Name
Lakeland High School
Date
Biology
Passive and Active Transport
Cell Membrane
The function of the cell membrane is to…
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Control what goes in and out of the cell
This helps keep the cell in balance – controlling the amount of substances in and out of the cell.
Types of Transport
We are going to take a deeper look at how things move across the cell membrane by examining
the two types of transport; passive transport and active transport.
Passive transport
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Movement does not require energy
Active Transport
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Movement requires energy (ATP)
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Passive Transport
Some substances can pass through the cell membrane without the requirement of energy, such
as carbon dioxide and oxygen.
There are 3 different types of passive transport: diffusion, facilitated diffusion, and osmosis
diffusion.
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The movement of molecules from an area of high concentration to an area of lower
concentration.
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Molecules are moving with the concentration gradient (a difference between
concentrations in a space).
High concentration
Low concentration
Facilitated Diffusion
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Diffusion with the help of transport proteins.
Osmosis
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Diffusion of water(H20) across a membrane.
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Types of solutions
When a cell is in a solution, water can move in or out of the cell depending on the
concentration of solutes and water in that solution.
There are three different types of solutions: isotonic, hypotonic, and hypertonic
Isotonic
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Concentration of water is equal on both sides
Cells stay the same
Hypotonic
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Concentration of water is higher outside the cell
Water moves in and cell swells
Hypertonic
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Concentration of water is greater inside the cell
Water leaves the cell and it shrinks
Plasmolysis
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The shrinking of plant cells due to osmosis
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Active Transport
Some substances require energy to pass through the cell
membrane.
Active transport
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Movement of substances against the concentration
gradient
Low concentration to high concentration
Requires energy (ATP)
Low concentration
High concentration
Movement of Substances
Endocytosis
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Things move INTO the cell
Exocytosis
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Things push OUT of the cell
Ex = Exit the cell
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Summary Questions
1. Explain the difference between passive and active transport in terms of concentration
gradient (high and low concentrations)?
2. Differentiate between diffusion and facilitated diffusion.
3. Explain why drinking large quantities of ocean water is dangerous to humans
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4. Describe and draw what would happen to a cell in each of the following solutions?
a. Isotonic
b. Hypertonic
c. Hypotonic
5. Why might an animal cell burst in a hypotonic solution, but not a plant cell?
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