Deck 4: Extensions of Mendelian Genetics

Question 1

Which of the following is an example of codominance?

A)a scorpion's venom is more potent when it's younger
B)in roan cattle,you can see a mix or both red and white furs
C)flowers of a certain plant can come in purple,blue,or yellow
D)there are many possible mutations that lead to white eyes in flies
E)a certain plant can have jagged,rough,or smooth edges on its leaves

Answer 1

B

Question 2

Which of the following statements is true?

A)Even in a seemingly clear- cut example of complete dominance,at the protein or enzyme level,one can detect about half the activity or gene product.
B)With both incomplete dominance and codominance,one expects heterozygous and homozygous classes to be phenotypically identical.
C)An individual won't show incomplete dominance if one allele is a loss of function allele.
D)The threshold effect is only seen in incomplete dominance,not in codominance.
E)In the threshold effect,one would expect the gain of function mutant to be recessive.

Answer 2

A

Question 3

Which of the following is true?

A)A mutation in the DNA can be observed at the macroscopic level even if there's no change in phenotype.
B)Each biochemical pathway is governed by one gene.
C)A neutral mutation leads to no discernable phenotype.
D)A neutral mutation leads to a phenotype that can help or hurt the organism depending on the environment.
E)A neutral allele leads to a change in function in a protein that neither harms nor helps an organism.

Answer 3

C

Question 4

In mice,there is a set of multiple alleles of a gene for coat color.Four of those alleles are as follows: C = full color wild type
C^ch = chinchilla
C^d = dilution
C = albino
Given that the gene locus is not sex- linked and that each allele is dominant to those lower in the list,give the ph ratios expected from the following cross.
Chinchilla heterozygous for albino)× albino

A)2 chinchilla : 1 albino
B)1 chinchilla :1 albino
C)1 full color : 1 chinchilla : 1 albino
D)1 dilution : 1 chinchilla : 1 albino
E)1 chinchilla : 2 albino

Question 5

Which mutations are generally dominant since one copy in a diploid organism is sufficient to alter the normal phenotype?

A)conditional
B)null
C)neutral
D)loss of function
E)gain of function

Question 6

A mutation in a gene often results in a reduction of the product of that gene.The term for this type of mutation is ________.

A)incomplete dominance
B)loss of function or null in the case of complete loss
C)codominance
D)multiple allelism
E)gain of function

Question 7

What is the blood type of individuals who cannot add the terminal sugar to the H substance?

A)Bombay phenotype
B)AB
C)A
D)B
E)O

Question 8

What is the most prevalent form of an allele called?

A)dominant
B)normal
C)neutral
D)recessive
E)wild type

Question 9

Assume that a mutation occurs in the gene responsible for the production of hexosaminidase A,such that only about 50% of the enzyme activity is found in the heterozygote compared with a homozygous normal individual.If heterozygotes are phenotypically normal,we would say that the mutant allele is ________to its normal allele.

A)gain of function
B)epistatic
C)recessive
D)auxotrophic
E)dominant

Question 10

Assume that a dihybrid cross AaBb × AaBb is made in which the gene loci are autosomal,independently assorting,and incompletely dominant.What phenotypic ratio would you expect from such a cross?

A)1:2:1:2:4:2:1:2:1
B)1:2:2:1:4:2:1:2:1
C)2:1:1:2:2:1:4:2:2
D)2:2:2:2:2:2:2:2
E)1:2:1:2:2:2:1:4:1

Question 11

The following coat colors are known to be determined by alleles at one locus in horses: palomino = golden coat with lighter mane and tail cremello = almost white chestnut = brown
The following table gives ratios obtained in matings of the above varieties: Assign gene symbols for the genetic control of coat color on the basis of these data.

A)C¹C¹ = chestnut,C²C² = cremello,C¹C² = palomino
B)C¹C¹ = cremello,C²C² = chestnut,C¹C² = palomino
C)C¹C¹ = palomino,C²C² = chestnut,C¹C² = cremello
D)C¹C¹ = chestnut,C²C² = palomino,C¹C² = cremello
E)C¹C¹ = palomino,C²C² = cremello,C¹C² = chestnut

Question 12

Assume that a dihybrid cross is made in which the genes' loci are autosomal,independently assorting,and incompletely dominant.How many different phenotypes are expected in the offspring?

A)6
B)4
C)2
D)12
E)9

Question 13

A situation in which there are more than two alternative forms of a given gene would be called ________ .

A)alternation of generations
B)incomplete dominance
C)codominance
D)multiple alleles
E)hemizygosity

Question 14

The trait of medium- sized leaves in iris is determined by the genetic condition PP'.Plants with large leaves are PP,whereas plants with small leaves are P'P'.A cross is made between two plants each with medium- sized leaves.What is the term for this allelic relationship?

A)positional effect
B)codominance
C)epistasis
D)incomplete dominance
E)multiple alleles

Question 15

With incomplete dominance,a likely ratio resulting from a monohybrid cross would be ________ .

A)9:3:3:1
B)3:1
C)1:2:1
D)3:3
E)1:2:2:4

Question 16

Typically,when one wishes to represent a gene,the symbol used is ________.

A)underlined
B)in bold print
C)in all lowercase letters
D)in all upper case letters
E)in italics

Question 17

The trait of medium- sized leaves in iris is determined by the genetic condition PP'.Plants with large leaves are PP,whereas plants with small leaves are P'P'.A cross is made between two plants each with medium- sized leaves.If they produce 80 seedlings,what would be the expected phenotypes,and in what numbers would they be expected?

A)20 large leaves ,20 medium leaves ,40 small leaves
B)40 large leaves ,0 medium leaves ,40 small leaves
C)20 large leaves ,40 medium leaves ,20 small leaves
D)40 large leaves ,40 medium leaves ,0 small leaves
E)10 large leaves ,60 medium leaves ,10 small leaves

Question 18

Assume that a cross is made between two organisms that are both heterozygous for a gene that shows incomplete dominance.What phenotypic and genotypic ratios are expected in the offspring?

A)phenotypic 1:2:1; genotypic 1:2:1
B)phenotypic 1:1:1:1; genotypic 1:2:1
C)phenotypic 1:2:1; genotypic 1:1:1:1
D)phenotypic 1:2:1; genotypic 1:3
E)phenotypic 3:1; genotypic 1:2:1

Question 19

The trait for medium- sized leaves in iris is determined by the genetic condition PP'.Plants with large leaves are PP,whereas plants with small leaves are P'P'.The trait for red flowers is controlled by the genes RR,pink by RR ',and white by R'R'.A cross is made between two plants each with medium- sized leaves and pink flowers.If they produce 320 seedlings,what would be the expected phenotypes,and in what numbers would they be expected? Assume no linkage.

A)35 large,red; 35 medium,red; 35 small,red; 35 large,pink; 35 medium,pink; 35 small,pink; 35 large,white; 35 medium,white; 35 small,white
B)20 large,red; 40 medium,red; 20 small,red; 80 large,pink; 40 medium,pink; 40 small,pink; 20 large,white; 40 medium,white; 20 small,white
C)40 large,red; 20 medium,red; 40 small,red; 20 large,pink; 80 medium,pink; 20 small,pink; 40 large,white; 20 medium,white; 40 small,white
D)20 large,red; 40 medium,red; 20 small,red; 40 large,pink; 80 medium,pink; 40 small,pink; 20 large,white; 40 medium,white; 20 small,white
E)80 large,red; 40 medium,red; 20 small,red; 40 large,pink; 20 medium,pink; 40 small,pink; 20 large,white; 40 medium,white; 20 small,white

Question 20

A ________ ratio indicates incomplete dominance.

A)1:2:1
B)2:2:2
C)9:7
D)3:1
E)1:1:1:1

Question 21

Achondroplasia is a form of human dwarfism.If two individuals with achondroplasia have children with the following ratio,2 dwarf to 1 wild type,what is the means of inheritance of this phenotype?

A)epistasis
B)simple recessive
C)dominant lethal
D)simple dominance
E)recessive lethal

Question 22

Typical ratios resulting from epistatic interactions in dihybrid crosses would be________ .

A)9:3:3:1,1:2:1
B)1:2:2:4:1:2:1:2:1,1:2:1
C)9:3:4,9:7
D)1:1:1:1,1:4:6:4:1
E)3:1,1:1

Question 23

Assume that a dihybrid F₂ ratio,resulting from epistasis,was 9:3:4.If a double heterozygote was crossed with the fully recessive type,what phenotypic ratio is expected among the offspring?

A)1:1:2
B)1:1:1
C)9:3:4
D)1:2:1
E)12: 3: 1

Question 24

With ________ ,there will be more than two genetic alternatives for a given locus.

A)incomplete dominance
B)codominance
C)gain of function mutant
D)epistasis
E)multiple alleles

Question 25

A condition in which one gene pair masks the expression of a nonallelic gene pair is called________ .

A)recessiveness
B)additive alleles
C)codominance
D)dominance
E)epistasis

Question 26

In a mating between individuals with the genotypes I^Ai × ii,what percentage of the offspring are expected to have the O blood type?

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

Question 27

Rabbits can come in an allelic series where brown > himilayan > chinchilla > albino,where > means dominant over.They also can come in long recessive)and short fur.You wish to obtain rabbit babies that are albino with long fur.Which of the following crosses would you do?

A)albino with long fur × albino with short fur homozygous
B)albino with long fur × brown chinchilla heterozygote with long fur
C)homozygous brown with long fur × albino with short fur heterozygote
D)albino with long fur × homozygous himilayan with short fur heterozygote
E)chinchilla heterozygous with albino with short fur heterozygous × brown heterozygous with albino with long fur

Question 28

An allele of RNA polymerase in Drosophila demonstrates a recessive lethal inheritance pattern.Which of the following is true?

A)Two homozygous recessive parents will have 100% homozygous offspring.
B)The threshold effect is not seen in recessive lethality.
C)Two heterozygotes will have offspring with a 2:1 pattern.
D)Homozygous lethal genes will always demonstrate a gain of function pattern.
E)Homozygous recessive offspring will never be seen.

Question 29

What would be a typical phenotypic monohybrid ratio in which a lethal allele is involved?

A)6:2:3:1
B)2:1
C)3:1
D)9:3:3:1
E)13:5

Question 30

The following F₂ results occur from a typical dihybrid cross: If a double heterozygote AaBb is crossed with a fully recessive organism aabb,what phenotypic ratio is expected in the offspring?

A)9 purple : 7 white
B)1 purple : 3 white
C)1 purple : 1 white
D)12 purple : 4 white
E)3 purple : 1 white

Question 31

A snapdragon plant has red,pink,or white flowers,inherited in an incomplete dominance pattern.It can come in tall or dwarf homozygous recessive varieties.What is the ratio expected if you cross a pink tall heterozygous plant with a pink short plant?

A)1 red tall : 1 red short : 2 pink tall : 2 pink short : 1 white tall : 1 white short
B)2 red tall : 2 red short : 1 pink tall : 1 pink short : 1 white tall : 1 white short
C)1 red tall : 1 red short : 1 pink tall : 1 pink short : 1 white tall : 1 white short
D)3 red tall : 3 red short : 1 white tall : 1 white short
E)2 red tall : 1 red short : 1 pink tall : 1 pink short : 2 white tall : 1 white short

Question 32

A mutant gene that produces brown eyes bw is located on chromosome #2 of Drosophila melanogaster,whereas a mutant gene producing bright red eyes,scarlet st ,is located on chromosome #3.Phenotypically,wild- type flies with dull red eyes ,whose mothers had brown eyes and whose fathers had scarlet eyes,were mated.The 800 offspring possessed the following phenotypes: wild type dull red ,white,scarlet bright red),and brown.Most of the 800 offspring had wild- type eyes,whereas those with white eyes were the least frequent. From the information presented above,how many white- eyed flies would you expect in the F₂ generation?

A)200
B)450
C)350
D)50
E)150

Question 33

Assume that a dihybrid F₂ ratio,resulting from epistasis,was 15:1.If a double heterozygote was crossed with the fully recessive type,what phenotypic ratio is expected among the offspring?

A)1:1
B)3:1
C)5:7
D)1:3
E)1:2

Question 34

Many of the color varieties of summer squash are determined by several interacting loci: AA or Aa gives white,aaBB or aaBb gives yellow,and aabb produces green.Assume that two fully heterozygous plants are crossed.Give the phenotypes with frequencies of the offspring.

A)4 white :9 yellow : 3 green
B)12 white : 3 yellow : 1 green
C)9 white : 3 yellow : 4 green
D)3 white : 9 yellow : 4 green
E)12 white : 1 yellow : 3 green

Question 35

In a mating between individuals with the genotypes I^AI^B × ii,what percentage of the offspring are expected to have the O blood type?

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

Question 36

Which of the following statements is false?

A)Epistasis would not be expected to occur in a biochemical pathway.
B)When an allele is dominant,the heterozygous combination is the same phenotypically as one of the homozygotes.
C)Epistasis refers to a gene or genes of one pair masking the expression of a gene or genes at a different locus.
D)Epistasis is a nonallelic interaction; dominance is an allelic interaction.
E)Dominance refers to the form of expression of a gene in relation to its allele or alleles .

Question 37

In the mouse,gene A allows pigmentation to be deposited in the individual coat hairs; its allele a prevents such deposition of pigment,resulting in an albino.Gene B gives agouti wild- type fur ; its allele b gives black fur.What would the expected ratio of the progeny be in a cross of a doubly heterozygous agouti mouse mated with a doubly homozygous recessive white mouse?

A)1 agouti :1 black :1 albino
B)9 black : 27albino
C)1 agouti :1 black : 2 albino
D)3 agouti :4 black : 9 albino
E)9 agouti :3 black : 4 albino

Question 38

Which of the following ratio is not likely to occur in crosses F₂ when one is dealing with two interacting,epistatic gene pairs?

A)3:1
B)9:3:4
C)9:7
D)12:3:1
E)15:1

Question 39

The ABO blood group locus in humans provides an example of ________ .

A)conditional alleles
B)epistasis
C)auxotrophy
D)incomplete dominance
E)multiple alleles

Question 40

What term is used to express the idea that several genes exert influence over the same characteristic?

A)co- adhesion
B)coextension
C)transformation
D)gene interaction
E)terminal interaction

Question 41

Alleles that are masked by an epistatic locus are said to be ________ to the genes at that locus.

A)functional
B)hypostatic
C)conditional
D)complementary
E)auxotrophic

Question 42

The white- eyed gene in Drosophila is recessive and sex- linked.Assume that a white- eyed female is mated to a wild- type male.What would be the phenotypes of the offspring?

A)females half wild type,half white eyed; males white eyed
B)all wild type
C)females wild type,males white eyed
D)all white eyed
E)females white eyed; males wild type

Question 43

The deficiency of the enzyme glucose- 6- phosphate dehydrogenase G6PD is inherited as a recessive gene on the X chromosome in humans.A phenotypically normal woman whose father had G6PD is married to a normal man.What fraction of their sons would be expected to have G6PD?

A)1/3
B)zero
C)1/2
D)100%
E)1/4

Question 44

With which of the following would hemizygosity most likely be associated?

A)incomplete dominance
B)sex- limited inheritance
C)X- linked inheritance
D)codominance
E)trihybrid crosses

Question 45

Many of the color varieties of summer squash are determined by several interacting loci: AA or Aa gives white,aaBB or aaBb gives yellow,and aabb produces green.Crosses among heterozygotes give a 12:3:1 ratio.What type of gene interaction would account for these results?

A)multiple alleles
B)epistasis
C)incomplete dominance
D)conditional lethal
E)complementation

Question 46

What is a heterogenous trait?

A)a trait in which offspring show a more severe phenotype depending on which parent donates the allele
B)a trait in which different sexes have different manifestations of severity
C)a trait in which the phenotype differs based on the environment
D)a trait that differs,but not based on environmental conditions
E)a trait in which many genes can potentially be mutated to lead to the same phenotype

Question 47

A cross was made between homozygous wild- type female Drosophila and yellow- bodied male Drosophila.All of the resulting offspring were phenotypically wild type.Offspring of the F₂ generation had the following phenotypes: Based on this information,how is the yellow allele inherited?

A)recessive,X linked
B)sex- influenced inheritance
C)recessive,autosomal
D)dominant,X linked
E)dominant,autosomal

Question 48

What is the term for a gene mutation that leads to a myriad of disparate effects?

A)lethal allele
B)expressivity
C)multiple allele
D)complementation
E)pleiotropy

Question 49

Two forms of hemophilia are determined by genes on the X chromosome in humans.Assume that a phenotypically normal woman whose father had hemophilia is married to a normal man.What is the probability that their first daughter will have hemophilia?

A)1/3
B)zero
C)1/4
D)1/2
E)100%

Question 50

A particular cross gives a modified dihybrid ratio of 9:7.What phenotypic ratio would you expect in a testcross of the fully heterozygous F₁ crossed with the fully recessive type?

A)1:1
B)3:1
C)1:3
D)2:3
E)2:1

Question 51

Multiple mutations that are found to be present in a single gene are said to belong to the same ________ group.

A)complementation
B)phenotypic
C)allelic
D)expression
E)transfer

Question 52

Two forms of hemophilia are determined by genes on the X chromosome in humans.Assume that a phenotypically normal woman whose father had hemophilia is married to a normal man.What is the probability that their first son will have hemophilia?

A)zero
B)1/2
C)100%
D)1/4
E)1/3

Question 53

Which of the following is true about X- linkage?

A)One result of X- linkage is a crisscross pattern of inheritance in which daughters express recessive genes of their fathers and sons express recessive genes of their mothers.
B)X linkage demonstrates that only the wild- type allele is the dominant allele.
C)Females will only express dominant alleles.
D)Males are more liable to express recessive alleles as they are hemizygous.
E)One result of X- linkage is a crisscross pattern of inheritance in which sons express recessive genes of their fathers and daughters express recessive genes of their mothers.

Question 54

The genes for zeste eyes and forked bristles are located on the X chromosome in Drosophila melanogaster.Both genes are recessive.A cross is made between a zeste- eyed female and a forked- bristled male.If 200 offspring from this cross were obtained,what is the expected offspring's phenotype and sex?

A)100 wild female; 100 zeste male
B)100 forked female; 100 zeste male
C)100 zeste female; 100 zeste forked male
D)50 wild female,50 forked female; 50 zeste forked male,50 zeste male
E)all wild type

Question 55

Comb shape in chickens represents one of the classic examples of gene interaction.Two gene pairs interact to influence the shape of the comb.The genes for rose comb R and pea comb P together produce walnut comb.The fully homozygous recessive condition rrppproduces the single comb.Assume that a rose- comb chicken is crossed with a walnut- comb chicken and the following offspring are produced: 17 walnut,16 rose,7 pea,and 6 single.What are the probable genotypes of the parents?

A)RrPp × RRPP
B)rrpp × RrPp
C)Rrpp × RrPp
D)rrPP × RRpp
E)RRPP × Rrpp

Question 56

Because of the mechanism of sex determination,males of many species can be neither homozygous nor heterozygous.Such males are said to be ________ .

A)hemizygous
B)recessive
C)dominant
D)complementary
E)None of the answers listed are correct.

Question 57

When two squash plants with disc- shaped fruit are crossed,depending on the genotype of the parents,disc,sphere,and long fruits may be seen in the offspring.This is an example of ________ .

A)two gene interaction with novel phenotypes
B)dominant lethal
C)heterogenous trait
D)complementation
E)epistasis

Question 58

Which of the following crosses would indicate that the mutants were in the same complementation group?

A)red eye fly × red eye fly -> 3 : 1 ratio
B)pink eye fly × pink eye fly -> purple eye flies
C)pink eye fly × pink eye fly -> pink eye fly
D)pink eye fly × pink eye fly -> all white eye offspring
E)pink eye fly × white eye fly -> all white eyes

Question 59

The accompanying figure is a pedigree of a fairly common human hereditary trait in which the boxes represent males and the circles represent females.Shading symbolizes the abnormal phenotype. Given that one gene pair is involved,what is the inheritance pattern?

A)recessive,autosomal
B)recessive,X linked
C)dominant,X linked
D)sex- influenced inheritance
E)dominant,autosomal

Question 60

If an X- linked disorder is lethal to the affected individual prior to the age at which one reaches reproductive maturation,the lethality will be expressed only in males.Why is this so?

A)Because it's sex- limited inheritance,females do not demonstrate the phenotype.
B)The only sources of the lethal allele in the population are heterozygous females who are "carriers" and do not express the disorder.
C)At the cellular level,the protein will work less well in the male's cells.
D)As it's a lethal allele,it will kill the homozygous recessive first.These are the males.
E)This is not true.We will see the lethality in females as well.

Question 61

What is a significant difference between X- linked and sex- influenced inheritances?

A)In X- linked inheritance,the gene in question is on the X chromosome; in sex- influenced inheritance,the gene is autosomal.
B)X- limited inheritance is only recessive.Sex- influenced inheritance can be recessive or dominant.
C)X- linked inheritance affects females and sex- influenced inheritance affects males.
D)There are no differences.They are the same.
E)Sex- influenced inheritance requires epistasis.X- linked inheritance does not.

Question 62

Name three modes of inheritance that are influenced by the sex of individuals.

A)X- linked,sex- influenced,sex- limited
B)penetrance,X- limited inheritance,X- linked inheritance
C)conditional alleles,sex- limited,X- linked
D)sex- influenced,epistasis,sex- limited
E)epistasis,conditional alleles,expressivity

Question 63

Which of the following statements is true?

A)Expressivity is the term used to describe the balanced genetic output from a hemizygous condition.
B)Genomic anticipation refers to observations that a genetic disorder occurs at an earlier age in successive generations,whereas genetic imprinting occurs when gene expression varies depending on parental origin.
C)Genomic imprinting occurs when one allele converts another.
D)The term expressivity defines the percentage of individuals who show at least some degree of expression of a mutant genotype.
E)Penetrance specifically refers to the expression of lethal genes in heterozygotes.

Question 64

Which of the following is an example of sex- limited inheritance?

A)hemophilia
B)hair color in humans
C)beard formation in humans
D)cat fur length
E)human baldness

Question 65

A ________ is one whose expression is influenced by some environmental condition.

A)multiple allele
B)X- linked allele
C)expressive allele
D)conditional mutant
E)positional effect