Name________________________________________
Period-Teacher__________________________
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PAP Biology Cell Transport Study Guide
CHAPTER 3
SECTION 3.3 CELL MEMBRANE
KEY CONCEPT
The cell membrane is a barrier that separates a cell from the external environment.
VOCABULARY
cell membrane
selective permeability
phospholipid
Receptor protein
fluid mosaic model
Marker protein
Channel/carrier transport protein
MAIN IDEA: Cell membranes are composed of two phospholipid layers.
1.Draw a phospholipid bilayer in the box below. Label the hydrophilic heads and hydrophobic tails.
2. Place a check mark in the appropriate box to show which parts of a phospholipid are charged, or polar,
and which parts are nonpolar.
Phospholipid part
Polar (charged)
Nonpolar
Phosphate group and
glycerol (Head)
Fatty acid tail
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© Houghton Mifflin Harcourt Publishing Company
Holt McDougal Biology
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Cell Structure and Function
A cell membrane has other types of molecules embedded in the phospholipid bilayer. Fill in
the type of protein that performs each function indicated in the sentences below:
Use transport, marker, and receptor.
3. ________________ protein functions in communication by sending and receiving chemical messages.
4. ________________ proteins help materials cross the membrane.
5. ________________ proteins help identify cell types.
Choose whether the statement is true or false.
6. true / false A selectively permeable membrane allows all molecules to cross.
Section 3.4 Diffusion & Osmosis
KEY CONCEPT
Materials move across membranes because of concentration differences.
VOCABULARY
passive transport
osmosis
hypotonic
diffusion
isotonic
facilitated diffusion
concentration gradient
hypertonic
MAIN IDEA: Diffusion and osmosis are types of passive transport.
1. The difference in the concentration of a substance from one location to another is called a
_______________________________.
2. A molecule that diffuses down a concentration gradient goes from an area of ____________
concentration into an area of ____________ concentration.
Suppose you have three solutions with different concentrations of particles. Relative to the
concentration of particles in a cell, one solution is isotonic, one is hypertonic, and one is
hypotonic. Use this information to answer the next two questions.
Choose from the following words: isotonic, hypertonic, hypotonic.
3. The ______________ solution has the highest concentration of particles.
4. The _______________ solution has the highest concentration of water molecules.
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MAIN IDEA: Some molecules diffuse through transport proteins.
Circle the word or phrase that best completes the statement.
5. Simple / Facilitated diffusion occurs across the membrane, but simple / facilitated diffusion occurs
through selective transport proteins.
Vocabulary Check
Fill in the blank with the word or phrase that best completes the sentence.
6. People with more energy than most other people are described as hyper. A solution with a higher
level of solutes than the solution it is being compared to is called ___________________.
7. The word facilitate means “to make easier.” ___________________ means that the transport protein
makes it easier for a molecule that cannot directly cross the cell membrane to enter or exit a cell.
Complete the table by checking the correct column(s) for each description
Description of solution surrounding the cell
Isotonic
Solution
Hypotonic
Solution
Hypertonic
Solution
8. A solution that has the same osmotic concentration as the
cell’s cytoplasm.
9. A solution that causes a cell to shrivel
10. A solution that causes a cell to swell
11. A solution that neither shrinks nor swells a cell
12. A solution in which there is more water outside the cell
than inside the cell
13. A solution that causes water to move out of a cell
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Read the following experiment scenario and answer the questions that follow.
The cell membrane of red blood cells is permeable to water but not to sodium chloride, NaCl (salt).
Suppose that you have three beakers:
 Beaker X contains a solution that is 0.5% NaCl (solute)
 Beaker Y contains a solution that is 0.9% NaCl (solute)
 Beaker Z contains a solution that is 1.5% NaCl (solute)
To each beaker you add red blood cells, which have an internal concentration of 0.9% NaCl (solute).
0.5%
0.9%
1.5%
0.9%
0.9%
0.9%
Beaker X
Beaker Y
Beaker Z
For the diagrams above, label the percentages as solute for each beaker and cells.
Then, calculate and label the solvent (water) for each.
Finally, draw an arrow to represent the way the solvent (water) moves for each.
Answer the three questions below.
14. Predict what will happen to the red blood cells in Beaker X: (shrink / swell / stay the same ).
The solution in the beaker is ( hypertonic / hypotonic / isotonic )
(circle one in each section)
(circle one in each section)
15. Predict what will happen to the red blood cells in Beaker Y: (shrink / swell / stay the same ).
The solution in the beaker is ( hypertonic / hypotonic / isotonic )
16. Predict what will happen to the red blood cells in Beaker Z: (shrink / swell / stay the same ).
The solution in the beaker is ( hypertonic / hypotonic / isotonic )
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For each of the following problems, do these things.
1. Determine the solute and solvent for the solution outside the cell (environment)
and for the inside of the cell and write the numbers in the blanks given.
2. Answer A, B, and C according to the instructions below.
A. Tell whether the solution outside the cell is hypotonic, hypertonic, or
isotonic.
B. Give the direction of the net movement of water (into cell, out of cell, or
into & out of cell at equal rates).
C. Tell what will happen to the cell (shrink, swell, or stay the same).
The first one has been done for you.
20 % solute
80 % solvent
70 % solute
_30_ % solvent
A. The solution outside the cell is hypotonic
B.
Water will move into the cell
C.
The cell will swell
17.
18.
___ % solute
25 % solvent
___ % solute
90 % solvent
A.
B.
C.
19.
40 % solute
___ % solvent
30 % solute
___ % solvent
A.
B.
C.
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35 % solute
20. ___ % solvent
____% solute
65 % solvent
A.
B.
C.
= Water
= Sugar molecule
Semi-permeable membrane
21. Look at the U-tube above. The semi-permeable membrane is permeable to only water.
Label the side that has a HIGH solvent and the side with the LOW solvent.
Which way will the water move? _____________________
Why?_______________________________________________________________________
____________________________________________________________________________
What will the U-tube look like in a few hours? (circle the correct diagram)
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Section 3.5 Active Transport
KEY CONCEPT
Cells use energy to transport materials that cannot diffuse across a membrane.
VOCABULARY
active transport
endocytosis
exocytosis
phagocytosis
pinocytosis
MAIN IDEA: Proteins can transport materials against a concentration gradient.
For each of the following statements, place a check mark in the appropriate box if it is true for simple
diffusion, facilitated diffusion, or active transport.
Simple
Diffusion
Statement
Facilitated
Diffusion
Active
Transport
1. The movement of molecules against a
concentration gradient (Low to High)
2. The movement of molecules down a
concentration gradient (High to Low)
3. The movement of molecules through
selective membrane proteins either down
or against the concentration gradient.
4. Active transport proteins have one key distinguishing feature, which is that they use
__________________ to move a substance against its concentration gradient.
5. Most active transport proteins use energy in the form of ____________ which is made by the
breaking down of glucose in cellular respiration.
6. The sodium-potassium pump, is a form of active transport where the protein pumps
______________________ ions out and ___________________ ions in against the gradient.
MAIN IDEA: Endocytosis and exocytosis transport materials across the membrane in vesicles.
Circle the word or phrase that best completes the statement.
7. A cell may transport a substance in lysosomes / vesicles if the substance is too large to cross the
membrane.
8. Complete the table below to compare and contrast the processes of endocytosis and exocytosis.
Characteristic
Endocytosis Exocytosis Both
Uses energy
Takes substances into a cell
Releases substances outside a cell
Moves substances in vesicles
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Vocabulary Check
Circle the word or phrase that best completes the statement.
9. Pinocytosis / Phagocytosis is a term that means “cell eating.” It describes a type of endocytosis.
10. The prefix exo- means “out of,” and the prefix endo- means “taking in.” Therefore, exocytosis /
endocytosis is a process that releases substances outside a cell, and exocytosis / endocytosis is a
process that takes substances into a cell.
11. Active transport / Facilitated diffusion drives molecules across a membrane against a concentration
gradient, from low concentration to high concentration.
Extension: Osmosis (Passive Transport)—optional
Experiment A
A selectively permeable membrane separates the solutions in the arms of the U-tube shown in Figure 1.
The membrane is permeable to water and to substance A, but not to substance B. Forty grams of
substance A and 20 g of substance B have been added to the water on side 1 of the U-tube. Twenty grams
of substance A and 40 g of substance B have been added to the water on side 2 of the U-tube. Assume
that after a period of time, the solutions on either side of the membrane have reached equilibrium.
(YOU MUST SHOW YOUR WORK by labeling in the diagrams to draw out what is happening in
the experiment.)
Figure 1A. Initial Solutions
Figure 1B. Final Solutions
1. How many grams of substance A will be in solution on side 1 of the U-tube? ___________
How many grams of substance A will be in solution on side 2? __________
Explain (assume that it is AFTER equilibrium has been reached).
_________________________________________________________________________________
_________________________________________________________________________________
How many grams of substance B will be in solution on side 1 of the U-tube? _____________
How many grams of substance B will be in solution on side 2? ___________
Explain (assume that it is AFTER equilibrium has been reached).
_________________________________________________________________________________
_________________________________________________________________________________
2. What has happened to the water level in the U-tube? (be specific as to which side of the tube the
water level increased. )
____________________________________________________________________
Explain. _________________________________________________________________
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