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From Gummy Bears to Celery Stalks

Diffusion and Osmosis

By Kevin M. Bonney

From Gummy Bears to Celery Stalks



This is an interrupted case study that intersperses information about diffusion and osmosis with content review and knowledge application questions, as well as a simple experiment that can be conducted without the use of a laboratory. This case study is appropriate for use in undergraduate or high school general biology courses. The case begins with a narrative followed by a set of review questions used to introduce background information about diffusion and osmosis and define the terms active transport and passive transport. The second part of the case includes instructions for a simple experiment using gummy bears soaked in different solution to demonstrate osmosis that can be conducted by students at home or in a classroom. This is followed by an explanation of how the principles of diffusion and osmosis affect animal and plant cells. The case concludes with review questions and discussion of two other simple experiments that further demonstrate osmosis, one of which can be conducted by students at home.


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  • Define the following terms: diffusion, active transport, passive transport, osmosis, selectively permeable, hypertonic, hypotonic, and isotonic.
  • Explain and identify what will happen to animal cells and plants cells when placed in a hypertonic, hypotonic, or isotonic solution.
  • Apply knowledge of the above concepts to design and conduct simple experiments that demonstrate osmosis, diffusion, and tonicity.
  • Explain at least two examples of how tonicity and osmosis are relevant to their everyday lives.


Diffusion; hypertonic; hypotonic; isotonic; osmosis; passive transport


Subject Headings

Biology (General)
Cell Biology


High school, Undergraduate lower division






Scientific method






Demonstration, Discussion, Interrupted, Laboratory



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