Deck 13: Mendel and the Gene

Question 1

When Mendel crossed yellow-seeded and green-seeded pea plants,all the offspring were yellow seeded.When he took these F₁ yellow-seeded plants and crossed them to green-seeded plants,what genotypic ratio is expected?

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

Answer 1

D

Question 2

Phenylketonuria is an inherited disease caused by a recessive autosomal allele.If a woman and her husband are both carriers,what is the probability that their first child will be a phenotypically normal girl?

A)1/4
B)1/16
C)1)0
D)3/16
E)3/8

Answer 2

E

Question 3

A heterozygous,but phenotypically wild-type fruit fly (gray body color and normal wings)was mated to a black fly with vestigial wings.The offspring had the following phenotypic distribution: wild type,720;black-vestigial,780;black-normal,280;gray-vestigial,220.What conclusion is likely from these results?

A)The black and vestigial loci assort independently from each other.
B)The black and vestigial loci are allelic.
C)Epistasis has modified a 9:3:3:1 ratio.
D)The black and vestigial loci are linked.

Answer 3

D

Question 4

Mendel crossed yellow-seeded and green-seeded pea plants and then allowed the offspring to self-pollinate to produce an F₂ generation.The results were as follows: 6022 yellow and 2001 green (8023 total).The allele for green seeds has what relationship to the allele for yellow seeds?

A)dominant
B)incompletely dominant
C)recessive
D)semidominant

Question 5

Assuming independent assortment for all gene pairs,what is the probability that the following parents,AABbCc × AaBbCc,will produce an AaBbCc offspring?

A)1/2
B)1/16
C)1/8
D)3/4
E)9/16

Question 6

A man and woman are both of normal pigmentation and have a child who is albino (without melanin pigmentation).Albinism is an autosomal (not sex-linked)recessive trait.What are the genotypes of the albino's parents?

A)One parent must be homozygous for the recessive allele,the other parent can be homozygous dominant,homozygous recessive,or heterozygous.
B)One parent must be heterozygous,the other parent can be homozygous dominant,homozygous recessive,or heterozygous.
C)Both parents must be heterozygous.
D)One parent must be homozygous dominant;the other parent must be heterozygous.
E)Both parents must be homozygous dominant.

Question 7

In birds,sex is determined by a ZW chromosome scheme that is much like the typical XY scheme seen in humans and many other organisms,except that the system is reversed: Males are ZZ (similar to XX in humans)and females are ZW (similar to XY in humans).A lethal recessive allele that causes death of the embryo occurs on the Z chromosome in pigeons.What would be the sex ratio in the offspring of a cross between a male heterozygous for the lethal allele and a normal female?

A)1:1 male to female
B)4:3 male to female
C)3:1 male to female
D)1:2 male to female
E)2:1 male to female

Question 8

A man and woman are both of normal pigmentation,but both have one parent who is albino (without melanin pigmentation).Albinism is an autosomal (not sex-linked)recessive trait.What is the probability that their first child will be an albino?

A)0%
B)1/8
C)1/2
D)1/4
E)100%

Question 9

A man has extra digits (six fingers on each hand and six toes on each foot).His wife and their daughter have a normal number of digits.Having extra digits is a dominant trait.The couple's second child has extra digits.What is the probability that their next (third)child will have extra digits?

A)1/2
B)1/16
C)1/8
D)3/4
E)9/16

Question 10

Suppose two AaBbCc individuals are mated.Assuming that the genes are not linked,what fraction of the offspring are expected to be homozygous recessive for the three traits?

A)1/4
B)1/8
C)1/16
D)1/64
E)1/256

Question 11

Gray seed color in peas is dominant to white.Assume that Mendel conducted a series of experiments where plants with gray seeds were crossed among themselves,and the following progeny were produced: 302 gray and 98 white.(a)What is the most probable genotype of each parent? (b)Based on your answer in (a)above,what genotypic and phenotypic ratios are expected in these progeny? (Assume the following symbols: G = gray and g = white.)

A)(a)GG × gg;(b)genotypic = 3:1,phenotypic = 1:2:1
B)(a)Gg × Gg;(b)genotypic = 1:2:1,phenotypic = 3:1
C)(a)GG × Gg;(b)genotypic = 1:2:1,phenotypic = 2:1
D)(a)gg × Gg;(b)genotypic = 1:2,phenotypic = 3:1
E)(a)Gg × Gg;(b)genotypic = 3:1,phenotypic = 9:3:3:1

Question 12

In Drosophila melanogaster,vestigial (short)wings (vg)are caused by a recessive allele of a gene that independently assorts with a gene pair that influences body hair.Hairy (h)results in a hairy body.A cross is made between a fly with normal wings and a hairy body and a fly with vestigial wings and a normal body.The phenotypically normal F₁ flies were crossed among each other,and 1024 F₂ flies were reared.What phenotypes would you expect in the F₂,and in what actual numbers (not ratios)would you expect to find them?

A)phenotypes-all wild;numbers expected-wild (1024)
B)phenotypes-hairy,vestigial hairy;numbers expected-hairy (512),vestigial hairy (512)
C)phenotypes-wild,vestigial,hairy,vestigial hairy;numbers expected-wild (256),vestigial (256),hairy (256),vestigial hairy (256)
D)phenotypes-wild,vestigial;numbers expected-wild (576),vestigial (576)
E)phenotypes-wild,vestigial,hairy,vestigial hairy;numbers expected-wild (576),vestigial (192),hairy (192),vestigial hairy (64)

Question 13

In rabbits,the homozygous CC is normal,Cc results in deformed legs,and cc results in very short legs.The genotype BB produces black fur,Bb brown fur,and bb white fur.If a cross is made between brown rabbits with deformed legs and white rabbits with deformed legs,what percentage of the offspring would be expected to have deformed legs and white fur?

A)25%
B)33%
C)0%
D)100%
E)50%

Question 14

A black guinea pig crossed with an albino guinea pig produced 12 black offspring.When the albino was crossed with a second black animal,6 blacks and 6 albinos were obtained.What is the best explanation for this genetic situation?

A)Albino is recessive;black is dominant.
B)Albino is dominant;black is incompletely dominant.
C)Albino and black are codominant.
D)Albino is recessive;black is recessive.
E)None of the above applies.

Question 15

In tigers,a recessive allele causes a white tiger (absence of fur pigmentation).If two phenotypically normal tigers that are heterozygous at this locus are mated,what percentage of their offspring is expected to be white?

A)50%
B)75%
C)about 66%
D)about 90%
E)25%

Question 16

A recessive allele on the X chromosome is responsible for red-green color blindness in humans.A woman with normal vision whose father is color blind marries a color-blind male.What is the probability that this couple's first son will be color blind?

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

Question 17

Different ratios occur in crosses with single gene pairs or two gene pairs.What types of ratios are likely to occur in crosses dealing with a single gene pair?

A)9:3:3:1,1:2:1
B)1:1:1:1,1:4:6:4:1
C)3:1,1:1,1:2:1
D)9:7,12:3:1
E)15:1,1:2

Question 18

A man and woman are both of normal pigmentation,but both have one parent who is albino (without melanin pigmentation).Albinism is an autosomal (not sex-linked)recessive trait.What is the probability that their first female child will have albinism?

A)0%
B)1/8
C)1/2
D)1/4
E)100%

Question 19

Hemophilia is caused by several genetic factors;one,a recessive allele of an X-linked gene,is the subject of this problem.Assume that a man with hemophilia marries a normal woman whose father had hemophilia.What is the probability that they will have a daughter with hemophilia?

A)1/16
B)1/8
C)1/4
D)1/2
E)3/4

Question 20

Pseudohypertrophic muscular dystrophy is a human disorder that causes gradual deterioration of the muscles.Only boys are affected,and they are always born to phenotypically normal parents.Due to the severity of the disease,the boys die in their teens.Is this disorder likely to be caused by a dominant or recessive allele? Is its inheritance sex-linked or autosomal?

A)dominant,sex-linked
B)recessive,autosomal
C)recessive,sex-linked
D)dominant,autosomal

Question 21

Glucose-6-phosphate dehydrogenase deficiency (G6PD)is inherited as a recessive allele of an X-linked gene in humans.A woman whose father suffered from G6PD marries a normal man.(a)What proportion of their sons is expected to be G6PD? (b)If the husband was not normal but was G6PD deficient,would you change your answer in part (a)?

A)(a)100%;(b)no
B)(a)1/2;(b)yes
C)(a)2/3;(b)no
D)(a)1/2;(b)no
E)(a)zero;(b)no

Question 22

A man who carries an allele of an X-linked gene will pass it on to

A)all of his daughters.
B)half of his daughters.
C)all of his sons.
D)half of his sons.
E)all of his children.

Question 23

The B-globin gene has many alleles.What is the maximum number of different alleles of the B-globin gene that could be carried by 6 children with the same mom and dad given that the parents are heterozygous?

A)4
B)6
C)8
D)12

Question 24

In humans,blue eyes are inherited as a recessive autosomal trait and color blindness is an X-linked recessive trait.A woman with blue eyes and normal color vision whose father was color blind marries a man who also has normal color vision.He has brown eyes but his mother had blue eyes.Which of the following do you expect to be true for their daughters?

A)One-half of their daughters will have normal color vision and brown eyes;1/2 of their daughters will have normal color vision and blue eyes.
B)Their daughters will all have normal color vision and brown eyes.
C)One-fourth of their daughters will be color blind and have blue eyes,1/4 of their daughters will be color blind and have brown eyes,1/4 of their daughters will have normal color vision and blue eyes,1/4 of their daughters will have normal color vision and brown eyes.
D)Their daughters will all have normal color vision and blue eyes.
E)One-half of their daughters will be color blind and have blue eyes;1/2 their daughters will be color blind and have brown eyes.

Question 25

In Drosophila melanogaster,vestigial wings are caused by a recessive allele of a gene that is linked to a gene with a recessive allele that causes black body color.Morgan crossed black-bodied,normal-winged females and gray-bodied,vestigial-winged males.The F₁ were all gray bodied,normal winged.After examining the F₂ progeny,Morgan calculated the map distance to be 17 map units.Which of the following is correct about the F₂ progeny?

A)black-bodied,normal-winged flies = 17%
B)black-bodied,normal-winged flies PLUS gray-bodied,vestigial-winged flies = 17%
C)gray-bodied,normal-winged flies PLUS black-bodied,vestigial-winged flies = 17%
D)black-bodied,vestigial-winged flies = 17%

Question 26

Two individuals of genotype AABBCCDD and aabbccdd are mated.The F1 generation is interbred (self-fertilized)to yield 5000 progeny.What proportion of the F2 is expected to be AabbCcDD?

A)1/64
B)1/78
C)1/2
D)1/8

Question 27

There are 40 different alleles for a gene involved in immune function.What is the maximum number of alleles that a human can have?

A)1
B)2
C)20
D)40
E)80

Question 28

Whenever the dominant allele of either (or both)gene A or gene B is present,red color is produced.A cross of AaBb × AaBb can be expected to yield how many red offspring out of 16? Assume the genes are not linked.

A)1
B)4
C)12
D)15
E)16

Question 29

A man is heterozygous for two genes (R and L)that are located on different chromosomes.Which of the following processes would result in different combinations of the alleles for these two genes in his sperm?

A)Independent assortment
B)Sister chromatid segregation
C)Recombination
D)Fertilization

Question 30

Snapdragons are flowers that come in a variety of colors,including red,pink,and white.A series of crosses with snapdragons having flowers of different colors produced the following results: pink × pink: 27 pink,13 red,14 white
Red × red: all red
White × white: all white
Pink × white: 29 pink,26 white
Pink × red: 28 pink,27 red
White × red: all pink
Based on the results,what is the most reasonable explanation for the inheritance of these flower colors?

A)more than two alleles
B)incomplete dominance
C)codominance
D)pleiotropic effects
E)qualitative effects

Question 31

What is the probability that a gamete from an individual with the genotype E₁E₂X₁X₁A₁A₂M₂M₂ will contain all paternally derived homologues?

A)1/6
B)1/4
C)1/8
D)1/16

Question 32

Figure 13.1
In a Drosophila experiment,a cross was made between homozygous wild-type females and yellow-bodied males.All of the resulting F₁s were phenotypically wild type.However,adult flies of the F₂ generation (resulting from matings of the F₁s)had the characteristics shown in the figure above: (a)Is the mutant allele for yellow body recessive or dominant?
(b)Is the yellow locus autosomal (not X-linked)or X-linked?

A)(a)recessive;(b)X-linked
B)(a)recessive;(b)not X-linked
C)(a)dominant;(b)X-linked
D)(a)dominant;(b)not X-linked
E)none of the above

Question 33

Regarding an allelic pair for flower color in snapdragons,heterozygotes have pink flowers,whereas the two homozygotes have red flowers or white flowers.When plants with red flowers are crossed with plants with white flowers,what proportion of the offspring is expected to have pink flowers?

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

Question 34

In humans,blue eyes are inherited as a recessive autosomal trait and color blindness is an X-linked recessive trait.A woman with blue eyes and normal color vision whose father was color blind marries a man who also has normal color vision.He has brown eyes,but his mother had blue eyes.Which of the following do you expect to be true for their sons?

A)One-half of their sons will have normal color vision and brown eyes;1/2 of their sons will have normal color vision and blue eyes.
B)Their sons will all have normal color vision and brown eyes.
C)One-fourth of their sons will be color blind and have blue eyes,1/4 of their sons will be color blind and have brown eyes,1/4 of their sons will have normal color vision and blue eyes,1/4 of their sons will have normal color vision and brown eyes.
D)Their sons will all have normal color vision and blue eyes.
E)One-half of their sons will be color blind and have blue eyes;1/2 their sons will be color blind and have brown eyes.

Question 35

Hemophilia is caused by several genetic factors;one,a recessive allele of an X-linked gene,is the subject of this problem.Assume that a man with hemophilia marries a normal woman whose father had hemophilia.What is the probability that their first son will have hemophilia?

A)1/16
B)1/8
C)1/4
D)1/2
E)3/4

Question 36

Figure 13.3
The distance between two genes is a determinant of their recombination frequency.Based on the image below,which of the following sets of genes will show the greatest recombination frequency?

A)A and B
B)B and C
C)C and D
D)A and E

Question 37

The second child of the couple above is unaffected (does not display the condition).What is the probability this child is a carrier for the ataxia condition?

A)0
B)2/3
C)1/2
D)1/4
E)1/16

Question 38

A homozygous tomato plant with red fruit and yellow flowers was crossed with a homozygous tomato plant with golden fruit and white flowers.The F₁ all had red fruit and yellow flowers.The following phenotypes were obtained in the F₂: Red fruit and yellow flowers-41
Red fruit and white flowers-7
Golden fruit and yellow flowers-8
Golden fruit and white flowers-44
How many map units separate these genes?

A)17.6
B)15
C)17.1
D)18.1
E)35

Question 39

In humans,ABO blood types refer to glyocproteins in the membranes of red blood cells.There are three alleles for this autosomal gene: IA,IB,and i.The IA allele codes for the A glycoprotein,the IB allele codes for the B glycoprotein,and the i allele doesn't code for any membrane glycoprotein.IA and IB are codominant,and i is recessive to both IA and IB.People with A type blood have the genotypes IAIA or IAi,people with type B blood are IBIB or IBi,people with type AB blood are IAIB,and people with O type blood are ii.If a woman with type AB blood marries a man with type O blood,which of the following blood types could their children possibly have?

A)A and B
B)AB and O
C)A,B,and O
D)A,B,and AB
E)A,B,AB,and O

Question 40

A couple has a child with Harman's ataxia (a recessive disorder).If this couple has second child,what is the probability that child will have ataxia?

A)0
B)2/3
C)1/2
D)1/4
E)1/16

Question 41

Figure 13.2 Analyze the results of crosses and pedigrees to determine whether genes or alleles are autosomal or X-linked, dominant or recessive, linked or on different chromosomes.

In the figure above,flower A was crossed with flower B to produce flower C.The phenotype of flower C is the result of

A)incomplete dominance.
B)codominance.
C)the passing on of a sex-linked trait.
D)aneuploidy.

Question 42

Julie has Harman's ataxia (hh)and also has achrondoplasia (Aa).Josh is a carrier for Harman's ataxia,an autosomal recessive disorder,and has achondroplasia (Aa),which is an autosomal dominant trait.AA human embryos do not survive beyond the first few cell divisions.What is the probability that a child born to them would have only Harman's ataxia? Assume the genes are unlinked.

A)0
B)1/4
C)1/6
D)1/12
E)1/16