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Diffusion: Random movement of particles from an area of high concentration to an area of low concentration, resulting in uniform distribution of particles. Examples of Diffusion: 1. Oxygen diffuses from lung into blood stream. Carbon dioxide diffuses from blood stream into lung 2. Food substances diffuse from interior of small intestine into the blood stream. 3. Carbon dioxide diffuses into the leaves for photosynthesis and oxygen diffuses out Note: Diffusion occurs more rapidly if there is a large difference of concentration also known as the steep diffusion gradient. Osmosis: Movement of water molecules from an area of high water potential to an area of low water potential through a selectively permeable membrane. - The membrane has tiny pores which allow small molecules like water to pass through but not bigger molecules like sugar. The water will move into an area where there is less water in an attempt to equalize the water potential. Osmosis and plant cells: If a plant cell is placed in distilled water the water will enter by osmosis through the selectively permeable membrane beneath the cell wall. The water enter because the sugars and salts dissolved in the cytoplasm lower the water potential. When water enters the cell the pressure increases and the cell is now turgid. Osmosis and plant cells: If a plant cell is placed in sugar solution water will leave if the water potential of the sugar solution is less than that of the cell contents. The cell will be far less rigid then before and is now called flaccid. If the majority of cells in the plant are flaccid the plant wilts. Plasmolysis: If a plant loses an excessive amount of water it enters this stage.
Approximate Word count = 1126
Approximate Pages = 4.5
(250 words per page double spaced)
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