I often have students that make the following mistakes: - The student includes no data. More trials may give us more precise and accurate data. Using cubes of agar allow the phenolphthalein to be evenly absorbed throughout, as opposed to one side being more saturated when using blocks. Hypothesis I think the 1st cube was aluminum I think the 2nd cube was steel I think the 3rd cube was brass I think the 4th cube was copper I think the 5th… Kimmi Dodia- Biomedical Science- 1019971 Lab partner- Kim Harcourt Lab report- Experiment 1: Microbial Genetics Abstract The objective of this experiment was to introduce the study of bacterial genetics in order to identify the potency of different mutagenic agents. Repeat steps 6 and 7 for the medium and small cubes. The more consistent you are with the implementation and embedding of the Crosscutting Concepts, the better they will get. Upon starting, our group set up an open system experiment that allowed gases to be released to avoid pressure build up.
If the tube is too flimsy, water will not be able to move easily to or from the semipermeable bag. To find the surface area, multiply the length of a side of the cube by the width of a side of the cube. The size of molecules in the cell will effect the cell model if the solution can diffuse through the semi permeable membrane which was represented by the dialysis tubing. What units did you use for volume, mass, and density? Because the water potential was derived from data of 6 different trails, the conclusion is stronger than it would have been with only our results. They are all ideas the students connected to because they were thinking about the Crosscutting Concepts as they read. The rate of reaction and the time taken to diffuse to the centre of the cube are not the same thing.
What relationships do you notice between surface area, volume, surface-area-to-volume ratio, and percentage penetration? This solution was an error because it should have continued the line and digressed but instead, it increased more that the solution of 75% sucrose sand 25% water. There were four infants affected by this cluster. Errors and Improvements: Error Improvement Parallax error, resulting in a misreading in volume. Stir at a slower rate for a longer time than stirring hard for a little time, in addition to that a thinner rod can be used for stirring. Diffusion in agar cubes Introduction: All cells are dependent on a processes called diffusion, which is the movement of a substance from an area of higher concentration to an area of lower concentration. Place a few millileters of the pH indicator into a small container either bromothymol blue or phenolphthalein. This Snack fits well into a series of investigations on osmosis and diffusion.
Write a hypothesis predicting the results on your lab sheet to predict which cube will have the highest rate of diffusion. Its volume is equal to cube 2x2x2 8cm3 , but its surface area and volume ratio is bigger 3. The first step to this lab was preparation of the Idaho potato. The groups of potatoes that decreased in weight, loss water and shriveled up. This student did an excellent job recognizing that phenolphthalein is a base indicator and that ammonia is a base. However, this lesson relates to all of the Crosscutting Concepts. Some mistakes that could have been made is errors with tying leading to the bags leaking, then if we didn't blot them thoroughly that could have caused our initial or final weights to be off.
See references for more details. Water, glucose and any other sugars pass slowly through the semi permeable dialysis tube since they are polar molecules. Acknowledgements: This experiment was funded by the selfless donations of Nick Fiore and Michael Ahrens, with additional funding from the University of Kansas. Class practical Set up cubes of agar jelly and see how far liquid penetrates them by diffusion over five minutes. The diagram below shows diffusion; Diffusion of molecules occurs down the concentration. This is because more surface area is exposed and diffusion takes place.
As hydrogen ions from the vinegar move into the agar cube, the color of the cube changes allowing you to see how far they have diffused. . There is confusion in the conclusion due to not being clear with the terms used. In the solution of 75% sucrose and 25% water, the potato's weight decreased by. Hypothesis: I believe that the rate of diffusion will decrease with the increase in the volume of the cell. Explain to students that you have prepared agar that contains phenolphthalein in it. Place the three agar cubes in the beaker.
The families from the infants would collect their water from wells. In this lab, chemotherapeutic agents were evaluated by the disk-diffusion method. Universal indicator is dissolved in ethanol, so it is highly flammable in the stock bottle, but not once added to agar. A mistake that could also occur is leaving the tubes in the beaker too long because if that occurs, you will not be able to see the definite difference of the initial and final weight. Data Processing: Calculations for each cube size: 1. We repeated these steps each time until every mold was filled.
You will then conclude which is better for diffusion and cell absorbing, more surface area, or more volume. Each group will cut three agar cubes: A 3cm cube, a 2cm cube, and a 1cm cube. Use the following link to see more about how to cite and reference. The pH rises above the equivalence point because we are adding base to a solution with a relatively large volume. Claim: Diffusion occurred completely through the small agar, which is why the agar cube was clear after diffusing Diffusion occurred more in the medium cube than the large cube As the size of the cube increased, the amount of diffusion decreased Evidence: Reasoning: The level of diffusion was different per bag due to the concentration of each solution.
Water diffuses in cells to move through membranes. Agar is used as an impression material in dentistry. In this experiment, I tested the diffusion in a cell- in this case, the dialysis tube. It is ok to not be at a 4 yet - it's about having the awareness of where you stand so you can make a plan to reach your goal. After 10 minutes, use a spoon or tongs to remove. In my experiment, we used artificial cells to study the relationship of surface area and volume. The food coloring in room temperature water will spread evenly after fifteen 15 minutes.