Question 1

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?

Accepted Answer

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 C

Question 2

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

Accepted Answer

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

Question 3

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?

Accepted Answer

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

Question 4

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

Accepted Answer

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

Question 5

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

Accepted Answer

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 6

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?

Accepted Answer

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

Question 7

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?

Accepted Answer

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

Question 8

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

Accepted Answer

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

Question 9

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?

Accepted Answer

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

Question 10

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?

Accepted Answer

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

Question 11

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?

Accepted Answer

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 12

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?

Accepted Answer

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 13

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?

Accepted Answer

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 14

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?

Accepted Answer

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

Question 15

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?

Accepted Answer

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

Question 16

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?

Accepted Answer

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

Question 17

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?

Accepted Answer

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 18

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?

Accepted Answer

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

Question 19

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?

Accepted Answer

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.

Question 20

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.

Accepted Answer

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

Exam 13: Mendel and the Gene

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?

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

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?

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

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?

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

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?

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 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 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?

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?

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?

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?

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?