LESSON PLAN: DIFFUSION AND OSMOSIS
||10th/11th grade Biology|
||2 class blocks (~2.5 hrs)|
||Students should have a basic understanding of cell structure and biological molecules. They should also be familiar with the concept of solute, solvents and concentration.|
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of active and passive transport and relating it to real-life examples.
Demo and lab activities to help students experience diffusion and osmosis first-hand.
||Diffusion demo: beaker, water, food coloring, hot plate
Osmosis lab: potato slices, salt, distilled water, centrifuge tubes, mass balance
a. Engage - Discuss with the class the necessity for the cell membrane as a physical barrier protecting the contents of the cell. The selective permeability of the cell should be emphasized.
b. Demo - Students explore the diffusion through a simple demo. Students will write down their observations as the teacher adds a drop of food coloring to a beaker of water. This demo is repeated in cold water and hot water to study the effect of temperature on the process of diffusion. Students are asked to write down and share other examples of diffusion experienced in everyday life.
b. Lab activity - Students work in groups of 2-3 to design and test their own hypothesis regarding the effects of various salt solutions on the mass and appearance of potato slices. Review the Elodea activity if necessary.
post-laboratory exercise, discuss mechanisms by which cells and our
body counter the effects of unfavorable osmotic environments.
||a. Students will be assessed on their ability to
formulate a good hypothesis and procedure for the lab. They will also tabulate the
collected data and be graded on their understanding and conclusions.
b. Students will also be given a quiz to assess their understanding of the concepts and vocabulary.
||If time permits, do another lab activity with a selectively permeable dialysis membrane. (see reference)|
|References||Optional osmosis lab activity on the web: - http://biology.arizona.edu/sciconn/lessons/mccandless/osmosis.html
Contemporary Biology: Exploring the Science of Life (Textbook)