Bio 111 Exam 4
If there are 24 centromeres in a cell at anaphase of mitosis, how many chromosomes will be found in each daughter cell following cytokinesis?
12
If a cell at metaphase of mitosis contains 32 sister chromatids, how many chromosomes will be present in a G1 cell?
16
In a diploid cell with four chromosome pairs (2n = 8), how many sister chromatids will be found in a nucleus at prophase of mitosis?
16
A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 10 picograms of DNA per nucleus. Approximately how many picograms of DNA would be found in a nucleus at prophase of mitosis?
20
Beginning with a fertilized egg (zygote), how many cells will be present in the embryo following five rounds of cell division?
32
Quaking aspen trees usually reproduce by extending underground stems that then push aboveground and grow into trees. Sexual reproduction is not as common, but when it does happen, the haploid gametes have 19 chromosomes. How many chromosomes are in the cells of the underground stems?
38
The figure represents the nucleus of an animal cell about to enter mitosis. How many different chromosomes are present in the diagram?
4
In a diploid cell with four chromosome pairs (2n = 8), how many centromeres will be found in a nucleus at G2 of the cell division cycle?
8
Which of the following properties is associated with a cyclin-dependent kinase (Cdk)?
A Cdk is an enzyme that attaches phosphate groups to other proteins.
Some cases of human melanoma have been shown to result from inhibition of apoptosis in these cells. The human analogue of which of the following defects in C. elegans could cause these cancers?
A ced-3 protein that is always inactive.
Which of the following statements describes an example of alternation of generations?
A diploid plant (sporophyte) produces a spore by meiosis that gives rise to a multicellular, haploid pollen grain (gametophyte).
Which of the following structures or molecules is required in order for motor proteins to facilitate movement of chromosomes toward the poles in mitosis?
ATP as an energy source
Which of the following statements best describes the mechanism by which the ced-9 protein in the nematode C. elegans prevents apoptosis in normal cells?
Active ced-9 prevents activation of the caspase activity of ced-3.
Which of the following statements best describes density-dependent inhibition?
As cells become more numerous, the cell surface proteins of one cell contact the adjoining cells, and they signal each other to stop dividing.
Chapter 11: Which of the following statements best describes a reason that C. elegans is an excellent model organism for investigating apoptosis?
C. elegans undergoes a fixed and easy-to-visualize number of apoptotic events during its normal development.
Which of the following molecules is maintained at a relatively constant level throughout the cell cycle but requires a cyclin to become catalytically active?
Cdk
Cells from advanced malignant tumors often have very abnormal chromosomes and an abnormal number of chromosomes. Which of the following best explains the association between malignant tumors and chromosomal abnormalities?
Cell cycle checkpoints are not in place to stop cells with chromosome abnormalities.
Certain unicellular eukaryotes, including diatoms and some yeasts, have mechanisms of nuclear division that resemble intermediate steps in the evolution of mitosis. Which of the following is a characteristic feature of nuclear division in these organisms?
Chromosomes are segregated by a mitotic spindle, but the nuclear envelope remains intact during division.
Chapter 12: Eukaryotic chromatin is composed of which of the following macromolecules?
DNA and proteins
Which of the following statements is true of a species that has a chromosome number of 2n = 16?
Each diploid cell has eight homologous pairs of chromosomes.
Cell A has half as much DNA as cells B, C, and D in a mitotically active tissue. Cell A is most likely in ________.
G1
The mass of DNA per nucleus in a certain fungus ranges from 4 to 10 picograms. Nuclei with 5 picograms of DNA are most likely derived from cells in which of the following parts of the cell cycle?
G1
Which of the following events happens at the conclusion of meiosis I?
Homologous chromosomes of a pair are separated from each other.
Cells from a diploid protist with n=1 are followed through mitosis and meiosis. The drawings in the figure below represent the chromosomes. Refer to the drawings and answer the following question(s). Which diagram represents anaphase I of meiosis?
I
Amount of DNA per nucleus over the cell division cycle. G1 is represented by which numbered part(s) of the cell division cycle in the accompanying figure?
I and V
Amount of DNA per nucleus over the cell division cycle. Which region of the accompanying figure represents S phase?
II
For the following question, match the key event of meiosis with the stages listed below. I. Prophase I V. Prophase II II. Metaphase I VI. Metaphase II III. Anaphase I VII. Anaphase II IV. Telophase I VIII. Telophase II Homologous chromosomes are aligned at the middle of the spindle.
II
The unlettered circle at the top of the accompanying figure shows a diploid nucleus with four unreplicated chromosomes. The circles labeled 1 to 5 show various combinations of these chromosomes. Which chromosomal configuration would be observed at prometaphase of mitosis?
II
Amount of DNA per nucleus over the cell division cycle. At which point in the accompanying figure does MPF reach its highest activity during the cell division cycle?
III
Amount of DNA per nucleus over the cell division cycle. Which numbered regions of the accompanying figure represent the DNA content associated with cells at metaphase?
III only
Which of the following statements about reproduction is correct?
In sexual reproduction, individuals transmit half of their nuclear genes to each of their offspring.
A research team used a culture of lymphocytes with radioactively labeled T nucleotides to study the cell cycle. They found that the lymphocytes incorporated the labeled nucleotide at a significantly higher rate after a pathogen was introduced into the culture. Which of the following conclusions is most consistent with the results?
Infection causes lymphocytes to divide more rapidly.
A cell has completed meiosis I and the first cytokinesis, and is just beginning meiosis II. Which of the following statements describes its genetic contents?
It has half the amount of DNA as the cell that began meiosis.
A particular organism has 46 chromosomes in its karyotype. Which of the following statements is correct regarding this organism?
It produces gametes with 23 chromosomes.
Which of the following characteristics would be most important for a chemotherapeutic drug designed to treat cancer cells?
It specifically inhibits the cell division cycle in rapidly dividing cells.
One type of eukaryotic cell (line 1) spends 24 minutes in S phase and another type of cell (line 2) spends 48 minutes in S phase. Which of the following statements is the best explanation for the difference in time spent in S phase by cell lines 1 and 2?
Line 2 contains more DNA than line 1.
Progression beyond the G2 checkpoint into mitosis is triggered by which of the following molecules?
MPF
Which of the following statements best describes how cytokinesis differs between plant and animal cells?
Plant cells deposit vesicles containing cell wall building blocks on the metaphase plate; animal cells form a cleavage furrow.
A triploid cell contains three sets of homologous chromosomes. Which of the following describes the chromosomes in a triploid cell where n = 6?
The cell has 18 total chromosomes in 6 sets.
Which of the following statements best describes the events of apoptosis?
The cell's DNA and organelles become fragmented, the cell shrinks and forms blebs, and the cell's parts are packaged in vesicles that are digested by specialized cells.
Which of the following statements describes the chromosomal makeup of each daughter cell after telophase of meiosis I?
The cells are haploid, and the chromosomes are each composed of two chromatids.
How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I?
The cells have half the number of chromosomes and one-fourth the amount of DNA.
Which of the following statements best describes cells in culture that do not exhibit either density-dependent inhibition or anchorage dependence?
The cells show characteristics of tumors.
Which of the following statements best describes what would happen if MPF (maturation-promoting factor) is introduced into immature frog oocytes that are arrested in G2?
The cells would enter mitosis.
Which of the following statements best describes what happens to MPF during mitosis?
The cyclin component of MPF is degraded.
The somatic cells of a particular plant each contain a total of 46 chromosomes. How do the chromosomes of this plant differ from the chromosomes of humans, who also have a total of 46?
The genes on this plant's largest chromosome are significantly different than those on the largest human chromosome.
Exposure of zebrafish nuclei to cytosol isolated from eggs at metaphase of mitosis resulted in phosphorylation of NEP55 and L68 proteins by cyclin-dependent kinase 2. NEP55 is a protein of the inner nuclear membrane, and L68 is a protein of the nuclear lamina. What is the most likely role of phosphorylation of these proteins in the process of mitosis?
They are involved in the disassembly of the nuclear envelope.
Which of the following statements best describes homologous chromosomes?
They carry information for the same traits.
Which of the following statements best explains how neurons and some other specialized cells divide infrequently?
They have entered into G0.
Cells from a diploid protist with n=1 are followed through mitosis and meiosis. The drawings in the figure below represent the chromosomes. Refer to the drawings and answer the following question(s). Which diagram represents anaphase II of meiosis?
V
The unlettered circle at the top of the accompanying figure shows a diploid nucleus with four chromosomes that have not yet replicated. The circles labeled 1 to 5 show various combinations of these chromosomes.
V
For the following question, match the key event of meiosis with the stages listed below. I. Prophase I V. Prophase II II. Metaphase I VI. Metaphase II III. Anaphase I VII. Anaphase II IV. Telophase I VIII. Telophase II Cohesins at centromeres of sister chromatids breakdown.
VII
For the following question, match the key event of meiosis with the stages listed below. I. Prophase I V. Prophase II II. Metaphase I VI. Metaphase II III. Anaphase I VII. Anaphase II IV. Telophase I VIII. Telophase II Haploid cells form containing joined sister chromatids.
VIII
Which of the following statements about the human X chromosomes is correct?
Which of the following statements about the human X chromosomes is correct?
Which of the following statements correctly describes a karyotype?
Which of the following statements correctly describes a karyotype?
A loss of function of Apaf1, the human homologue of ced-4 in nematodes, is most likely to result in which of the following?
a form of cancer in which normal apoptosis fails
Which of the following statements best describes a cleavage furrow?
a groove in the plasma membrane between daughter nuclei
Through a microscope, you can see a cell plate beginning to develop across the middle of a cell and nuclei forming on either side of the cell plate. This cell is most likely ________.
a plant cell in the process of cytokinesis
Which of the following characteristics are part of the sexual life cycle of most fungi but are not part of the sexual life cycles of plants or animals?
a unicellular haploid stage
Which of the following statements describes a characteristic feature of metaphase?
alignment of chromosomes on the equator of the cell
Which of the following processes will most likely produce a human zygote with 45 chromosomes?
an error during anaphase II while the sperm was produced
In which phase of mitosis do the sister chromatids become daughter chromosomes?
anaphase
In the cells of some organisms, mitosis occurs without cytokinesis. This will result in ________.
cells with more than one nucleus
What is the name of the microtubule-organizing center found in animal cells as an identifiable structure present during all phases of the cell cycle?
centrosome
Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol prevents microtubule depolymerization, which interferes with which of the following processes?
chromosome separation
The drug cytochalasin B blocks the function of actin. Which of the following aspects of the animal cell cycle would be most disrupted by cytochalasin B?
cleavage furrow formation and cytokinesis
The drug cytochalasin B blocks the polymerization of actin microfilaments. Which of the following events of the cell cycle in animal cells would be most directly disrupted by cytochalasin B?
cleavage furrow formation and cytokinesis
Chapter 13 If a plant biologist succeeds in generating a single plant with a particularly desirable flower, which of the following approaches would be the most efficient way to generate more plants with this trait?
clone the plant
One difference between cancer cells and normal cells is that cancer cells ________.
continue to divide even when they are tightly packed together
Which of the following molecules is synthesized at specific times during the cell cycle and forms an active complex with a kinase?
cyclin
Which of the following pairs of molecules make up an active MPF?
cyclin and a cyclin-dependent kinase
Vinblastine is a standard chemotherapeutic drug used to treat cancer. Because it interferes with the assembly of microtubules, its effectiveness must be related to ________.
disruption of mitotic spindle formation
During which of the following processes do sister chromatids separate from each other?
during both mitosis and meiosis II
Which of the following events characterizes the beginning of anaphase?
enzymatic cleavage of cohesin
Many diploid organisms produce haploid gametes for reproduction. Which of the following best describes how the diploid number of chromosomes is restored in the offspring of these organisms?
fertilization combines chromosomes from each parent into resulting zygote
Which of the following occurs during apoptosis?
fragmentation of the DNA
Which of the following processes best describes the mechanism of gamete production in plants?
gametophytes produce gametes by mitosis
At what stage of the cell cycle is the cyclin component of MPF destroyed?
in late M
Students in a biology lab isolated cells in various phases of the cell cycle. A population of cells that have twice the DNA of G1 phase cells was most likely isolated from which of the following part of the cell cycle?
in the G2 phase
Students in a biology lab isolated cells in various phases of the cell cycle. A population of cells that have 1 1/2 times the DNA of G1 phase cells was most likely isolated from which of the following parts of the cell cycle?
in the S phase
Besides the ability of some cancer cells to over proliferate, which of the following situations is most likely to result in a tumor?
lack of appropriate cell death
In a human karyotype, chromosomes are arranged in 23 pairs. If one of the autosomal pairs is examined, which of the following characteristics will the two chromosomes of the pair have in common?
loci and staining pattern
If all chromosomes are not attached to the mitotic spindle at the M phase checkpoint, the cells would most likely be arrested at which of the following points in the cell division cycle or mitosis?
metaphase
Asexual reproduction occurs during which of the following processes?
mitosis
Which of the following cellular events occur in the G1 phase of the cell division cycle?
normal growth and cell function
At which phase of the cell cycle do centrioles begin to move apart in animal cells?
prophase
Which of the following processes has just occurred when chiasmata can first be viewed under a microscope?
prophase I
Which of the following events would be most likely to produce cells with several nuclei?
repeated mitosis without cytokinesis
Which of the following events occurs during interphase of the cell cycle?
replication of the DNA
Which of the following occurs during S phase?
replication of the DNA
If the cell whose nuclear material is shown in the accompanying figure continues toward completion of mitosis, which of the following events would occur next?
segregation of daughter chromosomes
The mitotic spindle plays a critical role in which of the following processes?
separation of sister chromatids
Movement of the chromosomes during anaphase would be most directly affected by a drug that prevents which of the following events?
shortening of microtubules
After DNA replication, each duplicated chromosome consists of two of which of the following structures?
sister chromatids
Which of the following processes occurs in meiosis but not in mitosis?
synapsis of chromosomes
What is the name of the region on duplicated chromosomes where the sister chromatids are most closely attached to each other?
the centromere
FtsZ is a bacterial protein that forms a contractile ring involved in binary fission. Its function is analogous to which of the following structures in eukaryotic cells?
the cleavage furrow of eukaryotic animal cells
Which of the following phrases defines the term genome?
the complete set of an organism's genes and other DNA sequences
The decline of MPF activity at the end of mitosis is due to ________.
the degradation of cyclin