Transcript ch 14 clicker questions

CLICKER QUESTIONS
For CAMPBELL BIOLOGY, NINTH EDITION
Jane B. Reece, Lisa A. Urry, Michael L. Cain, Steven A. Wasserman, Peter V. Minorsky, Robert B. Jackson
Chapter 14
Mendel and the Gene Idea
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Questions prepared by
Janet Lanza
University of Arkansas at Little Rock
Louise Paquin
McDaniel College
© 2011 Pearson Education, Inc.
Independent Assortment
Imagine crossing a pea heterozygous at the loci for
flower color (white versus purple) and seed color
(yellow versus green) with a second pea homozygous
for flower color (white) and seed color (yellow). What
types of gametes will the first pea produce?
a) two gamete types: white/white and purple/purple
b) two gamete types: white/yellow and purple/green
c) four gamete types: white/yellow, white/green,
purple/yellow, purple/green
d) four gamete types: white/purple,
yellow/green,white/white, and purple/purple
e) one gamete type: white/purple/yellow/green
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Pea plants were particularly well suited for use
in Mendel's breeding experiments for all of the
following reasons except that
a) peas show easily observed variations in a number of
characters, such as pea shape and flower color.
b) it is possible to control matings between different pea
plants.
c) it is possible to obtain large numbers of progeny from any
given cross.
d) peas have an unusually long generation time.
e) many of the observable characters that vary in pea plants
are controlled by single genes.
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A cross between homozygous purple-flowered
and homozygous white-flowered pea plants
results in offspring with purple flowers. This
demonstrates
a) the blending model of genetics.
b) true-breeding.
c) dominance.
d) a dihybrid cross.
e) the mistakes made by Mendel.
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Imagine a genetic counselor working with a couple who
have just had a child who is suffering from Tay-Sachs
disease. Neither parent has Tay-Sachs, nor does anyone
in their families. Which of the following statements should
this counselor make to this couple?
a) “Because no one in either of your families has Tay-Sachs, you are not
likely to have another baby with Tay-Sachs. You can safely have another
child.”
b) “Because you have had one child with Tay-Sachs, you must each carry
the allele. Any child you have has a 50% chance of having the disease.”
c)
“Because you have had one child with Tay-Sachs, you must each carry
the allele. Any child you have has a 25% chance of having the disease.”
d) “Because you have had one child with Tay-Sachs, you must both carry
the allele. However, since the chance of having an affected child is 25%,
you may safely have thee more children without worrying about having
another child with Tay-Sachs.”
e) “You must both be tested to see who is a carrier of the Tay-Sachs allele.”
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Albinism in humans occurs when both alleles at a
locus produce defective enzymes in the biochemical
pathway leading to melanin. Given that heterozygotes
are normally pigmented, which of the following
statements is/are correct?
a) One normal allele produces as much melanin as two normal
alleles.
b) Each defective allele produces a little bit of melanin.
c) Two normal alleles are needed for normal melanin production.
d) The two alleles are codominant.
e) The amount of sunlight will not affect skin color of
heterozygotes.
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Imagine that the last step in a biochemical pathway to the red skin
pigment of an apple is catalyzed by enzyme X, which changes
compound C to compound D. If an effective enzyme is present,
compound D is formed and the apple skin is red. However, if the
enzyme is not effective, only compound C is present and the skin is
yellow. Thinking about enzyme action, what can you accurately say
about a heterozygote with one allele for an effective enzyme X and
one allele for an ineffective enzyme X?
a) The phenotype will probably be yellow
but cannot be red.
b) The phenotype will probably be red but
cannot be yellow.
c) The phenotype will be a yellowish red.
d) The phenotype will be either yellow or
red.
e) The phenotype will be either yellowish
red or red.
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In humans, alleles for dark hair are genetically
dominant, while alleles for light hair are
recessive. Which of the following statements
is/are most likely to be correct?
a) Dark hair alleles are more common than light hair alleles in all
areas of Europe.
b) Dark hair alleles are more common than light hair alleles in
southern Europe but not in northern Europe.
c) Dark hair alleles are equally common in all parts of Europe.
d) Dark hair is dominant to light hair in southern Europe but
recessive to light hair in northern Europe.
e) Dark hair is dominant to light hair in northern Europe but
recessive to light hair in southern Europe.
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Imagine a locus with four different alleles for
fur color in an animal. The alleles are named
Da, Db, Dc, and Dd. If you crossed two
heterozygotes, DaDb and DcDd, what genotype
proportions would you expect in the offspring?
a) 25% DaDc, 25% DaDd, 25% DbDc, 25% DbDd
b) 50% DaDb, 50% DcDd
c) 25% DaDa, 25% DbDb, 25% DcDc, 25% DdDdDcDd
d) 50% DaDc, 50% DbDd
e) 25% DaDb, 25% DcDd, 25% DcDc, 25% DdDd
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Imagine a family with two parents who both maintain
low fat levels through a combination of aerobic
activity and weight training. Which of the following
statements is/are most likely to apply to their two
children?
a) The parents’ fat levels are irrelevant to the fat levels of the
children.
b) One child is likely to have low fat levels but the other is more
likely to have high fat levels because of independent
assortment of genes.
c) The children may not have the same fat levels as their parents
because genes independently assort during meiosis.
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Envision a family in which the grandfather, age 47,
has just been diagnosed with Huntington’s
disease. His daughter, age 25, now has a 2-yearold baby boy. No one else in the family has the
disease. What is the probability that the daughter
will contract the disease?
a) 0%
b) 25%
c) 50%
d) 75%
e) 100%
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Review the family described in the previous
question. What is the probability that the baby
will contract the disease?
a) 0%
b) 25%
c) 50%
d) 75%
e) 100%
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Imagine that you are the daughter in the family
described in the previous questions. You had been
planning on having a second child. What kind of choices
would you make about genetic testing, for yourself and
for your child?
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When a disease is said to have a multifactorial
basis, it means that
a) both genetic and environmental factors contribute
to the disease.
b) it is caused by a gene with a large number of
alleles.
c) it affects a large number of people.
d) it has many different symptoms.
e) it tends to skip a generation.
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