Name:_____________ Date:_______ Class Period:______________Diffusion and Osmosis Video Questions:

1. The below picture represents diffusion of molecules. Place the following labels in the diagram: high concentration, low concentration, and an arrow showing the direction that the molecules would travel before equilibrium is reached.

2. Osmosis is a type of diffusion, but it involves the movement of water. Similar to diffusion, osmosis is the movement of molecules (water molecules if osmosis) from a high concentration to a low concentration.

The video clip explains that you can also look at water as moving to a __________________________________ concentration of solute molecules.

Why can it also be viewed this way?

3. Osmosis Scenario: The video clip mentioned a disaster scenario of a saltwater fish being placed in fresh water.What would occur if, instead, a freshwater fish was placed in saltwater?Your answer needs to have an arrow indicating the direction of water flow in osmosis, a label for “hypertonic,” and a label for “hypotonic.”

4. Osmosis Scenario: Fluid movement into the brain after traumatic brain injury can result in dangerous brain swelling.One treatment that can be used in some of these cases is adding a hypertonic/hypotonic (circle the correct answer) saline drip. Remember, you are trying to reduce the excessive fluid in the brain.

Explain your answer:

Hypertonic, Hypotonic, or Isotonic? Oh My!These red blood cells have all been placed in different solutions! Based on their appearance after being placed in these solutions for a period of time, place on each line (A) for hypertonic, (B) for hypotonic, or (C) for isotonic

7. The cells are_________________ compared to the ________________ solution.

8. The cells are_________________ compared to the ________________ solution.

9. The cells are_________________ compared to the ________________ solution.

NAME: __________________________ DATE: _____________________

Lab: Elodea Plant CellsBackground Information

Elodea (Elodea canadensis) is a common plant that grows in fresh water ponds, lakes, and is often used in freshwater aquariums. Remember that plant cells contain both a cell membrane and a cell wall. They also often contain a large water vacuole.

Homeostasis involves the maintenance of a stable set of conditions inside an organism’s cell(s).

Osmosis has important implications for organisms and their cells. Because cells contain mostly water, the water concentration of the environment in which they reside is very important. If cells are exposed to water concentrations that are different from their internal environment, they may loose or gain water. The picture at the right shows three beakers with isotonic, hypertonic, & hypotonic solutions for animal cells.

Turgor Pressure, Cytolysis and Plasmolysis: Using your blue text book (pg. 100) define turgor pressure, cytolysis, and plasmolysis. Make sure to use the terms hypotonic and hypertonic in your definitions where appropriate!

Turgor Pressure:

Plasmolysis:

Cytolysis:

InquireQuestion: How will Elodea be affected by tap water, salt water solution and a distilled water solution?

Independent variables: _________________ , ___________________ and _______________Dependent variable: ___________________

Hypothesis: (Use hypertonic, hypotonic, isotonic, turgor pressure, and plasmolysis in your hypothesis) ____________________________________________________________________________________________________________________________________________________________________________________________________

Design and Experiment

A. Elodea in Tap Water 1. Prepare a wet mount of an Elodea leaf with tap water. To do this, place a drop of water towards one end of the slide. Using forceps, remove a small leaf from the tip of an Elodea plant and lay it flat in the drop of water. Cover with a cover slip.2. Observe the leaf at 40X and record your observations. Increase the magnification to 100X and 400x respectively, observe, and record your observations at each magnification. Label all structures that you can identify.

Low Power (______ x) Medium Power (______ x) High Power (______ x)

B. Elodea in 20% SALT Solution 1. Remove the slide from the stage of the microscope. 2. Get an NEW piece of elodea, make the wet mount slide using 20% salt solution. 3. Return the slide to the microscope stage and observe the cells at 40X, 100X, 400X. Record your observations, and label all structures that you can identify.

Low Power (______ x) Medium Power (______ x) High Power (______ x)

C. Flushing Out the Salt Solution with DISTILLED Water 1. Remove the slide from the stage of the microscope. 2. Get an NEW piece of elodea, make the wet mount slide using distilled water. 3. Return the slide to the microscope stage and observe the cells at 40X, 100X, 400X. Record your observations, and label all structures that you can identify.

Low Power (______ x) Medium Power (______ x) High Power (______ x)

Clean up! Remove the slide from the microscope stage, clean it and the cover slip, then put them away carefully.

Clean Up Stamp!

Analyze and ConcludeAnswer the following questions completely and thoroughly. Questions 1-3: Use hypertonic, hypotonic, isotonic, turgor pressure and plasmolysis where appropriate. 1. What was the shape of your Elodea cells in tap water? Why?

2. What happened to your cells as the salt water flowed under the cover slip? Why?

3. What happened to the cells when the salt water was flushed out with distilled water? Why?

1-4 Checking for understanding:

4. Why do you think the cell walls did not change shape very much?

5. Which of the solutions were a. Isotonic - b. Hypotonic -c. Hypertonic -

6. Did any of the solutions cause cells to undergo cytolysis? Explain why or why not.

7. Did any of the solutions cause cells to undergo plasmolysis? Explain why or why not.