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Chapter 2—Cells and Cell Division
MULTIPLE CHOICE
1. The process of meiosis results in:
A. the production of four identical cells
B. no change in chromosome number from parental cells
C. a doubling of the chromosome number
D. a reduction in chromosome number
E. two interphase cells
ANS: D
2. In the cell cycle, the G1 phase represents:
A. the time of DNA synthesis
B. splitting of the chromosomes into chromatids
C. a period of growth
D. the stage just prior to mitosis
E. the stage just prior to meiosis
ANS: C
3. Ribosomes are organelles that function in:
A. separation of chromosomes by spindle fibers
B. cellular energy production
C. synthesis of gene products
D. transport of materials throughout the cytoplasm
E. conversion of chromatin into chromosomes
ANS: C
4. Which of the following genetic diseases involve defects in DNA repair, which affect cell division?
A. Gaucher disease and Werner syndrome
B. Kearns-Sayre syndrome and Progeria
C. Progeria and Werner syndrome
D. Gaucher disease and Cystic fibrosis
E. Progeria and Werner syndrome
ANS: E
5. For cells grown in the laboratory, the largest part of the cell cycle is:
A. Interphase.
B. Mitosis.
C. Cytokinesis.
D. They are all about equal.
E. There is no rule.
ANS: A
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6. Pieces of what are exchanged during crossing-over?
A. sister chromatids
B. the maternal and paternal chromosomes
C. centromeres
D. a chromatid of the maternal chromosome and a chromatid of the paternal chromosome
E. X and Y chromosome
ANS: D
7. If an organism has a diploid chromosome number of 4, how many chromosome pairs will be visible in
meiosis?
A. 0
B. 2
C. 4
D. 6
E. 8
ANS: B
8. Autosomes represent:
A. all chromosomes including the sex chromosomes
B. the half of the chromosomes inherited from one parent
C. all chromosomes other than the sex chromosomes
D. chromosome pairs with unlike members
E. those chromosomes found only in gametes
ANS: C
9. During meiosis in an organism where 2n = 6, how many chromatids will be present in a cell at the
beginning of meiosis II?
A. 2
B. 4
C. 6
D. 8
E. 12
ANS: C
10. The Hayflick limit describes:
A. the size limit to which a cell can grow
B. the number of divisions a cultured cell can undergo
C. the largest number of chromosomes an organism can possess
D. the ratio of nucleus to cytoplasm
E. none of these
ANS: B
11. In meiosis, the centromeres divide at:
A. metaphase I
B. anaphase I
C. metaphase II
D. anaphase II
E. telophase
ANS: D
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12. Haploid gametes contain:
A. the 2n chromosome number
B. half the 2n chromosome number
C. twice the 2n chromosome number
D. half the n chromosome number
E. none of these
ANS: B
13. Endoplasmic reticulum is involved in:
A. energy production
B. transport of materials throughout the cell
C. ribosome synthesis
D. carrying genetic information
E. generation of polar bodies
ANS: B
14. A cell that could not form spindle fibers could not perform:
A. mitosis
B. meiosis
C. mitosis or meiosis
D. DNA replication
E. protein synthesis
ANS: C
15. Gaucher disease is associated with abnormality of which part of the cell?
A. endoplasmic reticulum
B. lysosomes
C. mitochondria
D. Golgi apparatus
E. plasma membrane
ANS: B
16. Molecules on or in a cell's plasma membrane are responsible for:
A. transport of substances into the cell
B. providing a molecular identity for the cell
C. determining blood type
D. all of these
E. none of these
ANS: D
17. Which of the following is the first event that occurs in prophase of mitosis?
A. The chromosomes are duplicated.
B. The nuclear envelope starts to break up.
C. The mitotic spindle begins to form.
D. The chromosomes begin to condense.
E. The cleavage furrow forms and deepens.
ANS: D
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18. A cell in G0 state is a cell:
A. that will shortly enter G1
B. that never divides
C. that has just finished mitosis but has not yet begun cytokinesis
D. in cytokinesis
E. just after cytokinesis
ANS: B
19. Centromeres:
A. organize microtubules into spindle fibers
B. connect sister chromatids
C. attach chromosomes to spindle fibers
D. both connect sister chromatids and attach chromosomes to spindle fibers
E. all of the answers are correct
ANS: D
20. Which of the following are NOT haploid?
A. polar bodies and secondary spermatocytes
B. primary oocytes and spermatids
C. secondary spermatocytes and spermatogonia
D. primary oocytes and spermatogonia
E. secondary spermatocytes and spermatids
ANS: D
21. Formation of eggs and sperm are the same in what way(s)?
A. when during a person's life they begin and end
B. the way chromosomes behave during meiosis
C. the way cytoplasm divides during cytokinesis
D. both the way chromosomes behave during meiosis and the way cytoplasm divides during
cytokinesis
E. all of these
ANS: B
22.
Which of the following types of molecules serve primarily as energy sources or reserves?
A. carbohydrates
B. lipids
C. proteins
D. carbohydrates and lipids
E. carbohydrates and proteins
ANS: D
23. Which of the following is not a lipid?
A. fats
B. steroids
C. oils
D. monosaccharides
E. phospholipids
ANS: D
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TRUE/FALSE
1. The enzymes present in lysosomes must previously have been in the Golgi apparatus and endoplasmic
reticulum.
ANS: T
2. Skin cells typically do not divide.
ANS: F
3. Chromatin is the term for a chromosome before it is duplicated.
ANS: F
4. Mitotic divisions reduce the number of chromosomes found in daughter cells.
ANS: F
5. Cytokinesis usually occurs just after mitosis.
ANS: T
6. Autosomal chromosome pairs are identical, whereas the sex chromosome pair in males is not.
ANS: T
7. "Random Assortment" is partially responsible for our genetic diversity.
ANS: T
8. Crossing over occurs between chromatids of chromosome pairs.
ANS: T
9. There are 92 chromosomes in a normal human cell undergoing mitosis at the anaphase stage.
ANS: T
10. The S stage of interphase is followed immediately by mitosis.
ANS: F
11. A polar body, once formed, has no further function and dies.
ANS: T
12. The molecules on the surface of cells that give cells their identity are combinations of carbohydrates
and proteins.
ANS: T
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COMPLETION
1. How many autosomes are present in a human egg? ____________________
ANS: 22
2. ____________________ is a disease that occurs when cells escape from controls that are part of the
cell cycle.
ANS: cancer
3. What is the chromosomal structure that anchors the spindle fiber to the chromosome?
____________________
ANS: the centromere
4. What occurs during "S" phase of the cell cycle? ____________________
ANS: DNA duplication
5. In mitosis, chromatids separate and move to opposite poles of the spindle during
____________________.
ANS: anaphase
6. In many respects, the events of telophase seem to be the reverse of those occurring in
____________________.
ANS: prophase
7. In meiosis, sister chromatids separate and move to opposite poles of the spindle during
____________________.
ANS: anaphase II
8. In cell division, toward the end of nuclear division, the ____________________ divides by a process
called cytokinesis to produce two identical cells.
ANS: cytoplasm
9. The only cytoplasmic organelles that contain DNA are the ____________________.
ANS: mitochondria
10. Ribosomes exist either free in the cytoplasm or attached to the membranes of
____________________.
ANS: endoplasmic reticulum
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11. One primary spermatocyte produces ____________________ (how many?) functional sperm(s); one
primary oocyte produces ____________________ functional egg(s).
ANS:
4; 1
four; one
12. Proteins are polymers made of subunits called _________.
ANS: amino acids
13. “Mostly __________” proteins are insoluble in water and provide structure of hair, skin, and bones.
ANS: fibrous
SHORT ANSWER
1. Since in most specialized cells of the body only a relatively small number of genes is active, why must
mitosis involve the replication of a complete set of genes?
ANS:
Mitosis replicates and divides whole chromosomes. Since the genes active in any type of cell are
scattered among all the chromosomes, every cell needs a complete set of chromosomes.
2. From an evolutionary standpoint, does it seem logical that mitosis evolved before meiosis, and that
meiosis is really a specialized form of mitosis? Or should mitosis be regarded as a degenerate form of
meiosis?
ANS:
All organisms require cell division and mitosis since all muticellular organisms must grow and replace
dead cells and unicellular organisms multiply by going through cell division. Meiosis is only required
for sexual reproduction - something the simplest unicellular organisms do not do. Hence it is logical to
assume that mitosis evolved first.
3. Would an understanding of the mechanism of the Hayflick limit lead to an increase in the human life
span?
ANS:
Yes. The loss of cells’ ability to divide is one thing that causes the symptoms of old age. If the
mechanism of the Hayflick limit were fully understood, it might lead to the ability to extend or abolish
the limit and to an increase in life span.
4. What is the difference between life span and life expectancy? Which genetic and non-genetic factors
contribute to the gap between life span and life expectancy?
ANS:
Life span is the (theoretical) average age of an organism at death. Life expectancy is the age at which a
particular individual or group is likely to die. There are a large number of genetic and non-genetic
factors that influence individuals’ health and safety and thus their life expectancy.
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5. Compare and contrast the following:
a. prophase of mitosis and prophase I of meiosis
b. interphase preceding meiosis I and interphase preceding meiosis II
c. anaphase of mitosis and anaphase I of meiosis
ANS:
a. The same events occur in both, but only in prophase I of meiosis will homologous chromosomes
pair and crossing over occur.
b. There is essentially no visible difference; only the number of chromosomes present is different.
c. In both cases chromosomes move away from each other. In mitosis, centromeres split and sister
chromatids (which become chromosomes) separate. In anaphase I, centromeres do not split and
homologous chromosomes which had been paired, still containing two sister chromatids, separate.
6. What evidence exists that mitosis and the cell cycle are under genetic control?
ANS:
Many specific gene mutations which alter the cell cycle and/or events of mitosis have been identified.
They are transmitted from parents to offspring in the same manner as any other gene.
7. Of what significance is crossing over? What other event in Meiosis I is of similar significance?
ANS:
Crossing over produces new combinations of maternal and paternal genes, leading to sperm and egg
cells, and offspring, with unique sets of genes and traits. The random assortment of homologous
chromosomes plays the same role. But while random assortment leads to millions of different genetic
combinations, crossing over makes the number of variations possible almost infinite.
8. Describe the cell cycle. Do all cells go through this cycle at the same time?
ANS:
The cell cycle is a genetically controlled series of events during which a cell grows (G1), then its DNA
is replicated (S), then other preparations for division occur (G2). Then the cell divides (mitosis and
cytokinesis). Different cells divide at different times and their cycles and cycle stages are of different
lengths.
9. Compare and contrast five items in mitosis and meiosis.
ANS:
1. Mitosis produces two diploid daughter cells; meiosis produces four haploid cells.
2. The products of mitosis are somatic cells; the products of meiosis are gametes (or cells that will
produce gametes).
3. Mitosis is one division; meiosis is two.
4. Pairing of homologous chromosomes and crossing over occur during meiosis, but not mitosis.
5. Cells that divide by mitosis usually go through the cell cycle and divide again. Cells produced by
meiosis do not usually divide again (in animals).
10. What is accomplished by the unequal cytokinesis of oogenesis?
ANS:
Any egg cell needs a certain amount of cytoplasm and nutrients to support the young embryo. Because
of unequal cytokinesis, almost all the cytoplasm and nutrients in the oocyte are preserved in the single
egg.