2015 OsmosisLabs Onions Potatoes
A STUDY OF OSMOSIS
Han Cheng Water passes through aquaporins in cell membranes from an area of high water concentration (low solute concentration) to an area of low water concentration (high solute concentration). This process is called osmosis. It requires no cellular energy to be used, and occurs due to the random, continuous motion of all molecules. If a cell is placed in an environment in which the concentration of water is less than in the cell (hypertonic), water will flow from the cytoplasm and/or water vacuole through the membrane into the environment. (Some solute moves into the cell but this does not account for the dramatic changes that you see or weigh) The cytoplasm and/or vacuole of the cell shrinks. In an animal cell, the entire cell shrivels. In a plant cell, the cytoplasm shrinks away from the cell wall. A cell placed in a hypotonic environment will gain water by osmosis.
(http://www.williamsclass.com/SeventhScienceWork/CellsOrganization.htm)
Purpose: to observe and measure the process of osmosis in living cells, qualitatively and quantitatively.
Materials: red onion cell, slides, coverslip, compound microscope, 4% salt solution, distilled water, potatoes, beakers, balance, paper towels
Procedure:
Part A Qualitative Observations of Osmosis
1. Make a wet mount of a small, thin piece of purple epidermis from a red onion bulb's leaf scales.
2. Photograph and label what you observe under high power. Be sure to include: cell wall, cell membrane, nucleus, central vacuole (takes up most of the space in the cell and contains water and a reddish/ purple pigment called anthocyanin, central vacuole membrane).
3. Lift off the coverslip and place 2 drops of 4% salt solution directly on the sample.
4. Photograph your cells. Note the color and position/shape of the vacuole.
Label central vacuole membrane.
5. Lift the coverslip and dd 3-5 drops of distilled water to the slide.
6. Photograph the cells. Again, note the
Han Cheng Water passes through aquaporins in cell membranes from an area of high water concentration (low solute concentration) to an area of low water concentration (high solute concentration). This process is called osmosis. It requires no cellular energy to be used, and occurs due to the random, continuous motion of all molecules. If a cell is placed in an environment in which the concentration of water is less than in the cell (hypertonic), water will flow from the cytoplasm and/or water vacuole through the membrane into the environment. (Some solute moves into the cell but this does not account for the dramatic changes that you see or weigh) The cytoplasm and/or vacuole of the cell shrinks. In an animal cell, the entire cell shrivels. In a plant cell, the cytoplasm shrinks away from the cell wall. A cell placed in a hypotonic environment will gain water by osmosis.
(http://www.williamsclass.com/SeventhScienceWork/CellsOrganization.htm)
Purpose: to observe and measure the process of osmosis in living cells, qualitatively and quantitatively.
Materials: red onion cell, slides, coverslip, compound microscope, 4% salt solution, distilled water, potatoes, beakers, balance, paper towels
Procedure:
Part A Qualitative Observations of Osmosis
1. Make a wet mount of a small, thin piece of purple epidermis from a red onion bulb's leaf scales.
2. Photograph and label what you observe under high power. Be sure to include: cell wall, cell membrane, nucleus, central vacuole (takes up most of the space in the cell and contains water and a reddish/ purple pigment called anthocyanin, central vacuole membrane).
3. Lift off the coverslip and place 2 drops of 4% salt solution directly on the sample.
4. Photograph your cells. Note the color and position/shape of the vacuole.
Label central vacuole membrane.
5. Lift the coverslip and dd 3-5 drops of distilled water to the slide.
6. Photograph the cells. Again, note the