HSDE William St Human and Social Biology Date: December 2024
Test: Movement across membranes Instructor: Miss G. Murray
1. Molecules may move by the process of “diffusion”. Define “diffusion”.
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2. Give two reasons why diffusion is important to living organisms.
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3. Organisms must transport substances to and from the external environment.
Identify one substance which cells must transport across the cell membrane to support
cell functions.
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4.
Complete each row of the table with a tick () or a cross (X) to indicate whether it is a feature of osmosis.
Feature /X
Involves the movement of gases
Requires energy from respiration
Movement will occur across a partially permeable membrane
Particles that move down a concentration gradient
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5. During a science lesson, a student writes down the following statement about osmosis.
The active movement of molecules through a
membrane from a region of low concentration to a
region of high concentration.
Using your knowledge of osmosis, suggest what is wrong with this statement.
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6. Pre-cut potato chips can be stored in salt solution before being cooked in restaurants. To
avoid the chips becoming too salty, it is important to make sure that water does not
move in or out of the chips as they are stored.
A scientist wanted to collect some data about the salt content of potato chips to inform
the restaurants of the best storage concentration. The steps in the table refer to the
method that the scientist used to collect his results.
1 Measure out 100 ml of each salt solution into 5 different test
tubes.
Remove the chips, pat dry and reweigh.
Cut 5 potato chips of similar size and dimensions.
Place 1 chip into each concentration of salt solution and leave for
1 hour.
Record the mass of the potato chip.
Place the steps in the correct order by adding numbers 2 to 5 into the left hand column
of the table. The first stage has been labelled for you.
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7. State one way in which active transport differs from osmosis.
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8. A student puts some red blood cells into water and leaves them immersed for
fifteen (15) minutes.
Suggest what would happen to the cells.
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9. What part of the plant takes up ions from water in the soil?
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10. Give an example of human cells that use active transport.
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