Image of Particles Dispersing in Diffusion

Diffusion, Osmosis & Active Transport 
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Virtual Cell Biology Classroom of Science Prof Online


Diffusion, Osmosis & Active Transport Lecture 

These are the Diffusion, Osmosis & Active Transport Lecture materials of the Virtual Cell Biology Classroom. The resources below are used to supplement an actual college cell biology course.

Virtual Cell Biology

You have free access to a large collection of materials used in a college-level introductory Cell Biology Course. The Virtual Cell Biology Classroom provides a wide range of free educational resources including Power Point Lectures, Study Guides, Review Questions and Practice Test Questions.
Endomembrane System of a Eukaryotic Cell, Mariana Ruiz

Page last updated 6/2014
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Instructor's Corner
These lecture learning objectives are  a study guide based on the VCBC Diffusion, Osmosis & Active Transport Lecture PowerPoint:

  • Diffusion, osmosis, and active transport; Understand how these processes relate to molecules moving across the plasma membrane.
  • What is the plasma membrane, its role and what it is made of?
  • What is tonicity (isotonic, hypertonic, hypotonic), and how does it relate to osmosis.
  • Be able to solve tonicity problems (What would happen to a cell sitting in various concentrations of solution. Be able to tell me which way water would move, into or out of the cell.)​
  • What is active transport? How does it differ from diffusion and active transport?

Versions of Aerobic Respiration PPT:

The best way for students to print out the PowerPoint Show is to download the PDF version. Select Print, and, when the Print screen comes up, go to the Print Handling options. Under Page Scaling, select "Multiple pages per sheet", Under Pages per sheet, select "2". That uses up less paper, placing two slides on each page.

Word document of a single essay question given to students at the end of the lecture. This tool helps the students review the main messages of the lecture while allowing the instructor to assess the class' understanding of the material. 

Here is what you need to read, in addition to the PowerPoint, to master this topic. Check Moodle for additional readings.

These multiple-choice / matching practice test questions and essay review question are designed to help you better understand this material. 


  • Osmosis animation from St. Olaf College.

Anyone taking, teaching or interested in biology may find these resources helpful and is welcome to use them.

The Diffusion, Osmosis & Active Transport Lecture materials include:
  • a list of learning objectives
  • a PowerPoint lecture
  • a homework assignment
  • "class note" articles  
  • practice test questions
  • review questions
  • links to additional educational resources

3D rendering of diffusion of purple dye in water.
Random collisions of particles in a gas.