Chapter 12 : The Cell Cycle - Homework Questions
(Refer to table 12.3) For the experiment shown in Figure 12.3, which answer best describes what the prediction would be if chromosome movement were based on microtubule shortening at the spindle pole? a.) The darkened section will move toward the spindle pole but the distance between chromosomes and the darkened section will remain constant. b.) Daughter chromosomes will move toward the pole faster than the darkened section. c.) The darkened section will disappear as soon as chromosomes begin to move. d.) The darkened section will remain stationary but the distance between chromosomes and the darkened section will decrease.
A
(Refer to table 12.4) The experiment shown in Figure 12.4 was done using cytoplasm. What could the investigators do to determine whether the regulatory molecule was present in the cytosol or in a cytoplasmic organelle? a.) Use differential centrifugation to separate the organelles and cytosol from M-phase cells and microinject only the organelles into the frog oocytes. b.) Use gel electrophoresis to separate the organelles and cytosol from M-phase cells and microinject only the organelles into the frog oocytes. c.) Use radioactive isotope labeling to separate the organelles and cytosol from M-phase cells and microinject only the organelles into the frog oocytes. d.) Use fluorescent labels to separate the organelles and cytosol from M-phase cells and microinject only the organelles into the frog oocytes.
A
Acceding to this research, which of the following is in the correct order for cause of mutation leading to cancer from least likely to most likely? a.) Heredity, environment, random error b.) Environment, heredity, random error c.) Environment, random error, heredity d.) Random error, environment, heredity
A
Chromosomes become visible during _____. a.) prophase b.) anaphase c.) prometaphase d.) interphase e.) metaphase
A
Chromosomes contain __________. a.) two types of macromolecules: nucleic acid and protein b.) no macromolecules, just DNA c.) no macromolecules, just information d.) one type of macromolecule: nucleic acid
A
If a mutation has not occurred during DNA replication, how many different alleles of a gene would a replicated chromosome have? a.) one b.) one or two c.) two d.) many, depending on the gene
A
What major events occur during anaphase of mitosis? a.) The sister chromatids of replicated chromosomes separate, and the spindle poles are pushed farther apart. b.) Chromosomes condense and the nuclear envelope disappears. c.) Chromosomes replicate, so each chromosome consists of two identical sister chromatids. d.) The sister chromatids end up at opposite ends of the cell, and two nuclear envelopes form around them.
A
Which of the following people most likely got cancer because of environmental factors? a.) A 47-year-old woman with lung cancer. b.) A 52-year-old woman with bone cancer. c.) A 67-year-old man with prostate cancer. d.) A 36-year-old man with brain cancer.
A
_____ is a carcinogen that promotes colon cancer. a.) fat b.) UV light c.) estrogen d.) a virus e.) testosterone
A
(Refer to table 12.2) Identify whether each statement about this cell model is true or false. 1. There are 12 chromosomes. 2. There are 12 chromatids. 3. Each chromatid contains a single molecule of double-stranded DNA. 4. Each chromatid within a chromosome contains the same set of genes. 5. Each chromosome contains both DNA and protein.
1. False 2. True 3. True 4. True 5. True
Identify the events in the cell cycle that must be completed successfully for daughter cells to share an identical complement of chromosomes. 1. the sister chromatids of each replicated chromosome must be partitioned in anaphase and fully separated into daughter cells by cytokinesis 2. the sister chromatids of each replicated chromosome must be partitioned in the G2 phase and fully separated into daughter cells by cytokinesis 3. all the chromosomes must be replicated during the prophase 4. the spindle apparatus must connect with the kinetochores of each sister chromatid in prometaphase 5. the spindle apparatus must connect with the ends of each sister chromatid in prometaphase 6. all the chromosomes must be replicated during the S phase
1, 4, 6 only
Microtubules are actively __________ during the start of ___________, when the mitotic spindle is produced. During ______________, the kinetochore microtubules are _____________ as daughter chromosomes move to opposite poles of the cell. At the end of ___________, the spindle microtubules are _____________ to remove the spindle before entering ___________.
1. polymerized 2. M phase 3. anaphase 4. depolymerized 5. anaphase 6. depolymerized 6. G1 phase
(Refer to table 12.5) Use these results to hypothesize how the stathmin protein affects microtubule stability. a.) The stathmin protein binds to Taxol and inhibits its effect. b.) The stathmin protein decreases the stability of microtubules. When stathmin is absent, the microtubule-stabilizing effect of Taxol is enhanced, and the cells are more likely to arrest. c.) The stathmin protein makes the cell membrane less permeable for the compounds like Taxol, therefore, Taxol couldn't reach a satisfactory concentration within the cell and doesn't affect significantly on microtubules' depolymerization. d.) The stathmin protein enhances particular pathways of Taxol catabolism, so it is neutralized quite quickly in comparison to when the stathmin is absent.
B
Cytokinesis often, but not always, accompanies _____. a.) anaphase b.) telophase c.) interphase d.) prometaphase e.) metaphase
B
During _____ both the contents of the nucleus and the cytoplasm are divided. a.) G1 b.) the mitotic phase c.) G2 d.) mitosis e.) S
B
Nucleoli are present during _____. a.) anaphase b.) interphase c.) prophase d.) prometaphase e.) metaphase
B
The defining characteristic of a malignant tumor is that _____. a.) its cells cannot cause cancer b.) its cells can spread to other parts of the body and produce secondary tumors c.) it grows in a single location and does not spread to other locations d.) it is benign
B
What two types of defects does a cancerous cell possess? a.) Cancerous cells lack the ability to carry out cellular respiration and photosynthesis. b.) Cancerous cells possess defects that make proteins required for cell growth active and tumor suppressor genes inactive. c.) Cancerous cells possess defects that make proteins required for cell growth inactive and tumor suppressor genes active. d.) Cancerous cells are prevented from dividing and have inhibited growth patterns.
B
How many different alleles of a certain gene could a normal diploid organism have? a.) one b.) one or two c.) two d.) many, depending on the gene
B; A heterozygote organism can have up to two different alleles, but homozygotes have two copies of one allele.
What is the relationship among chromosomes, DNA, and genes? a.) Chromosomes are genes composed of DNA. b.) Genes are encoded by DNA and found within chromosomes. c.) Genes produce DNA and chromosomes. d.) The terms DNA, genes, and chromosomes can be used interchangeably.
B; Chromosomes are composed of DNA and protein, and DNA is composed of genes and noncoding regions.
According to this research, which of the following is true? a.) When it comes to cancer, the United States is unique compared to other countries. b.) When it comes to cancer, developed countries are very different from developing countries. c.) When it comes to cancer, developed countries are very similar to developing countries. d.) Comparisons of cancer among countries has not been looked at.
C
Cancer is characterized by mutations that do what? a.) Stop cell division. b.) Slow cell growth. c.) Promote abnormal cell growth and division. d.) Cause lysis in healthy cells.
C
Which answer correctly identifies a cell-cycle checkpoint with a criterion for passing it? a.) G1 checkpoint: Chromosomes have replicated successfully. b.) Metaphase checkpoint: DNA is undamaged. c.) G2 checkpoint: Chromosomes have replicated successfully. d.) S checkpoint: DNA is undamaged.
C
Which of the following is an example of a lifestyle factor? a.) Gender b.) Age c.) Diet d.) Genetic makeup
C
Chapter 12 : The Cell Cycle - Homework Questions
Chapter 12 : The Cell Cycle - Homework Questions
Case Study: Aggressive forms of breast cancer are resistant to Taxol chemotherapy. In these cancers, the gene encoding a protein called stathmin is overexpressed. To investigate the mechanism of action of stathmin, investigators measured tumor volume over time in mice with aggressive cancers under three conditions: no treatment (control), Taxol treatment, and Taxol treatment with stathmin gene expression turned off (Taxol + Δstathmin). Their results are shown below.
Continue
During _____ the cell grows and replicates both its organelles and its chromosomes. a.) cytokinesis b.) G1 c.) S d.) interphase e.) mitosis
D
How would the removal of growth factors affect asynchronous cultures of (1) normal human cells and (2) most human cancer cells? a.) (1) No effect; (2) arrest in G2. b.) (1) No effect; (2) arrest in G1 c.) (1) Arrest in G2; (2) no effect d.) (1) Arrest in G1; (2) no effect
D
What evidence suggests that during anaphase, kinetochore microtubules shorten at the kinetochore? a.) Microtubules shorten at the spindle pole. b.) The kinetochore microtubules remain stationary during anaphase, but shorten because tubulin subunits are lost from their minus ends. c.) Daughter chromosomes were observed to move toward the pole slower than do the marked regions of fluorescently labeled kinetochore microtubules. d.) Daughter chromosomes were observed to move toward the pole faster than do the marked regions of fluorescently labeled kinetochore microtubules.
D
What role(s) do gap phases play in the cell cycle? a.) They allow chromosome replication to occur. b.) They allow chromosomes to condense prior to mitosis. c.) They allow the nuclear envelope to re-form after mitosis. d.) They allow cells to replicate organelles and manufacture additional cytoplasm.
D; G1 and G2 phases allow the cell to complete these steps so that daughter cells produced in M phase will be normal in size and function.
What would happen if the kinase that adds the inhibitory phosphate to Cdk were defective? a.) Cdk concentrations would spike. b.) The onset of M phase would be delayed. c.) MPF levels would become abnormally high. d.) M phase would begin prematurely.
D; Inhibitory phosphorylation of Cdk normally occurs in interphase, when cyclin levels are increasing, and inhibits the Cdk subunit of MPF from prematurely catalyzing the phosphorylation reactions that trigger M phase.
A strain of Staphylococcus aureus bacteria has become resistant to the powerful antibiotic methicillin, causing numerous lethal infections at a local hospital. The outbreak is a direct result of changes to the bacteria's __________. a.) phenotype b.) alleles c.) genotype and phenotype d.) alleles, genotype, and phenotype e.) alleles and genotype
D; One or more mutations caused a new allele to increase in frequency in the antibiotic-resistant population of bacteria, changing both its genotype and phenotype.
(Refer to table 12.1) Which of these phases encompasses all of the stages of mitosis but no other events? a.) A b.) B c.) C d.) D e.) E
E
Centromeres divide and sister chromatids become full-fledged chromosomes during _____. a.) interphase b.) telophase c.) metaphase d.) prometaphase e.) anaphase
E
During prophase a homologous pair of chromosomes consists of _____. a.) two chromosomes and two chromatids b.) one chromosome and two chromatids c.) one chromosome and four chromatids d.) four chromosomes and two chromatids e.) two chromosomes and four chromatids
E
Spindle fibers attach to kinetochores during _____. a.) interphase b.) metaphase c.) anaphase d.) telophase e.) prometaphase
E
Which of these is NOT a carcinogen? a.) cigarette smoke b.) fat c.) UV light d.) testosterone e.) all of the above are carcinogens
E
