Question 1

What is the genotype of the tall, red, wide-leaved parent?

Accepted Answer

A)  Tt Rr Ww
B)  Tt Rr WW
C)  TT RR WW
D)  TT Rr Ww
E)  TT RR Ww

Question 2

A coefficient of coincidence of 0.5 in a region of three genes means that half as many double crossovers were observed as would have been expected if crossovers in the two intervals were independent.

Accepted Answer

A) True 
 B)False

Question 3

How many degrees of freedom are there?

Accepted Answer

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

Question 4

If an individual is heterozygous at two loci (Ab/aB)  which are on the same chromosome arm with the A locus closest the centromere under what conditions would a crossover in a somatic cell generate a twin spot?

Accepted Answer

A)  The crossover would have to occur between the A locus and the centromere locus and involve two homologous (non-sister)  chromatids.
B)  The crossover would have to occur between the A locus and the B locus and involve two homologous (non-sister)  chromatids.
C)  The crossover would have to occur between the B locus and the end of the chromosome locus and involve two homologous (non-sister)  chromatids.
D)  A double crossover would have to occur, with one crossover between the A locus and the centromere and a second crossover between the A and B loci locus and both crossovers would have to involve two homologous (non-sister)  chromatids.
E)  No crossover in a somatic cell could generate a twin spot.

Question 5

In tetrad analysis, second-division segregations result from

Accepted Answer

A)  single crossovers between linked genes.
B)  double crossovers between linked genes.
C)  single crossovers between a gene and a centromere.
D)  independent assortment of unlinked genes.
E)  nondisjunction of homologs.

Question 6

Suppose a woman has four sons, and two are colorblind but have normal blood clotting and two have hemophilia but normal color vision.What is the probable genotype of the woman?

Accepted Answer

A)  HR / hr
B)  Hr / hr
C)  hr / hR
D)  Hr / hR
E)  HR / Hr

Question 7

Which classes are the parental types?

Accepted Answer

A)  wild-type and orange
B)  brown and bright-red
C)  wild-type and brown
D)  bright-red and orange
E)  There is no way to determine this.

Question 8

A female mouse from a true-breeding wild-type strain was crossed to a male mouse with apricot eyes (ap)  and grey body (gy) .The F1 mice were wild-type for both traits.When the F1 were interbred, the F2 were distributed as follows: 1 mice were wild-type for both traits.When the F1 were interbred, the F2 were distributed as follows:   Which of the following statements is correct? A) ap and gy are unlinked. B) ap and gy are linked on an autosome and 10 map units apart. C) ap and gy are linked on an autosome and 20 map units apart. D) ap and gy are X-linked and 10 map units apart. E) ap and gy are X-linked and 20 map units apart." class="answers-bank-image d-inline" rel="preload" > Which of the following statements is correct?

Accepted Answer

A)  ap and gy are unlinked.
B)  ap and gy are linked on an autosome and 10 map units apart.
C)  ap and gy are linked on an autosome and 20 map units apart.
D)  ap and gy are X-linked and 10 map units apart.
E)  ap and gy are X-linked and 20 map units apart.

Question 9

The hypothesis that predicts no linkage between genes is known as the null hypothesis.

Accepted Answer

A) True 
 B)False

Question 10

Chiasmata are structures of cross over between sister chromatids of homologous chromosomes.

Accepted Answer

A) True 
 B)False

Question 11

If two or more of the genes are linked, what map distance separates them?

Accepted Answer

A)  4 mu
B)  12 mu
C)  24 mu
D)  50 mu
E)  None of the genes are linked to each other.

Question 12

A crossover that would result in genetic recombination (e.g., Abc or aBC)  could involve which chromatids?

Accepted Answer

A)  1 & 2 or 3 & 4
B)  1 & 3 or 2 & 4
C)  1 & 4 or 2 & 3
D)  1 & 3 or 1 & 4 or 2 & 3 or 2 & 4
E)  any two of the four chromatids

Question 13

Genes Q and R are 20 map units apart.If a plant of genotype QR / qr is selfed, what percentage of the progeny will be qr in phenotype?

Accepted Answer

A)  4%
B)  10%
C)  16%
D)  20%
E)  40%

Question 14

The R/r and S/s genes are linked and 10 map units apart.In the cross Rs/rS * rs/rs what fraction of the progeny will be RS/rs?

Accepted Answer

A)  5%
B)  10%
C)  25%
D)  40%
E)  45%

Question 15

The zipper-like connection between paired homologs in early prophase is known as a

Accepted Answer

A)  spindle fiber.
B)  synaptic junction.
C)  synaptonemal complex.
D)  chiasma.
E)  none of the choices are correct.

Question 16

Sturtevant's detailed mapping studies of the X chromosome of Drosophila established what genetic principle?

Accepted Answer

A)  That genes are arranged in a linear order on the chromosomes.
B)  That genes are carried on chromosomes.
C)  That sex determination is controlled by the X and Y chromosomes.
D)  That segregation of an allelic gene pair is accompanied by disjunction of homologous chromosomes.
E)  That different pairs of chromosomes assort independently.

Question 17

Calculate the coefficient of coincidence in this region.

Accepted Answer

A)  0
B)  0.16
C)  0.33
D)  0.5
E)  0.66

Question 18

In ascomycete fungi, the arrangement of the spores in the ascus that directly reflects the order in which they were produced during meiosis is called an ______.

Accepted Answer

A)  Unordered tetrad
B)  Unordered octad
C)  Ordered tetrad
D)  Ordered pentad

Question 19

The measured distance between genes D and E in a two point test cross is 50 map units.What does this mean in physical terms?

Accepted Answer

A)  D and E are on different pairs of chromosomes.
B)  D and E are linked and exactly 50 map units apart.
C)  D and E are linked and at least 50 map units apart.
D)  either D and E are on different pairs of chromosomes or D and E are linked and exactly 50 map units apart
E)  either D and E are on different pairs of chromosomes or D and E are linked and at least 50 map units apart

Question 20

ws; ws; ws+; ws+; ws; ws; ws+; ws+

Accepted Answer

A)  First-division segregation pattern
B)  Second-division segregation pattern

Exam 5: Linkage, Recombination, and the Mapping of Genes on Chromosomes

The hypothesis that predicts no linkage between genes is known as the null hypothesis.

Correct AnswerverifiedShow Answer

If an individual is heterozygous at two loci (Ab/aB) which are on the same chromosome arm with the A locus closest the centromere under what conditions would a crossover in a somatic cell generate a twin spot?

Correct AnswerverifiedShow Answer

Chiasmata are structures of cross over between sister chromatids of homologous chromosomes.

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Calculate the coefficient of coincidence in this region.

Correct AnswerverifiedShow Answer

Genes Q and R are 20 map units apart.If a plant of genotype QR / qr is selfed, what percentage of the progeny will be qr in phenotype?

Correct AnswerverifiedShow Answer

ws; ws; ws+; ws+; ws; ws; ws+; ws+

Correct AnswerverifiedShow Answer

The measured distance between genes D and E in a two point test cross is 50 map units.What does this mean in physical terms?

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The R/r and S/s genes are linked and 10 map units apart.In the cross Rs/rS * rs/rs what fraction of the progeny will be RS/rs?

Correct AnswerverifiedShow Answer

How many degrees of freedom are there?

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Which classes are the parental types?

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Sturtevant's detailed mapping studies of the X chromosome of Drosophila established what genetic principle?

Correct AnswerverifiedShow Answer

A female mouse from a true-breeding wild-type strain was crossed to a male mouse with apricot eyes (ap) and grey body (gy) .The F1 mice were wild-type for both traits.When the F1 were interbred, the F2 were distributed as follows: Which of the following statements is correct?

Correct AnswerverifiedShow Answer

In ascomycete fungi, the arrangement of the spores in the ascus that directly reflects the order in which they were produced during meiosis is called an ______.

Correct AnswerverifiedShow Answer

A crossover that would result in genetic recombination (e.g., Abc or aBC) could involve which chromatids?

Correct AnswerverifiedShow Answer

If two or more of the genes are linked, what map distance separates them?

Correct AnswerverifiedShow Answer

The zipper-like connection between paired homologs in early prophase is known as a

Correct AnswerverifiedShow Answer

In tetrad analysis, second-division segregations result from

Correct AnswerverifiedShow Answer

What is the genotype of the tall, red, wide-leaved parent?

Correct AnswerverifiedShow Answer

Suppose a woman has four sons, and two are colorblind but have normal blood clotting and two have hemophilia but normal color vision.What is the probable genotype of the woman?

Correct AnswerverifiedShow Answer

A coefficient of coincidence of 0.5 in a region of three genes means that half as many double crossovers were observed as would have been expected if crossovers in the two intervals were independent.

Correct AnswerverifiedShow Answer

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ws; ws; ws⁺; ws⁺; ws; ws; ws⁺; ws⁺

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A female mouse from a true-breeding wild-type strain was crossed to a male mouse with apricot eyes (ap) and grey body (gy) .The F₁ mice were wild-type for both traits.When the F₁ were interbred, the F₂ were distributed as follows: Which of the following statements is correct?

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