  Unaffected mothers have affected sons and daughters who are carriers. 
E)  None of the above

Question 2

Unattached earlobes are a dominant trait. Finn and Maggie both have unattached earlobes but their daughter, Celia, does not. If Finn and Maggie have a second child, what is the probability that it will have attached earlobes?

Accepted Answer

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

Question 3

Which statement about a test cross is not true?

Accepted Answer

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. 
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.

Question 4

Epistasis refers to

Accepted Answer

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. 
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 5

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

Accepted Answer

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

Question 6

Epistasis is

Accepted Answer

A)  the degree to which a particular genotype is expressed in an individual. 
B)  the proportion of individuals within a group with a particular genotype that show the expected phenotype. 
C)  a situation in which a heterozygotic individual expresses an intermediate phenotype of the parents. 
D)  a situation in which one gene masks the expression of another gene. 
E)  a situation in which both alleles are expressed equally. 
A)  the degree to which a particular genotype is expressed in an individual. 
B)  the proportion of individuals within a group with a particular genotype that show the expected phenotype. 
C)  a situation in which a heterozygotic individual expresses an intermediate phenotype of the parents. 
D)  a situation in which one gene masks the expression of another gene. 
E)  a situation in which both alleles are expressed equally.

Question 7

When reciprocal crosses produce identical results, the trait is

Accepted Answer

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

Question 8

Originally, genetic inheritance was thought to be a function of the blending of traits from the two parents. Which exception to Mendel's rules is an example of blending?

Accepted Answer

A)  X linkage 
B)  Polygenic inheritance 
C)  Incomplete dominance 
D)  Codominance 
E)  Pleiotropism 
A)  X linkage 
B)  Polygenic inheritance 
C)  Incomplete dominance 
D)  Codominance 
E)  Pleiotropism

Question 9

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?

Accepted Answer

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

Question 10

A cross between two heterozygous parents that differs by two independent traits is a(n) _______ cross.

Accepted Answer

The answer of A cross between two heterozygous parents that...

Question 11

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?

Accepted Answer

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

Question 12

Alleles for genes located on mitochondrial DNA are said to be maternally inherited. What is the reason for this pattern of inheritance?

Accepted Answer

A)  The egg and sperm contribute equal numbers of cytoplasmic organelles to the zygote. 
B)  The egg contributes virtually all of the cytoplasmic organelles to the zygote. 
C)  Half of the nuclear chromosomes in the zygote come from the father. 
D)  Half of the nuclear chromosomes in the zygote come from the mother. 
E)  All of the nuclear chromosomes in the zygote come from the mother. 
A)  The egg and sperm contribute equal numbers of cytoplasmic organelles to the zygote. 
B)  The egg contributes virtually all of the cytoplasmic organelles to the zygote. 
C)  Half of the nuclear chromosomes in the zygote come from the father. 
D)  Half of the nuclear chromosomes in the zygote come from the mother. 
E)  All of the nuclear chromosomes in the zygote come from the mother.

Question 13

A woman of blood group A has a child with a man of blood group B. The child's blood is type O. What are the genotypes of the parents?

Accepted Answer

A)  Mother: IAIA; father: IBIa 
B)  Mother: IAiO; father: IBIb 
C)  Mother: IAiO; father: IBiO 
D)  Mother: IAiB; father: IBIO 
E)  It is impossible for these individuals to have a child with type O blood. 
A)  Mother: IAIA; father: IBIa 
B)  Mother: IAiO; father: IBIb 
C)  Mother: IAiO; father: IBiO 
D)  Mother: IAiB; father: IBIO 
E)  It is impossible for these individuals to have a child with type O blood.

Question 14

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.

Accepted Answer

A)  22 
B)  40 
C)  60 
D)  90 
E)  None of the above 
A)  22 
B)  40 
C)  60 
D)  90 
E)  None of the above

Question 15

A cross between two parents that differs by a single trait is a(n) _______ cross.

Accepted Answer

The answer of A cross between two parents that differs...

Question 16

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

Accepted Answer

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. 
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 17

One particular allele of a gene may be defined as _______, or standard, because it is present in most individuals and gives rise to an expected trait, or phenotype.

Accepted Answer

The answer of One particular allele of a gene may...

Question 18

Draw a sample pedigree with three generations in which the maternal grandmother and paternal grandfather are carriers of a rare recessive autosomal trait. What is the probability that one of their children will be carriers of this trait? What is the probability that a grandchild will have the disease?

Accepted Answer

To draw a sample pedigree with three gen

Question 19

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?

Accepted Answer

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

Question 20

A(n) _______ is a portion of DNA that resides at a particular locus or site on a chromosome and encodes a particular function.

Accepted Answer

The answer of A(n) _______ is a portion of DNA...

Exam 12: Inheritance, Genes, and Chromosomes

What is the pattern of inheritance for a rare dominant allele?

Unattached earlobes are a dominant trait. Finn and Maggie both have unattached earlobes but their daughter, Celia, does not. If Finn and Maggie have a second child, what is the probability that it will have attached earlobes?

Which statement about a test cross is not true?

Epistasis refers to

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

Epistasis is

When reciprocal crosses produce identical results, the trait is

Originally, genetic inheritance was thought to be a function of the blending of traits from the two parents. Which exception to Mendel's rules is an example of blending?

A cross between two heterozygous parents that differs by two independent traits is a(n) _______ cross.

Alleles for genes located on mitochondrial DNA are said to be maternally inherited. What is the reason for this pattern of inheritance?

A woman of blood group A has a child with a man of blood group B. The child's blood is type O. What are the genotypes of the parents?

A cross between two parents that differs by a single trait is a(n) _______ cross.

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

One particular allele of a gene may be defined as _______, or standard, because it is present in most individuals and gives rise to an expected trait, or phenotype.

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(n) _______ is a portion of DNA that resides at a particular locus or site on a chromosome and encodes a particular function.

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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

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?