Exam 3

Question 1

A cleavage furrow is _____.

A) the space that is created between two chromatids during anaphase
B) a ring of vesicles forming a cell plate
C) the separation of divided prokaryotes
D) a groove in the plasma membrane between daughter nuclei
E) none of the above

Answer 1

D) a groove in the plasma membrane between daughter nuclei

Question 2

Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation. Surprisingly,
this stops mitosis. Specifically, Taxol must affect _____.
A) formation of the centrioles
B) chromatid assembly
C) anaphase
D) the nuclear membrane
E) none of the above

Answer 2

E) none of the above

Question 3

3) In meiosis, sister chromatids are separated during _____.
A) anaphase II
B) prophase I
C) mitosis
D) anaphase I
E) none of the above

Answer 3

A) anaphase II

Question 4

Sister chromatids _____.
A) align on the metaphase plate in meiosis II
B) carry the same alleles
C) are identical
D) separate during anaphase II
E) all of the above

Answer 4

E) all of the above

Question 5

5) What do we mean when we use the terms monohybrid cross and dihybrid cross?
A) A monohybrid cross results in a 9:3:3:1 ratio whereas a dihybrid cross gives a 3:1 ratio
B) A monohybrid cross is performed for one generation, whereas a dihybrid cross is performed for two generations
C) dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross
involves organisms that are heterozygous for only one character being studied
D) A monohybrid cross involves a single parent, whereas a dihybrid cross involves two parents
E) none of the above

Answer 5

C) dihybrid cross involves organisms that are heterozygous for two characters that are being studied, and a monohybrid cross

Question 6

6) A man has extra digits (six fingers on each hand and six toes on each foot). His wife and their daughter have a normal number of
digits. Having extra digits is a dominant trait. The couple’s second child has extra digits. What is the probability that their next (third)
child will have extra digits?
A) 1/8
B) 3/4
C) 1/2
D) 1/16
E) none of the above

Answer 6

C) 1/2

Question 7

7) Which of the following describes condition where a gene at one locus alters the phenotypic expression of a gene at a second locus?
A) incomplete dominance
B) multiple alleles
C) pleiotropy
D) epistasis
E) none of the above

Answer 7

D) epistasis

Question 8

8) The following macromolecule was labeled with 15N or 14N
A) protein
B) RNA
C) DNA
D) phospholipids
E) none of the above

Answer 8

C) DNA

Question 9

A man who carries an allele of an X-linked gene will pass it on to _____.
A) half of his daughters
B) all of his daughters
C) all of his sons
D) all of his children
E) none of the above

Answer 9

B) all of his daughters

Question 10

23) Replication in prokaryotes differs from replication in eukaryotes for which of the following reasons?
A) Prokaryotes produce Okazaki fragments during DNA replication, but eukaryotes do not
B) Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many
C) Prokaryotic chromosomes have histones, whereas eukaryotic chromosomes do not
D) The rate of elongation during DNA replication is slower in prokaryotes than in eukaryotes
E) none of the above

Answer 10

B) Prokaryotic chromosomes have a single origin of replication, whereas eukaryotic chromosomes have many

Question 11

24) The leading and the lagging strands differ in that _____.
A) the leading strand is synthesized by adding nucleotides to the 3’ end of the growing strand, and the lagging strand is
synthesized by adding nucleotides to the 5’ end
B) the leading strand is synthesized by adding nucleotides to the 5’ end of the growing strand, and the lagging strand is
synthesized by adding nucleotides to the 3’ end
C) the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction
D) the leading strand is synthesized at twice the rate of the lagging strand
E) none of the above

Answer 11

C) the leading strand is synthesized in the same direction as the movement of the replication fork, and the lagging strand is synthesized in the opposite direction

Question 12

25) Cohesins hold together sister chromatids during replication. At what stage of the mitotic cycle would you expect cohesins to be
cleaved to allow mitosis to continue?
A) prophase
B) interphase
C) metaphase
D) cytokinesis
E) none of the above

Answer 12

E) none of the above

Question 13

26) In some parts of Africa, the frequency of heterozygosity for the sickle-cell anemia allele is unusually high, presumably because this
reduces the frequency of malaria. Such a relationship is related to which of the following?
A) the malarial parasite changing the allele
B) Darwin’s explanation of natural selection
C) Mendel’s law of segregation
D) Mendel’s law of independent assortment
E) none of the above

Answer 13

B) Darwin’s explanation of natural selection

Question 14

For a chemotherapeutic drug to be useful for treating cancer cells, which of the following is most desirable?
A) It is safe enough to limit all apoptosis
B) It only attacks cells that are density dependent
C) It interferes with rapidly dividing cells
D) It interferes with cells entering G0 (quiescence)
E) It does not alter metabolically active cells

Answer 14

C) It interferes with rapidly dividing cells

Question 15

An animal cell contains 20 picograms of DNA during G1 phase of the cell cycle.
How much DNA does it contain during metaphase?
A) 5 picograms
B) 10 picograms
C) 20 picograms
D) 80 picograms
E) none of the above

Answer 15

E) none of the above

Question 16

33) The following proteins fluctuate in concentration during the cell cycle, bind to
kinase proteins, and regulate cell cycle progression:
A) cyclin-dependent kinases
B) cohesins
C) kinetochores
D) ubiquinones
E) cyclins

Answer 16

E) cyclins

Question 17

34) For many cells, what is the most importantly checkpoint?
A) G0 checkpoint
B) G1 checkpoint
C) S checkpoint
D) interphase checkpoint
E) none of the above

Answer 17

B) G1 checkpoint

Question 18

The human X and Y chromosomes
A) are almost entirely homologous, despite their different names
B) include genes that determine an individual’s sex
C) are about the same size and have approximately the same number of genes
D) are called autosomes
E) are both present in every somatic cell of males and females alike

Answer 18

B) include genes that determine an individual’s sex

Question 19

For what purpose(s) might a karyotype be prepared?
A) for prenatal screening, to determine if a fetus has the correct number of chromosomes
B) to determine whether a fetus is male or female
C) to detect the possible presence of chromosomal deletions
D) to detect the possible presence of chromosomal inversions or translocations
E) all of the above

Answer 19

E) all of the above

Question 20

37) Which of these is a way that the sexual life cycle increases genetic variation in a species?
A) by allowing an increase in cell number
B) by conserving chromosomal gene order
C) by decreasing mutation frequency
D) by allowing crossing over
E) by increasing gene stability

Answer 20

D) by allowing crossing over

Question 21

38) Which of the following occurs in meiosis but not in mitosis?
A) production of daughter cells
B) chromosome replication
C) alignment of chromosomes at the equator
D) condensation of chromatin
E) crossing over of chromosomes

Answer 21

E) crossing over of chromosomes

Question 22

What is an allele?
A) a type of chromosome
B) a variety of pea plant used by Mendel
C) the dominant form of a gene
D) an alternative version of a gene
E) the recessive form of a gene

Answer 22

D) an alternative version of a gene

Question 23

Why did Mendel continue some of his experiments to the F2 or F3 generation?
A) to be able to describe the frequency of recombination
B) to distinguish which alleles were segregating
C) to obtain a larger number of offspring on which to base statistics
D) to observe whether or not a recessive trait would reappear
E) to observe whether or not the dominant trait would reappear

Answer 23

D) to observe whether or not a recessive trait would reappear

Question 24

45) What were the advantages of utilizing fruit flies for genetic studies?
A) produce many offspring
B) a generation can be bred every two weeks
C) only have four pairs of chromosomes
D) relatively cheap
E) all of the above

Answer 24

E) all of the above

Question 25

46) Consanguineous matings
A) increase the chance of mating between two carriers of the same rare allele
B) decrease the chance of mating between two carriers of the same rare allele
C) are matings between genetically unrelated individuals
D) are of no consequence for inherited disorders
E) none of the above

Answer 25

A) increase the chance of mating between two carriers of the same rare allele

Question 26

When Thomas Hunt Morgan crossed his red-eyed F1 generation flies to each other, the F2 generation included both red- and
white-eyed flies. Remarkably, all the white-eyed flies were male. What was the explanation for this result?
A) the gene involved is on the Y chromosome
B) other male-specific factors influence eye color in flies
C) the gene involved is on the X chromosome
D) the gene involved is on an autosome, but only in males
E) other female-specific factors influence eye color in flies

Answer 26

C) the gene involved is on the X chromosome