Lab #4 Osmosis (pg S59)

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Lab #4 Osmosis
(pg S59)
• Katherine wants to investigate if she adds
fertilizer before she waters her plants or after
watering?
• 1. Will water move into or out of a plant cell if the cell has higher water potential
than the surrounding environment?
• 2. What would happen if you applied saltwater to
• the root of a plant?
• 3. If you place fertilizer before you water the grass,
• will that change the movement of water into
• the plant?
Lab #4 Osmosis
• Design an experiment to identify the Molar (M) concentrations of
the sucrose solutions and use the solutions to determine the water
potential of the plant tissue.
• *Use different potatoes (potatoes, yams, sweet potatoes)
• *Unknown M concentration
• *Different sizes of cubes
– (surface area)
Lab #4 Osmosis
• Procedures:
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1. Cut four (4) potato cubes (DO NOT include skin).
2. Mass your four cubes (1 set) for Initial weight.
3. Place cubes in cups with sucrose solution molarity. Label cups
4. Make observations and place cups in order of Molarity.
5. Let it stand overnight (24hrs)
6. Mass your four cubes for Final weight. Calculate % change in mass.
7. Construct a Graph with class data
Questions????
• 1. How can you measure the plant pieces to determine the rate of diffusion?
• 2. How would you calculate the water potential in the cells?
• 3. How can you determine which color of water is which M sucrose concentration?
• 4. Which solution had a water potential equal to that of the plant cells? how do you
know?
• 5. What would your results be if the potato were placed in a dry area for several
days before your experiment?
• 6. When potatoes are in the ground, do they swell with water when it rains?

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