Experiment reports
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Using passive voice to focus on what is done | page 2 of 4 |
The use of passive voice in Osmosis in a potato
The following text from a biology textbook talks about osmosis in a potato. The words
in bold are verbs in passive voice 
:
Osmosis in a potato
Aim
To study osmosis in a potato
Materials
Four peeled potato halves: two fresh (A & B), two boiled (C & D)
Four petri dishes
Sucrose solution
Distilled water
Knife
Diagram
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Procedure
A small but deep cavity was cut in each half. Two cavities (A & C) were filled with distilled water and two (B & D) with sucrose solution. The filled halves were each placed in a petri dish containing equal amounts of sucrose solution (A & C) or distilled water (B & D) as shown in Figure 1. The level of each solution was then carefully observed.
Results
In A, the level of distilled water inside the cavity dropped and the level of sucrose solution in the dish rose.
In B, the level of sucrose solution in the central cavity dropped at first but after 24 hours had risen.
In C and D, the levels of water and sucrose solution in the cavities both dropped until they were at the same level as the sucrose solution and water outside.
Conclusions
In A, cells on the outside of the potato lose water to the sucrose solution due to osmosis and the water is replaced with water from adjacent cells. This process is repeated until water is taken into the potato cells from the central cavity.
In B, water initially moves into the cells next to the cavity but over 24 hours, due to osmosis, the movement of water molecules is opposite to that seen in A.
In C and D, since the cell membranes have been destroyed by boiling, there is no longer a selectively permeable membrane across which osmosis can occur. The movement is simply due to water passing through the potato to "find its own level".
(Adapted from Wakefield, J. and Warren, J. (1989) Biology: A New Approach, Second Edition. Macmillan, pp 235-236.)
Introduction
The use of passive voice in Osmosis in a potato
