Download ch 4 study guide - Elmwood Park Memorial High School

Chapter 4 Study Guide
1. Know that diffusion always ends up balanced on both sides.
2. Know that diffusion is the movement from high to low concentration.
3. Know that when you place a drop of ink in a beaker of water this is a example of diffusion because the
ink moves from high to low until the molecules are equal throughout the water.
4. Know that the diffusion of water is called osmosis.
5. Know that osmosis is a type of passive transport.
6. Know that a cell will swell when placed in a hypotonic solution.
7. Know that transport proteins embedded in the cell membrane allow certain substances to enter and
leave the cell. The name given to the proteins that allow ions in and out is called ion channels. Recall an
example of ions are Na+.
8. Know that when sugar molecules move from high to low they enter and leave by a helper protein and
is a type of passive transport called facilitated diffusion.
9. Again diffusion DOES NOT require energy.
10. when molecules are too large to move through the cell membrane via phospholipids or protein
channel they use endocytosis (to take in) and exocytosis ( to get out).
11. The membrane contains channels and pumps embedded in the cell membrane these substances are
made of PROTEINS!!! I repeat they are made of PROTEINS!!!!!
12. When molecules on both sides of the membrane are equal yes it is said to have reached equilibrium.
We also say that the solution is isotonic. But it is important to note that although the molecules are
spread out evenly they continue to move. However, there is no change in concentration. Again!
molecules will continue to move even though the solution has reached equilibrium.
13. Sometimes the cell will let things in or out only if a signal molecule binds to a protein. This has been
shown to you using the analogy of a lock and key. the protein embedded in the membrane is the
receptor protein. The molecule that binds to it is called the signal molecule.
Performance task
14. Some organisms like paramecium have contractile vacuoles that pumps water out of their cell. Think
about the types of solutions a paramecium might find itself in. For example, hypotonic in water or
hypertonic salt water. When would it need to use its vacuole the most and what would happen to it if it
stopped working.