Name_________________________________________ Date_______________ Class____________
Cell Membrane Notes: Diffusion, Osmosis and Active Transport
Ø Functions of Cell Membrane
Ø Homeostasis:
Ø Picture of phospholipid bilayer:
o Polar heads are __________________ meaning “___________________________”
o Nonpolar tails are __________________ meaning “____________________________”
o This is what makes the membrane so ___________________ in what crosses.
o Fluid Mosaic Model:
Ø Solutions
o Solvent -
o Solute –
Ø Methods of Transport Across Membranes
o Diffusion
§ Movement of molecules from an area of _____________ concentration to an area of ____________ concentration. Movement from one side of a membrane to another, without ________________. The solute moves ________________ the concentration gradient (high to low).
o Facilitated Diffusion
§ Does NOT require __________________. It uses ________________________ to move things from ___________ to ____________ concentrations. It needs helpers to get things from one side to the other!
o Active Transport
§ Requires ________________________! It moves materials from _____________ to ______________ concentrations __________________ the concentration gradient. (Like a fish trying to swim upstream!)
o Osmosis
§ This is the diffusion of ________________ across a membrane.
§ It moves from a ___________ water amount to a ___________ water amount.
Hypertonic- ____________________________________________________________________
Isotonic- _______________________________ Hypotonic- ______________________________
Diffusion and Osmosis Worksheet
How are the molecules moving in the examples below (1-9)? Write OSMOSIS or DIFFUSION.
1. The student sitting next to you just came from gym class and forgot to shower and you can tell. _____________
2. After sitting in the bathtub for hours, your fingers start to look like prunes. _________
3. The girl sitting two rows ahead of you put on too much perfume this morning._________
4. One way to get rid of slugs in your garden is to sprinkle salt on them, so they shrivel up.
____________
5. Yum! Something smells good. The neighbors are cooking on the grill! _____________
6. Gargling with salt water when you have a sore throat causes your swollen throat cells to shrink and feel better. ________________
7. Oxygen molecules move from the air sacs in the lungs across the cell membranes into the blood _____________
8. Robert sprays water on the veggies in the produce section to “plump them up”.________
9. You put raisins in a glass of water and they plump up. _____________
10. Use arrows to indicate the direction of diffusion in each case: is a molecule that can pass through the cell membrane. is a cell membrane.
A) B)
11. For each of the situations below use an arrow to indicate the net movement of sugar into or out of the cell. (Assume that the sugar molecules can pass through the cell membrane in each case.)