SECTION
DIFFUSION AND OSMOSIS
3.4
Study Guide
KEY CONCEPT
Materials move
VOCABULARY
passive transport
osmosis
hypotonic
across membranes
because of
diffusion
isotonic
facilitated diffusion
concentration gradient
hypertonic
concentration
differences.
MAIN IDEA: Diffusion and osmosis are types of passive transport.
1. What is a concentration gradient?
The difference in the concentration of a substance from one location to another
2.
What does it mean for a molecule to diffiise down a concentration gradient?
the molecule defuses from one area of a higher concentration into a area of lower concentration.
Complete the concept map below about passive transport.
Passive transport
example
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7. energy from the cell
example
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osmosis
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6. the natural motion of
particles
the diffusion
of water
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8.
The higher the concentration of dissolved particles in a solution, the
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Unit 2 Resource Book
McDougal Litlell Biology
srudy Guide 13
Period
Name
Date
STUDY GUIDE, CONTINUED
Suppose you have three solutions with different concentrations of particles. Relative to the
concentration ofparticles in a cell, one solution is isotonic, one is hypertonic, and one is
hypotonic. Use this information to answer the next two questions.
9.
Which solution has the highest concentration of particles?
hypertonic
1O. rWhich solution has the highest concentration of water molecules?
hypotonic
MAIN IDEA:
Some molecules diffuse through transport proteins.
11. How does facilitated diffirsion differ from simple diffusion?
It occurs throuqh selective transport Droteins, not sim ply across the membrane
12. In facilitated diffirsion, do molecules move down a concentration gradient or against
a
concentration gradient?
down a concentration
radient
Vocabulary Gheck
13. The difference in
the concentration of a substance from one location to another is a
concentration gradient
c
14.
People with excess energy are described as hyper. How does this relate to the meaning
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of hypertonic?
15.
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Just as a hyper person has higher level of energy than most people, a hypertonic solution has a higher
level of solutes than the solution it is being compared to.
The wordfacilitate means "to make easier." How does this meaning apply to facilitated
diffusion?
The transport protein makes it easier for a molecule that cannot directly cross the cell membrane
to enter or exit a cell.
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Srudy Guide
Unit 2 Resource Book
McDougal Littell Biology