MCB 317 exam 3 questions with verified
answers graded A+
a. Frequency of recombination - correct answer ✔✔Which of the following was described in
lecture as a metric of genetic distance?
Select one:
a. Frequency of recombination
b. Banding pattern of chromosomes
c. A laser ruler
d. PCR using a pair of primers that are on the "outside" of the two linked genes
e. All of the above
c. x+ z+ y+ - correct answer ✔✔You carry out a three point cross in Drosphila involving the three
linked genes x+ y+ and z+. Your parental flies are x+x+ y+y+ z+z+ and xx yy zz. You perform a test
cross on many F1s and infer that the number and genotype of gametes formed by the F1 flies
were:
1008 x+ y+ z+
202 x y+ z+
98 x+ y z+
1012 xyz
5 x+ y+ z
223 x+yz
103 xy+z
8 x y z+
Which of the following is consistent with the order of these genes on the genetic map?
,Select one:
a. z+ x+ y+
b. x+ y+ z+
c. x+ z+ y+
b. True - correct answer ✔✔Genes that are on the same chromosome and are greater than 50
cM apart behave as if they are unlinked.
Select one:
a. False
b. True
b. True - correct answer ✔✔Genes that are on the same chromosome and are greater than 50
cM apart are part of the same linkage group.
Select one:
a. False
b. True
d. 3:1 Progeny with red eyes: progeny with white eyes, with all the females having red eyes and
half the males having red eyes and half the males having white eyes - correct answer ✔✔What
is the expected proportion of progeny from this cross?
Select one:
a. 3:1 Progeny with red eyes : progeny with white eyes, with all the males having red eyes and
half the females having red eyes and half the females having white eyes.
b. All the females have red eyes and all the males have white eyes
c. All progeny have red eyes
d. 3:1 Progeny with red eyes: progeny with white eyes, with all the females having red eyes and
half the males having red eyes and half the males having white eyes
e. All the males have red eyes and all the females have white eyes
,f. All the progeny have white eyes
a. False - correct answer ✔✔For a recessive X-linked trait, the mutation and trait pass from
father to half his sons.
Select one:
a. False
b. True
c. Linkage between two genes - correct answer ✔✔The set of crosses shown below provided
the first evidence for what?
Select one:
a. That the Y chromosome contains some genes
b. That some insect genes are dominant and that others are recessive
c. Linkage between two genes
d. A and B
e. All of the above
a. True - correct answer ✔✔Mitotic recombination can result in daughter cells that have
different genetypes and phenotypes than the parent cell.
Select one:
a. True
b. False
a. True - correct answer ✔✔Loss of heterozygosity as a result of mitotic recombination can
contribute to an increased risk of cancer.
Select one:
a. True
, b. False
a. True - correct answer ✔✔Recombination contributes to the proper formation of mitotic
spindles in meiosis I.
Select one:
a. True
b. False
b. True - correct answer ✔✔Double strand break repair of DNA and recombination are thought
to be evolutionarily related.
Select one:
a. False
b. True
b. False - correct answer ✔✔Budding yeast has ordered tetrads.
Select one:
a. True
b. False
b. False - correct answer ✔✔As described in lecture, the test for linkage between two genes in
yeast uses the same type of testcross as the test for linkage between two gene in Drosophila.
Select one:
a. True
b. False
a. PD - correct answer ✔✔A haploid yeast pyr1 thi3 auxotrophic mutant (requires pyridoxine
and thiamin in media to grow) is crossed to a haploid wild-type PYR1 THI3 yeast strain and the
answers graded A+
a. Frequency of recombination - correct answer ✔✔Which of the following was described in
lecture as a metric of genetic distance?
Select one:
a. Frequency of recombination
b. Banding pattern of chromosomes
c. A laser ruler
d. PCR using a pair of primers that are on the "outside" of the two linked genes
e. All of the above
c. x+ z+ y+ - correct answer ✔✔You carry out a three point cross in Drosphila involving the three
linked genes x+ y+ and z+. Your parental flies are x+x+ y+y+ z+z+ and xx yy zz. You perform a test
cross on many F1s and infer that the number and genotype of gametes formed by the F1 flies
were:
1008 x+ y+ z+
202 x y+ z+
98 x+ y z+
1012 xyz
5 x+ y+ z
223 x+yz
103 xy+z
8 x y z+
Which of the following is consistent with the order of these genes on the genetic map?
,Select one:
a. z+ x+ y+
b. x+ y+ z+
c. x+ z+ y+
b. True - correct answer ✔✔Genes that are on the same chromosome and are greater than 50
cM apart behave as if they are unlinked.
Select one:
a. False
b. True
b. True - correct answer ✔✔Genes that are on the same chromosome and are greater than 50
cM apart are part of the same linkage group.
Select one:
a. False
b. True
d. 3:1 Progeny with red eyes: progeny with white eyes, with all the females having red eyes and
half the males having red eyes and half the males having white eyes - correct answer ✔✔What
is the expected proportion of progeny from this cross?
Select one:
a. 3:1 Progeny with red eyes : progeny with white eyes, with all the males having red eyes and
half the females having red eyes and half the females having white eyes.
b. All the females have red eyes and all the males have white eyes
c. All progeny have red eyes
d. 3:1 Progeny with red eyes: progeny with white eyes, with all the females having red eyes and
half the males having red eyes and half the males having white eyes
e. All the males have red eyes and all the females have white eyes
,f. All the progeny have white eyes
a. False - correct answer ✔✔For a recessive X-linked trait, the mutation and trait pass from
father to half his sons.
Select one:
a. False
b. True
c. Linkage between two genes - correct answer ✔✔The set of crosses shown below provided
the first evidence for what?
Select one:
a. That the Y chromosome contains some genes
b. That some insect genes are dominant and that others are recessive
c. Linkage between two genes
d. A and B
e. All of the above
a. True - correct answer ✔✔Mitotic recombination can result in daughter cells that have
different genetypes and phenotypes than the parent cell.
Select one:
a. True
b. False
a. True - correct answer ✔✔Loss of heterozygosity as a result of mitotic recombination can
contribute to an increased risk of cancer.
Select one:
a. True
, b. False
a. True - correct answer ✔✔Recombination contributes to the proper formation of mitotic
spindles in meiosis I.
Select one:
a. True
b. False
b. True - correct answer ✔✔Double strand break repair of DNA and recombination are thought
to be evolutionarily related.
Select one:
a. False
b. True
b. False - correct answer ✔✔Budding yeast has ordered tetrads.
Select one:
a. True
b. False
b. False - correct answer ✔✔As described in lecture, the test for linkage between two genes in
yeast uses the same type of testcross as the test for linkage between two gene in Drosophila.
Select one:
a. True
b. False
a. PD - correct answer ✔✔A haploid yeast pyr1 thi3 auxotrophic mutant (requires pyridoxine
and thiamin in media to grow) is crossed to a haploid wild-type PYR1 THI3 yeast strain and the
