Genetic Inheritance - Chapter 21

Question 1

Mendel called the yellow trait that was expressed in all of his second-generation pea plants the [___________] trait.

Dominant

Recessive

Phenotype

Alleles

Genotype

Answer 1

Dominant

Question 2

Mendel called the green trait that was hidden the [____________] trait.

Dominant

Recessive

Alleles

Genotype

Phenotype

Answer 2

Recessive

Question 3

The factors that Mendel observed that came from the mother and the father and contributed to the traits in the offspring are called [__________].

Dominant

Recessive

Alleles

Genotype

Phenotype

Answer 3

Alleles

Question 4

The combination of alleles (either homozygous or heterozygous) is called the [__________].

Dominant

Recessive

Alleles

Genotype

Phenotype

Answer 4

Genotype

Question 5

The result (often a physical characteristic) of the genotype is a [___________].

Dominant

Recessive

Alleles

Genotype

Phenotype

Answer 5

Phenotype

Question 6

Which of the following terms refers to the genes of an individual?

Phenotype

Probability

Gamete

Genotype

Autosomal

Answer 6

Genotype

Question 7

Which of the following is a dominant allele?

ab

A

a

Ab

AA

Answer 7

A

Question 8

Which of the following is an example of a homozygous recessive genotype?

Short

AA

aa

Aa

ab

Answer 8

aa

Question 9

Which of the following represents a dihybrid cross?

AAbb x aaBB

ff x ff

AAbb Aabb

Gg x gg

Ss x ss

Answer 9

AAbb x aaBB

*A dihybrid cross involves mating between two individuals with different alleles as two separate genetic loci.

Question 10

Which of the following represents a gamete with a dominant allele?

Aa

bb

A

AA

b

Answer 10

A

*A gamete only has one allele for a particular trait and the dominant allele would be a capital letter.

Question 11

If two parents who are unaffected have a child that is affected, then the parents are both considered bearers.

True

False

Answer 11

False

*Two parents who are unaffected but are heterozygous for a recessive disorder are considered carriers.

Question 12

The square that is used to make all the possible combinations of gametes is called a Punnett square.

True

False

Answer 12

True

*Reginald Punnett introduced the Punnet square in his genetic classes in 1909.

Question 13

Unattached earlobes are a dominant trait in humans. Which phenotype does an individual with genotype EE show?

The right earlobe is attached and the left earlobe is unattached,

Both earlobes are attached.

Both earlobes are unattached.

The right earlobe is unattached and the left earlobe is attached.

Both earlobes are extremely elongated.

Answer 13

Both earlobes are unattached.

*Since unattached earlobes are a dominant trait in humans, the genotypes EE or Ee would produce unattached earlobes of both ears. Individuals would not have one attached earlobe and one unattached earlobe.

Question 14

Which of the following represents a cross to determine if an individual is homozygous dominant or heterozygous?

Aa x Aa

AA x AA

Aa x AA

Aa x aa

aa x aa

Answer 14

Aa x aa

*Crossing a homozygous recessive individual with a homozygous dominant individual will only produce offspring with a dominant phenotype. If a heterozygous individual is crossed with a homozygous recessive individiual, some of the offspring will display the recessive phenotype. Therefore, this type of cross will allow one to determine if an individual expressing the dominant phenotype is heterozygous or homozygous dominant.

Question 15

Probability calculations in which the word “or” is used involve the product rule.

True

False

Answer 15

False

*Probability calculations in which the word “or” is used, such as “heads or tails,” involve the sum rule.

Question 16

If you want to know the probability that tossing two coins will result in a particular outcome (two heads, for example), you use the

Sum rule.

Punnet square.

Product rule.

Genetics rule.

Bergman’s rule.

Answer 16

Product rule.

*The product rule gives the chance of two different events (the two coins being tossed) occurring simultaneously.

Question 17

A dihybrid cross shows the potential results from a cross that involves how many traits? [___________]

Two

9:3:3:1

Assortment

Answer 17

Two

Question 18

The Punnett square used in the RrYy x RrYy cross resulted in a [______________] phenotypic ratio in the offspring

Two

9:3:3:1

Assortment

Answer 18

9:3:3:1

Question 19

Mendel’s observation that allele factors (that determine traits like pea color and roundness) are passed down independently from one another became known as the Law of Independent [_____________]

Two

9:3:3:1

Assortment

Answer 19

Assortment

Question 20

Dad has a genotype if AaBb. He can produce sperm with how many different genotypes?

One

Two

Three

Four

Five

Answer 20

Four

*Dad can produce four different types of gametes (sperm): AB, Ab, aB, and ab.

Question 21

In a dihybrid cross, in which both parents are heterozygous for both traits, what is the probability that the offspring will exhibit both dominant phenotypes?

9/16

3/16

1/16

1

6/16

Answer 21

9/16

*Nine out of sixteen of the offspring will exhibit both of the dominant traits phenotypically. AaBb x AaBb will yield 3/4 dominant for A and 3/4 dominance for B. 3/4 x 3/4 = 9/16.

Question 22

In a dihybrid cross, if the resulting ratios are 1:1:1:1, what are the genotypes of the parents?

GgRr x GgRr

GG x RR

GGRR x ggrr

GrRr x ggrr

Gg x Rr

Answer 22

GgRr x ggrr

*A dihybrid would involve an individual with the genotype GgRr. In order to have a 1:1:1:1 ratio, the other parent must be homozygous recessive for both traits.

Question 23

Two parents that have a genetic disorder can never have a normal child.

True

False

Answer 23

False

*Yes if the disorder is dominant and they are heterozygous, the child can inherit a recessive allele from both parents.

Question 24

In a pedigree, an affected male would be designated by

A square with a line through it.

A shaded square.

An open circle.

An open square.

A shaded circle.

Answer 24

A shaded square.

*Affected individuals are shaded, and a male is represented by a square.

Question 25

Which of the following is a characteristic of an autosomal recessive disorder pedigree?

Affected children can have unaffected parents.

Two affected parents will always have affected children.

Affected individuals with homozygous unaffected mates will have unaffected children.

Both males and females are affected with equal frequency.

All of the answer choices are correct.

Answer 25

All of the answer choices are correct.

*All of the answer choices are characteristic of an autosomal recessive disorder pedigree.

Question 26

Which of the following is a characteristic of an autosomal dominant disorder pedigree?

Heterozygotes are affected.

Both males and females are affected with equal frequency.

Two affected parents can produce an unaffected child.

Two unaffected parents will not have an affected child.

All of the answer choices are characteristic of an autosomal recessive disorder pedigree.

Answer 26

All of the answer choices are characteristic of an autosomal recessive disorder pedigree.

*All of the answer choices are characteristic of an autosomal recessive disorder pedigree.

Question 27

Which of the following is an autosomal recessive disorder?

Cystic fibrosis

Sickle-cell disease

Tay-Sachs disease

All of the answer choices are autosomal recessive disorders.

None of the answer choices are autosomal recessive disorders.

Answer 27

All of the answer choices are autosomal recessive disorders.

*All of the answer choices are inherited as an autosomal recessive disorder.

Question 28

Even though sickle-cell disease is inherited as an autosomal recessive disorder, the heterozygote can express some variation of the recessive phenotype.

True

False

Answer 28

True

*Sickle-cell heterozygotes have sickle-cell traits in which the blood cells are normal unless they experience dehydration or mild oxygen deprivation.

Question 29

Which of the following disorders is caused by a defect in the production of elastic connective tissue protein called fibrillin?

Tay-Sachs disease

Marfan syndrome

Huntington disease

Sickle-cell disease

Cystic fibrosis

Answer 29

Marfan syndrome

*Marfan syndrome is caused by a defect in the production of an elastic connective tissue protein called fibirillin.

Question 30

Which of the following disorders is a trinucleotide repeat discorder.

Tay-Sachs disorder

Huntington disease

Cystic fibrosis

Sickle-cell disease

Marfan syndrome

Answer 30

Huntington disease

*Huntington disease is caused by the base sequence CAG repeated over and over again in the protein huntingtin.

Question 31

Which of the following traits/disorders is controlled by multiple genes?

Tay-Sachs disease

Skin color

ABO blood type

Curly hair

Familial hypercholesterolemia

Answer 31

Skin color

*Skin color is controlled by several sets of alleles. It is a polygenic trait.

Question 32

The definition of a multifactorial trait is one in which more than one set of alleles is involved, in which the environment plays no role.

True

False

Answer 32

False

*A multifactorial trait is a polygenic trait that is also influenced by the environment.

Question 33

What type of inheritance does familial hypercholesterolemia display?

Sex-linked dominant

Incompletely dominant

Codominant

Autosomal recessive

Autosomal dominant

Answer 33

Incompletely dominant

*Familial hypercholesterolemia is an incompletely dominant disorder.

Question 34

Of the three possible alleles for the ABO blood type, each individual can have how many?

Half an allele

Three

Two

One

Zero

Answer 34

Two

*Because each individual is diploid, each can only carry two alleles.

Question 35

If a person with type B blood marries a person with type A blood, what phenotypes can their children be?

All type B

Types B and O

Types A, B, O, and AB

All type A

Types A and O

Answer 35

Types A, B, O, and AB

*If both parents are heterozygous, all four blood types are possible: A, B, O, and AB.

Question 36

Which of the following designations indicates a sex-linked trait?

a

X^<em>B</em>

i

A

I^<em>A</em>

Answer 36

X^<em>B</em>

A sex-linked trait is shown as the letter attached to the X chromosome. A and a are alleles for autosomal traits. I^<em>a</em> and are the alleles for blood types.

Question 37

A male inherits his X-linked allele from his mother.

True

False

Answer 37

True

*A man will inherit his mother’s X chromosome and its associated alleles from his mother. He will inherit a Y chromosome and associated alleles form his father.

Question 38

Which of the following traits is an X-linked recessive disorder?

Sickle-cell disease

Color blindness

Cystic fibrosis

Marfan syndrome

Tay-Sachs

Answer 38

Color blindness

*Color blindness is a X-linked recessive disorder, Tay-Sachs, cystic fibrosis, and sickle-cell disease are autosomal recessive disorders. Marfan syndrome is an autosomal dominant disorder.

Question 39

If a mother is a carrier for color-blindness and her husband is not color-blind, what are the probable genotypes of the children?

One normal daughter, one carrier daughter, and two normal sons

One normal daughter, one carrier daughter, and two color-blind sons

One normal daughter, one carrier daughter, one normal son, and one color-blind son

Two carrier daughters, one normal son, and one color-blind son

Two normal daughters, one normal son, and one color-blind son

Answer 39

One normal daughter, one carrier daughter, one normal son, one color-blind son

*If a mother is a carrier for color-blindness (X^BX^<em>b</em>) and the father is normal (X^<em>B</em>Y) they would statistically produce a daughter who is normal, one daughter who is a carrier, one son who is normal, and one son who is color-blind.

Question 40

Which of the following is a characteristic of an X-linked recessive disorder pedigree?

The characteristic often skips a generation

If a woman has the characteristic, all of her sons will have it.

If a female has the trait, her father must also have it.

An affected son can have normal parents.

All of the answer choices are characteristic of an X-linked recessive disorder pedigree.

Answer 40

All if the answer choices are characteristic of an X-linked recessive disorder pedigree.

*All of the answer choices are characteristic of an X-linked recessive disorder pedigree.

Question 41

In an X-linked dominant trait, affected males pass the trait only to daughters.

True

False

Answer 41

True

*Since daughters must inherit an X chromosome from their fathers, they would receive and X chromosome with the dominant trait. Sons do not inherit their father’s X chromosome and will not be affected.

Question 42

Which of the following X-linked recessive disorders is characterized by a degeneration of the muscles?

Malaria

Color blindness

Fragile X

Hemophilia

Duchenne

Answer 42

Duchenne

*Duchenne muscular dystrophy is characterized by a degeneration of the muscles. Fragile X is characterized by mental impairment. Color blindness is the inability to distinguish between various colors, typically red and green. Hemophilia is the inability for the blood to clot normally. Malaria is caused by a protist and is not an X-linked disorder.

Question 43

Can a woman with an X-linked recessive disorder have normal sons?

True

False

Answer 43

False

*No, all of her sons would inherit their X chromosome with the defective allele from mom.

Question 44

How are Fragile X syndrome and Huntington disease similar?

Both exhibit a late onset in life.

Both are trinucleotide-repeat expansion disorders.

Both cause autism.

Both affect the muscles and lead to eventual paralysis.

Both are found only in males.

Answer 44

Both are trinucleotide-repeat expansion disorders.

*Both diseases involve repeats of three nucleotides.

Question 45

While a locus refers to a unit of heredity, a gene refers to a specific position on a chromosome.

True

False

Answer 45

False

*A gene refers to a unit of heredity, while a locus refers to a specific position on a chromosome.

Question 46

There are two different alleles for the number of fingers on the hands: five-finger allele and six-finger allele. When both the five-finger allele and six-finger allele are present in the same individual, the individual has six fingers on each hand. Which allele is dominant?

7 fingers

5 fingers

11 fingers

6 fingers

1 finger

Answer 46

6 fingers

*When both alleles are present, the dominant allele is expressed while the recessive allele is hidden. This would produce an individual with 6 fingers.

Question 47

Which of the following represents the genotype of a male who is color-blind?

X^BX^b

X^<em>B</em>X^<em>B</em>

X^<em>b</em>Y

X^<em>B</em>Y

X^<em>b</em>X^<em>b</em>

Answer 47

X^<em>b</em>Y

*A male who is color-blind would have an X chromosome, with one b allele and one Y chromosome.

Question 48

If a mother is a carrier for color-blindness and her husband is not color-blind, what are the probable genotypes of the children?

Two normal daughters, one normal son, and one color-blind son

Two carrier daughters, one normal son, and one color-blind son

One normal daughter, one carrier daughter, and two color-blind sons

One normal daughter, one carrier daughter, and two normal sons

One normal daughter, one carrier daughter, one normal son, one color-blind son

Answer 48

One normal daughter, one carrier daughter, one normal son, and one color-blind son

*If a mother is a carrier for color-blindness (X^BX^<em>b</em>) and the father is normal (X^<em>B</em>Y) they would statistically produce a daughter who is normal, one daughter who is a carrier, one son who is normal, and one son who is color-blind.

Question 49

Most of the sex-linked traits are only found on the X chromosome.

True

False

Answer 49

True

*Very few Y-linked alleles have been found on the much smaller Y chromosome.

Question 50

In a cross of a homozygous dominant parent and a homozygous recessive parent, what is the ratio of offspring that will exhibit the recessive phenotype?

1/2

3/4

1

1/4

0

Answer 50

0

*None of the offspring will exhibit the recessive phenotype. AA x aa will yield 100% Aa offspring.