Exam
Name___________________________________
MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question.
1)
Huntington’s disease involves ________.
1)
A)
the presence of an extra chromosome
B)
hyposecretion of thyroxine
C)
degeneration of the basal nuclei of the brain
D)
hypersecretion of growth hormone
Figure 29.1
2)
Given the information in Figure 29.1, what is the phenotype ratio (assuming C is dominant and
there is no incomplete dominance)?
2)
A)
1:2:1
B)
1:3
C)
4:0
D)
1:1:1:1
3)
Two alleles expressing exactly the same information for a trait are designated as ________.
3)
A)
homozygous
B)
hemizygous
C)
heterozygous
D)
monogamous
4)
Which of the following statements is true concerning genetic screening?
4)
A)
Screening is illegal in over half of the world.
B)
Screening can be done before conception by carrier recognition or during fetal testing.
C)
Screening can be done only in the first trimester of pregnancy.
D)
Genetic screening is rarely done because it yields very little accurate information.
5)
Sex chromosomes of a normal male are ________.
5)
A)
YY
B)
XY
C)
XX
D)
any of these, depending on the father
B
6)
An individual who is heterozygous for a particular trait, yet expresses both alleles of that trait, is an
example of ________.
6)
A)
incomplete dominance
B)
dominance
C)
sex–linked inheritance
D)
recessive inheritance
A
7)
Recessive genes are usually expressed in humans only when ________.
7)
A)
they are coding for genetic diseases
B)
they are coding for skin color
C)
both alleles are exactly the same, or homozygous
D)
the organism is in the embryonic stage
C
B
8)
A female infant is born with several hundred oocytes, each one genetically unique. This is due to
________.
8)
A)
chromosome deletion
B)
independent assortment and random crossover
C)
recessive inheritance
D)
mutation
Figure 29.1
9)
Given the information in Figure 29.1, what would be the genotype of the offspring designated by
the blank square?
9)
A)
Gg
B)
gg
C)
Dg
D)
GG
10)
In meiosis the spermatozoa that are produced are genetically unlike each other and unlike the cell
that produces them. This is one reason for the great variation among humans. What causes this
effect?
10)
A)
chromosome segregation and independent assortment only
B)
crossing–over, chromosome segregation, and independent assortment
C)
crossing–over and independent assortment only
D)
crossing–over and chromosome segregation only
11)
The main way a recessive allele would be expressed even when only one copy is present would be
________.
11)
A)
recessive inheritance
B)
incomplete dominance
C)
sex–linked inheritance
D)
dominance
12)
________ is the most common type of fetal testing.
12)
A)
Amniocentesis
B)
CVS
C)
Blood chemistry
D)
A DNA probe
A
13)
Dominant alleles are so called because under most circumstances they ________.
13)
A)
code for most phenotypic and genotypic expressions of a trait
B)
code for genes that are never considered lethal
C)
suppress the expression of other alleles
D)
code for desired traits only
C
Figure 29.1
14)
Given the information in Figure 29.1, what would the genotype ratio be for the offspring?
14)
A)
4:0
B)
1:2:1
C)
1:1:1:1
D)
1:3
B
C
15)
Which of the following is true concerning environmental influence on genetic expression?
15)
A)
Drugs and nutrition can alter normal gene expression.
B)
The only time a gene can be influenced by environmental factors is in the second trimester of
pregnancy.
C)
Environmental factors determine the way in which 90 percent of our genes are expressed.
D)
It is impossible to alter in any way the expression of a gene in humans.
Figure 29.1
16)
Given the information in Figure 29.1, if C were an incomplete dominant trait, what would the
phenotype ratio be for the offspring?
16)
A)
1:3
B)
1:1:1:1
C)
1:2:1
D)
4:0
C
17)
Gene mutations in the sex chromosomes of the human would tend to become visibly expressed
________.
17)
A)
equally frequently in both sexes
B)
more frequently in males
C)
in neither males or females
D)
more frequently in females
B
18)
The gene responsible for the condition known as sickle–cell anemia demonstrates ________.
18)
A)
a recessive genetic disorder
B)
a sex–linked genetic disorder
C)
incomplete dominance
D)
a dominant genetic disorder
C
A
19)
Amy’s hand was exposed to X rays. A gene in a skin cell of her hand mutated. This mutant gene
will ________.
19)
A)
definitely cause skin cancer
B)
not form an exact duplicate of itself when the cell divides
C)
replicate itself when the cell divides but will not be passed on to Amy‘s offspring
D)
replicate itself and be passed on to Amy’s children
20)
Those characteristics that can be determined on superficial inspection of an individual are known
as ________.
20)
A)
genotypic
B)
polyspermic
C)
phenotypic
D)
polygenic
21)
Is genetic diversity due entirely to inherited genes on the sex chromosomes?
21)
A)
Yes, because the female has two X chromosomes and the male has only one X chromosome.
B)
Yes, because genetic diversity is due to the Y influence on the autosomes.
C)
Yes, because the male has a Y chromosome.
D)
No, because genetic diversity has nothing to do with the sex chromosomes but is due to
crossing–over of chromosomes, independent assortment of chromosomes, and segregation of
chromosomes.
22)
For which of the following are newborn infants not routinely screened at birth?
22)
A)
imperforate anus
B)
PKU
C)
congenital hip dysplasia
D)
color blindness
23)
The reason recessive genetic disorders are more frequent than disorders inherited as dominant is
that ________.
23)
A)
recessive genetic disorders are limited to persons of the same ethnicity
B)
people carrying dominant genetic disorders always die before birth
C)
dominant genetic disorders are never expressed in males
D)
carriers are not eliminated by the disease before passing the defective alleles on to their
offspring
24)
A chromosomal aberration in which part of a chromosome is lost is known as ________.
24)
A)
inversion
B)
crossing–over
C)
translocation
D)
deletion
25)
A woman has blond hair and brown eyes. This statement is best described as indicating ________.
25)
A)
phenotype
B)
allelic pairs
C)
recessive traits
D)
genotype
26)
A couple whose blood types are A (IAi) and B (IBi) may have a child with which of the following
blood types?
26)
A)
AB only
B)
A or B only
C)
AB or O only
D)
A, B, AB, or O
27)
An example of multiple–allele inheritance is ________.
27)
A)
hair that seems to have several shades of a color
B)
the ABO blood group
C)
the appearance of birthmarks on the skin
D)
the appearance of freckles on the skin
28)
Inheritance of stature (height) in humans is probably due to ________.
28)
A)
incomplete dominance
B)
polygene inheritance
C)
polyploidy
D)
polymorphism
SHORT ANSWER. Write the word or phrase that best completes each statement or answers the question.
29)
Define phenocopy.
29)
30)
Two tall red pea plants, when crossed, produced some offspring that were white and
dwarf. Assuming that tallness and redness are dominant, what are the genotypes of the
parents?
30)
31)
What were the genotypes of the parental (P1) individuals?
31)
32)
The ABO blood type is a good example of a(n) ________ inheritance.
32)
33)
The second–generation phenotypes would follow what ratio? (Pair the number with a
phenotype in each case.)
33)
34)
When might amniocentesis be appropriate?
34)
35)
The X and Y chromosomes are considered the ________ chromosomes.
35)
Figure 29.2
Use Figure 29.2 to answer the following:
36)
Are there any male carriers?
36)
37)
An allele that completely masks the expression of the other alleles is called ________.
37)
38)
Color blindness is a(n) ________ trait.
38)
39)
The second–generation types would have what phenotypes?
39)
40)
What possible genotype(s) could the second–generation, fuzzy–longhaired individuals
possess?
40)
Figure 29.2
Use Figure 29.2 to answer the following:
41)
Is the trait sex–linked?
41)
42)
Identify, by numbers, any known carriers.
42)
43)
Albinism is a good example of a(n) ________ trait.
43)
44)
What would be the gametes of the first–generation individuals?
44)
45)
Define karyotype.
45)
46)
________ disease is a disorder of brain lipid metabolism and is an example of a recessive
trait.
46)
47)
The 23rd pair of human chromosomes are called ________ chromosomes.
47)
48)
Observable characteristics expressed by the genes for a trait are called the ________.
48)
Figure 29.2
Use Figure 29.2 to answer the following:
49)
Is the trait dominant or recessive?
49)
50)
Removing a sample of the fluid surrounding the fetus for the purpose of studying the
chromosomes is a procedure called ________.
50)
51)
What is (are) the genotype(s) of the first–generation offspring?
51)
52)
How might carriers of deleterious genes be recognized?
52)
53)
What would the parental gametes be from a cross of two second–generation,
straight–shorthaired individuals?
53)