Cells (Test 1)
2. Simple cuboidal epithelial cells line the ducts of certain
human exocrine glands. Various materials are transported
into or out of the cells by diffusion. (The formula for the SA
of a cube is 6 x S2, & volume is S3, where S = length of the
side of the cube.) Which of the following cube-shaped cells
would be most efficient in removing waste by diffusion?
Cells (Test 1)
5. A pathogenic bacterium has been engulfed by a phagocytic
cell as part of the nonspecific (innate) immune response.
Which of the following illustrations best represents the
response?
Cells (Test 1)
12. Paramecia are unicellular protists that have
contractile vacuoles to remove excess intracellular water.
In an experimental investigation, paramecia were placed
in salt solutions of increasing osmolarity. The rate at
which the contractile vacuole contracted to pump out
excess water was determined and plotted against
osmolarity of the solutions, as shown in the graph.
Which of the following is the correct explanation?
a. At higher osmolarity, lower rates of contracted are required
because more salt diffused into the paramecia.
b. The contraction rate increases as the osmolarity decreases
because the amount of water entering by osmosis increases.
c. The contractile vacuole is less efficient in solutions of high
osmolarity because of the reduced amount of ATP produced
from cellular respiration.
d. In an isotonic salt solution, there is no diffusion of water into or
out of the paramecia, so the contraction rate is zero.
Cells (Test 1)
17. The endocrine system incorporates feedback mechanisms
that maintain homeostasis. Which of the following
demonstrates negative feedback by the endocrine system?
a.
During labor, the fetus exerts pressure on the uterine wall, inducing
the production of oxytocin, which stimulates uterine wall contraction.
The contractions cause the fetus to further push on the wall,
increasing production of oxytocin.
b. After a meal, blood glucose levels become elevated, stimulating beta
cells of the pancreas to release insulin in the blood. Excess glucose is
then converted to glycogen in the liver, reducing blood glucose levels.
c. At high elevation, atmospheric oxygen is more scare. In response to
signals that oxygen is low, the brain decreases an individual’s rate of
respiration to compensate for the difference.
d. A transcription factor binds to the regulatory region of a gene,
blocking the binding of another transcription factor required for
expression.
Cells (Test 1)
23. An individual’s humoral response to a particular antigen
differs depending on whether or not the individual has been
previously exposed to that antigen. Which of the following
graphs properly represents the humoral immune response
when an individual is exposed to the same antigen more than
once?
Cells (Test 1)
30. A human kidney filters about 200 liters of blood each day.
Approximately 2 liters of liquid and nutrient waste are excreted as urine.
The remaining fluid and dissolved substances are reabsorbed and
continue to circulate throughout the body. Antidiuretic hormone (ADH)
is secreted in response to reduced plasma volume. ADH targets the
collecting ducts in the kidney, stimulating the insertion of aquaporins
into their plasma membranes and an increased reabsorption of water. If
ADH secretion is inhibited, which of the following would initially result?
a. The number of aquaporins would increase in response to the
inhibition of ADH.
b. The person would decrease oral water intake to compensate for the
inhibition of ADH.
c. Blood infiltration would increase to compensate for the lack of
aquaporins.
d. The person would produce greater amounts of dilute urine.
Cells (Test 1)
31. The diagram shows a developing
worm embryo at the four-cell stage.
Experiments have shown that when cell
3 divides, the anterior daughter cell gives
rise to muscle and gonads and the
posterior daughter cell gives rise to the
intestine. However, if the cells of the
embryo are separated from one another
early during the four-cell stage, no
intestine will form. Other experiments
have shown that if cell 3 and 4 are
recombined after the initial separation,
the posterior daughter of cell 3 will once
again give rise to normal intestine.
Which of the following is the most
plausible explanation for these findings?
a. A cell surface protein on cell 4 signals cell 3 to induce
formation of the worm’s intestine.
b. The plasma membrane of cell 4 interacts with the plasma
membrane of the posterior portion of cell 3, causing
invaginations that become microvilli.
c. Cell 3 passes an electrical signal to cell 4, which induces
differentiation in cell 4.
d. Cell 4 transfers genetic material to cell 3, which directs the
development of intestinal cells.
Cells (Test 2)
8. Which method is a means for membrane participation in
intercellular signaling?
a. Hormone release by cellular endocytosis.
b. Hydrogen ion gradients established during an electron
transport chain.
c. Glycoproteins with an attached carbohydrate chain
extending on the interior of the cell membrane.
d. Gap junctions and plasmodesmata as communicating
junctions.
Cells (Test 2)
14. Positive feedback in a living system serves to amplify signals
and to increase the activity of the system. Which of the
portions of the diagram indicate this type of feedback
mechanism?
a. Estrogen secreted by the hypothalamus acting upon the
ovaries.
b. Progesterone secreted by the ovaries acting upon the
hypothalamus.
c. FSH secreted by anterior pituitary acting upon the ovaries.
d. Progesterone secreted by the ovaries acting upon the
anterior pituitary.
Cells (Test 2)
15. Estrogen secreted by the ovaries and acting upon the
hypothalamus (see diagram from #14) is an example of which
type of feedback mechanism?
a.
b.
c.
d.
Both positive and negative feedback depend upon conditions.
Positive feedback only.
Negative feedback only.
Both positive feedback and an allosteric site change.
Cells (Test 2)
17. Positive feedback can be dangerous in some situations. An
example is when a fever causes metabolic changes that push the
fever even higher. What is most important in positive
feedback?
a. A stimulus that generates the positive feedback that rarely
occurs.
b. A definite cut off point for feedback.
c. A stimulus receptor that does not have nerve impulses
which reach the brain.
d. A response that is never harmful to the organism.
Cells (Test 2)
18. Homeostasis is so critical to life that humans have multiple
regulating mechanism. In a negative feedback mechanism:
a. temperature of the human can be decreased from a
temperature below normal.
b. temperature of the human can be decreased from a
temperature above normal.
c. There is a fluctuation below and above normal.
d. A regulatory center communicates with other body parts.
Cells (Test 2)
35. The movement of molecules across a membrane is of
particular interest to biologists. Rank the following molecules
in the order in which they move easily across the cell
membrane without expenditure of energy.
1. Alcohol 2. Protein 3. CO2 4. O2 5. Glycerol 6. Macromolecules
a.
b.
c.
d.
1, 3, 4, 5
1, 2, 4, 6
2, 3, 4, 6
1, 2, 3, 6
Cells (Test 2)
37. Signal transduction is known to cause a response in plant cells
that ultimately results in a response by the whole organism. Which
of these is most correctly associated with cellular signal transduction?
a. Receptors – specialized regions that are activated by a specific
signal, consisting of groups of phospholipids and cholesterol
embedded in the membrane structure.
b. Transduction pathway – proteins embedded in the cellular
membrane allowing a pore for the movement of the signal across
the membrane.
c. Receptors – proteins embedded in the cellular membrane
allowing for movement of electrons along the membrane and the
production of ATP.
d. Cellular response – occurs as a result of the transduction
pathway.
Cells (Test 2)
38. The movement of a signal along a neuron travels in a
direction that follows which path?
a.
b.
c.
d.
Cell body, dendrite, axon, axon terminal
Dendrite, cell body, axon, axon terminal
Axon, cell body, dendrite, axon terminal
Axon, dendrite, cell body, axon terminal
Cells (Test 2)
42. The process of osmosis is based upon the fact that
molecules are in a constant state of random motion. The
random molecular motion can be observed with any type of
molecule. If a cell were losing 100 molecules of water each
second through its plasma membrane, what would be necessary
to know in order to determine the net movement of water for
the cell?
a. The temperature of the water both inside & outside the cell
b. The # of water molecules entering the cell through the
membrane each second
c. The pressure of the water both inside and outside of the cell
d. The molecular size of the water both inside & outside the
cell
Cells (Test 2)
43. One of the main differences between prokaryotes and
eukaryotes is the membrane-bound organelles of the eukaryotic
cell. Which of the statements below is a contribution of these
organelles to the eukaryotic cell?
a. Membrane bound organelles create a symbiotic relationship
between mitochondria & chloroplasts.
b. They allow for compartmentalization & separation of
cellular activities.
c. Organelles allow for a decrease in surface area with no
change to the volume of the cell.
d. Organelles cause chemical reactions to occur randomly
within the cell.