Deck 5: Extensions of Mendelian Inheritance

Question 1

The phenylketonuria phenotype in humans is an example of ________.

A) incomplete penetrance
B) codominance
C) an environmental-influenced trait
D) incomplete dominance
E) All of these choices are correct.

Answer 1

C

Question 2

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

Answer 2

D

Question 3

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.

Answer 3

E

Question 4

Sickle-cell anemia in humans is an example of ________.

A) codominance
B) incomplete penetrance
C) heterozygote advantage
D) multiple allele systems

Question 5

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 these choices are correct.

Question 6

Polydactyly in humans is an example of ________.

A) simple Mendelian inheritance
B) incomplete dominance
C) incomplete penetrance
D) codominance
E) gene dosage

Question 7

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.

Question 8

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

A) codiminance
B) incomplete dominance
C) overdominance
D) incomplete penetrance
E) multiple allele systems

Question 9

A paralog ________.

A) is found for every gene in mammals
B) is only found on the X but not the Y chromosome
C) can explain the lack of phenotype for a gene knockout
D) cannot be mutated
E) has the same DNA sequence as the original duplicated gene

Question 10

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

Question 11

Alleles that cause death in a certain temperature range are examples of ________.

A) essential genes
B) lethal alleles
C) semilethal alleles
D) nonessential genes
E) conditional lethal alleles

Question 12

If a geneticist describes a trait as being 70% penetrant,what would that 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 have a particular genotype express the trait.
D) The trait is present in 70% of the population.

Question 13

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 these choices are correct.

Question 14

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

Question 15

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

Question 16

At the molecular level,which of the following best explains heterozygous advantage and overdominance?

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.

Question 17

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

Question 18

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

Question 19

New research indicates that male-pattern baldness is a sex-linked trait in humans because of mutations of an androgen receptor gene on the X chromosome.

Question 20

Huntington disease in humans is an example of ________.

A) essential genes
B) lethal alleles
C) semilethal alleles
D) nonessential genes
E) sex linked allele

Question 21

In a dihybrid cross of two heterozygous individuals,you expect a 9:3:3:1 phenotypic ratio in the offspring,but observe a ratio of 9:7.What is the most likely explanation?

A) codominace
B) a sex-limited trait
C) simple Mendelian inheritance
D) incomplete penetrance
E) epistatic interactions of the two genes

Question 22

Scurs are small horn-like growths in cattle that exhibit sex-influenced inheritance.The allele that determines scurs (Sc)is dominant in males and recessive in females.From a mating between a heterozygous male with scurs and a heterozygous female without scurs,what proportion of male offspring will lack scurs (be hornless)?

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

Question 23

Human blood groups are determined by antigens on the surface of red blood cells.

Question 24

If a combination of two or more genes is required to produce a specific trait,it is called a(n)________.

A) overdominance
B) simple mendelian trait
C) sex-influenced trait
D) sex-linked trait
E) gene interaction

Question 25

Variable expressivity means that the phenotype of a trait can vary between individuals.

Question 26

In an epistatic interaction,the genes must be located on the same chromosome.

Question 27

In overdominance,the ________ genotype is beneficial over the ________ genotypes.

A) heterozygous; homozygous
B) homozygous; heterozygous
C) homozygous dominant; homozygous recessive
D) homozygous recessive; homozygous dominant
E) incomplete dominant; codominant

Question 28

Epistasis is ________.

A) another term for overdominance
B) when one gene can mask the expression of a second gene
C) a trait that is only expressed in one sex of the species
D) when two dominant alleles can be expressed in the same individual
E) None of these choices are correct.

Question 29

Because loss-of-function alleles typically do not make a functional gene product,they usually follow the recessive allele inheritance pattern.

Question 30

When wild-type offspring are produced from a cross between parents that both display the same recessive phenotype,this illustrates the genetic phenomenon of ________.

A) simple recessive alleles
B) incomplete penetrance
C) complementation
D) gene dosage
E) a spontaneous mutation

Question 31

The multiple effects of a single gene on the phenotype of an organism is called ________.

A) epistasis
B) penetrance
C) expressivity
D) overdominance
E) pleiotropy

Question 32

Which of the following is not correct concerning epistatic interactions?

A) They are often associated with enzymatic pathways.
B) They produce variations in the expected 9:3:3:1 ratio of a dihybrid cross.
C) They can result when a gene at one locus masks the expression of a gene at a different locus.
D) They always result in a 9:7 ratio of a dihybrid cross.
E) They are due to gene interactions.

Question 33

Incomplete dominance is an example of blending of phenotypes,not genotypes.

Question 34

In cattle,the scurs trait follows a sex-influenced pattern of inheritance. A heterozygous male has the ________ phenotype and a heterozygous female has a ________ phenotype.

A) Y-linked; X-linked
B) nonbald; bald
C) X-linked; Y-linked
D) scurs; hornless

Question 35

Typically,a recessive allele increases the expression of a functional protein.

Question 36

An experiment in which plants with the same genotype are raised under conditions that differ in soil quality could evaluate ________.

A) the norm of reaction
B) overdominance
C) genetic polymorphisms
D) gene interactions

Question 37

Paralogs are often functionally redundant and can compensate for the loss of either of the paralogs in a set.

Question 38

A ________ allele encodes a protein that is made in the proper amount and functions normally.

A) loss-of-function
B) mutant
C) wild-type
D) gain-of-function
E) lethal

Question 39

Because most lethal alleles are inherited in a recessive manner,a cross between two heterozygous individuals could result in a 2:1 genotypic ratio in their surviving offspring.

Question 40

Incomplete penetrance indicates that individuals who possess a dominant trait always express the trait.