Download 18) How do the membranes of different eukaryotic cells vary? A

18) How do the membranes of different eukaryotic cells vary?
A) Certain proteins are unique to each membrane.
B) Phospholipids are found only in certain membranes.
C) Only certain membranes of the cell are selectively permeable.
D) Some membranes have hydrophobic surfaces exposed to the cytoplasm, while others have hydrophilic surfaces
facing the cytoplasm.
19) Which of the following is characterized by a cell releasing a signal molecule into the environment, followed by a
number of cells in the immediate vicinity responding?
A) synaptic signaling
B) autocrine signaling
C) paracrine signaling
D) endocrine signaling
20) Which of the following is true for a signaling system in an animal cell that lacks the ability to produce GTP?
A) It would employ a transduction pathway directly from an external messenger.
B) It would be able to carry out reception and transduction but would not be able to respond to a signal.
C) It would not be able to activate and inactivate the G protein on the cytoplasmic side of the plasma
membrane.
D) It would use ATP instead of GTP to activate and inactivate the G protein on the cytoplasmic side of the plasma
membrane.
21) Which of the following would be inhibited by a drug that specifically blocks the addition of
phosphate groups to proteins?
A) receptor protein kinase
B) ligand-gated ion channels
C) G protein-coupled receptors
D) all of these mechanisms would be inhibited
22) Which of the following is the best explanation for the fact that most transduction pathways have
multiple steps?
A) Multiple steps in a pathway require the least amount of ATP.
B) Multiple steps provide for greater possible amplification of a signal.
C) Each individual step can remove excess phosphate groups from the cytoplasm.
D) Most of the steps were already in place because they are steps in other pathways.
23) The centromere is a region in which
A) chromosomes are grouped during telophase.
B) new spindle microtubules form at either end.
C) chromatids remain attached to one another until anaphase.
D) metaphase chromosomes become aligned at the metaphase plate.
24) At which phase are centrioles beginning to move apart in animal cells?
A) prophase
B) metaphase
C) anaphase
D) telophase
25) If cells in the process of dividing are subjected to colchicine, a drug that interferes with the
formation of the spindle apparatus, at which stage will mitosis be arrested?
A) prophase
B) metaphase
C) anaphase
D) telophase
26) Movement of the chromosomes during anaphase would be most disrupted by a drug that
A) increases cyclin concentrations.
B) prevents elongation of microtubules.
C) prevents shortening of microtubules.
D) prevents attachment of the microtubules to the kinetochore.
Figure 12.3:
27) In Figure 12.3 above, mitosis is represented by which numbered part of the cycle?
A) I
B) II
C) III
D) IV
28) What causes the decrease in the amount of cyclin at a specific point in the cell cycle?
A) the changing ratio of cytoplasm to genome
B) an increase in production once the restriction point is passed
C) its destruction by a process initiated by the activity of its complex with Cdk
D) the cascade of increased production once its protein is phosphorylated by Cdk
29) Proteins that are involved in the regulation of the cell cycle, and that show fluctuations in
concentration during the cell cycle, are called
A) cyclins.
B) kinases.
C) ATPases.
D) kinetochores.
30) Density-dependent inhibition is explained by which of the following?
A) As cells become more numerous, the level of waste products increases, eventually slowing
down metabolism.
B) As cells become more numerous, the cell surface proteins of one cell contact the adjoining
cells and they stop dividing.
C) As cells become more numerous, they begin to squeeze against each other, restricting their
size and ability to produce control factors.
D) As cells become more numerous, the protein kinases they produce begin to compete with
each other, such that the proteins produced by one cell essentially cancel those produced by
its neighbor.
37) When a neuron responds to a particular neurotransmitter by opening gated ion channels, the
neurotransmitter is serving as which part of the signal pathway?
A) receptor
B) relay molecule
C) signal molecule
D) endocrine molecule
38) One of the major categories of receptors in the plasma membrane reacts by forming dimers, adding
phosphate groups, and then activating relay proteins. Which type does this?
A) steroid receptors
B) ligand-gated ion channels
C) receptor tyrosine kinases
D) G protein-coupled receptors
39) Lipid-soluble signaling molecules, such as testosterone, cross the membranes of all cells but affect
only target cells because
A) most cells lack the Y chromosome required.
B) intracellular receptors are present only in target cells.
C) only target cells retain the appropriate DNA segments.
D) only target cells possess the cytosolic enzymes that transduce the testosterone.
40) Consider this pathway: epinephrine → G protein-coupled receptor → G protein → adenylyl cyclase
→ cAMP. Identify the second messenger.
A) GTP
B) cAMP
C) G protein
D) G protein-coupled receptor