Activity Number
Overview and Learning Objectives
Central Concepts
Textbook References
Benchmarks and Standards
Activity Credits

Osmosis and Osmotic Pressure (a simple model in 1-page with interactivity)

Interactive model, with minimal support

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Overview and Learning Objectives

This is a very simple osmosis model. The white particles are meant to represent water molecules, while the green ones represent solute molecules. The two columns of big blue particles in the middle stand for the semipermeable membrane. They are horizontally linked and restrained at the positions indicated by the "x" letters, in order to mimic the stability of the membrane's molecular structure.

Initially, the concentration of "water" molecules in the left compartment is higher than that of the right one, and the concentration of "solute" is lower on the left than that of the right. As the simulation proceeds, you will observe that "water" molecules from both sides diffuse through the "membrane" (but not the "solute" molecules). After some time, you may discover that the amount of "water" molecules that travel from left to right is more than that flowing in the reverse direction.

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Central Concepts

Key Concept:

Osmosis is the movement of materials across a membrane.

Additional Related Concepts


  • Membrane
  • Transportation
  • Waste Disposal

Molecular Biology

  • Membrane pore
  • Molecular separation
  • Osmosis


  • Barrier
  • Diffusion
  • Gradient
  • Pressure

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Textbook References

  • Biology (Miller and Levine) Prentice Hall 5th Edition - Unit 2: Chapter 5 - Cell Structure and Function
  • Biology (Prentice-Hall) New York Edition - Chapter Seven: Cell Structures and Functions
  • Biology: Concepts and Connections (Pearson) 5th Edition - Chapter 22: Respiration: The Exchange of Gases
  • Biology: Exploring Life - Chapter 6: A Tour of the Cell
  • BSCS Human - Chapter 4: The Internal Environment of Organisms
  • Web of Life - Chapter 2: Chemical Basis of Life

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Benchmarks and Standards


  • THE LIVING ENVIRONMENT: CELLS - Every cell is covered by a membrane that controls what can enter and leave the cell (Full Text of Standard)

  • THE LIVING ENVIRONMENT: CELLS - Within every cell are specialized parts for the transport of materials, energy transfer, protein building, waste disposal, information feedback, and even movement (Full Text of Standard)


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Activity Credits

Created by CC Project: Molecular Workbench using Molecular Workbench

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  • Java 1.5+ - Java 1.5+ is available for Windows, Linux, and Mac OS X 10.4 and greater. If you are using Mac OS X 10.3, you can download MW Version 1.3 and explore within it instead.

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NSF Logo
These materials are based upon work supported
by the National Science Foundation under grant numbers
9980620, ESI-0242701, EIA-0219345, DUE-0402553, and 0628181.

Any opinions, findings, and conclusions or recommendations expressed in this
material are those of the author(s) and do not necessarily reflect
the views of the National Science Foundation.