Name:
Passive Transport Workbook
Year 12 Science
Ruawai College 2014
Osmosis:
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is the movement of water from a high water concentration to a low water concentration
across a semi-permeable membrane
does not require any energy to occur
is a form of passive transport
is a special case of diffusion
Diffusion is the movement of particles in liquids and gases from an area of high concentration to an
area of low concentration. It does not need energy.
The diagram below shows diffusion of gas particles in a sealed container.
1.
When the gas is introduced to the container, where are the particles placed?
On the LHS of the container
2.
What is the concentration of the gas particles, high or low?
high
3.
As time passes, what happens to the particles?
Spreads out through the container
4.
At the end of the time period, the gas particles are spread evenly in the sealed container.
What is the concentration of the gas particles, high or low?
low
5.
What is the name of the process where the gas particles move from a high concentration to
a low concentration?
Diffusion
6.
Where is the high concentration of particles located?
On the outside of the cell
7.
What are the particles moving through to get to an area of low concentration?
Through the cell membrane
8.
Draw an arrow on the diagram to show the movement of particles.
9.
When is the concentration the same inside the cell and outside the cell?
At the end of the time period
The difference in concentration between two areas is called the concentration gradient. The higher
the concentration gradient, the faster the rate of diffusion. Other factors that affect diffusion are:
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size – small particles diffuse faster than large ones
temperature – particles diffuse faster at high temperatures than they do at low
temperatures
state – gas particles diffuse faster than particles in a liquid
10. Why are the particles moving through the
cell membrane?
Moving from a high concentration to a low
centration
11. Why are the molecules of oxygen diffusing
into the cell?
Diffusing from a high concentration to a low
concentration
12. Why are the molecules of carbon dioxide
diffusing out of the cell?
Diffusing from a high concentration to a low
concentration
Small molecules like oxygen and carbon dioxide are able to simply diffuse through the cell
membrane. The direction of their movement is only dependent on their concentration. Large
molecules e.g. starch, are unable to diffuse through the membrane.
Special carrier or transport proteins can carry molecules across the cell membrane. The proteins
provide a channel for movement of molecules and are specific – they carry only one type of
molecule. Facilitated diffusion is fast but is passive. Molecules can only move from a high
concentration to a low concentration.
13.
What is the concentration of molecules outside the cell?
high
14.
What is the concentration of molecules inside the cell?
low
15.
In which direction do the molecules move?
From outside of the cell to inside of the cell
16.
What does the channel protein do?
Provide a channel for particles to diffuse through the cell membrane into the cell
17.
What does the carrier protein do?
Provide a pathway for particles to diffuse through the cell membrane into the cell
18.
What are two types of passive transport?
Diffusion and facilitated diffusion
19.
What is the similarity between diffusion and facilitated diffusion?
Molecules move through the cell membrane, no energy required
20.
What is the difference between diffusion and facilitated diffusion?
Diffusion happens to small molecules
Facilitated diffusion happens to large molecules using proteins
21.
What is diffusion?
The movement of small molecules through the cell membrane from a high concentration to a low
concentration
22.
What is facilitated diffusion?
The movement of larger molecules through the cell membrane from a high concentration to a low
concentration using proteins as carriers
23.
What is osmosis?
The movement of water across a semi-permeable membrane from a high water concentration to a
low concentration
24.
What is the difference between diffusion and osmosis?
Diffusion is the movement of particles from a high concentration to a low concentration
Osmosis is the movement of water across a semi-permeable membrane from a high water
concentration to low water concentration
25.
Compare and contrast osmosis and diffusion. Use the information in the venn diagram.
Compare – similarities
Movement from a high concentration to a low concentration
No energy required
Contrast – differences
Diffusion – movement of particles, no semi-permeable membrane required
Osmosis – movement of water, requires semi-permeable membrane
Glossary
Keyword
Definition