PracticeQuestions_18

PracticeQuestions_18 - Chapter 18 Sample Questions 1. Fill...

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Chapter 18 Sample Questions 1. Fill in the blanks with the best word or phrase selected from the list below. The four phases of the cell cycle, in order, are G 1 , __________________, __________________, and __________________. A cell contains the most DNA after __________________ phase of the cell cycle. A cell is smallest in size after __________________ phase of the cell cycle. Growth occurs in __________________, __________________, and __________________ phases of the cell cycle. A cell does not enter mitosis until it has completed __________________ synthesis. DNA M protein G1 nucleotide S G2 organelle 2. What would be the most obvious outcome of repeated cell cycles consisting of S phase and M phase only? (a) Cells would not be able to replicate their DNA. (b) The mitotic spindle could not assemble. (c) Cells would get larger and larger. (d) The cells produced would get smaller and smaller. 3. A mutant yeast strain stops proliferating when shifted from 25°C to 37°C. When these cells are analyzed at the two different temperatures, using a machine that sorts cells according to the amount of DNA they contain, this graphs were obtained. Which of the following would not explain the results with the mutant? (a) inability to initiate DNA replication (b) inability to begin M phase (c) inability to activate proteins needed to enter S phase number of cells amount of DNA/cell (arbitrary units) 12 amount of DNA/cell (arbitrary units) 37 o C 25 o C
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(d) inappropriate production of a signal that causes the cells to remain in G 1 4. Which of the following events does not usually occur during interphase? (a) Cells grow in size. (b) The nuclear envelope breaks down. (c) DNA is replicated. (d) The centrosomes are duplicated. 5. Are the statements below true or false ? Explain your answer. A. Statement 1: Generally, in a given cell type, the S, G 2 , and M phases of the cell cycle take a defined and stereotyped amount of time in most cells. B. Statement 2: Therefore, the cell-cycle control system operates primarily by a timing mechanism, in which the entry into one phase starts a timer set for sufficient time to complete the required tasks. After a given amount of time has elapsed, a molecular “alarm” triggers movement to the next phase. 6. Which of the following statements about the cell cycle is false ? (a) Once a cell decides to enter the cell cycle, the time from start to finish is the same in all eucaryotic cells. (b) An unfavorable environment can cause cells to arrest in G 1 . (c) A cell has more DNA during G 2 than it did in G 1 . (d) The cleavage divisions that occur in an early embryo have short G 1 and G 2 phases. 7. Which of the following descriptions is consistent with the behavior of a cell that lacks a protein required for a checkpoint mechanism that operates in G 2 ? (a) The cell would be unable to enter M phase. (b) The cell would be unable to enter G 2 . (c) The cell would enter M phase under conditions when normal cells would not.
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This note was uploaded on 11/21/2011 for the course PCB 3134 taught by Professor Multiple during the Fall '08 term at University of Florida.

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PracticeQuestions_18 - Chapter 18 Sample Questions 1. Fill...

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