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Osmosis: Concentration and Potato Tissue

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Osmosis: Concentration and Potato Tissue
Unit 4 Lab – Effects of Osmosis on Living Tissue
Assignment Total: 35 Points Course Weight: 6 Pre-Lab Preparation - Review the following resources to complete this assignment:
Textbook: Chapter 5, pg. 83-86 Mastering Biology / Study Area / Chapter 05 – The Working Cell / Student Home Key Concepts Video: Plasmolysis Video: Turgid Elodea Activity: Membrane Structure Activity: Diffusion Activity: Osmosis and Water Balance in Cells Bioflix: Membrane Transport Additional Resources Blast Animation: Diffusion Blast Animation: Passive Diffusion Across a Membrane TLM / Handouts: View the PowerPoint presentation titled ‘Identifying Variables’. Print out the Osmosis Lab Student Worksheet on pages 4-7 of this document and complete it as instructed throughout the lab.

Introduction:
Water, the major component of cytoplasm and extra-cellular fluids, can diffuse back and forth through membranes with little difficulty. This process is known as osmosis. The direction of motion is regulated by the relative concentrations of water and dissolved substances inside and outside the cell. Water will move from an area of high concentration of water molecules (low concentration of dissolved particles) to an area of low concentration of water molecules (high concentration of dissolved particles). It is difficult to observe osmosis at the cellular level since cells are very tiny and can only be seen with a microscope, so you are going to use sticks of potato tissue in solutions that have different concentrations of dissolved substances to observe the effects of osmosis on living tissue. There are three basic relative concentrations of solutions. An isotonic solution has a concentration of dissolved particles equal to that of cells or body tissues; no net water flow occurs. A hypertonic solution has a lower concentration of water (higher concentration of dissolved particles) than that of cells or body tissues; water flows out of the cell. A hypotonic solution has a higher concentration of

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