Observing Osmosis Through the Membrane of an Egg

Observing Osmosis Through the Membrane of an Egg

Gabby Davidson

Group members: Adam Klinger and Jenna Kshatri

Mr. Laub

Period 6/7 Even

Grade 10

12/15/15

Abstract

In the experiment, the problem that was trying to be solved was how the solute concentration affected the movement of water across a biological membrane. The lab experiment was carried out using two eggs immersed in distilled water and corn syrup. This affected the movement and transport of concentrations through a membrane. In the experimentation done, two eggs were placed in vinegar to decalcify.  After weighing both eggs on a balance, the conclusion was that Egg A’s initial mass was 74.7 grams and Egg B’s was 73.5 grams. Egg A was then placed in distilled water while Egg B was placed in corn syrup. The corn syrup contains a higher solute concentration than the egg therefore making it a hypertonic solution. The distilled water contained a lower solute concentration than the egg making it a hypotonic solution. After 10 minutes, the eggs were taken out to measure the weight again on a balance scale. Egg A had a mass of 75 grams and Egg B had a mass of 72.5 grams. As a result of osmosis, Egg A gained mass and Egg B lost mass. After the next 10-minute testing, Egg A had a mass of 75.6 grams and Egg B had a mass of 70.5 grams. The next 10 minutes after that and Egg A had a mass of 75.5 grams and Egg B had a mass of 69.2 grams. After the last process, which totaled up to 40 minutes of testing, Egg A had a mass of 75.8 grams and Egg B was 67.5 grams. After the results of the experiment were gained, it can be concluded that Egg A gained more mass because it was in a hypotonic solution and Egg B lost mass because it was in a hypertonic solution.

Purpose/ Hypothesis

The purpose of the experiment is to find out how solute concentration affects the movement of water across a biological membrane. Diffusion is the movement of molecules from an area of higher concentration to an area of lower concentration. This difference in the concentration of molecules across a space is called a concentration gradient. Diffusion is a type of passive transport, meaning it does not require energy put in by the cell (Biology Corner, n.d.). This type of transport and osmosis are the two processes used in this lab. Osmosis is the process by which water molecules diffuse across a cell membrane from an area of higher concentration to an area of lower concentration. Osmosis stops occurring when both solutions reach an equilibrium and become an isotonic solution. When the concentration of the solute is higher outside of the cell, it is known as a hypertonic solution. When the concentration of the solute is lower outside of the cell, it is known as a hypotonic solution (Shmoop Editorial Team, 2008). Due to osmosis, the water will try to compensate for the high solute concentration. The molecules would diffuse around the solution, dispersing to lower concentrations to create balance. Solutions with higher solute concentrations contain lower amounts of free water molecules. As a result of this, osmosis and diffusion tend to occur.  Osmosis equalizes the concentration of water on both sides of the egg membrane. Since a container of corn syrup has a lower concentration of water than an egg, the water molecules moved out of the egg to try to balance the number of molecules on each side of the membrane, causing the eggs to shrink in mass (Allard, 2002). An egg has a semi-permeable membrane when decalcified, so osmosis and diffusion would occur if there is concentration gradient. When placed in a hypertonic solution, the water molecules moved into the cell. When the egg was placed in hypotonic solution, it transported out of the cell (Miller, K. R., & Levine, J. S., 2004). If the solute concentration is greater on one side of the biological membrane, then the water on the lesser concentration side will move across the membrane to the higher solute concentration.