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CHAPTER 11—MEIOSIS: THE CELLULAR BASIS OF SEXUAL
REPRODUCTION
MULTIPLE CHOICE
1. The advantage of sexual reproduction over asexual reproduction is
a.
that sexual reproduction requires an interaction between two individuals.
b.
that there is a mixing of genetic information into a new combination in the next
generation.
c.
that it ensures a greater number of progeny.
d.
that it keeps the number of chromosomes constant more effectively.
e.
that it allows for the production and use of gametes.
2. ____ reproduction generates more ____ than does ____ reproduction.
a.
Asexual; genetic diversity; sexual
b.
Sexual; genetic stability; asexual
c.
Sexual; genetic diversity; asexual
d.
Asexual; haploid cells; sexual
e.
Sexual; identical offspring; asexual
3. A homologous chromosome pair is best described as two chromosomes having
a.
the same genes in the same order but possibly having different alleles of those genes.
b.
the same alleles of the same genes in the same order.
c.
different genes in the same order and possibly having different alleles of some genes.
d.
different alleles of the same genes arranged in a different order.
e.
an identical DNA sequence.
4. If a normal diploid germ cell in a bird has eight chromosomes, then
a.
there are eight homologous pairs of chromosomes per diploid germ cell.
b.
there are eight chromatids per diploid germ cell after DNA replication.
c.
there are four chromosomes per cell after the first meiotic division and cytokinesis.
d.
sperm cells made from this diploid germ cell would have eight chromosomes.
e.
there are eight copies of each chromosome in this diploid germ cell.
5. Homologous chromosomes undergo recombination during
a.
prophase II.
b.
metaphase I.
c.
metaphase II.
d.
both prophase I and II.
e.
prophase I.
6. Sister chromatids are best described as two chromosomes having
a.
the same genes in the same order but possibly having different alleles of those genes.
b.
the same alleles of the same genes in a different order.
c.
different genes in the same order and possibly having different alleles of some genes.
d.
different alleles of the same genes arranged in a different order.
e.
an identical DNA sequence.
7. This stage of meiosis is characterized by DNA condensation into compact chromosomes.
a.
prophase II
b.
anaphase I
c.
prophase I
d.
prometaphase I
e.
metaphase I
8. Sex chromosomes are
a.
completely different between the two sexes.
b.
partially homologous but also have unique regions.
c.
found only in males.
d.
unable to line up properly at the metaphase plate.
e.
completely homologous but always have different alleles.
9. Recombination occurs
a.
during prophase I and II and involves swapping of chromosome fragments between all 4
chromatids.
b.
only during prophase I and involves swapping of chromosome fragments between
homologous chromatids.
c.
only during prophase I and involves swapping of chromosome fragments between sister
chromatids.
d.
during prophase I and II and involves swapping of chromosome fragments between sister
chromatids.
e.
during prophase I, prophase II, and prometaphase; it involves exchange of alleles between
homologous chromosomes.
10. Nondisjunction in Meiosis I results in
a.
a failure of spindle fibers to separate a homologous pair of chromosomes.
b.
a change in the status of a daughter cell from diploid to haploid.
c.
a change in the status of a daughter cell from haploid to diploid.
d.
one pole of the cell receiving neither member of a homologous pair of chromosomes.
e.
a gamete that cannot fuse with another gamete.
11. Meiosis results in the generation of
a.
four haploid cells.
b.
two diploid cells.
c.
two diploid cells and two haploid cells.
d.
four diploid cells.
e.
one haploid and three diploid cells.
12. Which of the following statements is TRUE about chromosomes?
a.
Chromosomes are always spread out as chromatin.
b.
Chromosomes are always condensed.
c.
Homologous chromosomes have the same genes on them but can have different alleles.
d.
Homologous chromosomes have the same genes on them and always have the same alleles
of those genes.
e.
Chromosomes always consist of two sister chromatids.
13. Homologous pairs of chromosomes
a.
consist of two chromosomes with the same genes.
b.
consist of two chromosomes with the same alleles.
c.
consist of two chromosomes that came from the same parent.
d.
are found in sperm and eggs.
e.
are found in haploid cells.
14. In meiosis, sister chromatids separate
a.
before DNA replication.
b.
before crossing over.
c.
during Anaphase I.
d.
during Anaphase II.
e.
never; sister chromatids do not separate in meiosis.
15. In a frog in which the diploid number of chromosomes per cell is 24, what is the total number of
chromatids present during Prophase I?
a.
0
b.
6
c.
12
d.
24
e.
48
16. In a frog in which the diploid number of chromosomes per cell is 24, what is the total number of
chromatids present per cell in Prophase II after the first division and cytokinesis?
a.
0
b.
6
c.
12
d.
24
e.
48
17. Whether a germ cell develops into eggs or sperm is determined by
a.
the presence of the X chromosome.
b.
the presence of the Y chromosome.
c.
the time at which meiosis begins during development.
d.
the genetic sex of the individual.
e.
whether or not meiosis and mitosis can occur.
18. Koopman’s research on mouse meiosis showed that
a.
there is a meiosis promoting gene.
b.
a meiosis inhibiting gene leads to retinoic acid production.
c.
retinoic acid prevents meiosis.
d.
the Cyp26b1 gene is expressed in testes but not ovaries.
e.
there is no effect if male mice do not have a Cyp25b1 gene.
19. The purpose of the synaptonemal complex is to
a.
hold the homologous chromosomes tightly together.
b.
support homologous chromosomes as they undergo recombination.
c.
prevent chromosome fragments from floating free in the cytosol after DNA breakage for
recombination.
d.
ensure that the process of crossing over is random.
e.
hold the homologous chromosomes tightly together, support homologous chromosomes as
they undergo recombination, and prevent chromosome fragments from floating free in the
cytosol after DNA breakage for recombination.
20. Recombination at the synaptonemal complex always results in
a.
two changed and two unchanged chromatids.
b.
four unchanged chromatids.
c.
four changed chromatids.
d.
a random number of changed vs. unchanged chromatids.
e.
one unchanged and three changed chromatids from two subsequent recombination events.
21. The importance of crossing over during meiosis is
a.
to hold homologous pairs of chromosomes together.
b.
to result in chromosomes consisting of two identical sister chromatids.
c.
to result in daughter nuclei with too much or too little genetic material.
d.
to ensure that the developing zygote receives cytoplasm from one of the parents.
e.
to allow formation of parental chromosomes.
22. Random segregation of chromosomes (by itself) means that a particular daughter cell
a.
has some paternal chromosomes and some maternal chromosomes.
b.
has only paternal chromosomes.
c.
has only maternal chromosomes.
d.
has chromosomes containing genes from the paternal and maternal chromosomes.
e.
has some paternal chromosomes and some maternal chromosomes and has chromosomes
containing genes from the paternal and maternal chromosomes.
23. If a species has 42 pairs of chromosomes, which value represents the number of combinations of
maternal and paternal chromosome combinations that will be sorted to the poles?
a.
422
b.
242
c.
221
d.
212
e.
842
24. Identical twins can result from
a.
the fusion of two sets of identical gametes.
b.
a division of a zygote into two separate cells that develop into two separate embryos.
c.
the fusion of two paternal gametes with a single maternal gamete that then divides.
d.
a lack of chromosomal separation during meiosis resulting in gametes that are diploid and
don't need to be fertilized.
e.
a mechanism that is not understood.
25. The process of fertilization
a.
is random in the selection of which gametes fuse.
b.
is not random but selects for gametes with a greater number of paternal chromosomes.
c.
is not random but selects for gametes with a greater number of maternal chromosomes.
d.
is not random but selects for gametes with the fewest mutations.
e.
is not a source of genetic variability in progeny.
26. Two genes on each of four homologous chromosomes (HC) are described here, but only one of each
pair of sister chromatids is listed (HC1 and HC2). Capital and lower case indicate different alleles of
the same gene. What four gametes will result from a single chiasma if the chromosomes have the
following genes: HC1: Ab; HC2: aB?
a.
Ab, AB, ab, aB
b.
Ab, Ab, aB, aB
c.
Aa, Bb, ab, Ab.
d.
Ab, Ab, AB, AB
e.
AB, AB, ab, ab
27. Two genes on each of four homologous chromosomes (HC) are described here, but only one of each
pair of sister chromatids is listed (HC1 and HC2). Capital and lower case indicate different alleles of
the same gene. What four gametes will result from a single chiasma if the chromosomes have the
following genes: HC1: ab; HC2: AB?
a.
Ab, AB, ab, aB
b.
Ab, Ab, aB, aB
c.
Aa, Bb, ab, Ab.
d.
Ab, Ab, AB, AB
e.
AB, AB, ab, ab
28. Which pattern of diploid and haploid phases reflect the life cycle in animals?
a.
alternation between haploid and diploid generations
b.
two haploid generations followed by a diploid generation
c.
one haploid generation followed by two diploid generations
d.
a single generation that limits the haploid state to gametes while the rest of the organism is
diploid
e.
a single generation that limits the diploid state to gametes while the rest of the organism is
haploid
29. Which pattern of diploid and haploid phases reflect the life cycle in plants?
a.
alternation between haploid and diploid generations
b.
two haploid generations followed by a diploid generation
c.
one haploid generation followed by two diploid generations
d.
a single generation that limits the haploid state to gametes while the rest of the organism is
diploid
e.
a single generation that limits the diploid state to gametes while the rest of the organism is
haploid
30. Which pattern of diploid and haploid phases reflect the life cycle in some fungi and algae, but not
plants or animals?
a.
alternation between haploid and diploid generations
b.
two haploid generations followed by a diploid generation
c.
one haploid generation followed by two diploid generations
d.
a life cycle that limits the diploid state to a single cell produced by fertilization
e.
a life cycle that limits the haploid state to a single cell which is immediately fertilized
31. An unknown organism from an alien planet is observed and found to have a diploid state only
following fertilization. Meiosis follows and the majority of this organism's life is spent in a haploid
state. Which multicellular organism on earth most closely resembles this type of life cycle strategy?
a.
humpback whale
b.
maple tree
c.
fern
d.
some algae
e.
all plants and some fungi
32. An unknown organism from an alien planet is observed and found to have a diploid state in every
other generation and results from fertilization. The haploid state is able to grow into a gametophyte-
like structure. This alien organism most closely mimics the life cycle strategy of which of the
following earth organisms?
a.
humpback whale
b.
maple tree
c.
fungi and algae
d.
algae
e.
all plants and some fungi
33. In plants, the gametes produced by a particular gametophyte are
a.
always identical because they result from meiosis.
b.
always identical because they result from mitosis.
c.
sometimes identical because they result from meiosis.
d.
sometimes identical because they result from mitosis.
e.
never identical because they result from meiosis.
34. Which of the following is not yet known about meiosis?
a.
Proteins in the nuclear envelope connect chromosomes to the cytoskeletal network.
b.
Specific motor proteins move chromosomes so the homologs can find each other.
c.
A proteinaceous structure called the synaptonemal complex forms between homologous
chromosomes.
d.
Crossovers form between homologs in order to maintain pairing prior to the first meiotic
division.
e.
A long list of specific chemicals has been shown to impair specific stages of meiosis.
35. The primary difference between mitosis and meiosis in animals includes all of the following except
a.
the generation of haploid cells from diploid cells.
b.
the number of daughter cells that result (2 or 4).
c.
the number of times chromosomes align at the metaphase plate.
d.
the purpose of generating reproductive cells as opposed to generating somatic cells.
e.
the number of times the DNA is replicated.
36. If an organism has the same life strategy as a maple tree, the synaptonemal complex will be observed
a.
only in alternating generations.
b.
in each generation.
c.
only in a unicellular haploid phase.
d.
only in a multicellular haploid phase.
e.
only in gametophyte.
Select the Exception
37. Which of the following is NOT TRUE about meiosis?
a.
Homologous chromosomes pair up in Prophase I.
b.
Each chromosome has two sister chromatids during Prophase I.
c.
Each chromosome is attached by one spindle during Prophase I.
d.
After the first division, the two resulting cells are still diploid.
e.
Meiosis only occurs in germ cells and not in somatic cells.
242
38. In the following list, pick the one that is NOT a source of genetic variability from meiosis and
fertilization.
a.
recombination of homologous chromosomes
b.
segregation of chromosomes
c.
genes contained in the gametes that fuse to form a zygote
d.
recombination between sister chromatids
e.
physical arrangement of chromosomes along the metaphase plate in preparation for
anaphase
MATCHING
Match each of the following terms with its correct definition.
a.
Cell division that is modified to generate haploid cells
b.
The haploid products of meiosis
c.
The matching of homologous pairs of chromosomes during prophase I
d.
A term used to describe cells having two sets of chromosomes
e.
Diploid body cells that do not undergo meiosis
f.
A term used to describe cells having a single set of chromosomes
g.
A life strategy that involves fusion of haploid gametes from two source organisms to form
a diploid cell
h.
Another name for crossover sites
i.
A variant of a particular gene having a slightly different DNA sequence than another
variant of the same gene
j.
The diploid product of gamete fusion
k.
The process of gamete fusion
39. gametes
40. somatic cells
41. sexual reproduction
42. zygote
43. fertilization
44. meiosis
45. haploid
46. diploid
47. allele
48. synapsis
49. chiasmata
Classification
Use the processes listed below for the following question(s).
a.
Prophase I
b.
Prometaphase I
c.
Metaphase I
d.
Anaphase I
e.
Telophase I
f.
Prophase II
g.
Prometaphase II
h.
Metaphase II
i.
Anaphase II
j.
Telophase II
50. This stage is characterized by the first breakdown of the nuclear envelope.
51. Homologous chromosomes undergo recombination.
52. Tetrads align at the metaphase plate.
53. Spindles are disassembled and replaced by new spindles.
54. In some species, the nuclear envelope may reform during this stage.
55. Nuclear envelope reforms in ALL species.
56. Sister chromatids are separated.
244
Labeling
Identify each numbered part of the following illustration.
57. chiasma
58. nuclear envelope
59. spindle microtubules
60. tetrad
61. centriole
SHORT ANSWER
62. Explain the purpose of meiosis.
63. List and briefly explain the three ways in which genetic variability is increased during meiosis.
64. Triploid cells have three copies of each chromosome rather than two. If a triploid cell undergoes
meiosis, it produces inviable products. Why is this the case?
65. Some organisms do not have crossing over, and hold their homologous chromosomes together via
some other mechanism. Even though crossing over leads to genetic diversity, the absence of crossing
over in these organisms does not prevent the production of diverse gametes. Why is this?
66. What is the main difference between the haploid and diploid phases of animal and plant life cycles?
246
TOP: Section 11.3
OTHER
67. Arrange the following in the order in which they occur. Write the letter of the first step next to 1 and
the letter of the last step next to 12.
A.
Anaphase I
B.
Anaphase II
C.
Interkinesis
D.
Metaphase I
E.
Metaphase II
F.
Premeiotic Interphase
G.
Prometaphase I
H.
Prometaphase II
I.
Prophase I
J.
Prophase II
K.
Telophase I
L.
Telophase II
1.
2.
3.
4.
5.
6.
7.
8.
9.
10.
11.
12.
ANS:
MODIFIED TRUE/FALSE
If the statement is true, answer "T". If the statement is false, answer "F" and make it correct by
changing the underlined word(s) and writing the correct word(s) in the answer blank(s).
68. A slipper limpet can change its sex from female to male.
69. Prokaryotic cells can undergo meiosis.
70. A portion of the Y chromosome is homologous to the X chromosome.
71. Crossing over is limited to a single occurrence for a chromosome.
72. Spore is another name for gamete.
73. Haploid organisms growing via mitosis from spores are called gametophytes.
74. Even if chromosomes are not a perfect match, pairing centers sometimes allow synapsis.
75. Haploid cells have homologous chromosomes.
76. The mechanisms that control the number of crossover events in a cell have been well characterized.
ESSAY
77. Describe the two stages in meiosis where the most genetic recombination occurs.
78. Compare the functions of meiosis I and II in the overall generation of gametes.
79. Describe the life cycles of animals, plants/some fungi, and other fungi/algae with respect to the amount
of time each type of organism spends in their haploid and diploid phases. Also indicate whether those
haploid and diploid phases are unicellular or multicellular.
