Name __________________________________________ Period __________
Chapter 9 – The Plasma Membrane and its Function
Review
Use each of the terms below just once to complete the passage.
Glucose
Organism
plasma membrane
balance
homeostasis
selective permeability
Living cells maintain a (1) ___BALANCE_______________ by controlling
materials that enter and leave. Without this ability, the cell cannot maintain (2)
__HOMEOSTASIS___________and will die. The cell must regulate internal
concentrations of water, (3) __GLUCOSE____________________, and other
nutrients and must eliminate waste products. Homeostasis in a cell is maintained
by the (4) ___PLASMA MEMBRANE_____________________, which allows
only certain particles to pass through and keeps other particles out. This property
of a membrane is known as (5) ____SELECTIVE PERMEABILITY _______. It
allows different cells to carry on different activities within the same (6)
_____ORGANISM___.
For each statement below write true or false.
The structure and properties of the cell wall allow it to be
____F_______1. selective and maintain homeostasis.
The plasma membrane is a bilayer of lipid molecules with
____T_______2. protein molecules embedded in it.
A phospholipids molecule has a nonpolar water in-soluble
____F_______3. head attached to a long polar, soluble tail.
The fluid mosaic model describes the plasma membrane as a
____F_______4. structure that is liquid and very rigid.
Cell organelles, such as the nucleus, vacuoles, mitochondria
____T_______5. and chloroplasts are enclosed in membranes.
The greater the number of saturated fatty acids a membrane
____F_______6. contains, the more fluid it is.
In animals, cholesterol strengthens the fluid mosaic and
_____T______7. makes the plasma membrane more stable.
Circle the letter of the choice that best completes the statement.
1. All molecules
a) have constant random movement. b) move in an orderly fashion
.
c) are static and stay in one place
d) contain random energy.
2. Most of the cell and its surrounding environment are in a
a) solid solution. b) gaseous solution.
c) solid phase.
d) water solution.
3. The net movement of particles from an area of higher concentration to an
area of lower concentration is called
a) active transport. b) nonrandom movement.
c) osmosis.
d) diffusion.
4. Diffusion occurs because of
a) nonrandom movement of particles.
b) random movement of particles.
c) a chemical reaction between particles.
d) chemical energy.
5. When a few crystals of potassium permanganate are dropped into a
beaker of water, the ions of the dissolving compound will
a) move from low concentration to high concentration.
b) form a polar bond.
c) start to diffuse.
d) Remain on the bottom of the beaker.
6. When materials pass into and out of the cell at equal rates, there is no net
change in concentration inside the cell. The cell is in a state of
a) dynamic equilibrium. b) metabolism. c) imbalance. d) inertia
7. Oxygen diffuses into the capillaries of the lungs because there is a
a) lesser concentration of oxygen in the air sacs of lungs than in the
capillaries.
b) equal concentration of carbon dioxide in the air sacs of the lungs
and in the capillaries.
c) equal concentration of oxygen in the air sacs of the lungs and in the
capillaries.
d) greater concentration of oxygen in the air sacs of the lung
than in the capillaries.
8. The difference in concentration from one region to another is called
a) dynamic equilibrium. b) concentration gradient.
c) homeostasis.
d) Brownian movement.
9. Molecules of the following needs a transport protein and will not diffuse
directly across the lipid bilayer:
a) carbon dioxide b) water. c) oxygen
Complete the table by checking the correct column for each statement.
Statement
Isotonic
Hypotonic Hypertonic
The concentration of dissolved substances
outside the cell is lower than inside the
cell. The environment out side the cell is:
X
When a cell is placed in this type of
solution, water will enter the cell by
osmosis, resulting in turgor pressure.
X
The concentration of dissolved substances
is the same inside the cell as it is outside
the cell.
X
The concentration of the substances
outside the cell is greater than inside the
cell the environment is:
When injected into the body, it will not
cause cellular damage if what you are
injecting is _______ to the cell.
Putting a plant cell in this type of solution
will result in a loss of water, and a drop of
turgor pressure (or plasmolysis), which will
cause the cell to wilt.
X
X
X
Answer the following questions.
1. If a cell is placed in a hypotonic solution what happens to the volume of
the cell? This affects what type of pressure? What affect would this have
on a plant?
HYPOTONIC MEANS THERE IS MORE WATER OUTSIDE THE CELL.
THEREFORE THE WATER MOVES INTO THE CELL, PARTICULARLY THE
CENTRAL VACUOLE OF THE PLANT. WHEN THIS VACUOLE FILLS WITH
WATER, IT PRESSES AGAINST THE CELL WALL, GIVING IT FIRMNESS
AND STRUCTURE THAT IS REFERRED TO AS TURGOR PRESSURE. IT IS
TURGOR PRESSURE THAT ALLOWS PLANTS TO STAND UPRIGHT.
2. What happens to a plant when it is deprived of water or is placed in a
hypertonic solution? What is this called?
WITH HYPERTONIC SOLUTION, THERE IS MORE WATER INSIDE THE
CELL THAN OUTSIDE. AS A RESULT, THE WATER WILL MOVE OUT OF
THE CENTRAL VACUOLE, WHICH WILL SHRINK. THIS CAUSES THE LOSS
OF TURGOR PRESSURE AND THE PLANT WILL WILT. SEE ABOVE
DIAGRAM FOR DETAILS.
Here are some lab reports that need help. Write a response to each report.
1. Experiments show that lipid molecules can pass across the plasma
membrane from an area of high concentration to low concentration. By
which process do the molecules move across the membrane? Does the
cell expend energy? Explain.
THIS PARTICULAR TRANSPORT IS STRAIGHT FORWARD DIFFUSION.
DIFFUSION IS A FORM OF PASSIVE TRANSPORT, WHICH DOES NOT
REQUIRE ENERGY FROM THE CELL. MOLECULES IN DIFFUSION WILL
MOVE DOWN THE CONCENTRATION GRADIENT, HIGH TO LOW
CONCENTRATION.
2. A biochemical test shows the passive transport of sugar molecules into a
muscle cell. What are the proteins embedded in the lipid bilayer that aid in
its movement called?
TRANSPORT PROTEINS.
3. In a nerve cell, sodium ions move across the membrane from an area of
lower concentration to an area of higher concentration. Does the nerve
cell expend energy? What type of transport is taking place?
THIS MOVEMENT IS CALLED ACTIVE TRANSPORT AND REQUIRES CELL
ENERGY TO MOVE MOLECULES UP THE CONCENTRATION GRADIENT,
FROM LOW TO HIGH CONCENTRATION.
4. An experiment reveals a carrier protein involved in active transport of an
amino acid across a membrane into a cell. Explain how the protein moves
the molecule up the concentration gradient.
THE CARRIER PROTEIN IN THE MEMBRANE WILL BOND WITH THE AMINO
ACID, AND THEN USING ENERGY, CHANGES SHAPE TO FACE THE INSIDE
OF THE CELL, WHERE IT DEPOSITS THE AMINO ACID.