NAME: ____________________
PERIOD: _____
DATE: _______________
MR. LASTOWSKI
BIOLOGY I HONORS
CELL STRUCTURE & FUNCTION
Movement Across the Membrane
Part A – Components of the Cell Membrane
The cell membrane forms a boundary that separates the inside of a cell from the outside
environment. It plays an active role by controlling the passage of materials into and out of a cell and by
responding to signals. The cell membrane includes a variety of molecules that give the membrane
properties it would not otherwise have.
READ pages 81 to 82 and identify structures a through j using the following terms:
carbohydrate chain
cholesterol
identification tag
cytoskeletal proteins
phosphate-glycerol head
protein channel
fatty acid tails
phospholipid
protein
sugar molecule
a. _______________
b. _______________
c. _______________
d. _______________
e. _______________
f. _______________
g. _______________
h. _______________
i. _______________
j. _______________
Part B – Transport Mechanisms
READ pages 85 to 91 and answer the following questions 1 through 10 using complete sentences.
1.
Define the term concentration gradient.
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Explain what it means for a molecule to diffuse down its concentration gradient.
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2.
Explain why facilitated diffusion does not require energy from the cell.
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3a.
In the diagram below, label the type of solution each red blood cell is in (isotonic, hypotonic, or
hypertonic) for numbers 2, 4, and 6. Draw arrows on each cell to show the direction of osmosis
for numbers 1, 3, and 5 (HINT: see Figure 3.23).
3b.
A cell is bathed in fluid. However, you notice that water is flowing out of the cell.
In what kind of solution is this cell immersed: isotonic, hypotonic, or hypertonic? (circle one)
Explain why water is moving out of the cell into the surrounding solution.
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4.
Describe how receptors and transport proteins are similar.
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5.
When a person becomes dehydrated due to the loss of fluids and solutes, saline solution (water
and salts) is infused into the bloodstream intravenously (commonly called I.V.) by medical
personnel. Why is saline solution used instead of pure water?
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6.
How do transport proteins that are pumps differ from those that are channels?
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7.
Describe endocytosis and exocytosis. How do these processes differ from diffusion?
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8.
Small lipid molecules are in high concentration outside a cell. They slowly cross the cell membrane
into the cell. What term describes this action? Does it require energy?
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9.
Ions are in low concentration outside a cell. They move rapidly into the cell via (by means of)
protein molecules. What term describes this action? Does it require energy?
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10.
Suppose molecules were unable to diffuse into and out of cells. How might life be different if
cells had to use active transport to move every substance? Explain your reasoning.
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Part C – Florida Benchmark Review
Answer questions 1 through 6 on the back of this page by circling the correct response.
Please see page 97 in the biology textbook if you have trouble reading the questions below.