“Membranes”
Bell
Ringer
Mrs. Loyd 
Page 1 of 12
1/29/15
Question:
Use the word bank to label the parts of the cell membrane. Answers are on the back.
Intracellular side of cell
Extracellular side of cell
Phospholipid bilayer
Glycoprotein (“address
label”)
Glycolipid
Integral Protein
Microfilaments of
Cytoskeleton
Peripheral Protein
Carbohydrate
Extracellular Matrix
Answers:
Mrs. Loyd 
Page 2 of 12
1/29/15
Question:
Describe the function of each of the integral proteins shown in the pictures.
Answers:
(a) Left image: Facilitated diffusion (Passive Transport) allows specific substances to diffuse down their concentration
gradient while by-passing the need to come in contact with the plasma membrane. Works for substances that are: charged
(ions), polar or too large to diffuse across the membrane unassisted.
(a) Right image: Active Transport by a molecular pump powered by ATP moves substances against their concentration
gradient.
(b) Sometimes enzymes must catalyze sequentially. These enzymes need to be imbedded in a membrane to keep them in
the proper sequence.
(c) When a messenger molecule (like adrenaline or insulin) binds to its receptor molecule on target tissue, the receptor protein
changes its shape. This activates another molecule (the second messenger) to carry the message to the nucleus where the
DNA causes the cell to produce the appropriate response.
Mrs. Loyd 
Page 3 of 12
1/29/15
Question:
Identify the image(s) that show(s) the solute at equilibrium.
Which image(s) show(s) the solute moving down its concentration gradient?
Answers:
The solute is at equilibrium in the last image. I can tell because the arrows indicate that the solutes are moving equally into
and out of the cell.
The first two images show the solute moving down the concentration gradient. There are more arrows pointing in one
direction than the other showing that the net movement of solute is in one direction.
Mrs. Loyd 
Page 4 of 12
1/29/15
Questions:
Each of these cells is responding to the solution in which they were placed.
a. Describe each result.
b. Name the solution concentration in which it was placed as: isotonic, hypertonic or hypotonic.
Answers:
Mrs. Loyd 
Page 5 of 12
1/29/15
Question:
This is a single-celled organism in the kingdom Protista called a paramecium.
Compare the “before” and “after” images.
The organelle on the left is called a contractile vacuole.
What is it for?
Answer:
These organisms live in fresh water and are always gaining water by osmosis. The organelle counters this by pumping water
out of the cell to maintain water balance. Without them the paramecia would lyse.
Mrs. Loyd 
Page 6 of 12
1/29/15
Question:
These figures show different ways that cells maintain homeostasis. Only a small portion of the plasma membrane is shown.
Talk out each process. Identify the movement of the solutes as:
[High] to [Low] or [Low] to [High]
active (uses ATP)
or
passive (no ATP used) transport.
Answer:
Purple
Orange
Blue
Last image
[High] to [Low]
passive (no ATP used)
transport.
Diffusion or Osmosis if it is
water.
[High] to [Low]
passive (no ATP used)
transport.
Facilitated Diffusion
[High] to [Low]
passive (no ATP used)
transport.
[Uniport (don’t worry about
it)]
[Low] to [High]
active (uses ATP)
(Na+/K+ Pump)
Mrs. Loyd 
Page 7 of 12
1/29/15
Question:
Name the process shown in the picture and explain why a cell would need to use it?
Answer:
This process is called endocytosis. It uses energy to bring in large chunks of food. It is likened to “gulping” while pinocytosis
is likened to “sipping” or bringing in fluids.
The opposite process is known as exocytosis. It delivers proteins that the cell has made to the blood stream or ejects waste.
Mrs. Loyd 
Page 8 of 12
1/29/15
Question:
Use the given concentration to predict the direction that water will move.
Answer choices:
Into the cell causing it to swell and, perhaps, lyse.
Out of the cell causing the cell to shrink or crenate.
No net movement, the cell is isotonic to the environment.
The beaker contains a
solution hypertonic to the
contents of the bag.
Answer:
Out of the cell causing the cell to shrink or crenate.
The solution in the beaker is hypertonic or “over salty” therefore, it is “under watery.”
The water concentration is lowest in the beaker and will cause water to move out of the bag.
Mrs. Loyd 
Page 9 of 12
1/29/15
Question:
Use the given concentration to predict the direction that water will move.
Answer choices:
Into the cell causing it to swell and, perhaps, lyse.
Out of the cell causing the cell to shrink or crenate.
No net movement, the cell is isotonic to the environment.
The beaker contains a solution
hypotonic to the contents of the
bag.
Answer:
Into the cell causing it to swell and, perhaps, lyse.
The beaker is hypotonic or “under salty”; therefore it is “over watery.”
The concentration of water is highest outside the cell and will move into the cell.
Mrs. Loyd 
Page 10 of 12
1/29/15
Question:
Use the given concentration to predict the direction that water would move.
Answer choices:
Into the cell causing it to swell and, perhaps, lyse.
Out of the cell causing the cell to shrink or crenate.
No net movement, the cell is isotonic to the environment.
The beaker contains a solution
isotonic to the contents of the
bag.
Answer:
No net movement, the cell is isotonic to the environment.
The water concentration is the same in the bag as in the beaker, therefore, the water will move equally in and out and there
will be no net movement.
Mrs. Loyd 
Page 11 of 12
1/29/15
Question:
Use the given concentration to predict the direction that water will move.
Answer choices:
Into the cell causing it to swell and, perhaps, lyse;
Out of the cell causing the cell to shrink or crenate.
No net movement, the cell is isotonic to the environment.
The bag (cell) contains 0.9% saline
(salt water concentration similar to
our body tissues.)
The beaker contains distilled water
(100%).
Answer:
The water will move into the cell causing it to swell and, perhaps, lyse
The concentration of the water is 100% in the beaker and will move down its gradient into the bag.
Mrs. Loyd 
Page 12 of 12
1/29/15