Osmosis & Diffusion

Osmosis & Diffusion 1/9/15 Key Question: How do you think things like water and food, which cells need to live, get into and out of cells? Initial Thoughts:

Evidence #1 : Demos and Background Notes What does “concentration” mean? For example: the concentration of salt in sea water. Concentration means: The number of “particles” in a given space. Which is more concentrated? OR

Diffusion Demos Perfume Food coloring and beaker Food coloring and graduated cylinder Make a prediction. Why did you predict what you did?

Diffusion Diffusion is the natural movement of any molecule from high concentration (where there’s lots of them) to low concentration (where there’s not as much) until they are equally spread out.

Osmosis Diffusion of water from high to low concentration

Vocabulary/Background Osmosis – the movement of water molecules from high concentration to low concentration

Diffusion Movement from high to low concentration until they are spread out equally in all areas Movement of ANY molecule, while…. Osmosis is the diffusion of WATER.

Diffusion is a slow process because it relies on the random movement of atoms and molecules.

Why is this important to cells? This is how things like oxygen, food, and water get transported into and out of cells. http://molo.concord.org/database/activities/223.html

Egg Lab: Background Hypotonic: it causes it to swells up (think Hypo = Hippo) Hypertonic: it causes it to shrivel up (Think hyper skinny kid)

Egg Lab: Background Vinegar is an acid that will dissolve the hard shell, leaving only the thin membrane around the egg “cell”. Water is small enough that it can enter or leave through the egg membrane. (it is selectively permeable).

Evidence #2: Egg Lab Day 1 Variables: Manipulated Variable:_____________ Responding Variable:______________ Controlled Variables:______________

Evidence #2: Egg Lab Variables: Manipulated Variable: Type of liquid Responding Variables: Weight of egg and Volume of liquid Controlled Variables: same egg, same amount of time in liquid, same amount of liquid

Evidence #2: Egg Lab Day 1 #1 Testable Question: What will happen when an egg is soaked in vinegar? Hypothesis: If an egg is soaked in vinegar, then the egg will....because…..

Evidence #2: Egg Lab Day 2 #2 Testable Question: What will happen when an egg is soaked in corn syrup? Hypothesis: If an egg is soaked in corn syrup, then the egg will....because…..

Evidence #2: Egg Lab Day 3 #3 Testable Question: What will happen when an egg is soaked in colored water? Hypothesis: If an egg is soaked in colored water, then the egg will....because…..

Analysis Questions Explain why diffusion and osmosis are important to cells. Why do grocery store owners spray fresh fruits and vegetables with water? Explain using what you learned about osmosis. If a shipwrecked crew drinks sea water, they will probably die. Why?

Summary/Conclusion Write a summary of the Egg Lab. Remember to: Restate your hypotheses (there were 3 in this experiment) Tell if it was supported or not. Use your data to back up #2 Explain your data using the principles behind Osmosis/Diffusion. Was the corn syrup and colored water hypotonic or hypertonic? Further thoughts, improvements, extensions, etc.

Reflection Draw what happens when a cell is placed in sea water, using arrows to show the direction water is moving (in or out of the cell).

Big Idea Cells use diffusion and osmosis to get things like food & water into and out of cells.