Deck 11: Mendel and the Gene Idea

Question 1

Which of the following statements correctly describes one difference between the law of independent assortment and the law of segregation?

A)The law of independent assortment explains the segregation of two or more genes relative to one another.
B)The law of segregation explains the segregation of two or more genes relative to one another.
C)The law of segregation requires having two or more generations to describe.
D)The law of segregation is accounted for by anaphase of mitosis.

Answer 1

A

Question 2

Which of the following statements correctly describes a monohybrid cross?

A)A monohybrid cross involves a single parent.
B)A monohybrid cross produces a single offspring.
C)A monohybrid cross involves organisms that are heterozygous for one character.
D)A monohybrid cross is performed for one generation.

Answer 2

C

Question 3

Which of the following phases of cell division confirms Mendel's observation of the segregation of alleles in gamete formation?

A)prophase I of meiosis
B)anaphase II of meiosis
C)metaphase I of meiosis
D)anaphase I of meiosis

Answer 3

D

Question 4

How many unique gametes could be produced through independent assortment by an individual with the genotype AaBbCCDdEE?

A)4
B)8
C)16
D)64

Question 5

Why did the F₁ offspring of Mendel's classic pea cross always look like one of the two parental varieties?

A)No genes interacted to produce the parental phenotype.
B)Each allele affected phenotypic expression.
C)The traits blended together during fertilization.
D)One allele was dominant.

Question 6

The addition rule of probability can be defined as

A)the probability that two or more independent events will both occur.
B)the probability that two or more independent events will both occur in the offspring of one set of parents.
C)the probability that either one of two mutually exclusive events will occur.
D)the probability of producing two or more heterozygous offspring.

Question 7

What was Mendel's explanation for his observation that traits that had disappeared in the F₁ generation reappeared in the F₂ generation of the pea plants he used in his experiments?

A)New mutations were frequently generated in the F₂ progeny,"reinventing" traits that had been lost in the F₁.
B)The mechanism controlling the appearance of traits was different between the F₁ and the F₂ plants.
C)Traits can be dominant or recessive,and the recessive traits were "hidden" by the dominant ones in the F₁.
D)The traits were lost in the F₁ due to dominance of the parental traits.

Question 8

When crossing an organism that is homozygous recessive for a single trait with one that is heterozygous for the same trait,what is the chance of producing an offspring with the homozygous recessive phenotype?

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

Question 9

Which of the following statements correctly describes a dihybrid cross?

A)A dihybrid cross involves two parents.
B)A dihybrid cross produces two offspring.
C)A dihybrid cross involves organisms that are heterozygous for two characters.
D)A dihybrid cross results in a 3:1 phenotype ratio in the F₂ offspring.

Question 10

A sexually reproducing animal has two unlinked genes,one for head shape (H)and one for tail length (T).Its genotype is HhTt.Which of the following genotypes is possible in a gamete from this organism?

A)tt
B)Hh
C)HhTt
D)HT

Question 11

Black fur in mice (B)is dominant to brown fur (b).Short tails (T)are dominant to long tails (t).What fraction of the progeny of crosses BbTt × BBtt will be expected to have black fur and long tails?

A)1/16
B)3/16
C)3/8
D)1/2

Question 12

All seven of the pea plant traits studied by Mendel obeyed the principle of independent assortment.Which of the following statements correctly describes what this indicates about those traits?

A)None of the traits obeyed the law of segregation.
B)Some traits obeyed the law of segregation,and some did not.
C)All of the genes controlling the traits were located on the same chromosome.
D)All of the genes controlling the traits behaved as if they were located on different chromosomes.

Question 13

What was the most significant conclusion that Gregor Mendel drew from his experiments with pea plants?

A)There is considerable genetic variation in garden peas.
B)Traits are inherited in discrete units and are not the results of the "blending" of traits.
C)Recessive genes occur more frequently in the F₁ generation than do dominant ones.
D)An organism that is homozygous for many recessive traits is at a disadvantage.

Question 14

In certain plants,the tall trait is dominant to the short trait.If a heterozygous plant is crossed with a homozygous tall plant,what is the probability that the offspring will be short?

A)1
B)1/2
C)1/4
D)0

Question 15

Which of the following events of meiosis I confirms Mendel's second law of independent assortment?

A)synapsis of homologous chromosomes
B)crossing over
C)alignment of synapsed pairs of homologous chromosomes on the metaphase plate
D)separation of homologs at anaphase

Question 16

Why did Mendel continue some of his experiments to the F₂ generation?

A)to obtain a larger number of offspring on which to base statistics
B)to observe whether or not a recessive trait would reappear
C)to observe whether or not the dominant trait would reappear
D)to distinguish which alleles were segregating

Question 17

Given the following cross between parents of the genotypes AABBCc × AabbCc,assume complete dominance for each trait and independent assortment.What proportion of the progeny will be expected to phenotypically resemble the first parent?

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

Question 18

Which of the following statements describes the major reason that an individual with the genotype AaBbCCDdEE can make many kinds of gametes?

A)segregation of maternal and paternal alleles
B)crossing over during prophase I
C)different possible assortment of chromosomes into gametes
D)the tendency for dominant alleles to segregate together

Question 19

In the cross AaBbCc × AaBbCc,what is the probability of producing the genotype AABBCC?

A)1/4
B)1/8
C)1/16
D)1/64

Question 20

Two plants are crossed,resulting in offspring with a 3:1 ratio for a particular trait.What does this suggest about the trait?

A)that the parents were true-breeding for contrasting traits
B)that the trait shows incomplete dominance
C)that a blending of traits has occurred
D)that the parents were both heterozygous for a single trait

Question 21

In humans,wavy hair occurs in heterozygotes (H^SH^C)offspring of people with straight hair (H^SH^S)and curly hair (H^CH^C).Which of the following crosses would produce offspring with the ratio of 1 straight:2 wavy:1 curly?

A)straight × straight
B)wavy × wavy
C)curly × wavy
D)curly × curly

Question 22

The figure above shows a pedigree chart for a family,some of whose members exhibit the dominant trait,W.Affected individuals are indicated by a dark square or circle.
What is the genotype of individual II-5?

A)WW
B)Ww
C)ww
D)WW or ww

Question 23

Which of the following describes the ability of a single gene to have multiple phenotypic effects?

A)incomplete dominance
B)multiple alleles
C)pleiotropy
D)epistasis

Question 24

The figure above shows a pedigree chart for a family,some of whose members exhibit the dominant trait,W.Affected individuals are indicated by a dark square or circle.
What is the likelihood that the offspring of IV-3 and IV-4 will have the trait?

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

Question 25

The figure above represents a pedigree for a family in which dark-shaded symbols represent individuals with one of the two major types of colon cancer.Numbers under the symbols are the individuals' age at the time of diagnosis.A slash through the symbol indicates that the individual is deceased.The affected woman in generation IV is thinking about her future and asks her oncologist (cancer specialist)whether she can know if any or all of her children will have a high risk of the same cancer.The doctor would be expected to advise which of the following: (I)genetic counseling; (II)prenatal diagnosis when/if she becomes pregnant; (III)testing to see whether she has the allele; (IV)testing to see whether her future spouse or partner has the allele?

A)I: genetic counseling only
B)II: prenatal diagnosis when/if she becomes pregnant
C)I: genetic counseling;II: prenatal diagnosis when/if she becomes pregnant;and IV: testing to see whether her future spouse or partner has the allele only
D)III: testing to see whether she has the allele only

Question 26

The figure above represents a pedigree for a family in which dark-shaded symbols represent individuals with one of the two major types of colon cancer.Numbers under the symbols are the individuals' age at the time of diagnosis.A slash through the symbol indicates that the individual is deceased.From this pedigree,what is the most likely manner by which this trait is inherited?

A)from mothers
B)as a recessive trait
C)as a result of epistasis
D)as a dominant trait

Question 27

In a particular plant,leaf color is controlled by gene locus D.Plants with at least one D allele have dark green leaves,and plants with the homozygous recessive dd genotype have light green leaves.A true-breeding dark-leaved plant is crossed with a light-leaved one,and the F₁ offspring is allowed to self-pollinate.The predicted outcome of the F₂ is diagrammed in the Punnett square shown in the figure above,where 1,2,3,and 4 represent the genotypes corresponding to each box within the square.Which of the boxes marked 1-4 correspond(s)to plants with dark leaves?

A)1 only
B)1 and 2
C)2 and 3
D)1,2,and 3

Question 28

Skin color in humans has a wide variety of phenotypes.The expression of this trait is caused by more than two genes.What type of inheritance pattern is responsible for this expression?

A)codominance
B)incomplete dominance
C)complete dominance
D)polygenic inheritance

Question 29

A scientist discovers a DNA-based test for one allele of a particular gene.This and only this allele,if homozygous,produces an effect that results in death at or about the time of birth.Which of the following statements describes the best use of this discovery?

A)Screen all newborns of an at-risk population.
B)Design a test for identifying heterozygous carriers of the allele.
C)Introduce a normal allele into deficient newborns.
D)Follow the segregation of the allele during meiosis.

Question 30

Which of the following statements correctly describes an example of epistasis?

A)Recessive genotypes for each of two genes (aabb)result in an albino corn snake.
B)In rabbits and many other mammals,one genotype (ee)prevents any fur color from developing.
C)In Drosophila (fruit flies),white eyes can be due to a combination of multiple genes.
D)In cacti,there are several genes for the type of spines.

Question 31

In a particular plant,leaf color is controlled by gene locus D.Plants with at least one D allele have dark green leaves,and plants with the homozygous recessive dd genotype have light green leaves.A true-breeding dark-leaved plant is crossed with a light-leaved one,and the F₁ offspring is allowed to self-pollinate.The predicted outcome of the F₂ is diagrammed in the Punnett square shown in the figure above,where 1,2,3,and 4 represent the genotypes corresponding to each box within the square.Which of the plants will be true-breeding?

A)1 and 4 only
B)2 and 3 only
C)1,2,3,and 4
D)1 only

Question 32

Achondroplasia,a form of dwarfism in humans,is caused by a dominant allele.What is the probability of a heterozygous dwarf man and a normal,homozygous woman having a child who is a heterozygous dwarf?

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

Question 33

In a particular plant,leaf color is controlled by gene locus D.Plants with at least one D allele have dark green leaves,and plants with the homozygous recessive dd genotype have light green leaves.A true-breeding dark-leaved plant is crossed with a light-leaved one,and the F₁ offspring is allowed to self-pollinate.The predicted outcome of the F₂ is diagrammed in the Punnett square shown in the figure above,where 1,2,3,and 4 represent the genotypes corresponding to each box within the square.Which of the boxes correspond(s)to plants with a heterozygous genotype?

A)1 only
B)1 and 2
C)2,and 3
D)1,2 and 3

Question 34

Which of the following calculations described in the following statements require that you use the addition rule?

A)Calculate the probability of black offspring from the cross AaBb × AaBb,when B is the symbol for the black allele.
B)Calculate the probability of children with both cystic fibrosis and polydactyly when parents are each heterozygous for both genes.
C)Calculate the probability of each of four children having cystic fibrosis if the parents are both heterozygous.
D)Calculate the probability of a child having only sickle-cell anemia or cystic fibrosis if each parent is each heterozygous for both traits.

Question 35

Phenylketonuria (PKU)is a disease in humans that results from the abnormal metabolism of the amino acid phenylalanine.If untreated,it can lead to severe brain damage in infants.Two normal parents have a child who has PKU.What can you determine about the inheritance of the PKU allele from this information?

A)It is recessive.
B)It is dominant.
C)It is pleiotropic.
D)It is epistatic.

Question 36

The frequency of heterozygosity for the sickle-cell anemia allele is unusually high,presumably because this reduces the frequency of malaria.Such a relationship is related to which of the following concepts?

A)Mendel's law of independent assortment
B)Mendel's law of segregation
C)Darwin's explanation of natural selection
D)Darwin's observations of competition

Question 37

The figure above represents a pedigree for a family in which dark-shaded symbols represent individuals with one of the two major types of colon cancer.Numbers under the symbols are the individuals' age at the time of diagnosis.A slash through the symbol indicates that the individual is deceased.In each generation of this family after generation I,the age at diagnosis is significantly lower than would be found in nonfamilial (sporadic)cases of this cancer (~63 years).What is the most likely reason?

A)Members of this family know to be checked for colon cancer early in life.
B)Hereditary (or familial)cases of this cancer typically occur at earlier ages than do nonfamilial forms.
C)This is pure chance;it would not be expected if you were to look at a different family.
D)This cancer requires mutations in more than this one gene.

Question 38

Cystic fibrosis affects the lungs,the pancreas,the digestive system,and other organs,resulting in symptoms ranging from breathing difficulties to recurrent infections.Which of the following terms best describes this expression of phenotypes?

A)incomplete dominance
B)multiple alleles
C)pleiotropy
D)epistasis

Question 39

Characters in humans such as a person's red and white blood cell counts vary quite a bit depending on such factors as altitude and physical activity.Traits like this are referred to as

A)polygenic.
B)completely dominant.
C)recessive.
D)multifactorial.

Question 40

The figure above shows a pedigree chart for a family,some of whose members exhibit the dominant trait,W.Affected individuals are indicated by a dark square or circle.
What is the probability that individual III-1 is Ww?

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

Question 41

Drosophila (fruit flies)usually have long wings (+ is the symbol used to represent this allele),but mutations in two different genes can result in bent wings (bt)or vestigial wings (vg).In symbolizing fruit fly alleles,it is common to use two letters as opposed to only one.If a homozygous bent wing fly is mated with a homozygous vestigial wing fly,which of the following offspring would you expect?

A)all btvg heterozygotes,long-winged flies
B)1/2 bent and 1/2 vestigial flies
C)all homozygous + flies,long-winged
D)3/4 bent and 1/4 vestigial flies

Question 42

Gene S controls the sharpness of spines in a type of cactus.Cactuses with the dominant allele,S,have sharp spines,whereas homozygous recessive ss cactuses have dull spines.At the same time,a second gene,N,determines whether or not cactuses have spines.Homozygous recessive nn cactuses have no spines at all.The relationship between genes S and N is an example of

A)incomplete dominance.
B)epistasis.
C)complete dominance.
D)pleiotropy.

Question 43

Radish flowers may be red,purple,or white.A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring.The part of the radish we eat may be oval or long,with long being the dominant trait.If true-breeding red-flowered long radishes are crossed with true-breeding white-flowered oval radishes,the F₁ will be expected to be which of the following?

A)red-flowered and long
B)red-flowered and oval
C)white-flowered and long
D)purple-flowered and long

Question 44

Radish flowers may be red,purple,or white.A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring.The part of the radish we eat may be oval or long,with long being the dominant trait.True-breeding red-flowered long radishes are crossed with true-breeding white-flowered radishes.All of the F₁ offspring are purple-flowered and long radishes.The flower color trait in radishes is an example of which of the following types of inheritance?

A)a multiple allelic system
B)sex linkage
C)codominance
D)incomplete dominance

Question 45

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative.Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r,respectively.Which of the following is a possible phenotype for the father?

A)A negative
B)O negative
C)B positive
D)AB negative

Question 46

Labrador retrievers are black,brown,or yellow.In a cross of a black female with a brown male,results can be all black puppies,1/2 black to 1/2 brown puppies,or 3/4 black to 1/4 yellow puppies.How many genes must be responsible for these coat colors in Labrador retrievers?

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

Question 47

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative.Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r,respectively.Which of the following is a possible partial genotype for the mother?

A)I^AIA
B)I^BIB
C)ii
D)I^Ai

Question 48

Tallness (T)in snapdragon plants is dominant to dwarfness (t),and red (C^R)flower color is not dominant to white (C^W).The heterozygous condition results in pink (C^RC^W)flower color.If snapdragons are heterozygous for height as well as for flower color,a mating between them will result in what ratio?

A)9:3:3:1
B)6:3:3:2:1:1
C)1:2:1
D)27:9:9:9:3:3:3:1

Question 49

Labrador retrievers have black,brown,or yellow fur.Fur color is controlled by two genes,one of which exhibits epistasis.Black (B)is dominant over brown (b)in one gene,and (E)is dominant over (e)in the other gene.The (E)gene is epistatic to the (B)gene.In a cross of a black female with a brown male,results can be all black puppies,1/2 black to 1/2 brown puppies,or 3/4 black to 1/4 yellow puppies.In one cross of black × black,the results were as follows:9/16 black,4/16 yellow,3/16 brown.
The genotype eebb must result in which of the following?

A)black
B)brown
C)yellow
D)a lethal result

Question 50

Two true-breeding stocks of pea plants are crossed.One parent has red axial flowers,and the other has white terminal flowers;all F₁ individuals have red axial flowers.The genes for flower color and location assort independently.Among the F₂ offspring,what is the probability of plants with white axial flowers?

A)9/16
B)1/16
C)3/16
D)1/8

Question 51

Drosophila (fruit flies)usually have long wings (+ is the symbol used to represent this allele),but mutations in two different genes can result in bent wings (bt)or vestigial wings (vg).The bent and vestigial wing alleles segregate independently.In symbolizing fruit fly alleles,it is common to use two letters as opposed to only one.If flies that have long wings and are heterozygous for both the bent wing gene and the vestigial wing gene are mated,what is the probability of offspring with bent wings only?

A)1/8
B)3/8
C)1/4
D)3/16

Question 52

Radish flowers may be red,purple,or white.A cross between a red-flowered plant and a white-flowered plant yields all-purple offspring.The part of the radish we eat may be oval or long,with long being the dominant trait.True-breeding red-flowered long radishes are crossed with true-breeding white-flowered radishes.All of the F₁ offspring are purple-flowered and long radishes.In the F₂ generation of this cross,which of the following phenotypic ratios would be expected?

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

Question 53

Tallness (T)in snapdragon plants is dominant to dwarfness (t),and red (C^R)flower color is not dominant to white (C^W).The heterozygous condition results in pink (C^RC^W)flower color.A dwarf red snapdragon is crossed with a plant homozygous for tallness and white flowers.What are the genotype and phenotype of the F₁ individuals?

A)^{W- ttCRCW}, dwarf and pink
B)- ttC^WCW,dwarf and white
C)-TtC^RCW,tall and red
D)-TtC^RCW,tall and pink

Question 54

Gene S controls the sharpness of spines in a type of cactus.Cactuses with the dominant allele,S,have sharp spines,whereas homozygous recessive ss cactuses have dull spines.At the same time,a second gene,N,determines whether or not cactuses have spines.Homozygous recessive nn cactuses have no spines at all.A cross between a true-breeding sharp-spined cactus and a spineless cactus homozygous for dull spines would produce

A)all sharp-spined progeny.
B)50% sharp-spined,50% dull-spined progeny.
C)25% sharp-spined,50% dull-spined,25% spineless progeny.
D)all spineless progeny.

Question 55

Two true-breeding stocks of pea plants are crossed.One parent has red axial flowers,and the other has white terminal flowers;all F₁ individuals have red axial flowers.The genes for flower color and location assort independently.If 1,000 F₂ offspring resulted from the cross,approximately how many of them would you expect to have red terminal flowers?

A)65
B)190
C)250
D)565

Question 56

A woman who has blood type A positive has a daughter who is type O positive and a son who is type B negative.Rh positive is a trait that shows simple dominance over Rh negative and is designated by the alleles R and r,respectively.Which of the following is a possible genotype for the son?

A)I^BIB
B)I^AIB
C)ii
D)I^Bi

Question 57

Labrador retrievers are black,brown,or yellow.In a cross of a black female with a brown male,results can be all black puppies,1/2 black to 1/2 brown puppies,or 3/4 black to 1/4 yellow puppies.These results indicate which of the following about the inheritance pattern of fur color in Labrador retrievers?

A)Brown is dominant to black.
B)Black is dominant to brown and to yellow.
C)Yellow is dominant to black.
D)Epistasis is involved.