Active Transport
In diffusion and osmosis, particles move down a concentration gradient. This means particles are moving from a
region of higher concentration to a region of lower concentration.
Before
The diagram shows the percentage concentration
of sugar solution in cells P, Q and R.
After
b. Osmosis – Water can move from cell to cell.
Into which cell, P, Q or R, will water move the
fastest? _____________
a. Diffusion – complete the diagram on the
right to show what happens to the particles
after diffusion
c. Sometimes, particles need to move against a concentration gradient. This means particles are moving from a
region of __________________ concentration to a region of ___________________ concentration. This process
requires _____________ and is called active transport.
d. Complete the table below to describe two examples of active transport
Active transport in plants
Active transport in animals
What substance is involved?
Why is this substance important?
Where does it need to be moved from?
Where does it need to be moved to?
What would happen if diffusion alone
was used?
The table shows the concentrations
of some mineral ions in the cells of a
pond plant and in the surrounding
pond water.
Concentration in mmol per dm3
Potassium
Calcium
Sulphate
Plant cells
49.0
7.0
7.0
Pond water
0.5
0.7
0.4
e. The plant cells would not have been able to absorb these mineral ions from the pond water by diffusion. Explain
why not.
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f. What process could be used to absorb these ions into the plant cell? ………………………………………………………………………