Diffusion Osmosis Active and Passive Transport Substances can

Diffusion & Osmosis

Active and Passive Transport Substances can move into and out of a cell by means of active or passive transport. Active transport requires cellular energy to move substances, such as large molecules, across the cell membrane. Passive transport does not require energy to move substances across the cell membrane. Diffusion and osmosis are both methods of passive transport.

Define Diffusion

Define Diffusion The movement of molecules from a area in which they are highly concentrated to a area in which they are less concentrated.

Draw a diagram of an example of diffusion we saw in class.

Draw a diagram of an example of diffusion we saw in class.

Define osmosis

Define osmosis u The diffusion of water across a selectively permeable membrane.

Define osmosis u Water moves from a high concentration of water (less salt or sugar dissolved in it) to a low concentration of water (more salt or sugar dissolved in it). This means that water would cross a selectively permeable membrane from a dilute solution (less dissolved in it) to a concentrated solution (more dissolved in it).

Define osmosis

Define osmosis u In this picture a red blood cell is put in a glass of distilled water (all water with no salt or sugar in it). Because there is a higher concentration of water outside the cell, water enters the cell by OSMOSIS. In this case too much water enters and the cell swells to the point of bursting open. In the end pieces of cell membrane are left in the water.

See an animation of Osmosis here: http: //integrativebiology. o kstate. edu/zoo_lrc/biol 111 4/tutorials/Flash/Osmosis_ Animation. htm

Define selectively permeable membrane

Define selectively permeable membrane u A membrane that allows only certain materials to cross it u Materials pass through pores in the membrane

Why are osmosis & diffusion important?

Why are osmosis & diffusion important? All living things have certain requirements they must satisfy in order to remain alive – maintain homeostasis u These include exchanging gases (usually CO 2 and O 2), taking in water, minerals, and food, and eliminating wastes. u These tasks happen at the cellular level. u Molecules move through the cell membrane by diffusion u

Why are osmosis & diffusion important? u All living things have certain requirements they must satisfy in order to remain alive. These include exchanging gases (usually CO 2 and O 2), taking in water, minerals, and food, and eliminating wastes. These tasks ultimately occur at the cellular level, and require that molecules move through the membrane that surrounds the cell.

Why are osmosis & diffusion important? u This membrane is a complex structure that is responsible for separating the contents of the cell from its surroundings, for controlling the movement of materials into and out of the cell, and for interacting with the environment surrounding the cell.