Biology Osmosis Lab Report Essay

In this experiment, we will investigate the effect of solute concentration on osmosis. A semi‐permeable membrane (dialysis tubing) and sucrose will create an osmotic environment similar to that of a cell. Using different concentrations of sucrose (which is unable to cross the membrane) will allow us to examine the net movement of water across the membrane.

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.

The dialysis bag experiment resulted with beaker one having relatively similar numbers, showing as an isotonic medium. Beaker two’s solution gradually increased within an hour which caused the product to

The experiment of the lab was to demonstrate knowledge of the concepts of diffusion and osmosis. Diffusion is the movement of substances moving from a high concentration to a low concentration. For this lab the rate of osmosis was measured in concentration. The concentration stayed the same and increased through the experiment. At the beginning of the experiment the sacs were weighed to determine the tonicity of water throughout the experiment. Timing was also a factor each 15, 30, 45 minute interval the sacs were weighed and recorded. Each sac had a different amount of solution in them. The tonicity of the sacs was determined as well by the final weights and the final percent of gain or loss of water in the sacs.

The movement of materials through a dialysis membrane was conducted in this experiment. In this experiment, dialysis tubing was used to model a semi-permeable membrane. Glucose and starch solutions were placed into the dialysis tubing, which was placed into the beaker that contained water and 35 drops of iodine (initially only 20 but 15 were added). The solution in the beaker tested negative in the glucose test. The initial color of the glucose and starch in the tubing was cloudy and translucent, and the initial color of the liquid in the beaker was a translucent yellow orange. After a few minutes of sitting in the beaker, the liquid in the dialysis tubing had become a purple color and the liquid in the beaker became a darker yellow. Iodine

We hypothesize that as the solute concentration increases, more water will diffuse into the dialysis tubing (shown by a greater percent increase in mass).

When glucose carriers in the membrane were set to 500, the glucose transport rate for 2.00 mM of glucose was .0008 mM/min. Equilibrium was reached at 43 minutes. At 700 glucose carriers the rate was .0010 mM , and equilibrium was reached at 33 minutes. When the glucose carriers was set at 900 the rate was .012 mM/min, and equilibrium was reached at 27 minutes. After changing the glucose concentration to 8.0 mM, the glucose transport rate with 500 carrier proteins was .0023 mM/min, and equilibrium was reached at 58 minutes. With the simulation set at 700 carrier proteins the rate was .0031mM/min, and equilibrium was reached at 43 minutes. When the simulation was done with 900 carrier proteins the glucose transport rate was .0038, and equilibrium was reached at 35 minutes.

The dialysis tubing will be clamped at one end in order to fill it and then clamped at the other end to seal the filled bag. If the bag is not soft and floppy, the experiment will not work. Blot a bag with a paper towel to absorb the moisture and weigh it, if this blotting process is not done it could interfere with the weight readings creating inaccurate information. After the bags of the solutions are prepared, they will be placed into five different beakers with different solutions. Beakers 1-4 will be filled with tap water and the fifth beaker is filled with 40% sucrose and water. Fill each beaker with just enough water or solution so that the bag is covered and place the bags in the beakers simultaneously and record each time. Every 10 min the bags are to be taken out, blotted, and weighed again before returning them back into their respective beaker for another 10 min. The process is repeated until you have reached 90 min. The weights should be recorded in grams (g).

Group 1 received 107% for 0.0m, 109% for 0.25m, 112% for 0.5m, and 126% for 0.75m. Group 2 received 100% for 0.0m, 107% for 0.25m, 116% for 0.5m, and 117% for 0.75m. Group 3 received 100% for 0.0m, 106% for 0.25m, 114% for 0.5 m, and 117% for 0.75m. Group 4 received 100% for 0.0m, 106% for 0.25m, 113% for 0.5m, and 116% for 0.75m. Group 5 received 98% for 0.0m, 105% for 0.25m, 110% for 0.5m, and 115% for 0.75m. Group 6 received 104% for 0.0m, 108% for 0.25m, 111% for 0.5m, and 104% for 0.75m. The trend line that occurred for the rate of osmosis was an upward increase as the solute concentration increased.

In this study we constructed we researched whether different sucrose concentrations affect the rate of osmosis. In order to do this, we constructed artificial cells out of dialysis tubing filled with 20% sucrose and 40% sucrose and weighed them every 10 minutes for 90 minutes. In doing so, we concluded that the higher the sucrose concentration, the faster the rate of osmosis.

A concentration gradient is a gradual change in solute concentration between two areas, these areas are usually separated by a membrane. A gradient result from an unequal distribution across the cell membrane. When this happens, the solutes travel along the concentration gradient (Seeley, Stephens, Tate, 2005). This type of movement is called diffusion. Diffusion is the tendency of molecules to move from a higher concentrated environment to a lower concentrated environment. This movement continues until both sides are even. Diffusion across a cell membrane is a type of passive transport, a transport that does not require energy (Karp, 2010).

The overall purpose of this experiment is to determine how solute concentration, particle size, and a membrane’s selective permeability affect the occurrence of diffusion.

Hypothesis: If we add higher concentrations of sugar to the dialysis tubing, then the net movement of coffee into the dialysis tubing will increase.

The difference is that along with large molecules, living cells prevent molecules with positive charges and solubility. This is not representing in dialysis tubing, and is only found in living cells because the tubing is only based on molecular size (98). When referring the rate of diffusion, the concentration gradient influences the diffusion rate, based on the factors of temperature. The ability for molecules diffuse from high to low concentrations primarily depends on the concentration gradient between the two areas.(96-99). My hypothesis for the study is that in the hypotonic, hypertonic, and isotonic solutions, the direction and rate of osmosis will determine based on the concentration inside the dialysis tubing. My prediction is that if the solution is hypotonic the results will decrease, if the solution is hypertonic the results will increase and if the solution is isotonic the solution will vary and or remain constant.

With gained knowledge from this experiment, our group performed another experiment and tested how certain amounts of solute concentration impacted the rate of osmosis. We hypothesized that high solute concentrations affected the rate of osmosis. Tubes with high solute concentrations were bound to show higher rates of osmosis than tubes with