Download Unit IIA Practice Exam (KEY) Unit_IIA_Exam_2.0_Key

Unit IIA Exam (v. 2.0: Practice Key)
1. Duchenne’s muscular dystrophy is inherited as a sex-linked recessive allele. From whom does a
male with this disease inherit the defective allele? (PT1-15)
a. Only his mother
b. Only his father
c. The mother or the father, but not both
d. Both the mother and the father
e. It is impossible to determine with certainty using only the given information
2. Hemophilia is inherited as a sex-linked recessive trait. A woman without hemophilia has a
hemophiliac father. If she marries a man without hemophilia, what is the probability that their
child will be a boy with hemophilia? (PT1-19)
a. 0%
b. 25%
c. 50%
d. 75%
e. 100%
3. A man and a woman have blood types A and B, respectively. Both have one parent with O blood
type. What is the probability that the man and woman have a child with O blood type? (PT1-54)
a. 0%
b. 25%
c. 50%
d. 75%
e. 100%
4. Four genes, A, B, C, and D, occur on the same chromosome. Use the following crossover frequencies
to determine the order of the genes on the
chromosome. (PT1-74)
a. BCAD
b. CBDA
c. BACD
d. CDAB
e. CBAD
The next two questions refer to the following pedigree. Filled boxes or filled circles indicate
the inheritance of a biochemical disorder.
5. The disorder illustrated in the pedigree is probably
inherited as _____. (PT1-79)
a. An autosomal dominant allele
b. An autosomal recessive allele
c. An X-linked dominant allele
d. An X-linked recessive allele
e. A Y-linked dominant allele
6. The best explanation for the inheritance of the disorder in
individual F is that she received _____. (PT1-80)
a. An allele for the disorder only from her mother
b. An allele for the disorder from her father
c. Alleles for the disorder from both parents
d. Two alleles for the disorder from her mother
e. Two alleles for the disorder from her father
7. Sickle-cell anemia results from a point mutation in the HBB gene. The mutation results in the
replacement of an amino acid that has a hydrophilic R-group with an amino acid that has a
hydrophobic R-group on the exterior of the hemoglobin protein. Such a mutation would most
likely result in altered ______. (2012-20)
a. Properties of the molecule as a result of abnormal interactions between adjacent hemoglobin
molecules
b. DNA structure as a result of abnormal hydrogen bonding between nitrogenous bases
c. Fatty acid structure as a result of changes in ionic interactions between adjacent fatty acid
chains
d. Protein secondary structure as a result of abnormal hydrophobic interactions between Rgroups in the backbone of the protein
8. A woman with type A blood requires a blood transfusion. With respect to this trait, all of the
following individuals would have a blood type with a safe match for this transfusion EXCEPT
______. (PT2-12)
a. An individual with the genotype IAIA
b. An individual with the genotype IAi
c. An individual with the genotype ii
d. An individual with the genotype IAIB
e. An individual with type O blood
9. A cell contains four pairs of homologous chromosomes represented by A1/A2; B1/B2; C1/C2; and
D1/D2. Which of the following represents the chromosome makeup of a gamete derived from this
cell? (PT2-16)
a. A1A2B1B2C1C2D1D2
b. B1B1C1D1
c. A1A2B1B2
d. A1B2C2D2
e. A1C1C2D1
10. In which of the following are nuclear activities most similar? (PT2-34)
a. Mitosis prophase and meiosis anaphase I
b. Mitosis prophase and meiosis telophase I
c. Mitosis prophase and meiosis telophase II
d. Mitosis metaphase and meiosis metaphase I
e. Mitosis metaphase and meiosis metaphase II
11. If A represents a dominant allele and a represents the recessive allele, what are the genotypes of
parents that produce 300 progeny with the dominant trait and 100 progeny with the recessive
trait? (PT2-37)
a. AA x AA
b. AA x Aa
c. AA x aa
d. Aa x aa
e. Aa x Aa
The next two questions refer to the following.
a. Complete dominance
b. Codominance
c. Incomplete dominance
d. X-linked
12. If a gene has two alleles and a cross of two heterozygotes produces offspring with phenotypes in
the ratio of 3:1, what is the mode of inheritance? (PT2-48) A
13. If a gene has two alleles and a cross of two heterozygotes produces offspring with phenotypes in
the ratio of 1:2:1, what is the mode of inheritance if the heterozygous phenotype is not
intermediate between the homozygous phenotypes? (PT2-49) B
The next three questions refer to the following sexual life
cycle.
14. The nucleus divides during this phase. (PT2-61) A
15. The cell divides during this phase. (PT2-62) B
16. DNA replication occurs during this phase. (PT2-63) D
An experimental cross produced the results shown in the following table. Use these data for
the next three questions.
Phenotype
Red-eyed
White-eyed
Females
30
20
Males
20
30
17. Which of the following is the null hypothesis? (PT2-89)
a. Because the experiment is controlled, the experimental results will be close to the expected
results
b. If the expected and experimental results differ markedly, one or more variable are not
controlled.
c. The difference between the expected results and the observed results is the result of mating
errors.
d. The difference between the expected results and the observed results is the result of
experimental error.
e. There is no statistically significant difference between the expected and observed results.
18. What is the chi-square (x2) statistic for the observed results? The formula for calculating x2 is given
here. (PT2-90)
x2 = ∑(Observed-Expected)2/Expected
a.
b.
c.
d.
e.
Between 0 and 1.99
Between 2 and 3.99
Between 4 and 5.99
Between 6 and 7.99
8 or greater
19. How many degrees of freedom (df) are there in this experiment? (PT2-91)
a. 1
b. 2
c. 3
d. 4
e. 5
20. All of the following are true statements about meiosis in mammals EXCEPT _____.
a. It serves as a factor in bringing about variation among offspring
b. It follows DNA replication
c. It occurs only in reproductive structures
d. It produces cells with the haploid number of chromosomes
e. It produces four genetically identical gametes
(1994-13)
21. Segregation of alleles does NOT occur in which of the following groups of organisms? (1994-14)
a. Flowering plants
b. Insects
c. Flatworms
d. Bacteria
e. Ferns
22. In garden peas, a single gene controls stem length. The recessive allele (t) produces short stems
when homozygous. The dominant allele (T) produces long stems. A short-stemmed plant is
crossed with a heterozygous long-stemmed plant. Which of the following represents the expected
phenotypes of the offspring and the ratio in which they will occur? (1994-27)
a. 3 long-stemmed plants : 1 short-stemmed plant
b. 1 long-stemmed plant : 1 short-stemmed plant
c. 1 long-stemmed plant : 3 short-stemmed plants
d. Long-stemmed plants only
e. Short-stemmed plants only
The next two questions refer to the following information.
Achondroplastic dwarfism is a dominant genetic trait that causes severe malformation of the skeleton.
Homozygotes for this condition are spontaneously aborted (hence, the homozygous condition is lethal) but
heterozygotes will develop to be dwarfed.
Matthew has a family history of the condition, although he does not express the trait. Jane is an
achondroplastic dwarf. Matthew and Jane are planning a family of several children and want to know the
chances of producing a child with achondroplastic dwarfism.
23. The probability that Matthew and Jane’s first child will be an achondroplastic dwarf is _____. (1994100)
a.
b.
c.
d.
e.
0%
25%
50%
75%
100%
24. If three children are born to Matthew and Jane, what are the chances that the first two children
will not express the trait but that the third child will be an achondroplastic dwarf? (1994-101)
a. 5/8
b. 4/8
c. 3/8
d. 1/8
e. 1/16
The next two questions refer to the following information.
A male fruit fly (Drosophila melanogaster) with red eyes and long wings was mated with a female with purple
eyes and vestigial wings. All of the offspring in the F1 generation had red eyes and long wings. These F1 flies
were test crossed with purple-eyed, vestigial-winged flies. Their offspring, the F2 generation, appeared as
indicated below.
F2 Generation
125
124
18
16
283
red eyes, long wings
purple eyes, vestigial wings
purple eyes, long wings
red eyes, vestigial wings
Total
25. If in the F1 and F2 generations the same characteristics appeared in both males and females, it
would be safe to assume that these traits for eye color and wing length _____. (1994-106)
a. Are sex-linked
b. Vary in dominance according to sex
c. Are sex-influenced characteristics
d. Are autosomal characteristics
e. Follow the Mendelian rule of independent assortment
26.
a.
b.
c.
d.
e.
If a single locus controls wing shape, then the alleles for this gene act as _____. (1994-108)
Dominant-recessive alleles
Incomplete-dominance alleles
Codominant alleles
Multiple alleles
Variable alleles
27. Which of the following is true about the production of polar bodies in humans? (2002-56)
a. It increases genetic diversity.
b. It proves the maximum amount of cytoplasm and resources to the ovum.
c. It occurs in male and female vertebrates during meiosis I.
d. It is completed prior to fertilization.
e. It results in non-disjunction.
28. Which of the following can be diagnosed by examining a karyotype of an individual’s white blood
cells? (2002-58)
a. Sickle cell anemia
b. Alzheimer disease
c. Down Syndrome
d. Cystic fibrosis
e. Duchenne muscular dystrophy
The next two questions refer to the probabilities below.
A. 0
B. 1/16
C. ¼
D. ½
E. ¾
29. Probability that the genotype Aa will be produced by the parents Aa x Aa (2002-66) D
30. Probability that the genotype ccdd will be produced by the parents CcDd x CcDd (2002-67) )B
31. In a species that has five different alleles for a gene at a particular locus, how many different alleles
may be present in the somatic cells of one diploid individual? (2008-3)
a. One
b. Two
c. Three
d. Four
e. Five
32. The occurrence of a particular genetic condition in a family is
shown in the pedigree to the right. Which of the following is
the most likely inheritance pattern for the individuals with
the condition? (2008-18)
a. Autosomal dominant
b. Sex-linked dominant
c. Y linked
d. Autosomal recessive
e. Sex-linked recessive
The next two questions refer to the following types of hereditary information.
A. Unpaired unreplicated linear chromosomes
B. Unpaired replicated linear chromosomes
C. Paired replicated linear chromosomes
D. Circular chromosomes
E. Extra-chromosomal circular DNA
33. Typical of prokaryotic cells after fission (2008-69) D
34. Eukaryotic cells at prophase of mitosis (2008-70) C
The relative location of four genes on a chromosome can be mapped from the following data on
crossover frequencies
Genes
B and D
C and A
A and B
C and B
C and D
Frequency of Crossover
5%
15%
30%
45%
50%
35. Which of the following represents the relative positions of these four genes on the chromosome?
(2010-14)
a.
b.
c.
d.
e.
ABCD
ADCB
CABD
CBAD
DBCA