Shrinking Elodea Lab Report

Cells and molecules in the environment are constantly moving and changing, for cells to function properly there is a need for equilibrium to be met. The size of the cell and the solution outside of the cell affects the rate of diffusion and osmosis in the cell. Cells are constantly trying to reach an equilibrium with the molecules and substances around it, which is why there are such terms as: hypertonic, hypotonic and isotonic. The procedures allowed testing of whether or not surface area or volume increased diffusion and how different substance control diffusion. Cells are constantly moving to reach equilibrium through diffusion and osmosis.

In order to test this theory, we filled two different beakers, one with a 1% concentration of sucrose and another with 10% concentration, and obtained 4 bags made of dialysis tubing. Dialysis tubing works as a replica of a plasma membrane in the cell. Water (H2O) passes through the membrane since the molecules are so small. Other molecules that are larger in size will not pass through and therefore will remain in it’s initial solution and will not diffuse. Therefore, the results we see in our test corresponds to how a cell membrane will diffuse the water and sucrose in our solution.

The Diffusion and Osmosis Lab determines the molarities of various sucrose solutions based on change in mass. Using table sugar in different amount of molar concentration 0.0M, 0.2M, 0.4M, 0.6M, 0.8M and 1.0M. The molarity of the solution of the sucrose solution in the dialysis tubing determines the amount of water that either move into the bag or out the bag, which also means its mass changed.

Concentration of solutionsconcentrations were kept constant by using the same digital scale (with an uncertainty of 0.01 g) to measure the amount of glucose to be added to the water

Despite its importance osmosis may also damage cells by causing them to; a) shrink from water loss or b) burst from too much water gain. Plant cells [fig 3] have adapted themselves to ensure that these factors do not affect them, by forming a ridged wall, known as the cell wall, around their cells. The cell wall maintains the shape of the cell, and prevents the cell from bursting in a hypotonic medium by resisting water pressure. Plant cells have also adapted a larger vacuole, which occupies 80% or more of the cells cytoplasm (Davidson, 2004); allowing plants to store more water and nutrients per cell. Vacuoles also play a structural role in plant cells; by swelling when liquids contact them, plant vacuoles are able to control turgor pressure within the cell. This helps maintain the structural integrity of the cell as well as providing the plant with suitable amounts of water and nutrients; however the cell will never burst because the vacuole is contained within the cell wall. If plant cells are deprived of water their vacuole will begin to shrink, yet due to the cell the wall, the plant cell will be able to maintain its shape. [fig.4] Animal cells [fig 5] on the other hand do not have this

2. A hypertonic solution will cause the cell to shrink because more particles are in the solution and not in the cell.

The molarity of the solutions in each dialysis bag, and the percent change in mass are both included to best show effect of increasing molarities of sucrose and osmosis. The percent change in mass exhibits the process of osmosis, because osmosis must take place for water molecules to transfer from one side of the semi-permeable (in the surrounding distilled cup) to another (within the dialysis tubing), in order to reach equilibrium.

The weight of the egg after it was soaked in corn syrup for one day was 42.00g with the dimension of 4.3 cm×5.5 cm. The weight of the egg after it was placed back in water was 85.74g with the dimension of 5.2 com×7cm, and it was dyed blue. Both the mass and volume of the egg decreased after it had been placed in the corn syrup; however, the mass and volumes increased after the egg was placed back in water. This kind of result was caused by the osmosis of water, a process that water molecules passed through the membrane of the egg and moved from the region of higher solute concentration to the region of lower concentration. When a cell is in a hypertonic environment, like in corn syrup, it will lose water to the environment and shrink, but when it is in a hypotonic environment, like in water, it will gain water from the environment and swell

A cell placed in a solution that is in equilibrium (an isotonic solution) will remain the same and no water will enter nor leave the cell.

The claim to this Agar Pieces lab is that the cells that have a larger surface area to volume ratio are more efficient at diffusing essential nutrients. Another solution, is the rate of diffusion is related to cell size. Nutrients diffuse at a faster rate through small cells than they do through large cells. In this lab of Agar gel, the purpose of this experiment is to find the surface area and volume of the cell that may affect the ability of the molecule to be able to diffuse the cellular space.

The Effect of Different Light Colors on Elodea and the Production of Oxygen Through Photosynthesis Introduction: Life could not exist without oxygen and one of easiest ways for oxygen production is through photosynthesis. Photosynthesis is a process that converts solar energy into chemical energy which can then be used by the autotroph, an organism that can sustain itself without consuming another organism. Photosynthesis as an energy source is mainly used by green plants. The equation for photosynthesis is 6CO2 + 6H2O + light energy =

If an organism is placed into a hypotonic solution it will absorb water due to the fact that has been exposed to a lower concentration of water molecules, the water will flow through the semipermeable membrane and into the cells resulting in the organism gaining mass. An example of this would be an egg in

Those three experiments showed that the way onion cells are dealing with the movement of water in and out of the cell is by osmosis. That Osmosis is the diffusion of water across a membrane into a solution having a greater solute concentration. The cell

Qualitative Raw Data It was observed that as the temperature of the water increased, the number of oxygen bubbles produced by the Elodea did as well, however the number decreased after passing its optimal temperature, thus supporting the hypothesis made. For some of the trials in the experiment, in particular for the higher temperatures, there was no data recorded for the first 10 seconds. Afterwards, however, oxygen bubbles were produced in quick succession for a short period before slowing down again. This suggests that there may have been a blockage in the inside of the xylem or phloem vessels in the Elodea after cutting the stem.

Plant cells react differently to osmosis than animal cells. When an animal cell is placed in a hypertonic solution, water will leave the cell causing it to shrink, this is known as crenation. When a plant cell is placed in a hypertonic solution the cell membrane will pull away from the cell wall, making the plant flaccid, this is known as plasmolysis. When an animal cell is placed in a hypotonic solution, water will rush in to the cell, causing it to swell and sometimes burst. A plant cell placed in a hypotonic solution will also swell due to water rushing in, but will resist rupturing due to the rigid cell wall. Plant cells become more rigid in a hypotonic solution.