Essential Cell Biology CH 18 test bank
18-65 Programmed cell death occurs ________________.
(a) by means of an intracellular suicide program.
(b) rarely and selectively only during animal development.
(c) only in unhealthy or abnormal cells.
(d) only during embryonic development. - ANS - a
\A cell with nuclear lamins that cannot be phosphorylated in M phase will be
unable to ________________.
(a) reassemble its nuclear envelope at telophase.
(b) disassemble its nuclear lamina at prometaphase.
(c) begin to assemble a mitotic spindle.
(d) condense its chromosomes at prophase. - ANS - b
\A friend declares that chromosomes are held at the metaphase plate by
microtubules that push on each chromosome from opposite sides. Which of the
following observations does not support your belief that the microtubules are
pulling on the chromosomes?
(a) the jiggling movement of chromosomes at the metaphase plate
(b) the way in which chromosomes behave when the attachment between sister
chromatids is severed
(c) the way in which chromosomes behave when the attachment to one
kinetochore is severed
(d) the shape of chromosomes as they move toward the spindle poles at
anaphase - ANS - a
\Apoptosis differs from necrosis in that necrosis ________________.
(a) requires the reception of an extracellular signal.
(b) causes DNA to fragment.
(c) causes cells to swell and burst, whereas apoptotic cells shrink and condense.
(d) involves a caspase cascade. - ANS - c
\At the end of DNA replication, the sister chromatids are held together by the
___________.
(a) kinetochores.
(b) securins.
(c) cohesins.
(d) histones. - ANS - c
\Cells in the G0 state ________________.
(a) do not divide.
(b) cannot re-enter the cell cycle.
, (c) have entered this arrest state from either G1 or G2.
(d) have duplicated their DNA. - ANS - a
\Condensins ________________.
(a) are degraded when cells enter M phase.
(b) assemble into complexes on the DNA when phosphorylated by M-Cdk.
(c) are involved in holding sister chromatids together.
(d) bind to DNA before DNA replication begins. - ANS - b
\Cytokinesis in animal cells ________________.
(a) requires ATP.
(b) leaves a small circular "scar" of actin filaments on the inner surface of the
plasma membrane.
(c) is often followed by phosphorylation of integrins in the plasma membrane.
(d) is assisted by motor proteins that pull on microtubules attached to the cell
cortex. - ANS - a
\Disassembly of the nuclear envelope ________________.
(a) causes the inner nuclear membrane to separate from the outer nuclear
membrane.
(b) results in the conversion of the nuclear envelope into protein-free membrane
vesicles.
(c) is triggered by the phosphorylation of integrins.
(d) must occur for kinetochore microtubules to form in animal cells. - ANS - d
\How does S-Cdk help guarantee that replication occurs only once during each
cell cycle?
(a) It blocks the rise of Cdc6 concentrations early in G1.
(b) It phosphorylates and inactivates DNA helicase.
(c) It phosphorylates the Cdc6 protein, marking it for destruction.
(d) It promotes the assembly of a prereplicative complex. - ANS - c
\In which phase of the cell cycle do cells check to determine whether the DNA is
fully and correctly replicated?
(a) at the transition between G1 and S
(b) when cells enter G0
(c) during M
(d) at the end of G2 - ANS - d
\Levels of Cdk activity change during the cell cycle, in part because
________________.
(a) the Cdks phosphorylate each other.
(b) the Cdks activate the cyclins.
(c) Cdk degradation precedes entry into the next phase of the cell cycle.
(d) cyclin levels change during the cycle. - ANS - d
\Mitogens are _____.
18-65 Programmed cell death occurs ________________.
(a) by means of an intracellular suicide program.
(b) rarely and selectively only during animal development.
(c) only in unhealthy or abnormal cells.
(d) only during embryonic development. - ANS - a
\A cell with nuclear lamins that cannot be phosphorylated in M phase will be
unable to ________________.
(a) reassemble its nuclear envelope at telophase.
(b) disassemble its nuclear lamina at prometaphase.
(c) begin to assemble a mitotic spindle.
(d) condense its chromosomes at prophase. - ANS - b
\A friend declares that chromosomes are held at the metaphase plate by
microtubules that push on each chromosome from opposite sides. Which of the
following observations does not support your belief that the microtubules are
pulling on the chromosomes?
(a) the jiggling movement of chromosomes at the metaphase plate
(b) the way in which chromosomes behave when the attachment between sister
chromatids is severed
(c) the way in which chromosomes behave when the attachment to one
kinetochore is severed
(d) the shape of chromosomes as they move toward the spindle poles at
anaphase - ANS - a
\Apoptosis differs from necrosis in that necrosis ________________.
(a) requires the reception of an extracellular signal.
(b) causes DNA to fragment.
(c) causes cells to swell and burst, whereas apoptotic cells shrink and condense.
(d) involves a caspase cascade. - ANS - c
\At the end of DNA replication, the sister chromatids are held together by the
___________.
(a) kinetochores.
(b) securins.
(c) cohesins.
(d) histones. - ANS - c
\Cells in the G0 state ________________.
(a) do not divide.
(b) cannot re-enter the cell cycle.
, (c) have entered this arrest state from either G1 or G2.
(d) have duplicated their DNA. - ANS - a
\Condensins ________________.
(a) are degraded when cells enter M phase.
(b) assemble into complexes on the DNA when phosphorylated by M-Cdk.
(c) are involved in holding sister chromatids together.
(d) bind to DNA before DNA replication begins. - ANS - b
\Cytokinesis in animal cells ________________.
(a) requires ATP.
(b) leaves a small circular "scar" of actin filaments on the inner surface of the
plasma membrane.
(c) is often followed by phosphorylation of integrins in the plasma membrane.
(d) is assisted by motor proteins that pull on microtubules attached to the cell
cortex. - ANS - a
\Disassembly of the nuclear envelope ________________.
(a) causes the inner nuclear membrane to separate from the outer nuclear
membrane.
(b) results in the conversion of the nuclear envelope into protein-free membrane
vesicles.
(c) is triggered by the phosphorylation of integrins.
(d) must occur for kinetochore microtubules to form in animal cells. - ANS - d
\How does S-Cdk help guarantee that replication occurs only once during each
cell cycle?
(a) It blocks the rise of Cdc6 concentrations early in G1.
(b) It phosphorylates and inactivates DNA helicase.
(c) It phosphorylates the Cdc6 protein, marking it for destruction.
(d) It promotes the assembly of a prereplicative complex. - ANS - c
\In which phase of the cell cycle do cells check to determine whether the DNA is
fully and correctly replicated?
(a) at the transition between G1 and S
(b) when cells enter G0
(c) during M
(d) at the end of G2 - ANS - d
\Levels of Cdk activity change during the cell cycle, in part because
________________.
(a) the Cdks phosphorylate each other.
(b) the Cdks activate the cyclins.
(c) Cdk degradation precedes entry into the next phase of the cell cycle.
(d) cyclin levels change during the cycle. - ANS - d
\Mitogens are _____.
