Name ______________________________ Class ___________________ Date __________________
Skills Worksheet
CH8.1 Directed Reading
Section: Cell Membrane
Read each question, and write your answer in the space provided.
1. What is homeostasis, and what is the main way that the cell membrane helps
maintain homeostasis?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
2. List three other functions of the cell membrane.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
Complete each statement by writing the correct term or phrase in the space provided.
3. The ______________________ ______________________ is made of a
double layer of phospholipids. The double layer of phospholipids is called a(n)
______________________ ______________________.
4. The lipid bilayer forms because there is ______________________ both
inside and ______________________ of the cell.
5. The phosphate ______________________ of a phospholipid is polar. It is
______________________ ______________________ water.
6. The long fatty acid ______________________ of a phospholipid are nonpolar.
They are ______________________ ______________________ water.
7. The lipid bilayer forms a barrier, preventing most molecules from passing
through it. Only molecules that are ______________________ in size and
______________________ can pass through the lipid bilayer.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
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Cells and Their Environment
Name ______________________________ Class ___________________ Date __________________
Directed Reading continued
8. Ions, which are ______________________ particles, and
______________________ molecules are repelled by the nonpolar interior of
the lipid bilayer.
9. The cell membrane includes various kinds of ______________________.
Some face the inside of the cell. Some face the ______________________ of
the cell. Others span the entire width of the ______________________
______________________.
Read each question, and write your answer in the space provided.
10. What are proteins made of? ________________________________________
11. Why do proteins stay within the lipid bilayer of the cell membrane?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
12. List the four types of proteins found in a cell membrane.
_______________________________________________________________
_______________________________________________________________
In the space provided, write the letter of the description that best matches each term.
a. helps with chemical reactions
inside the cell
b. recognizes and binds to
substances outside the cell,
enabling the cell to sense its
environment
c. helps substances move across
the cell membrane
d. identifies the cell type
_____ 13. cell-surface marker
_____ 14. receptor protein
_____ 15. enzyme
_____ 16. transport protein
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Biology
2
Cells and Their Environment
Name ______________________________ Class ___________________ Date __________________
Skills Worksheet
CH8.2 Directed Reading
Section: Cell Transport
Read each question, and write your answer in the space provided.
1. What is the purpose of cell transport? What is the difference between active
transport and passive transport?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
2. What is equilibrium?
_______________________________________________________________
_______________________________________________________________
3. What is diffusion? Why is diffusion an example of passive transport?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
In the space provided, write the letter of the description that best matches each term .
_____ 4. simple diffusion
_____ 5. facilitated diffusion
with channel
proteins
_____ 6. facilitated diffusion
with carrier proteins
a. a substance binds to a protein, which
changes shape; both move together
across the cell membrane, where the
substance is released
b. small, nonpolar molecules passing
directly through the cell membrane
c. an ion, sugar, or amino acid moving
through a specific pore, based on the
size and charge of the moving
substance
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Biology
3
Cells and Their Environment
Name ______________________________ Class ___________________ Date __________________
Directed Reading continued
Read each question, and write your answer in the space provided.
7. What is osmosis, and why is it important in cells?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
8. Explain how water moves across a cell membrane.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
Match the condition on the right with the numbered action on the left.
_____ 9. water moves into the
cell
_____ 10. a state of ongoing
equilibrium occurs
_____ 11. water moves out of
the cell
a. The solution a cell is in is hypertonic,
meaning that it has a higher solute.
concentration than the cytoplasm does
b. The solution a cell is in is isotonic,
meaning that it has the same solute.
concentration as the cytoplasm does
c. The solution a cell is in is hypotonic,
meaning that it has a lower solute
concentration than the cytoplasm does.
Complete each statement by writing the correct term or phrase in the space
provided.
12. The transport of a substance across the cell membrane against its
concentration gradient is called ______________________
______________________.
13. The energy needed for active transport is usually supplied by _____________.
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Biology
4
Cells and Their Environment
Name ______________________________ Class ___________________ Date __________________
Directed Reading continued
Read each question, and write your answer in the space provided.
14. What is the sodium-potassium pump? Describe how it works.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
15. Explain why proteins and polysaccharides cannot be transported across a cell
membrane by carrier proteins. How do these substances cross the cell
membrane?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
16. What is endocytosis? Describe how it works.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
17. What is exocytosis? Describe how it works.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
18. What are some circumstances in which cells use exocytosis?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Biology
5
Cells and Their Environment
Name ______________________________ Class ___________________ Date __________________
Skills Worksheet
CH8.3 Directed Reading
Section: Cell Communication
Read each question, and write your answer in the space provided.
1. What is the main way cells communicate and coordinate activities?
_______________________________________________________________
_______________________________________________________________
2. What is a target cell?
_______________________________________________________________
_______________________________________________________________
3. How might neighboring cells communicate?
_______________________________________________________________
_______________________________________________________________
4. What is an environmental signal? Give an example.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
5. Cells are constantly bombarded by signals. How are they able to respond to
only the few signals important to their cell function?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
6. What is a binding site, and why does it have a specific shape?
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Biology
6
Cells and Their Environment
Name ______________________________ Class ___________________ Date __________________
Directed Reading continued
7. Summarize the three responses cells generally have to a specific signal.
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
_______________________________________________________________
In the space provided, write the letter of the description that best matches each term.
_____ 8. signal
_____ 9. receptor protein
_____ 10. enzyme
_____ 11. second messenger
a. forms in response to information from
outside a cell and acts as an information
carrier within a cell, causing changes in the
cytoplasm or the nucleus
b. binds to a specific signal molecule, causing
a cell to respond
c. speeds up a specific chemical reaction in
the cell
d. carries information from one cell or cells to
other cells
Original content Copyright © by Holt, Rinehart and Winston. Additions and changes to the original content are the responsibility of the instructor.
Holt Biology
7
Cells and Their Environment