Biology (Raven), 10th Edition

Chapter 13: Chromosomes, Mapping, and the Meiosis–Inheritance Connection

Post-Test

1
In fruit flies, eye color is X-linked: Xw = red eye, Xw = white eye. If a white-eyed female is mated to a red-eyed male, the male offspring will
A)have red eyes.
B)have white eyes.
C)be one-half red-eyed and one-half white-eyed.
D)be three-fourths red-eyed and one-fourth white-eyed.
E)be one-forth red-eyed and three-forth white-eyed.
2
If a woman is a carrier for the color-blind allele and her husband is perfectly normal, what are their chances of having a color-blind son?
A)None, because the father is perfectly normal.
B)50%, because the mother is a carrier.
C)100%, because the mother has the gene.
D)25%, because the mother is a hybrid.
E)More information is needed to determine the chances.
3
What determines the sex of a human?
A)Presence or absence of an X chromosome
B)Presence or absence of a Y chromosome
C)Presence of two X chromosomes
D)Absence of a Y chromosome
E)Environmental conditions
4
What phenotypes would you expect to see in a cross between a white-eyed female and red-eyed male Drosophila melanogaster? This trait is X-linked.
A)All males and females red-eyed
B)All males and females white-eyed
C)Females all red; males all white
D)Females 3:1 red: white; males 1:1 red: white
E)Females 1:1 red: white; males 3:1 red: white
5
In most mammals dosage compensation is achieved by random inactivation of one of the X chromosomes in the somatic cells of females. However, in the marsupials (kangaroos, etc.) activation is non-random, and it is the X chromosome that is inherited from the father (the paternal X) that is preferentially inactivated in all somatic cells of females. What are the consequences of this for X-linked traits in marsupials?
A)Both male and female heterozygotes will be somatic mosaics.
B)Heterozygous females will not be somatic mosaics but will show one phenotype or the other.
C)Heterozygous females will not occur.
D)Their individual cells may express different alleles, depending on which chromosome is inactivated.
E)None of the above.
6
The maximum recombination frequency that can ever occur is:
A)25%
B)50%
C)75%
D)100%
E)None of the above
7
Which of the following statement(s) is true about the sickle-cell allele?
A)It occurs in some parts of the world at much higher frequencies than can be due to mutation alone.
B)It is caused by mutations in multiple genes.
C)It confers some resistance to malaria in the heterozygous state.
D)Both 1 and 2
E)Both 1 and 3
8
Which statement(s) is/are true about X-linked inheritance in Drosophila?
A)X-linked traits are only shown in males.
B)A male inherits his X chromosome from his mother.
C)A male inherits his X chromosome from his father.
D)There are many genes carried on the Y chromosome.
E)Both 1 and 2
9
Mitochondrial genes are inherited only from the female parent because:
A)after fertilization the mitochondria from the male parent are eliminated.
B)of dosage compensation.
C)males don't have mitochondria.
D)mitochondria come from the egg, not from the sperm.
E)mitochondrial genes are inherited equally from both parents.
10
Nondisjunction can occur in meiosis I (Primary Nondisjunction) if the homologs do not separate, or in meiosis II (Secondary Nondisjunction) if the sister chromatids do not separate. What chromosome compositions could occur in the offspring from a couple where there was normal gamete formation in the female but nondisjunction of the Y chromosome in the male?
A)XX, XO, XY, YY
B)XX, XY, XXX, XYY
C)XX, XYY, XO
D)XX, XYY, XY, XO
E)XO, XYY
11
What conclusion(s) is/are suggested if a normal and a mutant fly are crossed and the only mutant progeny observed are male?
A)Mutation is located on the X chromosome.
B)Mutation is located on the Y chromosome.
C)Mutation is lethal to females.
D)Mutation is lethal to males.
E)Both 1 and 3 are possible explanations.
12
On which of the sex chromosomes is a sex-linked gene usually carried?
A)13
B)15
C)18
D)Y
E)X
13
Morgan discovered that the white eye mutation in fruit flies is:
A)autosomal.
B)lethal in females.
C)sex-linked.
D)on the Y chromosome.
E)dominant.
14
What molecular structure is responsible for the mosaic coloring of calico cats?
A)Y chromosome
B)Barr body
C)Nuclear envelope
D)Cell membrane
E)Mitochondria
15
In humans, non-sex chromosomes are called
A)somatic.
B)polymorphic.
C)non-sex.
D)retrograde.
E)autosomal.
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