Diffusion And Osmosis Lab Report

Abstract

Diffusion and osmosis in living cells are greatly effected by factors such as solution concentration, temperature, and surface area of the cell. This was studied using agar cubes of different sizes, dialysis tubing, and potato cores to demonstrate how the different factors affect cells. The process of cellular respiration can be altered due to temperature differences. Enzymes also greatly affect the molecular processes that occur. Enzymes are denatured at variety of pH and causes inactivity of the enzyme in the reactions.

Introduction

Cells are all around us and must do cellular processes to live. Although all cells on earth have cellular processes, not all are living under the same conditions. Conditions on earth vary in concentration,

temperature, pH, and so forth. How is it that similar cells can live in different conditions but still survive? The aim of this investigation is to gain a better understand of how different conditions affect the rates of osmosis, diffusion, cellular respiration, and enzyme activity. In general, our investigation led us to the knowledge that these processes vary in rates under different conditions and perform optimally in different conditions.

Materials and Procedures
Diffusion and Osmosis lab:
One milliliter of 1% phenolphthalein solution was placed in two test tubes.

In one test tube 0.1M of HCl was added. In the other test tube, 0.1M of NaOH was added. Color change occurred in the NaOH solution. Three agar cubes were cut in 1X1X1 cm, 1X1X2 cm, and 1X0.5X2 cm lengths. Surface area and volume were calculated to get ratios of 6:1, 5:1, and 7:1. Cubes were placed in separate test tubes. In each test tube we covered the cubes with HCl. Time was recorded to show absorption speed when the cube changed color from light pink to clear (table 1).

Five dialysis tubing was filled with either NaCl, glucose, sucrose, distilled water, or ovalbumin. The dialysis tubes were weighed for starting weight. Each dialysis tube was placed in a separate beaker with 250ml of distilled water. Five minutes was allowed for osmosis and diffusion to occur. Weight was recorded for final weight and to calculate the change in weight that occurred for each tube. For the second portion of lab, five beakers were filled with 250ml of distilled water and filled each dialysis tube with 10 ml of either NaCl, sucrose, glucose, ovalbumin, and distilled water. Weight was obtained for the starting weight. The beakers of distilled water were placed on a hot plate and temperature was raised to 50 C°. Dialysis tubes were placed in beakers for five minutes and then final weight was recorded of each

tube.

For procedure three, six potato cores were weighted placed in six separate beakers with 100 ml of the various unknown sugar concentrations. One beaker was filled with distilled water for control. After 30 minutes, the potato cores were retrieved and weighted for final weight and comparison.

Cellular Respiration Lab:
Twenty-five germinating pea, barley, alfalfa, and mung seeds were prepared by placing the seeds into a cup or beaker and cover with water at 3 times their height. They were allowed to soak for 3 days. (Carolina)

Respirometers were assembled by affixing a metal washer to the bottom of each vial with silicone. Para film was cut into 2-inch squares to place 1 inch from top of respirometer to connect to rubber stopper. In 5 respirometers, at the bottom of each vial, absorbent cotton was placed and 2 ml of 15% KOH was placed on the cotton. Non-absorbent cotton was then placed on top. (Carolina) In either of the respirometers was placed either peas germinated, peas non germinated with beads, beads (control), non-germinated mung with beads, and germinated mung seeds. Both the non-germinated seeds were added with beads to maintain the same volume of the germinated seeds. Each respirometer was placed in water bath with water at a temperature of 36 C°. Temperature and oxygen used was collected at 0, 5, 10, 15, and 20 minutes.

Enzyme Activity Lab:
In one test tube 7 ml of distilled water, 0.3 ml of 0.1 % hydrogen peroxide and 0.2 ml of guaiacol was placed and labeled substrate. In another test tube 6 ml of distilled water 1.5 ml of peroxidase enzyme from turnip and labeled this tube enzyme. Both solutions were mixed together and pictures were taken at 0,1,2,3,4, and 5 minutes. These pictures were then compared to the Turnip Peroxidase Color Chart (Haderlie) to determine the activity level of the enzyme.

For Procedure 2 the same procedure for creating the substrate solution was done for six separate test tubes. In another six test tube 6 ml of the various pH buffer solutions were placed in each test tube. The pH solutions were at pH’s of 3,5,6,7,8, and 10. Also, 1.5 ml of peroxidase was added along with the specific pH solution. The test tubes were mixed with their appropriate substrate solution and a picture was taken at 0 minutes and then at 5 minutes. This was then compared to the Turnip Peroxidase Color Chart (Haderlie) to determine the level of the enzyme activity in each pH solution.