Page 78 - Biology Form Two
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Biology for Secondary Schools
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Figure 3.9: Potted plant with an accumulation of organic substances above the ring
4. Write a brief report of what you have observed.
The differences between diffusion, osmosis and mass flow is summarised in the
following Table.
Table 8.1: Differences between diffusion, osmosis and mass flow
Characteristic Diffusion Osmosis Mass flow
Substance transported Gases, liquids, Water Solids, liquids,
and ions and gases
Transport structures None Semi-permeable Cytoplasm or
membrane vessels
Cause of movement Diffusion Osmotic pressure Difference in
gradient pressure
Chapter summary 3. Concentration gradient is the
1. Transport is necessary for the difference in the concentration of
movement of substances within, a substance between two regions.
into, and out of cells to enable
vital life processes to take place. 4. The important processes in the
body that involve diffusion
2. Transport of materials in living
organisms can be carried out include gas exchange in the lungs,
through diffusion, osmosis, or absorption of nutrients into cells,
mass flow. absorption of digested food in
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