Chapter 4—How Genes are Transmitted from Generation to Generation
MULTIPLE CHOICE
1. Sickle-cell is
a.
found commonly in people whose ancestors originate from parts of North America.
b.
inherited as a dominant disorder.
c.
caused by abnormal hemoglobin molecules.
d.
not associated with any known health problems.
e.
more common in males than females.
2. A phenotype is
a.
the physical appearance of an organism.
b.
the genetic make-up of an organism.
c.
determined by the presence or absence of recessive alleles.
d.
a genetic disorder.
e.
a dominant allele.
3. A genotype is
a.
the genetic make-up of an organism.
b.
how an organism appears physically.
c.
based on the interaction of recessive alleles only.
d.
caused by genetic mutation.
e.
a genetic disorder.
4. A recessive allele is
a.
an allele that expresses its phenotypic effect even when it is present with a dominant
allele.
b.
an allele whose presence can be hidden.
c.
only present in males.
d.
only present in females.
e.
always present in homozygous individuals.
5. A dominant allele is
a.
an allele that expresses its phenotypic effect even when it is present with a recessive allele.
b.
an allele whose presence can be hidden.
c.
only present in males.
d.
only present in females.
e.
always present in homozygous individuals.
6. Which of the following statements is true concerning a homozygote?
a.
Both alleles for a trait are the same in this individual.
b.
There is only one copy of a gene for a particular trait.
c.
Males are more likely to be homozygous than females.
d.
Two different alleles for a trait are present in a homozygote.
e.
Homozygotes and heterozygotes will always show the same phenotype.
7. Mendel’s law of segregation states that
a.
the two copies of a gene separate from each other during meiosis.
b.
members of a gene pair segregate into gametes independently of other gene pairs.
c.
genes pair with each other.
d.
two copies of each gene will wind up in each gamete.
e.
meiosis produces gametes.
8. Mendel’s law of independent assortment states that
a.
homologous chromosomes are independent and don’t pair up.
b.
genes do not sort independently during meiosis.
c.
each pair of alleles segregates independently of other pairs of alleles during meiosis.
d.
gametes will only contain combinations of genes that match the combinations from one of
the parents.
e.
gametes will contain only one copy of each gene after meiosis.
9. Genetic counselors typically construct pedigrees
a.
whenever a baby is born with a genetic birth defect.
b.
to use evidence in criminal trials.
c.
when an individual requests genetic counseling.
d.
only for families with members who have cystic fibrosis.
e.
for every individual they counsel.
10. Huntington disease (HD)
a.
is never lethal.
b.
is inherited in a dominant manner.
c.
affects people between the ages of 10 and 20 years.
d.
is not inherited.
e.
involves a very rapid progression of the disease.
11. A trait
a.
is a characteristic that a parent passes onto his/her offspring.
b.
cannot be passed from mother to daughter.
c.
only comes in one form.
d.
is only expressed when the individual is homozygous.
e.
is only expressed when the individual is heterozygous.
12. Huntington disease is caused by
a.
the absence of a gene.
b.
a gene found on the X chromosome.
c.
two copies of a recessive allele.
d.
the accumulation of a defective protein.
e.
several defective genes.
13. Which of the following properties is characteristic of an autosomal recessive pattern of inheritance?
a.
Every affected individual will have at least one affected parent.
b.
More males than females will be affected.
c.
Male and female children are affected in roughly equal numbers.
d.
More females than males will be affected.
e.
Individuals who inherit one copy of the disease allele will be affected.
14. Which is of the following statements is true about sex-linked traits?
a.
Females are hemizygous for any gene on the Y chromosome.
b.
X-linked recessive genes are always expressed when present in females.
c.
In general, females are affected by X-linked recessive disorders far more frequently than
males.
d.
Fathers do not donate their X chromosome to their sons.
e.
If the mother is heterozygous for an X-linked recessive allele, all of her sons will be
affected.
15. Which of the following is true about the genetic disease cystic fibrosis (CF)?
a.
CF demonstrates autosomal recessive inheritance.
b.
CF increases the risk of skin cancer.
c.
CF patients produce abnormal blood cells.
d.
CF causes excessive accumulation of phenylalanine in the blood.
e.
CF causes improper metabolism in nerve cells.
16. Which of the following is true about the genetic disease familial hypercholesterolemia (FH)?
a.
FH is a condition characterized by very high levels of cholesterol in the blood.
b.
FH is inherited as an autosomal recessive trait.
c.
FH is a form of dwarfism.
d.
FH results from the accumulation of a protein called huntingtin.
e.
FH is inherited as a X-linked recessive trait.
17. Which of the following is an example of an X-linked recessive genetic trait?
a.
porphyria
b.
familial hypercholesterolemia
c.
Marfan syndrome
d.
red-green colorblindness
e.
achondroplasia
18. Which of the following is an example of an autosomal dominant genetic disorder?
a.
Duchenne muscular dystrophy
b.
Lesch-Nyhan syndrome
c.
hemophilia A
d.
porphyria
e.
sickle-cell anemia
19. Which of the following is an example of an autosomal recessive genetic disorder?
a.
hemophilia A
b.
Duchenne muscular dystrophy
c.
Marfan syndrome
d.
brachydactyly
e.
cystic fibrosis (CF)
20. What is the distinctive pattern of inheritance found for X-linked recessive traits?
a.
Only males are affected.
b.
Affected males have an affected father.
c.
Hemizygous males and homozygous females are affected.
d.
Only females are affected.
e.
Affected individuals will always have an affected parent and an unaffected parent.
21. Which of the following is true about the genetic disease Duchenne muscular dystrophy (DMD)?
a.
DMD affects females at a higher frequency than males.
b.
DMD is inherited in an autosomal dominant manner.
c.
DMD results from a gene located on the Y chromosome.
d.
DMD is inherited as a sex-linked trait.
e.
There are three forms of X-linked muscular dystrophy.
22. Which of the following is true about Huntington disease?
a.
Symptoms typically appear between the ages of 10 and 20 years.
b.
Individuals have a 25% chance of inheriting the condition from an affected parent.
c.
Many individuals have already had children before developing the disorder.
d.
Most affected individuals are homozygous for the gene (HH).
e.
Once symptoms appear, the disease progresses very rapidly.
23. Which of the following is true about hemophilia A?
a.
Today recombinant DNA technology is used to make clotting factors free from
contamination of viruses to treat hemophilia patients.
b.
Hemophilia A is less common than hemophilia B.
c.
More females have hemophilia A than males.
d.
Hemophilia A is associated with a lack of clotting-factor X.
e.
Hemophilia A leads to muscle wasting.
24. Which type of genetic condition is much more common in males than females?
a.
X-linked recessive
b.
dominant autosomal
c.
recessive autosomal
d.
mutations
e.
aneuploidy
25. Hemophilia A is a(n) ____ disorder.
a.
X-linked recessive
b.
autosomal dominant
c.
autosomal recessive
d.
X-linked dominant
e.
non-genetic
26. Males donate their ____ chromosome to their daughters and their ____ chromosome to their sons.
a.
X, X
b.
X, Y
c.
X, O
d.
O, O
e.
Y, Y
27. In hemophilia A, clotting factor ____ is either absent or present in reduced amounts.
a.
V
b.
VI
c.
VIII
d.
IV
e.
X
28. In X-linked disorders, daughters of affected males are
a.
usually carriers.
b.
always homozygous.
c.
mutant.
d.
always affected.
e.
aneuploid
29. In neurofibromatosis, a(n) ____ gene produces many different types of phenotypes.
a.
mutant
b.
normal
c.
recessive
d.
X-linked
e.
Y-linked
30. What is usually true about autosomal recessive disorders?
a.
Affected parents have unaffected children.
b.
Unaffected parents can have affected children.
c.
Autosomal recessive disorders are always the result of matings between individuals who
are related to each other.
d.
All relatives of affected parents will always have affected children.
e.
None of these statements are true.
31. Mitochondrial disorders
a.
are due to inheriting defective mitochondria from both parents.
b.
are passed from father to all of his children.
c.
often affect the muscular system.
d.
are X-linked traits.
e.
are due to mutant autosomal genes.
TRUE/FALSE
1. The most serious form of muscular dystrophy is Becker muscular dystrophy.
2. If the proband is adopted, pedigrees of the adoptive parents are of little value.
3. In the case of autosomal recessive traits, male and female children are affected in roughly equal
numbers.
4. In the case of autosomal recessive traits, unaffected parents can have affected children.
5. The Y chromosome has the same genes as found on the X chromosome.
42
6. Adult-onset disorders occur shortly after birth.
7. In the case of dominant disorders, a heterozygote who carries one copy of a mutant dominant allele has
the condition.
8. Today, clotting factor VIII used to treat people with hemophilia A is made using recombinant DNA
technology.
9. Very few females have hemophilia A.
10. In the case of autosomal transmitted diseases, the numbers of affected males and females are roughly
equal.
MATCHING
Match the description to the disorder.
a.
Production of thick mucus
b.
Inability to form a clotting factor
c.
Results in muscle wasting
d.
Deformed red blood cells are destroyed faster than they can be replaced
e.
Tumors can cause paralysis or blindness
f.
Destruction of cells in parts of the brain
g.
Lack of pigmentation
1. Hemophilia A
2. Cystic fibrosis
3. Duchenne muscular dystrophy
4. Albinism
5. Neurofibromatosis
6. Sickle cell anemia
7. Huntington disease
Chapter 4 – How Genes are Transmitted from Generation to Generation
43
Match the type of inheritance to the disorder.
a.
autosomal recessive
b.
autosomal dominant
c.
X-linked recessive
8. Red-green colorblindness
9. Albinism
10. Duchenne muscular dystrophy
11. Neurofibromatosis
12. Sickle cell anemia
13. Huntington disease
14. Hemophilia A
15. Cystic fibrosis
Match the type of inheritance to the description.
a.
autosomal recessive only
b.
autosomal dominant only
c.
X-linked recessive only
d.
autosomal recessive and autosomal dominant only
e.
None of the above.
16. Affected individuals have at least one affected parent.
17. Equal frequency of males and females affected.
18. More males than females are affected.
19. More females than males are affected.
20. Affected individuals may have two unaffected parents.
21. Heterozygous individuals do not show the trait.
22. Heterozygous individuals show the trait.
Chapter 4 – How Genes are Transmitted from Generation to Generation
ESSAY
1. Achondroplasia is one form of dwarfism that is associated with abnormalities in growth. It is inherited
as a dominant trait. Consider a couple, both of whom are dwarfs due to achondroplasia. Both are
heterozygous. In fact, embryos that inherit two copies of the achondroplasia allele do not develop
properly and are spontaneously aborted. With this in mind, what are the chances that they will have a
child that does not suffer from achondroplasia? There have been cases where couples in these
circumstances have chosen to use assisted reproductive technologies to ensure that their children also
have achondroplasia. Do you feel that this is a proper use of assisted reproductive technologies?
Explain your answer.
2. Why might an insurance company or possible employer want access to an individual’s genetic
information? Do you feel that there are good reasons for an insurance company or employer to have
access? What safeguards are in place to prevent this access?
SHORT ANSWER
1. Why do males show a higher incidence of certain genetic disorders than females?
2. If an individual has Huntington disease (autosomal dominant condition) and is heterozygous, what is
the probability that an offspring will receive this detrimental allele?
3. Two individuals, each exhibiting albinism (autosomal recessive condition), are expecting a child. What
is the probability that they will have a child with albinism?
4. If a male has an X-linked recessive condition such as red-green colorblindness, is it possible for him to
pass this condition on to his sons? to his daughters? Explain your answers.