Transcript Chapter 7

Chapter 7
Membrane Structure
and Function
Active Lecture Questions for use with Classroom Response Systems
Biology, Seventh Edition
Neil Campbell and Jane Reece
Edited by William Wischusen, Louisiana State University
Copyright © 2005 Pearson Education, Inc. publishing as Benjamin Cummings
1. Based on the model of sucrose uptake in this figure, which of
the following experimental treatments would increase the rate
of sucrose transport into the cell?
a) decreasing extracellular
sucrose concentration
b) decreasing extracellular pH
c) decreasing cytoplasmic pH
d) adding an inhibitor that blocks
the regeneration of ATP
e) adding a substance that
makes the membrane more
permeable to hydrogen ions
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
2. The carbohydrates attached to some of the
proteins and lipids of the cell membrane are
added as the membrane is refined in the
Golgi apparatus; the new membrane then
forms transport vesicles that travel to the cell
surface. On which side of the vesicle
membrane are the carbohydrates?
a) Interior surface of the vesicle membrane
b) Exterior (cytoplasmic) surface of the vesicle
membrane
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
For Questions 3-7
An artificial cell consisting of an aqueous solution enclosed in
a selectively permeable membrane has just been immersed
in a beaker containing a different solution. The membrane is
permeable to water and to the simple sugars glucose and
fructose but completely impermeable to the disaccharide
sucrose.
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
3. Which solute(s) will exhibit a net diffusion into
the cell?
a) sucrose
b) glucose
c) fructose
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
4. Which solute(s) will exhibit a net diffusion out
of the cell?
a) sucrose
b) glucose
c) fructose
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
5. Which solution is hypertonic to the other?
a) the cell contents
b) the environment
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
6. In which direction will there be a net osmotic
movement of water?
a) out of the cell
b) into the cell
c) neither
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
9. A solution of 1 M glucose is separated by a selectively
permeable membrane from a solution of 0.2 M fructose and 0.7
M sucrose. The membrane is not permeable to the sugar
molecules. Which of the following statements is correct?
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
a)
Side A is hypotonic relative to side B.
b)
The net movement of water will be
from side B to side A.
c)
The net movement of water will be
from side A to side B.
d)
Side B is hypertonic relative to side A.
e)
There will be no net movement
of water.
10. You observe plant cells under a microscope that have just been
placed in an unknown solution. First the cells plasmolyze; after a few
minutes, the plasmolysis reverses and the cells appear normal. What
would you conclude about the unknown solute?
a)
It is hypertonic to the plant cells, and its solute can not cross the
pant cell membranes.
b)
It is hypotonic to the plant cells, and its solute can not cross the
pant cell membranes.
c)
It is isotonic to the plant cells, but its solute can cross the plant
cell membranes.
d)
It is hypertonic to the plant cells, but its solute can cross the
plant cell membranes.
e)
It is hypotonic to the plant cells, but its solute can cross the plant
cell membranes.
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings
8.
An experiment is designed to study the mechanism of sucrose uptake by plant cells.
Cells are immersed in a sucrose solution, and the pH of the solution is monitored with a
pH meter. Samples of the cells are taken at intervals, and the sucrose in the sampled
cells is measured. The measurements show that sucrose uptake by the cells correlates
with a rise in the pH of the surrounding solution. The magnitude of the pH change is
proportional to the starting concentration of sucrose in the extracellular solution. A
metabolic poison known to block the ability of cells to regenerate ATP is found to inhibit
the pH changes in the extracellular solution. Based on this information which of the
following statements would you predict is correct? *
a)
Sucrose uptake is the result of simple diffusion
b)
Hydrogen ion movement is the result of facilitated diffusion.
c)
Sucrose moving through the membrane forces hydrogen ions in to the cell
d)
Sucrose and Hydrogen ions are transported in opposite directions across the
membrane
e)
Sucrose transport is the result of a hydrogen ion contransporter.
Copyright © 2004 Pearson Education, Inc. publishing as Benjamin Cummings