Question 1

A woman who is heterozygous for pattern baldness marries a man who is nonbald. Which of the following would be true of their offspring?
A) All would be bald
B) All of the females would be nonbald, all males would be bald
C) All of the females would be nonbald, ½ of the males would be bald
D) ½ of females would be bald, and ½ of the females would be bald
E) All would be nonbald

Accepted Answer

Pattern baldness is a sex-linked trait, and since the woman is heterozygous, she carries one allele for baldness. The nonbald man does not carry the baldness allele. Therefore, all females (XX) would inherit one nonbald allele from their father and one bald allele from their mother, making them nonbald. Half of the males (XY) would inherit the bald allele from their mother, making them bald.

Question 2

At the molecular level, type A and type B blood differ in which of the following characteristics?
A) The antigens present on the surface of the red blood cells
B) The type of sugar found in each type
C) The antibodies that are generated against the other type of blood
D) All of the answers are correct

Accepted Answer

The antigens present on the surface of red blood cells, the type of sugar found in each type, and the antibodies generated against the other type of blood are all characteristics that distinguish type A and type B blood at the molecular level.

Question 3

If an allele is dominant in one sex and recessive in another, it is an example of .
A) Sex-limited inheritance
B) Sex-influenced inheritance
C) Incomplete dominance.
D) Simple Mendelian inheritance
E) Incomplete dominance

Accepted Answer

Sex-influenced inheritance occurs when an allele is dominant in one sex but recessive in the other, due to hormonal differences affecting gene expression.

Question 4

The coat characteristics of Siamese cats and Himalayan rabbits, where proteins in the extremities function differently than in other parts of the body is an example of .
A) Incomplete dominance
B) Multiple allele systems
C) Semilethal alleles
D) Temperature-sensitive allele
E) None of the answers are correct

Accepted Answer

The coat characteristics of Siamese cats and Himalayan rabbits are due to temperature-sensitive alleles, where the cooler extremities allow for the expression of darker fur color.

Question 5

A heterozygote possesses a phenotype that is intermediate between the homozygous dominant and homozygous recessive phenotypes. This is most likely an example of .
A) Lethal alleles
B) Incomplete dominance
C) Gene dosage
D) Sex-influenced inheritance

Accepted Answer

Incomplete dominance occurs when the phenotype of the heterozygote is intermediate between the phenotypes of the homozygous dominant and homozygous recessive individuals.

Question 6

Huntington disease in humans is an example of .
A) Essential genes
B) Lethal alleles
C) Semilethal alleles
D) Nonessential genes
E) Conditional lethal alleles

Accepted Answer

The answer of Huntington disease in humans is an example...

Question 7

Temperature-sensitive alleles are examples of .
A) Essential genes
B) Lethal alleles
C) Semilethal alleles
D) Nonessential genes
E) Conditional lethal alleles

Accepted Answer

Temperature-sensitive alleles are conditional lethal alleles because their expression and the resulting phenotype depend on environmental conditions, such as temperature.

Question 8

The interaction of two genes to produce a phenotype was first described by .
A) Morgan and Bridges
B) Mendel
C) Darwin
D) Bateson and Punnett
E) None of the answers are correct

Accepted Answer

Bateson and Punnett first described the interaction of two genes to produce a phenotype in their 1905 publication on sweet pea genetics.

Question 9

An individual with type A blood and an individual with type B blood mate and have offspring. What blood type is not possible in their offspring?
A) Type O blood
B) Type A blood
C) Type B blood
D) Type AB blood
E) All blood types are possible

Accepted Answer

Individuals with type A and type B blood can produce offspring with any blood type (A, B, AB, or O) depending on their genotype (whether they carry recessive alleles).

Question 10

Genes that are not required for survival, but are likely to be beneficial to the organism, are called .
A) Essential genes
B) Lethal alleles
C) Semilethal alleles
D) Nonessential genes
E) Conditional lethal alleles

Accepted Answer

Nonessential genes are those that are not required for survival but may provide advantages under certain conditions.

Question 11

If a geneticist describes a trait as being 70% penetrant, what would they mean?
A) The expression of the trait varies by individual
B) It is lethal in 30% of the individuals who have the trait
C) Only 70% of the individuals who carry the trait express the trait
D) The trait is present in 70% of the population

Accepted Answer

Penetrance refers to the proportion of individuals with a particular genotype that actually express the associated phenotype. If a trait is 70% penetrant, it means that 70% of individuals with the genotype will express the trait.

Question 12

Sickle-cell anemia in humans is an example of .
A) Codominance
B) Incomplete penetrance
C) Heterozygous advantage
D) Multiple allele systems
E) None of the answers are correct

Accepted Answer

Sickle-cell anemia is an example of heterozygous advantage, where individuals with one sickle-cell allele (heterozygous) have a survival advantage in malaria-endemic regions.

Question 13

Phenylketonuria in humans is an example of .
A) Incomplete penetrance
B) Codominance
C) An environmental-influenced trait
D) Incomplete dominance
E) All of the answers are correct

Accepted Answer

Phenylketonuria (PKU) is a genetic disorder that is influenced by environmental factors, such as diet. Individuals with PKU can manage the condition by adhering to a strict diet low in phenylalanine, demonstrating the environmental influence on the trait.

Question 14

In four-o'clock plants, red flower color is dominant to white flower color. However, heterozygous plants have a pink color. If a pink-flowered plant is crossed with a white-flowered plant, what will be the phenotypic ratios of their offspring?
A) ¼ red, ½ pink, ¼ white
B) All pink
C) All white
D) ½ pink, ½ white
E) ½ red, ½ pink

Accepted Answer

In this scenario, the pink-flowered plant is heterozygous (Rr) for the flower color gene, with R being the allele for red and r being the allele for white. The white-flowered plant is homozygous recessive (rr). When these plants are crossed (Rr x rr), the offspring will have a 1:1 ratio of Rr (pink) to rr (white) phenotypes.

Question 15

In human blood groups, the fact that an individual can have an AB blood type is an example of .
A) Incomplete dominance
B) Incomplete penetrance
C) Sex-influenced trait
D) Temperature-sensitive conditional allele
E) Codominance

Accepted Answer

AB blood type is an example of codominance, where both A and B alleles are equally expressed.

Question 16

At the molecular level, which of the following best explain heterozygous advantage and over dominance?
A) A heterozygous individual can produce more varieties of homodimer proteins
B) The alleles produce two different proteins with slightly different functions
C) The proteins produced by the alleles may provide a broader range of environmental tolerance, such as temperature ranges
D) Infectious organisms may recognize only a specific functional protein
E) All of the answers are possibilities

Accepted Answer

Each of the options (A through D) provides a plausible molecular mechanism by which heterozygous advantage or overdominance could occur, suggesting that a combination of these mechanisms could contribute to the phenomenon.

Question 17

Male-pattern baldness is a sex-linked trait in humans.

Accepted Answer

Male-pattern baldness is not a sex-linked trait; it is influenced by multiple genes, including those on autosomes, and is affected by hormonal factors.

Question 18

In rabbits, full coat color (c) is the dominant trait. A second allele, chinchilla (cch) is recessive to full coat color. Himalayan coat color (ch) is recessive to chinchilla and full coat colors and albino (c)
Is recessive to all coat colors. If two chinchilla rabbits mate, what coat color is not possible in their offspring?
A) Full coat color
B) Chinchilla coat color
C) Himalayan coat color
D) Albino coat color
E) All coat colors are possible

Accepted Answer

The answer of In rabbits, full coat color (c) is...

Question 19

For a certain trait, a heterozygous individual has a selective advantage than a homozygous dominant or homozygous recessive individual. This is called .
A) Codiminance
B) Incomplete dominance
C) Over dominance
D) Incomplete penetrance
E) Multiple allele systems

Accepted Answer

Overdominance, also known as heterozygote advantage, occurs when the heterozygous genotype has a higher relative fitness than either the homozygous dominant or homozygous recessive genotypes.

Question 20

Polydactyly in humans is an example of .
A) Simple Mendelian inheritance
B) Incomplete dominance
C) Incomplete penetrance
D) Codominance
E) Gene dosage

Accepted Answer

Polydactyly in humans is an example of incomplete penetrance, where not all individuals with the genetic mutation express the trait.

Quiz 4: Extensions of Mendelian Inheritance

A woman who is heterozygous for pattern baldness marries a man who is nonbald. Which of the following would be true of their offspring?

At the molecular level, type A and type B blood differ in which of the following characteristics?

If an allele is dominant in one sex and recessive in another, it is an example of .

The coat characteristics of Siamese cats and Himalayan rabbits, where proteins in the extremities function differently than in other parts of the body is an example of .

A heterozygote possesses a phenotype that is intermediate between the homozygous dominant and homozygous recessive phenotypes. This is most likely an example of .

Huntington disease in humans is an example of .

Temperature-sensitive alleles are examples of .

The interaction of two genes to produce a phenotype was first described by .

An individual with type A blood and an individual with type B blood mate and have offspring. What blood type is not possible in their offspring?

Genes that are not required for survival, but are likely to be beneficial to the organism, are called .

If a geneticist describes a trait as being 70% penetrant, what would they mean?

Sickle-cell anemia in humans is an example of .

Phenylketonuria in humans is an example of .

In four-o'clock plants, red flower color is dominant to white flower color. However, heterozygous plants have a pink color. If a pink-flowered plant is crossed with a white-flowered plant, what will be the phenotypic ratios of their offspring?

In human blood groups, the fact that an individual can have an AB blood type is an example of .

At the molecular level, which of the following best explain heterozygous advantage and over dominance?

Male-pattern baldness is a sex-linked trait in humans.

For a certain trait, a heterozygous individual has a selective advantage than a homozygous dominant or homozygous recessive individual. This is called .

Polydactyly in humans is an example of .