Transcript File - jj-sct

CAMPBELL
BIOLOGY
TENTH
EDITION
Reece • Urry • Cain • Wasserman • Minorsky • Jackson
15
The Chromosomal
Basis of Inheritance
Clicker Questions by
Roberta Batorsky
© 2014 Pearson Education, Inc.
Why did the improvement of microscopy techniques in the
late 1800s set the stage for the emergence of modern
genetics?
a) It revealed new and unanticipated features of
Mendel’s pea plant varieties.
b) It allowed the study of meiosis and mitosis, revealing
parallels between behaviors of the Mendelian
concept of the gene and the movement/pairing of
chromosomes.
c) It allowed scientists to see the nucleotide sequence of
DNA.
d) It led to the discovery of mitochondria.
e) It showed genes functioning to direct the formation of
enzymes.
© 2014 Pearson Education, Inc.
Why did the improvement of microscopy techniques in the
late 1800s set the stage for the emergence of modern
genetics?
a) It revealed new and unanticipated features of
Mendel’s pea plant varieties.
b) It allowed the study of meiosis and mitosis, revealing
parallels between behaviors of the Mendelian
concept of the gene and the movement/pairing of
chromosomes.
c) It allowed scientists to see the nucleotide sequence of
DNA.
d) It led to the discovery of mitochondria.
e) It showed genes functioning to direct the formation of
enzymes.
© 2014 Pearson Education, Inc.
Morgan and his colleagues worked out a set of symbols
to represent fly genotypes. Which of the following is
representative?
a) AaBb  AaBb
b) 46 or 46w
c) w or w on X
d) 2  3
© 2014 Pearson Education, Inc.
Morgan and his colleagues worked out a set of symbols
to represent fly genotypes. Which of the following is
representative?
a) AaBb  AaBb
b) 46 or 46w
c) w or w on X
d) 2  3
© 2014 Pearson Education, Inc.
Imagine that Morgan had used a grasshopper
(2n  24, and sex is determined as follows: male has X,
and female has XX) to study sex linkage. Predict where
the first mutant would have been discovered.
a) on the O chromosome of a male
b) on the X chromosome of a male
c) on the X chromosome of a female
d) on the Y chromosome of a male
© 2014 Pearson Education, Inc.
Imagine that Morgan had used a grasshopper
(2n  24, and sex is determined as follows: male has X,
and female has XX) to study sex linkage. Predict where
the first mutant would have been discovered.
a) on the O chromosome of a male
b) on the X chromosome of a male
c) on the X chromosome of a female
d) on the Y chromosome of a male
© 2014 Pearson Education, Inc.
Think about bees, which have no X and Y sex chromosomes. Males
are haploid, whereas fertilization results in females, as diploid cells
become females. Which of the following are accurate statements
about bee males when they are compared to species in which males
are XY and diploid for the autosomes?
a)
Bee males have half the DNA of bee females, whereas human
males have nearly the same amount of DNA as human
females.
b)
Considered across the genome, harmful (deleterious)
recessives will negatively affect bee males more than
Drosophila males.
c)
Human and Drosophila males have sons, but bee males
do not.
d)
Inheritance in bees is like inheritance of sex-linked characteristics
in humans.
e)
none of the above
© 2014 Pearson Education, Inc.
Think about bees, which have no X and Y sex chromosomes. Males
are haploid, whereas fertilization results in females, as diploid cells
become females. Which of the following are accurate statements
about bee males when they are compared to species in which males
are XY and diploid for the autosomes?
a)
Bee males have half the DNA of bee females, whereas human
males have nearly the same amount of DNA as human
females.
b)
Considered across the genome, harmful (deleterious)
recessives will negatively affect bee males more than
Drosophila males.
c)
Human and Drosophila males have sons, but bee males
do not.
d)
Inheritance in bees is like inheritance of sex-linked characteristics
in humans.
e)
none of the above
© 2014 Pearson Education, Inc.
Determination of sex in Drosophila is similar to that in humans. In
some species of Drosophila, there are genes on the Y chromosome
that do not occur on the X chromosome. Imagine that a mutation of
one gene on the Y chromosome reduces the size by half of individuals
with the mutation. Which of the following statements is accurate with
regard to this situation?
a) This mutation occurs in all offspring of a male with the
mutation.
b) This mutation occurs in all male but no female offspring
of a male with the mutation.
c) This mutation occurs in all offspring of a female with the
mutation.
d) This mutation occurs in all male but no female offspring
of a female with the mutation.
e) This mutation occurs in all offspring of both males and females
with the mutation.
© 2014 Pearson Education, Inc.
Determination of sex in Drosophila is similar to that in humans. In
some species of Drosophila, there are genes on the Y chromosome
that do not occur on the X chromosome. Imagine that a mutation of
one gene on the Y chromosome reduces the size by half of individuals
with the mutation. Which of the following statements is accurate with
regard to this situation?
a) This mutation occurs in all offspring of a male with the
mutation.
b) This mutation occurs in all male but no female offspring
of a male with the mutation.
c) This mutation occurs in all offspring of a female with the
mutation.
d) This mutation occurs in all male but no female offspring
of a female with the mutation.
e) This mutation occurs in all offspring of both males and females
with the mutation.
© 2014 Pearson Education, Inc.
In cats, a sex-linked gene affects coat color. The O allele produces an
enzyme that converts eumelanin, a black or brown pigment, into
phaeomelanin, an orange pigment. The o allele is recessive to O and
produces a defective enzyme, one that does not convert eumelanin into
phaeomelanin. Which of the following statements is/are accurate?
a)
The phenotype of o-Y males is black/brown because the nonfunctional
allele o does not convert eumelanin into phaeomelanin.
b)
The phenotype of OO and Oo males is orange because the functional allele
O converts eumelanin into phaeomelanin.
c)
The phenotype of Oo males is mixed orange and black/brown because the
functional allele O converts eumelanin into phaeomelanin in some cell
groups (orange) and because in other cell groups the nonfunctional allele o
does not convert eumelanin into phaeomelanin.
d)
The phenotype of O-Y males is orange because the nonfunctional allele O
does not convert eumelanin into phaeomelanin, while the phenotype of o-Y
males is black/brown because the functional allele o converts eumelanin into
phaeomelanin.
© 2014 Pearson Education, Inc.
In cats, a sex-linked gene affects coat color. The O allele produces an
enzyme that converts eumelanin, a black or brown pigment, into
phaeomelanin, an orange pigment. The o allele is recessive to O and
produces a defective enzyme, one that does not convert eumelanin into
phaeomelanin. Which of the following statements is/are accurate?
a)
The phenotype of o-Y males is black/brown because the nonfunctional
allele o does not convert eumelanin into phaeomelanin.
b)
The phenotype of OO and Oo males is orange because the functional allele
O converts eumelanin into phaeomelanin.
c)
The phenotype of Oo males is mixed orange and black/brown because the
functional allele O converts eumelanin into phaeomelanin in some cell
groups (orange) and because in other cell groups the nonfunctional allele o
does not convert eumelanin into phaeomelanin.
d)
The phenotype of O-Y males is orange because the nonfunctional allele O
does not convert eumelanin into phaeomelanin, while the phenotype of o-Y
males is black/brown because the functional allele o converts eumelanin into
phaeomelanin.
© 2014 Pearson Education, Inc.
Imagine two species of cats that differ in the timing of Barr body
formation during development. Both species have genes that
determine coat color, O for the dominant orange fur and o for the
recessive black/brown fur, on the X chromosome. In species A,
the Barr body forms during week 1 of a 6-month pregnancy,
whereas in species B, the Barr body forms during week 3 of a 5month pregnancy. What would you predict about the coloration
of heterozygous females (Oo) in the two species?
a) Both species will have similar sized patches of orange
and black/brown fur.
b) Species A will have smaller patches of orange or
black/brown fur than will species B.
c) The females of both species will show the dominant fur
color, orange.
© 2014 Pearson Education, Inc.
Imagine two species of cats that differ in the timing of Barr body
formation during development. Both species have genes that
determine coat color, O for the dominant orange fur and o for the
recessive black/brown fur, on the X chromosome. In species A,
the Barr body forms during week 1 of a 6-month pregnancy,
whereas in species B, the Barr body forms during week 3 of a 5month pregnancy. What would you predict about the coloration
of heterozygous females (Oo) in the two species?
a) Both species will have similar sized patches of orange
and black/brown fur.
b) Species A will have smaller patches of orange or
black/brown fur than will species B.
c) The females of both species will show the dominant fur
color, orange.
© 2014 Pearson Education, Inc.
Imagine a species with three loci thought to be on the same
chromosome. The recombination rate between locus A and
locus B is 35%, and the recombination rate between locus B and
locus C is 33%. Predict the recombination rate between A and C.
a) The recombination rate between locus A and locus C is either
2% or 68%.
b) The recombination rate between locus A and locus C is
probably 2%.
c) The recombination rate between locus A and locus C is
either 2% or 50%.
d) The recombination rate between locus A and locus C is
either 2% or 39%.
e) The recombination rate between locus A and locus C
cannot be predicted.
© 2014 Pearson Education, Inc.
Imagine a species with three loci thought to be on the same
chromosome. The recombination rate between locus A and
locus B is 35%, and the recombination rate between locus B and
locus C is 33%. Predict the recombination rate between A and C.
a) The recombination rate between locus A and locus C is either
2% or 68%.
b) The recombination rate between locus A and locus C is
probably 2%.
c) The recombination rate between locus A and locus C is
either 2% or 50%.
d) The recombination rate between locus A and locus C is
either 2% or 39%.
e) The recombination rate between locus A and locus C
cannot be predicted.
© 2014 Pearson Education, Inc.
Triploid species are usually sterile (unable to reproduce),
whereas tetraploids are often fertile. Which of the following
is likely a good explanation of these facts? (Hint: Synapsis.)
a) In mitosis, some chromosomes in triploids have no
partner at synapsis, but chromosomes in tetraploids
do have partners.
b) In meiosis, some chromosomes in triploids have no
partner at synapsis, but chromosomes in tetraploids
do have partners.
c) In mitosis, some chromosomes in tetraploids have no
partner at synapsis, but chromosomes in triploids do
have partners.
d) In meiosis, some chromosomes in tetraploids have no
partner at synapsis, but chromosomes in triploids do
have partners.
© 2014 Pearson Education, Inc.
Triploid species are usually sterile (unable to reproduce),
whereas tetraploids are often fertile. Which of the following
is likely a good explanation of these facts? (Hint: Synapsis.)
a) In mitosis, some chromosomes in triploids have no
partner at synapsis, but chromosomes in tetraploids
do have partners.
b) In meiosis, some chromosomes in triploids have no
partner at synapsis, but chromosomes in tetraploids
do have partners.
c) In mitosis, some chromosomes in tetraploids have no
partner at synapsis, but chromosomes in triploids do
have partners.
d) In meiosis, some chromosomes in tetraploids have no
partner at synapsis, but chromosomes in triploids do
have partners.
© 2014 Pearson Education, Inc.
Chromosomal rearrangements can occur after
chromosomes break. Which of the following statements is
most accurate with respect to alterations in chromosome
structure?
a) Chromosomal rearrangements are more likely to occur
in mammals than in other vertebrates.
b) Translocations and inversions are not deleterious
because no genes are lost in the organism.
c) Chromosomal rearrangements are more likely to occur
during mitosis than during meiosis.
d) An individual that is homozygous for a deletion of a
certain gene is likely to be more damaged than one
that is homozygous for a duplication of that same
gene because loss of a function can be lethal.
© 2014 Pearson Education, Inc.
Chromosomal rearrangements can occur after
chromosomes break. Which of the following statements is
most accurate with respect to alterations in chromosome
structure?
a) Chromosomal rearrangements are more likely to occur
in mammals than in other vertebrates.
b) Translocations and inversions are not deleterious
because no genes are lost in the organism.
c) Chromosomal rearrangements are more likely to occur
during mitosis than during meiosis.
d) An individual that is homozygous for a deletion of a
certain gene is likely to be more damaged than one
that is homozygous for a duplication of that same
gene because loss of a function can be lethal.
© 2014 Pearson Education, Inc.
Which of the following statements about crossing over
is false?
a) It accounts for the recombination of linked genes.
b) It occurs while replicated homologus are paired
during prophase I of meiosis.
c) Portions of sister chromatids change places.
d) It breaks the physical connection between specific
alleles on the same chromosome.
e) Recombinants may result.
© 2014 Pearson Education, Inc.
Which of the following statements about crossing over
is false?
a) It accounts for the recombination of linked genes.
b) It occurs while replicated homologus are paired
during prophase I of meiosis.
c) Portions of sister chromatids change places.
d) It breaks the physical connection between specific
alleles on the same chromosome.
e) Recombinants may result.
© 2014 Pearson Education, Inc.
Which of the following is a type of chromosomal
alteration that differ from all of the others?
a) aneuploidy
b) polyploidy
c) triploidy
d) tetraploidy
e) octaploidy
© 2014 Pearson Education, Inc.
Which of the following is a type of chromosomal
alteration that differs from all of the others?
a) aneuploidy
b) polyploidy
c) triploidy
d) tetraploidy
e) octaploidy
© 2014 Pearson Education, Inc.