Cell Bio Chapter 14
9) The period in the cell cycle between the end of dell division and the beginning of DNA synthesis is called the _____ phase. a) G1 b) S c) G2 d) M e) G0
a) G1
19) Which part of the cell cycle is the most variable? a) G1 phase b) S phase c) G2 phase d) M phase e) G0 phase
a) G1 phase
65) Which of the following is a multiprotein complex that acts primarily during interphase to ubiquitinate proteins and target them for destruction by a proteasome? a) SCF b) APC c) anaphase promoting complex d) both SCF and APC e) proteasomal activating complex
a) SCF
6) What is the average length of M phase? a) about 1 hour b) about 10 minutes c) about 10 hours d) 4 hours and 35 minutes e) about a day
a) about 1 hour
59) The nuclear pore complexes are disassembled _________. a) as the interactions between nucleoporin complexes are disrupted and the proteins dissociate into the surrounding medium b) by depolymerization of the lamin filaments c) as their integrity is disrupted mechanically as holes are torn in the complexes by cytoplasmic dyneins associated with the outer nuclear membrane d) by cytoplasmic dyneins e) by cytoplasmic microtubules and microfilamnets
a) as the interactions between nucleoporin complexes are disrupted and the proteins dissociate into the surrounding medium
1) The stages through which a cell passes from one cell division to the next constitute the _________. a) cell cycle b) life cycle c) biocycle d) energy cycle e) regeneration cycle
a) cell cycle
12) Which cells typically have very short cell cycles on the order of less than 30 minutes? a) cells in a cleaving frog embryo b) mammalian liver tissue c) mammalian muscle cells d) both cells in a cleaving frog embryo and mammalian muscle cells e) nerve cells
a) cells in a cleaving frog embryo
40) When is a kinetochore assembled on the centromere? a) during prophase b) during anaphase c) during telophase d) during metaphase e) during interphase
a) during prophase
79) In the human female, after their long arrest, when do oocytes resume meiosis? a) just prior to their ovulation b) prior to birth c) between the ages of 4 and 6 d) at the end of each menstrual cycle e) just after birth
a) just prior to their ovulation
80) When do homologous regions of DNA in homologous chromosomes first make contact? a) leptotene b) zygotene c) pachytene d) diplotene e) diakinesis
a) leptotene
51) What controls the progression of a cell from G2 to M? a) mitotic Cdk b) synthetic Cdk c) the spindle d) chromosome compaction e) mitotic Cpk
a) mitotic Cdk
53) What allows the interaction between the mitotic spindle and the chromosomes to occur? a) nuclear envelope breakdown b) nucleosome breakdown c) nucleolus breakdown d) chromatin dissolution e) chromosome condensation
a) nuclear envelope breakdown
27) Once a fission yeast cell passes START, the cell is committed to replication. What is responsible for activating cdc2 at this time? a) one or more G1 cyclins b) one or more G2 cyclins c) one or more S cyclins d) one or more M cyclins e) one or more G0 cyclins
a) one or more G1 cyclins
42) How would you describe the orientation of the two centrioles of the centrosome relative to each other? a) oriented at right angles b) oriented in the same direction c) obverse d) reversed e) converse
a) oriented at right angles
87) What stage of prophase I of meiosis begins when synapsis ends? a) pachytene b) leptotene c) diakinesis d) zygotene e) diplotene
a) pachytene
58) What initiates the disassembly of the three major components of the nuclear envelope? a) phosphorylation of key substrates by mitotic kinases, particularly cyclin B-Cdk1 b) dephosphorylation of key substrates by mitotic phosphatases, particularly cyclin B-Cdk1 c) a cascade begun by ATP synthase d) phosphorylation of key substrates by mitotic phosphatases, particularly cyclin B-Cdk e) methylation of key substrates by mitotic kinases, particularly cyclin B-Cdk1
a) phosphorylation of key substrates by mitotic kinases, particularly cyclin B-Cdk1
56) The current view of the fate of the ER during mitosis is that ________. a) the ER network remains relatively intact during mitosis b) the ER is broken into its component macromolecules during mitosis, but it is built up from scratch after mitosis c) the ER is broken up into small vesicles that reassemble later d) the ER becomes part of the Golgi complex during mitosis e) the ER joins with mitochondria at the beginning of mitosis
a) the ER network remains relatively intact during mitosis
11) The total length of the cell cycle of cells in a cell culture is 24 hours. M phase is found to be 1 hour, S phase is found to be 9 hours and G2 is found to be 4.5 hours. How long is G1? a) 24 hours b) 9.5 hours c) 9 hours d) 1 hour e) 4.5 hours
b) 9.5 hours
68) What is the name of the enzyme that responds to the lack of bipolar tension when both chromatids are attached to microtubules from the same spindle pole and helps to correct the abnormality? a) streptokinase b) Aurora B kinase c) Cdc kinase d) protein kinase e) tubulin kinase
b) Aurora B kinase
44) The start of centrosome duplication begins at the ______ transition. a) M-G1 b) G1-S c) S-G2 d) G2-M e) G1-M
b) G1-S
55) As revealed by recent studies, which organelles do not seem to remain intact during mitosis? a) mitochondria b) Golgi complex c) ER d) peroxisomes e) chloroplasts
b) Golgi complex
83) What may be the purpose of the clustering of telomeres in a variety of eukaryotic cells that presumably causes chromosomes to look like a flower bouquet? a) It may terminate synapsis. b) It may facilitate chromosome alignment in preparation for synapsis. c) It may prevent chromosome alignment until synapsis begins. d) It may spread chromosomes out in preparation for synapsis. e) It may start the dissolution of the nuclear envelope.
b) It may facilitate chromosome alignment in preparation for synapsis.
5) What evidence suggests that a cell spends the majority of its time in interphase? a) Interphase is more useful. b) Only a small percentage of cells in a tissue or cell culture are seen to be in mitosis at any given time. c) A large percentage of cells in a tissue or cell culture are seen to be in mitosis at any given time. d) A moderate percentage of cells in a tissue or cell culture are seen to be in mitosis at any given time. e) Mitosis is too intricate a process to last very long.
b) Only a small percentage of cells in a tissue or cell culture are seen to be in mitosis at any given time.
10) DNA replication and the production of additional histones occur during what part of the cell cycle? a) G1 phase b) S phase c) G2 phase d) M phase e) G0 phase
b) S phase
66) How does securin get its name? a) Securin secures chromosomes to the cell membrane. b) Securin secures the attachment between sister chromatids. c) Securin determines which substances can enter the nucleus and which cannot. d) Securin secures the binding of the kinetochore to the chromosome. e) Securin attaches kinetochores to the spindle.
b) Securin secures the attachment between sister chromatids.
99) Why do the centromeres of sister chromatids stay firmly connected during anaphase I? a) They are fused together at the level of their double helices. b) The cohesin situated at the centromeres is protected from proteolytic attack. c) The cohesin situated at the centromeres is digested by nucleolytic enzymes. d) The DNA of the centromeres is hydrolyzed by proteolytic enzymes. e) The proteins of the centromere region are impervious to lipase digestion.
b) The cohesin situated at the centromeres is protected from proteolytic attack.
97) During which stage of meiosis is cohesion between chromosome arms lost? The homologous chromosomes of each bivalent separate during this stage as well, but the cohesion between the sister chromatids and their centromeres remains strong. a) anaphase II of meiosis b) anaphase I of meiosis c) telophase I of meiosis d) metaphase I of meiosis e) telophase II of meiosis
b) anaphase I of meiosis
60) The nuclear lamina are disassembled _________. a) as the interactions between nucleoporin complexes are disrupted and the proteins dissociate into the surrounding medium b) by depolymerization of the lamin filaments c) as their integrity is disrupted mechanically as holes are torn in the complexes by cytoplasmic dyneins associated with the outer nuclear membrane d) by cytoplasmic dyneins e) by cytoplasmic microtubules and microfilaments
b) by depolymerization of the lamin filaments
22) What disease can be defined as resulting from a breakdown in a cell's ability to regulate its own division? a) multiple sclerosis b) cancer c) emphysema d) diabetes e) heart disease
b) cancer
48) Even before cytokinesis has been completed, the two centrioles of a daughter cell disengage, an event that is triggered by the enzyme _________, which becomes activated late in mitosis. a) invertase b) centriolase c) separase d) disengagase e) activase
b) centriolase
41) As cells enter mitosis, their microtubules disassemble and then reassemble forming the mitotic spindle with a focus at the ________, a special animal cell microtubule-organizing structure. a) kinetosome b) centrosome c) kinetochore d) centromere e) chromosome
b) centrosome
89) As they separate, homologous chromosomes are seen to remain attached to each other at specific points by X-shaped structures at the crossover sites called _________. a) crossover sites b) chiasmata c) chiastrata d) diplonema e) crenata
b) chiasmata
37) What is responsible for holding sister chromatids together after replication? It holds the two chromatids together through G2 and into mitosis. a) compressin b) cohesin c) condensin d) connexin e) contractin
b) cohesin
34) What multiprotein complex has recently been shown to play a significant role in chromosome compaction? a) compressin b) condensin c) elastin d) loopin e) mitosin
b) condensin
4) The separation of the entire cell and its cytoplasm into two daughter cells is known as _______. a) meiosis b) cytokinesis c) chromokinesis d) chromatosis e) mitosis
b) cytokinesis
71) What occurs during pairing of chromosomes in prophase of meiosis I that increases genetic variability? a) further condensation of chromosomes b) genetic recombination between homologous chromosomes c) lots of mutations d) chromosomes lose lots of fragments e) gene duplication
b) genetic recombination between homologous chromosomes
96) The random assortment of chromosomes at anaphase I accounts for a large amount of the _________ within a species. a) stability b) genetic variability c) biochemical inhibition d) genetic uniformity e) genetic forbearance
b) genetic variability
76) What word below characterizes the adult generation that is produced after zygotic meiosis? a) diploid b) haploid c) enormous d) polyploid e) aneuploid
b) haploid
70) Cells that have a single set of chromosomes are said to have a _______ number of chromosomes; cells that contain two full sets of paired chromosomes are said to have a ______ number of chromosomes. a) diploid, haploid b) haploid, diploid c) diploid, diploid d) haploid, haploid e) monoploid, polyploidy
b) haploid, diploid
103) Due to the reciprocal exchange of DNA strands that occurs during genetic recombination, the two duplexes are covalently linked to one another to form a joint molecule called a(n) __________ that contains a pair of DNA crossovers called __________. a) homoduplex, Holliday junctions b) heteroduplex, Holliday junctions c) Holliday junction, heteroduplexes d) Holliday junction, homoduplexes e) heteroduplexes, junctional complexes
b) heteroduplex, Holliday junctions
25) The regulatory subunit of maturation-promoting factor ________. a) transfers a phosphate group to certain serine and threonine residues of specific protein substrates b) is called cyclin because its concentration rises and falls predictably as the cell cycle progresses c) converts ATP to ADP d) converts ADP to ATP e) transfers a phosphate group to certain tyrosine residues of specific protein substrates
b) is called cyclin because its concentration rises and falls predictably as the cell cycle progresses
82) During what stage do studies of mice and yeast cells suggest that DNA breaks leading to recombination begin? a) pachytene b) leptotene c) diakinesis d) zygotene e) diplotene
b) leptotene
13) Which cells typically have cell cycles lasting several months? a) cells in a cleaving frog embryo b) mammalian liver tissue c) mammalian embryo cells d) both cells in a cleaving frog embryo and mammalian embryo cells e) nerve cells
b) mammalian liver tissue
69) What is the name of the process during which chromosome number is reduced so that each cell has a haploid number of chromosomes? a) mitosis b) meiosis c) cytokinesis d) sexual differentiation e) meitosis
b) meiosis
102) During which phase of meiosis do the kinetochores of sister chromatids face opposite poles as they line up in the center of the cells? The centromeres of sister chromatids become attached to chromosomal spindle fibers from opposite spindle poles. a) prophase II b) metaphase II c) anaphase II d) metaphase I e) telophase II
b) metaphase II
32) Movement past the transition point near the end of G2 that moves cells on to mitosis requires cdc2 activation by _______. a) Na+ ions b) mitotic cyclins c) ATP d) Na+-K+ ATPase e) mitotic chromatin
b) mitotic cyclins
50) What apparently drives the separation of centrosomes? a) motor proteins associated with microfilaments b) motor proteins associated with adjacent microtubules c) contraction of individual microfilaments d) sliding of adjacent microfilaments over one another e) contraction of adjacent microtubules
b) motor proteins associated with adjacent microtubules
93) At metaphase I, the two homologous chromosomes of each bivalent are connected to spindle fibers from the _________. a) same spindle pole b) opposite spindle poles c) the centromere of its neighboring chromosome d) the centromere of its homologue e) random centromeres of other chromosomes
b) opposite spindle poles
94) Kinetochores of sister chromatids are connected as a unit to microtubules from __________. a) the same spindle pole b) opposite spindle poles c) the centromere of its neighboring chromosome d) the centromere of its homologue e) random centromeres of other chromosomes
b) opposite spindle poles
43) What triggers the start of centrosome duplication? a) phosphorylation of a centrosomal protein by ATPase b) phosphorylation of a centrosomal protein by Cdk2 c) dephosphorylation of a centrosomal protein by Cdk2 d) dephosphorylation of a centrosomal protein by ATPase e) phosphorylation of a centrosomal protein focal adhesion kinase
b) phosphorylation of a centrosomal protein by Cdk2
36) What activates condensin at the onset of mitosis? a) Na+ ions b) phosphorylation of several of its subunits by the Cdk-cyclin that drives cells from G2 into mitosis c) phosphorylation of several of its subunits by the Cdk-cyclin that drives cells from G1 into mitosis d) phosphorylation of several of its subunits by the Cdk-cyclin that drives cells from G1 into S phase e) dephosphorylation of several of its subunits by the Cdk-cyclin that drives cells from G2 into mitosis
b) phosphorylation of several of its subunits by the Cdk-cyclin that drives cells from G2 into mitosis
78) In the human female, when is prophase I of meiosis initiated? a) at puberty b) prior to birth c) between the ages of 4 and 6 d) at the beginning of each menstrual cycle e) at the end of each menstrual cycle
b) prior to birth
45) The process of centriole "replication" begins in the cytoplasm with the appearance of a small ________. a) pericentriole b) procentriole c) precentriole d) procentrosome e) pericentrosome
b) procentriole
72) Organisms in which meiotic divisions are closely linked to gamete formation, as in the case where meiosis occurs just prior to the differentiation of the spermatozoa, exhibit ___________. a) initial meiosis b) terminal meiosis c) zygotic meiosis d) sporic meiosis e) intermediate meiosis
b) terminal meiosis
98) What is required for the separation of homologous chromosomes at anaphase I? a) the separation of sister centromeres b) the dissolution of the chiasmata c) the dissolution of the centromeres d) the dissolution of the centrosomes e) the separation of nucleosomes
b) the dissolution of the chiasmata
33) What triggers the entry of a cell into mitosis? a) the addition of inhibitory phosphate groups to Cdk1 by the Cdc25 phosphatase b) the removal of inhibitory phosphate groups from Cdk1 by the Cdc25 phosphatase c) the addition of inhibitory phosphate groups to Cdk1 by the Wee1 kinase d) the removal of inhibitory phosphate groups from Cdk1 by the Wee1 kinase e) the removal of phosphate groups from the Wee1 kinase
b) the removal of inhibitory phosphate groups from Cdk1 by the Cdc25 phosphatase
29) Mammalian cells pass through a point comparable to START during G1, at which time they become committed to DNA replication and, ultimately, the completion of mitosis. What is this point called? a) START b) the restriction point c) the limitation point d) the commitment point e) BEGIN
b) the restriction point
35) What happens if any of the condensin proteins are removed from the frog egg extracts within which chromosome compaction can occur in vitro? a) Compaction continues unabated. b) Compaction occurs more quickly than normal. c) Compaction is prevented. d) The DNA expands further and fills the entire cell. e) Compaction occurs but occurs more slowly.
c) Compaction is prevented.
85) What is the function of the synaptonemal complex presently thought to be? a) It serves to initiate genetic recombination. b) It maintains RNA in association with the chromosomes. c) It functions primarily as a scaffold to allow interacting chromatids to complete crossover activities. d) It prevents the breakage of the DNA double helix at the wrong place. e) It assures that the DNA double helix breaks at exactly the right place.
c) It functions primarily as a scaffold to allow interacting chromatids to complete crossover activities.
21) What must happen in order for a cell to move to S phase from G1? a) It must divide. b) It must generate an external signal. c) It must receive a growth-promoting signal. d) It must divide and receive a growth-promoting signal. e) It must grow greatly.
c) It must receive a growth-promoting signal.
73) ___________ in males and _______ in females undergo mitosis giving rise to the cells that will carry out meiosis and eventually produce mature gametes. a) Oogonia, spermatogonia b) Spermatogonia, oocytes c) Spermatogonia, oogonia d) Oogonia, spermatocytes e) Spermatocytes, oocytes
c) Spermatogonia, oogonia
7) What is the average length of interphase? a) It is exactly 10 hours in all cells. b) It is 12 hours long. c) There is not a good average since it may extend for days, weeks or longer depending on the cell type and the conditions. d) It may last up to a day. e) On average, it lasts about 3 hours.
c) There is not a good average since it may extend for days, weeks or longer depending on the cell type and the conditions.
38) What appears to be responsible for the tighter adhesion between chromosomes seen at centromeres rather than along the chromosome arms? a) elevated phosphorylation b) a kinase found at the centromere that phosphorylates cohesin c) a phosphatase found at the centromere that removes phosphate groups from cohesin if they are added d) a phosphatase found in the chromosome arms that removes phosphate groups from cohesin e) a phosphatase found in the chromosome arms that adds phosphate groups to cohesin
c) a phosphatase found at the centromere that removes phosphate groups from cohesin if they are added
61) The integrity of the nuclear envelope is disrupted _________. a) as the interactions between nucleoporin complexes are disrupted and the proteins dissociate into the surrounding medium b) by depolymerization of the lamin filaments c) as its integrity is disrupted mechanically as holes are torn into it by cytoplasmic dyneins associated with the outer nuclear membrane d) by cytoplasmic kinesins e) by cytoplasmic microtubules and microfilaments
c) as its integrity is disrupted mechanically as holes are torn into it by cytoplasmic dyneins associated with the outer nuclear membrane
49) The sunburst arrangement of microtubules that forms around each centrosome during early prophase is called a(n) ________. a) sunburst b) arnost c) aster d) astral fiber e) barrel
c) aster
28) In fission yeast cells, at which sites is replication initiated? a) at randomly selected sites b) at sites where histones bind c) at sites where prereplication complexes have previously assembled d) at sites where RNA polymerase binds e) at sites that bind nucleosomes bind
c) at sites where prereplication complexes have previously assembled
90) What holds together the chromatid from one homologous chromosome to a non-sister chromatid of the other homologue at the site of a chiasma? a) H bonds b) ionic bonds c) covalent bonds d) disulfide linkages e) van der Waals forces
c) covalent bonds
54) What molecular motor has been implicated in the model of nuclear envelope dissolution that involves microtubules? a) myosin b) kinesin c) dynein d) calpain e) calmodulin
c) dynein
52) Microtubules are nucleated in cells with centrosomes in the vicinity of the centrosomes. Where do they nucleate in cells lacking centrosomes? a) in the vicinity of the nucleolus b) in the vicinity of the mitochondria c) in the vicinity of the chromosomes d) in the vicinity of the cell membrane e) in the vicinity of the lysosomes
c) in the vicinity of the chromosomes
100) The generally short-lived stage between the two meiotic divisions is called ________. a) interphase b) intermediacy c) interkinesis d) middlephase e) zwitterphase
c) interkinesis
8) When do most of the preparations for mitosis occur, including such activities as DNA replication? a) cytokinesis b) M phase c) interphase d) telophase e) enterophase
c) interphase
39) At the outer surface of the centromere of each chromatid is a proteinaceous, buttonlike structure called the __________. a) primary constriction b) residence c) kinetochore d) proteasome e) kinetosome
c) kinetochore
77) By what process are gametes produced from a gametophyte? a) meiosis b) cytokinesis c) mitosis d) fission e) replication
c) mitosis
57) What are the three major components of the nuclear envelope? a) nuclear pore complex, nuclear lemina, nuclear membranes b) RER, nuclear lamina, Na+-K+ pump c) nuclear pore complexes, nuclear lamina, nuclear membranes d) mitotic kinases, nuclear lemina, nuclear pore complexes e) phospholipids, nuclear pore complexes, nucleoplasm
c) nuclear pore complexes, nuclear lamina, nuclear membranes
30) What external stimulation is required by mammalian cells to progress through the cell cycle prior to reaching the restriction point? a) presence of steroid hormones in their culture medium b) presence of Na+ ions in their culture medium c) presence of growth factors in their culture medium d) no external stimulation is required e) presence of vitamins in their culture medium
c) presence of growth factors in their culture medium
101) During which stage of meiosis have the chromosomes become recompacted after interkinesis? They begin to line up at the metaphase plate and if the nuclear envelope had reformed earlier, it is once again broken down. a) telophase I b) telophase II c) prophase II d) metaphase II e) prophase I
c) prophase II
14) What stimulus can induce liver cells to proliferate? a) interaction with an appropriate antigen b) interaction with an appropriate antibody c) surgical removal of part of the liver d) a buildup of bile in the liver e) glycogen buildup in the liver
c) surgical removal of part of the liver
84) Synapsis is accompanied by the formation of a complex, ladderlike structure made of three parallel bars with transverse protein filaments connecting its central element with two lateral elements. What is the name of this structure? a) synaptonemal ladder b) ladderellen c) synaptonemal complex d) nuclear complex e) nucleolar complex
c) synaptonemal complex
67) On occasion, the two kinetochores of sister chromatids will become attached to microtubules from the same spindle pole; this condition is referred to as ________. a) osteosarcoma b) systolic attachment c) syntelic attachment d) opposite chromatid attachment e) synthetisism
c) syntelic attachment
63) What is the event that begins prometaphase? a) the complete compaction of the chromosomes b) the disappearance of the nucleolus c) the dissolution of the nuclear envelope d) the reappearance of the nucleolus e) the completion of the connection of chromosomes to the spindle
c) the dissolution of the nuclear envelope
86) What event marks the end of zygotene? a) the beginning of synapsis b) the beginning of genetic recombination c) the end of synapsis d) the start of metaphase e) the formation of the synaptonemal complex
c) the end of synapsis
81) What is the first step in genetic recombination? a) lengthening of the chromosomes b) the introduction of single-stranded breaks in aligned DNA molecules c) the introduction of double-stranded breaks in aligned DNA molecules d) the accurate alignment of DNA molecules e) the exchange of pieces of DNA between homologous chromosomes
c) the introduction of double-stranded breaks in aligned DNA molecules
2) Based on cell activities readily visible in the light microscope, there are two major cell cycle phases, ________ and __________. a) M phase, cytokinesis b) interphase, cytokinesis c) M phase, C phase d) M phase, interphase e) C phase, interphase
d) M phase, interphase
74) What usually happens to vertebrate eggs immediately after they have been fertilized? a) Cytokinesis begins. b) They start to grow. c) Mitosis begins. d) Meiosis is completed. e) The egg sheds lots of cytoplasm.
d) Meiosis is completed.
95) Anaphase I is the cytological event that corresponds to which scientific law? a) the first law of thermodynamics b) the second law of thermodynamics c) Mendel's law of segregation d) Mendel's law of independent assortment e) the Lambert - Beer law
d) Mendel's law of independent assortment
24) You are carrying out experiments in cell fusion by fusing together cells at different stages of the cell cycle. You then observe the behavior of each nucleus residing in the combined cytoplasm of the two cells. Which of the following responses would occur if you fused an S-phase cell to a cell in the M phase? a) The nucleus from the M phase cell started to replicate its DNA. b) The S-phase nucleus undergoes premature chromosomal condensation to form a set of elongated compacted chromosomes. c) The M phase nucleus is affected in such a way that its compacted chromosomes decondense. d) The chromatin in the S-phase nuclei is compacted, but pulverized chromosomal fragments form. e) The S-phase nucleus undergoes premature chromosomal condensation; the compacted chromosomes are visibly doubled.
d) The chromatin in the S-phase nuclei is compacted, but pulverized chromosomal fragments form.
62) What is an alternative to the classical view of the fate of the membranous portion of the nuclear envelope? a) fragmentation into a population of small vesicles that disperse throughout the mitotic cell b) absorption of the membranes of the nuclear envelope into the membranes of the Golgi complex c) absorption of the membranes of the nuclear envelope into the membranes of the peroxisomes d) absorption of the membranes of the nuclear envelope into the membranes of the ER e) absorption of the membranes of the nuclear envelope into the membranes of the nucleoplasm
d) absorption of the membranes of the nuclear envelope into the membranes of the ER
64) Which stage of mitosis starts as sister chromatids split apart and begin to move toward opposite poles? a) prophase b) metaphase c) prometaphase d) anaphase e) telophase
d) anaphase
104) The Holliday junction recombination intermediate is not a static structure because the linkage point may move in one direction or another, a process known as _________. a) slippage b) intrusion c) branch fusion d) branch migration e) extrusion
d) branch migration
75) At what stage of meiosis are vertebrate eggs usually fertilized? a) prophase II b) metaphase I c) interkinesis d) metaphase II e) anaphase I
d) metaphase II
31) What external stimulation is required by mammalian cells to progress through the cycle after they have passed the restriction point? a) the presence of steroid hormones in their culture medium b) the presence of Na+ ions in their culture medium c) the presence of growth factors in their culture medium d) no external stimulation is required after the restriction point is passed e) the presence of vitamins in their culture medium
d) no external stimulation is required after the restriction point is passed
92) Crossing-over is important for ___________. 1) for ensuring proper chromosome segregation 2) for ensuring proper chromosome miscegenation 3) introducing additional genetic variation into the population 4) delaying meiosis for an appropriate and necessary amount of time a) 1 b) 2 c) 3 d) 4 e) 1 and 3
e) 1 and 3
47) Even before cytokinesis has been completed, the two centrioles of a daughter cell _______. 1) are pulled closer together 2) lose their close association to one another 3) become disengaged 4) become disingenuous a) 1 b) 2 c) 3 d) 4 e) 2 and 3
e) 2 and 3
17) Asymmetric divisions _________. 1) allow stem cells to engage in self-immolation 2) allow stem cells to engage in apoptosis 3) allow stem cells to engage in self-renewal 4) allow stem cells to engage in the formation of differentiated tissue cells a) 1 b) 2 c) 3 d) 4 e) 3 and 4
e) 3 and 4
23) You are carrying out experiments in cell fusion by fusing together cells at different stages of the cell cycle. You then observe the behavior of each nucleus residing in the combined cytoplasm of the two cells. Which of the following responses would occur if you fused a G2 cell to a cell in the M phase? 1) The nucleus from the G1 cell started to replicate its DNA. 2) The G2 nucleus undergoes premature chromosomal condensation to form a set of elongated compacted chromosomes. 3) The M phase nucleus is affected in such a way that its compacted chromosomes decondense. 4) The G2 nucleus undergoes premature chromosomal condensation, but the compacted chromosomes are visibly doubled. a) 1 b) 2 c) 3 d) 1 and 3 e) 4
e) 4
15) Which of the cells below normally possess a relatively high level of mitotic activity? a) stem cells of various adult tissues b) hematopoietic stem cells that give rise to red and while blood cells c) stem cells at the base of numerous epithelia that line the body cavities d) the relatively unspecialized cells found near the tips of plant roots and stems e) All of these are correct.
e) All of these are correct.
46) Which of the following has been implicated as a possible linker of a kinetochore to dynamic microtubules? a) motor proteins b) a rod-shaped protein called Ndc80 c) a member of the kinesin superfamily, CENP-E d) Dam-1 e) All of these are correct.
e) All of these are correct.
20) Cells that have stopped dividing and are arrested in a stage preceding the initiation of DNA synthesis are said to be in a ______ state. a) G1 phase b) S phase c) G2 phase d) M phase e) G0 phase
e) G0 phase
26) The first transition point in yeast cells that commits the cells to entering S phase occurs just before the end of ___ and is called _______. a) G2, START b) G1, MPF c) G2, MPF d) G1, BEGIN e) G1, START
e) G1, START
16) What property below do stem cells not share with most cells? a) They exhibit asymmetric cell division. b) They do not replicate their DNA before cell division. c) The two daughter cells have different properties or fates. d) They exhibit symmetric cell division. e) They exhibit asymmetric cell division and the two daughter cells have different properties or fates.
e) They exhibit asymmetric cell division and the two daughter cells have different properties or fates.
18) What types of non-stem cells below also engage in asymmetric or unequal divisions? a) formation of oocytes and polar bodies b) formation of spermatogonia c) division of the T cell d) division of the B cell e) both formation of oocytes and polar bodies and division of the T cell
e) both formation of oocytes and polar bodies and division of the T cell
88) What stage of prophase I is usually recognized by the dissolution of the synaptonemal complex and the tendency of homologous chromosomes of the bivalents to pull away somewhat from each other? a) pachytene b) leptotene c) diakinesis d) zygotene e) diplotene
e) diplotene
91) During which stage of prophase I does the bulk of oocyte growth occur? a) pachytene b) leptotene c) diakinesis d) zygotene e) diplotene
e) diplotene
3) The separation of duplicated chromosomes into two daughter nuclei is known as ________. a) meiosis b) cytokinesis c) chromokinesis d) chromatosis e) mitosis
e) mitosis
