Bell Work 1/5/2015 Welcome back! I hope you had a great break. Please start a new page of notebook paper for today’s bell work. You do not have to write the question, but you do need to use prior knowledge to explain what you think is the correct answer. Students placed a plastic bag containing a corn starch solution into a highly concentrated solution of red dye. If the concentration of red dye in the solution is greater than inside the bag, which of these is most likely to occur? ARed dye will move through the bag into the corn starch solution. BCorn starch will move through the bag into the red dye solution. CThe red dye solution will dissolve the bag. DWater will move through the bag causing the bag to expand.

Agenda 1. Bell Work 2. Word Wall 3. Cell Review 4. Demonstration 5. Introduction to Osmosis and Diffusion 6. Exit Ticket

Word Wall Semipermeable: allowing certain substances to pass through it but not others T.O.C. “Word Wall- 3 rd Nine Weeks”

Objectives Can I explain the function of the semipermeable membrane in diffusion? SPI Explain how materials move through simple diffusion. T.O.C. “Diffusion Notes”

Diffusion & Osmosis Notes What is Diffusion?  The movement of particles from regions or areas of _________ concentration (crowded) to areas of ________ concentration (less crowded) is called ____________.  Look at Figure 1 on pg. 78!  The dye moved from an area of high concentration and spread to the area of low concentration. Why?  Ex: when oxygen diffuses into the cell and carbon dioxide diffuses out. high low diffusion

Equilibrium Sugar molecules, initially in a high concentration at the bottom of a beaker, will move about randomly through diffusion and eventually reach equilibrium. At equilibrium the sugar concentration will be the same throughout the beaker. Diffusion occurs naturally because of the kinetic energy the molecules possess.

Diffusion of Water  Diffusion also happens with and between living cells.  The cells of organisms are surrounded by and filled with fluids that are made mostly of ________.  The diffusion of water through a _____________ (partially allows things through) membrane is so important that it has been given a special name- __________.  Look at Figure 2 on pg. 79! water osmosis semipermeable

Moving Small Particles  In a cell, the movement of particles across a cell membrane _________ the use of energy by the cell is called __________ ___________.  During passive transport, particles move from an area of _______ concentration to an area of _______ concentration.  Examples:__________ & __________  A process of transporting particles that requires the cell to use energy is called ________ ____________.  Active transport usually involves the movement of particles from an area of _______ concentration to an area of _______ concentration. This happens a lot in neurons. The membrane proteins are constantly pumping ions (atoms or molecules that have a + or – electrical charge) in and out to get the membrane of the neuron ready to transmit electrical impulses. without passivetransport highlow Diffusion Osmosis active transport low high =

Moving Large Particles  The active transport by which a cell surrounds a large particle, such as a large _________, and encloses the particle in a vesicle to bring the particle into the cell is called _______________.  Vesicles are _____ formed from pieces of cell membrane.  Ex: when iron diffuses into the cell using active transport because the iron molecules are too large.  When large particles, such as ________, leave the cell, the cell uses an active transport called ______________.  During exocytosis, a vesicle forms around the large particle, carries the particle to the cell membrane, fuses with the cell membrane, and releases the particle outside of the cell. protein endocytosis sacs wastes exocytosis

Exit Ticket 1. What is the function of the semi-permeable cell membrane? 2. What part of the school can we compare the semi- permeable membrane to? 3. In diffusion, molecules are most likely to move from: Aan area at equilibrium to an area of low concentration Ban area of high concentration to an area of low concentration Can area at equilibrium to an area of high concentration Dan area of low concentration to an area of high concentration