Lab Question:

Which drink hydrates cells the best? Restated scientifically, this would be: "How do various drinks affect the mass of potato cells?"

Lab Hypothesis:

List in order (from best to worst) the drinks you tested plus water. State your reasoning for this ranking using the info obtained from the drink labels. Which drinks are hypotonic? Which will be most hypertonic? Which will most likely cause an increase in mass? Which will most likely cause a decrease in mass (dehydration)?

Raw Data Table = the original, unmanipulated data that was collected) (Click here for examples of data tables.) Please include the beginning mass!

Displays raw data (that was collected in a table with all columns labelled (units included) and a descriptive title (See your hypothesis!) Also include with the units some indication what the accuracy of the measurement device was! This can be shown as (+/- 0.1 g or +/- 0.1 cm, etc....)

In the past many students have left off a descriptive title or did not include the raw data at all!

Your tables & graph should be your own. Using someone else's will result in a zero for both persons!

Data Manipulation:

a) Student uses averaging, calculates % change where needed, and calculates standard deviation correctly. Explain why some data manipulations were made (like need to convert results to % change, ect.) (How to use Excel to calculate the standard deviation.) % change = ((final - start) / start) X 100

b) Show an example of the equation for each manipulation used, and one example of how to use the equation to find the result is a nice addition.

c) Display manipulated data in table form with title and all labels. (This may be the same title as that used for the raw data.) All students should do this! See the StDev link above for examples of a final data table.

d) In the past, some students did a good job explaining how they used the differences between the averged results along with the standard deviations of the different solutions tested to validate their experiment. Many others did not do this, or interpreted their results wrong! Some of you did this as part of your conclusion, which was ok.

e) Graphs the final results. (Click here for examples of graphing.)

i) Graphs should show averaged trial data for each parameter tested (type of drink). Hint: Be sure to process your data so it can all be compared!

ii) Represent the standard deviation for each liquid tested too! See me far enough ahead of the due date to see how to do this! (How to add standard deviation error bars to an Excel graph.)

iii) The X- and Y- regions of the graph should be labelled with appropriate units.

iv) A descriptive title should be used (See hypothesis). "IV vs DV" is not adequate!

iv) Use a key to identify drinks if needed.

v) Uses the correct graph form to clearly demonstrate results. Line and scatter plot graphs work well for graphing data where both the X and Y data are numerical. Bar graphs work well when one set of data is a set of names.

Examples of Graphs

vi) Some students have typed or written a description of what the graph shows on their graph. This can be a nice touch!

Conclusion:

a) Restate your hypothesis to compare to results.

b) State general trends (rank all the drinks) and then list specific averaged results. The averaged results should include the units and the standard deviation (mean +/- stdev) of the trials!

c) State which results agree with the hypothesis, and which ones don't. (Be aware that you have not "proved" anything here! Results agree or disagree with the hypothesis or suggest trends.)

d) Explain the results. Have you identified any drinks that will rehydrate better than others? Which drinks should be avoided for rehydration purposes? Explain!.............. It would be wise to use the words hypertonic, hypotonic and isotonic when talking about the drinks and the cells tested!

e) If the standard deviations support your conclusions, state so... Be aware that the standard deviations for some drinks may work, those for other data may not! (See data manipulation above.)

Analysis of experiment and suggestions to improve the design:

a) Identifies key variables that needed to be controlled. Yes some of these are human error kinds of things, which you can list. But most of you need to think about and state design flaws that were put into the experiment by your instructor. There is one major assumption about this lab that needs to be discussed. Some of the key variables were not fully "controlled", especially by some groups!

b) Suggests specific design steps to improve upon these problems. List specific numbers of trials, amounts of materials useds, and how it would be done. You could also just list a whole new design here too!

Place this section last. You will not actually do this experiment, but instead it is a plan of an experiment you could do if given the time. Each person will write up their own design (so when it is submitted to turnitin.com, you should not have much overlap with any other student!) Choose a new independent variable and dependent variable to test.

Research Question (Click here to choose a research question.)

Introduction / Background Info:

a) must reflect what your lab is about

b) introduce and describe key terms and concepts, but write in story/ report form rather than as a list of words and definitions.

diffusion, osmosis, isotonic, hypertonic, hypotonic

c) information pertinent to the investigation (how solutions that are hypertonic, hypotonic or isotonic to the cells)

d) This is very important!........Paraphrase and write this info in your own words! Too many people are just copying and pasting info from a website and using it as their own material. Changing a couple words in a "lifted" sentence is not paraphrasing! I will be grading students down heavily for this lab for using plagiarized material. Info used verbatim (intact) should be quoted and cited. Paraphrased info should be adequately cited. Do not use Mr. Slichter's website as a citation (the info there is too subversive for scientific use!). Take the time to use other source material!

Question

Something along the lines of "How does the IV affects the DV.....?"

Hypothesis

Write the hypothesis so there is a definite answer and an explanation of why your hypothesis would occur. (The reasoning for the hypothesis could be listed in the introduction.) It might help to predict and explain what a graph of this hypothesis would look like.

Variables:

a) Identify the Independent and Dependent (measured) variables.

b) Identify the control. What are you comparing your IV to?

c) Identify key variables which need to be maintained constant.

i) any equipment usage variables.

ii) any measurement variables.

iii) Variables affecting rate of osmosis: These are any variables (like in enzyme reactions) that would affect the rate of movement of molecules. Do a Google search or "Ask Jeeves" or look at Wikipedia to help find what factors affect particle movement (thus affect osmosis or affect diffusion).

 

Materials: List all materials you would like to use.

Design/ Procedure: Provide enough details so that someone else who is inexperienced (say your English or History teacher) could repeat the experiment exactly the way you planned it. Provide details of how to make any key measurements (diagrams can help with this!). State specific quantities of materials and solutions to be used or tested and any steps that need to be done to keep the variables from above constant.

Sufficiency: # of trials and # of the IV tested.....the more the better! Assume you have plenty of time (several periods in a row) to plan and carry out the experiment.