ESSENTIAL CELL BIOLOGY 5TH
ACTUAL TEST WITH VERIFIED
SOLUTIONS
⩥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. - (b) The nuclear envelope breaks
down.
⩥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 - (d) at the end of G2
⩥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 eukaryotic cells.
,(b) An unfavorable environment can cause cells to arrest in G1.
(c) A cell has more DNA during G2 than it did in G1.
(d) The cleavage divisions that occur in an early embryo have short G1
and G2 phases. - (a) Once a cell decides to enter the cell cycle, the time
from start to finish is the same in all eukaryotic cells.
⩥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 G2?
(a) The cell would be unable to enter M phase.
(b) The cell would be unable to enter G2.
(c) The cell would enter M phase under conditions when normal cells
would not.
(d) The cell would pass through M phase more slowly than normal cells
- (c) The cell would enter M phase under conditions when normal cells
would not.
⩥Progression through the cell cycle requires a cyclin to bind to a Cdk
because _________.
(a) the cyclins are the molecules with the enzymatic activity in the
complex.
(b) the binding of a cyclin to Cdk is required for Cdk enzymatic activity.
(c) cyclin binding inhibits Cdk activity until the appropriate time in the
cell cycle.
, (d) without cyclin binding, a cell-cycle checkpoint will be activated. -
(b) the binding of a cyclin to Cdk is required for Cdk enzymatic activity.
⩥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. - (d) cyclin levels change
during the cycle.
⩥The concentration of mitotic cyclin (M cyclin) ________________.
(a) rises markedly during M phase.
(b) is activated by phosphorylation.
(c) falls toward the end of M phase as a result of ubiquitylation and
degradation.
(d) is highest in G1 phase. - (c) falls toward the end of M phase as a
result of ubiquitylation and degradation.
⩥You have isolated a strain of mutant yeast cells that divides normally at
30°C but cannot enter M phase at 37°C. You have isolated its mitotic
cyclin and mitotic Cdk and find that both proteins are produced and can
form a normal M-Cdk complex at both temperatures. Which of the
following temperature-sensitive mutations could not be responsible for
the behavior of this strain of yeast?
ACTUAL TEST WITH VERIFIED
SOLUTIONS
⩥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. - (b) The nuclear envelope breaks
down.
⩥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 - (d) at the end of G2
⩥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 eukaryotic cells.
,(b) An unfavorable environment can cause cells to arrest in G1.
(c) A cell has more DNA during G2 than it did in G1.
(d) The cleavage divisions that occur in an early embryo have short G1
and G2 phases. - (a) Once a cell decides to enter the cell cycle, the time
from start to finish is the same in all eukaryotic cells.
⩥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 G2?
(a) The cell would be unable to enter M phase.
(b) The cell would be unable to enter G2.
(c) The cell would enter M phase under conditions when normal cells
would not.
(d) The cell would pass through M phase more slowly than normal cells
- (c) The cell would enter M phase under conditions when normal cells
would not.
⩥Progression through the cell cycle requires a cyclin to bind to a Cdk
because _________.
(a) the cyclins are the molecules with the enzymatic activity in the
complex.
(b) the binding of a cyclin to Cdk is required for Cdk enzymatic activity.
(c) cyclin binding inhibits Cdk activity until the appropriate time in the
cell cycle.
, (d) without cyclin binding, a cell-cycle checkpoint will be activated. -
(b) the binding of a cyclin to Cdk is required for Cdk enzymatic activity.
⩥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. - (d) cyclin levels change
during the cycle.
⩥The concentration of mitotic cyclin (M cyclin) ________________.
(a) rises markedly during M phase.
(b) is activated by phosphorylation.
(c) falls toward the end of M phase as a result of ubiquitylation and
degradation.
(d) is highest in G1 phase. - (c) falls toward the end of M phase as a
result of ubiquitylation and degradation.
⩥You have isolated a strain of mutant yeast cells that divides normally at
30°C but cannot enter M phase at 37°C. You have isolated its mitotic
cyclin and mitotic Cdk and find that both proteins are produced and can
form a normal M-Cdk complex at both temperatures. Which of the
following temperature-sensitive mutations could not be responsible for
the behavior of this strain of yeast?
