Cells Phases

Answer Key 1) A 2) C 3) B 4) D 5) A 6) B 7) B 8) D 9) A 10) C 11) B 12) A 13) D 14) A 15) A 16) B 17) B 18) A 19) D 20) B 21) C 22) D 23) B 24) A 25) C 26) A 27) D 28) C 29) D 30) A 31) D 32) B 33) C 34) D 35) C 36) C 37) D 38) D 39) D 40) A Exam Name___________________________________ MULTIPLE CHOICE. Choose the one alternative that best completes the statement or answers the question. 1) What is the final result of mitosis in a human? A) genetically identical 2n somatic cells C) genetically identical 1n somatic cells B) genetically different 2n somatic cells D) genetically identical 2n gamete cells 2) Starting with a fertilized egg (zygote), a series of five cell divisions would produce an early embryo with how many cells? A) 8 B) 16 C) 32 3) If there are 20 duplicated chromosomes in a cell, how many centromeres are there? A) 10 B) 20 C) 30 4) Scientists isolate cells in various phases of the cell cycle. They find a group of cells that have 1 D) 64 D) 40 1 2 times more DNA than G 1 phase cells. The cells of this group are _____. A) between the G1 and S phases in the cell cycle B) in the G 2 phase of the cell cycle C) in the M phase of the cell cycle D) in the S phase of the cell cycle 5) The first gap in the cell cycle (G 1) corresponds to _____. A) normal growth and cell function B) the phase in which DNA is being replicated C) the beginning of mitosis D) the phase between DNA replication and the M phase 6) The microtubule-organizing center found in animal cells is an identifiable structure present during all phases of the cell cycle. Specifically, it is known as the _____. A) microtubulere B) centrosome C) centromere D) kinetochore 7) In human and many other eukaryotic species' cells, the nuclear membrane has to disappear to permit _____. A) cytokinesis B) the attachment of microtubules to kinetochores C) the splitting of the centrosomes D) the disassembly of the nucleolus 8) The mitotic spindle is a microtubular structure that is involved in _____. A) splitting of the cell (cytokinesis) following mitosis B) triggering the compaction and condensation of chromosomes C) dissolving the nuclear membrane D) separation of sister chromatids 9) Metaphase is characterized by _____. A) aligning of chromosomes on the equator C) cytokinesis B) splitting of the centromeres D) separation of sister chromatids 10) Some cells have several nuclei per cell. How could such multinucleated cells be explained? A) The cell underwent repeated cytokinesis but no mitosis. B) The cell underwent repeated mitosis with simultaneous cytokinesis. C) The cell underwent repeated mitosis, but cytokinesis did not occur. D) The cell had multiple S phases before it entered mitosis. 11) How is plant cell cytokinesis different from animal cell cytokinesis? A) The contractile filaments found in plant cells are structures composed of carbohydrates; the cleavage furrow in animal cells is composed of contractile phospholipids. B) Plant cells deposit vesicles containing cell-wall building blocks on the metaphase plate; animal cells form a cleavage furrow. C) The structural proteins of plant cells separate the two cells; in animal cells, a cell membrane separates the two daughter cells. D) Plant cells divide after metaphase but before anaphase; animal cells divide after anaphase. 12) If there are 20 centromeres in a cell at anaphase, how many chromosomes are there in each daughter cell following cytokinesis? A) 10 B) 20 C) 40 D) 80 13) A group of cells is assayed for DNA content immediately following mitosis and is found to have an average of 8 picograms of DNA per nucleus. How many picograms would be found at the end of S and the end of G 2? A) 8; 8 B) 8; 16 C) 16; 8 D) 16; 16 Use the following information to answer the questions below. The unlettered circle at the top of the figure shows a diploid nucleus with four chromosomes that have not yet replicated. There are two pairs of homologous chromosomes, one long and the other short. One haploid set is black, and the other is gray. The circles labeled A to E show various combinations of these chromosomes. 14) What is the correct chromosomal condition at prometaphase of mitosis? A) B B) C C) D D) E The following questions are based on the accompanying figure. 15) In the figure above, G1 is represented by which numbered part(s) of the cycle? A) I or V B) II or IV C) III only 16) Which of the following does NOT occur during mitosis? A) condensation of the chromosomes C) spindle formation D) V only B) replication of the DNA D) separation of the spindle poles 17) Neurons and some other specialized cells divide infrequently because they _____. A) no longer have active nuclei B) have entered into G 0 C) can no longer bind Cdk to cyclin D) show a drop in MPF concentration 18) Which of the following is released by platelets in the vicinity of an injury? A) PDGF B) MPF C) cyclin D) Cdk 19) Which of the following defines a genome? A) the complete set of an organism's polypeptides B) the complete set of a species' polypeptides C) a karyotype D) the complete set of an organism's genes and other DNA sequences 20) Asexual reproduction occurs during _____. A) meiosis B) mitosis C) fertilization D) chromosome exchange between organisms of different species 21) Which of the following is true of a species that has a chromosome number of 2n = 16? A) The species is diploid with 32 chromosomes per cell. B) The species has 16 sets of chromosomes per cell. C) Each diploid cell has eight homologous pairs. D) A gamete from this species has four chromosomes. 22) A given organism has 46 chromosomes in its karyotype. Therefore, we can conclude that it must _____. A) be human B) be an animal C) reproduce sexually D) have gametes with 23 chromosomes 23) Homologous chromosomes _____. A) are identical C) carry the same alleles B) carry information for the same traits D) align on the metaphase plate in meiosis II 24) If a cell has completed meiosis I and is just beginning meiosis II, which of the following is an appropriate description of its contents? A) It has half the amount of DNA as the cell that began meiosis. B) It has half the chromosomes but twice the DNA of the originating cell. C) It has one-fourth the DNA and one-half the chromosomes as the originating cell. D) It is identical in content to another cell formed from the same meiosis I event. 25) How do cells at the completion of meiosis compare with cells that are in prophase of meiosis I? They have _____. A) half the number of chromosomes and half the amount of DNA. B) the same number of chromosomes and half the amount of DNA. C) half the number of chromosomes and one-fourth the amount of DNA. D) half the amount of cytoplasm and twice the amount of DNA. Refer to the drawings in the figure below of a single pair of homologous chromosomes as they might appear during various stages of either mitosis or meiosis, and answer the following questions. 26) Which diagram represents anaphase I of meiosis? A) I B) II C) IV D) V 27) Which diagram represents anaphase II of meiosis? A) I B) III C) IV D) V 28) Which of the following can occur by the process of meiosis but not mitosis? A) Haploid cells fuse to form diploid cells. B) Haploid cells multiply into more haploid cells. C) Diploid cells form haploid cells. D) A diploid cell combines with a haploid cell. 29) Genetic variation leads to genetic diversity in populations and is the raw material for evolution. Biological systems have multiple processes, such as reproduction, that affect genetic variation. They are evolutionarily conserved and shared by various organisms. Which statement best represents the connection between reproduction and evolution? A) Plants that use sexual reproduction are rare since this type of reproduction in plants does not contribute to genetic diversity. B) In order to increase genetic diversity for evolution in sexually reproducing organisms, mutations must occur in the zygote after fertilization. C) Since prokaryotic organisms reproduce asexually, there is no mechanism for them to add genetic diversity for evolution. D) Sexual reproduction increases genetic variation because random mutations can be shuffled between organisms. 30) Which of the following happens at the conclusion of meiosis I? A) Homologous chromosomes of a pair are separated from each other. B) The chromosome number per cell remains the same. C) Sister chromatids are separated. D) Four daughter cells are formed. 31) Sister chromatids separate from each other during _____. A) meiosis I only C) mitosis and meiosis I B) meiosis II only D) mitosis and meiosis II 32) Which of the following occurs in meiosis but not in mitosis? A) chromosome replication C) alignment of chromosomes at the equator B) synapsis of chromosomes D) condensation of chromosomes 33) The somatic cells of a privet shrub each contain 46 chromosomes. How do privet chromosomes differ from the chromosomes of humans ,who also have 46? A) Privet cells cannot reproduce sexually. B) Privet sex cells have chromosomes that can synapse with human chromosomes in the laboratory. C) Genes of privet chromosomes are significantly different than those in humans. D) Privet shrubs must be metabolically more like animals than like other shrubs. 34) If meiosis produces haploid cells, how is the diploid number restored for those organisms that spend most of their life cycle in the diploid state? A) DNA replication C) synapsis B) reverse transcription D) fertilization 35) The human X and Y chromosomes _____. A) are both present in every somatic cell of males and females B) are the same size and have the same number of genes C) include genes that determine an individual's sex D) are called autosomes 36) Which of the following is a protein synthesized at specific times during the cell cycle that associates with a kinase to form a catalytically active complex? A) PDGF B) MPF C) cyclin D) Cdk 37) Which of the following is a protein maintained at steady levels throughout the cell cycle that requires cyclin to become catalytically active? A) PDGF B) MPF 38) MPF is a dimer consisting of _____. A) a growth factor and mitotic factor C) cyclin and tubulin C) cyclin D) Cdk B) ATP synthetase and a protease D) cyclin and a cyclin-dependent kinase 39) Cyclin-dependent kinase (Cdk) is _____. A) inactive, or "turned off," in the presence of cyclin B) present only during the S phase of the cell cycle C) the enzyme that catalyzes the attachment of chromosomes to microtubules D) an enzyme that attaches phosphate groups to other proteins 40) Taxol is an anticancer drug extracted from the Pacific yew tree. In animal cells, Taxol disrupts microtubule formation. Surprisingly, this stops mitosis. Specifically, Taxol must affect _____. A) the structure of the mitotic spindle B) anaphase C) formation of the centrioles D) chromatid assembly