NSWTSCN312A- Investigating biological processes
Osmosis in Gummi Bears
Aim of the experiment:
The aim of this experiment is to investigate the diffusion of water through a selectively permeable
membrane by soaking gummi bears in tap water over a 24 hour period.
Background Information:
Molecules in solution are in constant motion, and tend to move from areas of higher concentrations
to areas of lower concentrations. This process is called diffusion. The diffusion of water through a
selectively permeable membrane is known as osmosis. Diffusion and osmosis are passive forms
of transport that do not require the input of energy.
Key terms: Hypertonic = _______________ concentration of solute
Hypotonic = _______________ concentration of solute
Isotonic = _______________ concentrations of solute
**Remember: Water moves from hypotonic to hypertonic solutions!**
We will use gummi bears to represent living cells because they are small and contain dissolved
substances.
Gummi bear ingredients:
_______________________
_______________________
_______________________
Hypothesis:
This statement makes a prediction about what you will find, it is an if/then statement, eg:
“If gummi bears are soaked in tap water, at room temperature for a total period of 24 hours, then
water would diffuse into the matrix of the gummi bears causing them to swell up by XXX (your
prediction) percent.”
Materials:
gummi bears
toothpicks
water
beaker
ruler
Method: (This is usually written in past tense and third person in your report).
1. Place a toothpick into each gummi bear, so you can pick it up and measure it once it has
been placed it the beaker.
2. Using a ruler, measure the height and width of 8 gummy bears to the nearest millimeter.
Record your results in a table such as the one below. Then find the average height and
width of all 8.
Filename: Theory notes for week 6- 11 March 2014
Document Owner: General Education Cooma Queanbeyan Campus
Page 1 of 3
Table 1: Table which can be used to record raw gummi bear data
Gummi bear
Width- Height- WidthHeightWidth(campus)
start
start
1hr
1hr
24hrs
1
2
3
4
5
6
7
8
Average
Height24hrs
3.
4.
5.
6.
Fill each with 100ml of tap water, at the same temperature.
Place gummi bear (on toothpick) into the water
Let it soak for 1hour (ensure all gummi bears soak for the same amount of time).
Measure height and width of each gummi bear to the nearest mm. Record your results.
Then find the average width of all 8.
7. Return gummi bears to beakers.
8. Leave overnight for next class (ensure all gummi bears soak for the same amount of time).
9. Measure height and width of each gummi bear to the nearest mm. Record your results.
Then find the average width of all 8.
10. Discard gummi bears into bin, tip water into sink, dispose of beakers.
Data Analysis:
1. Share your results with the other campuses.
2. Calculate the average height and width of gummi bears when you combine all the
data. Compare the results to your own campuses averages. Are they the
same/different how does repetition affect the results? Which is more accurate (your
campus data or the combined results)?
3. Graph the results (of all campuses)- what type of graph would be the most
appropriate?
4. Calculate the percentage change in size (using the average height and width) of the
gummi bears using the formula below.
Change in width = (Difference in width) ÷ (Original width) x 100%
Change in height = (Difference in height) ÷ (Original height) x 100%
Results:
Do not include your raw data, report only those results you derived from the data analysis.
Include your graphs. Write a sentence or two (under each graph) explaining what each
graph shows, refer reader to your graph. Label figures and use appropriate scientific
notation.
Discussion:
This section reports on what you think the results indicate, whether this supports your
hypothesis and explains you findings in terms of how they relate back to the original
concept we were testing. We try to explain/discuss unexpected results. Also, in a
discussion we review what went well, what could have been improved and what other
related research we might carry out in the light of the findings. .
Filename: Gummi bear prac worksheet for week 7- 17 Feb 2014
Document Owner: GEAP Cooma
Page 2 of 3
Use the questions below as a guide for what to include in your experimental report:
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What happened to the gummi bears? (Cite specific data! and identify trends)
Why did you get these results? (Use the terms osmosis, diffusion, hyper/hypotonic)
Did you support or reject your hypothesis? Why or why not?
What would happen to the gummi bears if you soaked them in salt water over night?
Explain.
Can you relate what you have observed back to how osmosis works in a biological
organism? (Give one real life example, include a diagram. Explain how the experiment we
conducted is relevant to how osmosis was demonstrated in your experiment.)
What other factors might have affected the results (name at least two)? How were they
controlled?
How accurate/precise were your results? What could have affected this?
How could the experiment have been improved? What worked well?
What other related research might we carry out?
Conclusion:
Make a final statement that summarises your experiment, related to the aim.
References:
Need at least two, include in-text referencing. Evaluate two references for reliability and
appropriateness of information.
Appendices:
Includes risk assessment & logbook.
Filename: Gummi bear prac worksheet for week 7- 17 Feb 2014
Document Owner: GEAP Cooma
Page 3 of 3