Elodea Lab Report

Introduction When plant and animal cells are placed in a hypotonic environment, osmosis will occur. The structure of these cells determines the response to the difference in gradient, whether this be lysis (the explosion of cells due to the sudden increase in water pressure within the cell) in animal cells or turgor pressure (the pressure created by the increase in water pressure within the cell) in plant cells. Turgor pressure prevents further osmosis, which causes the water potential outside the cell to be lower than that inside the cell. When placed in a hypertonic environment, the gradient in animal and plant cells are reversed and water exits the cell. This sudden release of water results in a shrinking membrane, called crenation, which
Three test tubes were filled with 5 mL of A, B, and C, respectively. 10 drops of mammal blood was added to each of these and mixed. The transparency and translucency of these tubes was tested. The solutions in the opaque tubes were placed on a slide with a drop of blood and observed under a microscope and compared to a control slide with just a drop of blood. Sketches of the observations were made and analyzed. A leaf of Elodea was placed on a slide along with solution X, observed, and drawn. Solution Y was then drawn through the slide and the previous method was repeated. The same was done with solution Z. The results were gathered and
This indicates that solution X is isotonic because the concentrations are similar, resulting in no difference in appearance. Solution Y is hypertonic because it shrank the membrane in plasmolysis, which forced all of the chloroplasts to the center of the cell. The cell possessed a higher concentration of water than the solution, which expelled all of the water in the cell, causing it to shrink. Solution Z is hypotonic because of the visible turgor pressure forcing the chloroplasts to the edge of the cell. The sudden rush of water in the cell forced the chloroplasts to the edge of the cell.
Blood plasma could be expected to be isotonic to blood cells because blood’s normal function and shape requires the cells to be intact, which rules out hypotonicity due to hemolysis, and of an average shape, which rules out hypertonicity due to crenation. Isotonicity would maintain the cells’ ability to function and perform the best they possibly could. In a similar way, pond water would also be hypotonic to elodea, which provides a high enough turgor pressure to maintain an upright posture in plants. Hypotonicity does not cause the cells to expand and explode, as seen in animal cells, due to the cell