4.1: Exchange with the Environment Cell Transport EQ: Explain how cells take in nutrients and expel wastes.

What is Diffusion? Diffusion: the movement of particles from areas of high concentration/density to areas of low concentration/density. (crowded to less crowded) Does NOT require energy.

Diffusion of Water Osmosis: The diffusion of water Semipermeable membrane – only some substances can pass through Cell membrane Osmosis helps keep things in balance

Moving Small Particles Active Transport Passive Transport the movement of particles from low to high concentration REQUIRES energy the movement of particles from high to low concentration Does NOT require energy Diffusion & Osmosis

How do small particles move across the cell membrane? Through channels Channels: passageways in the cell membrane that allow particles through.

Moving Large Particles Endocytosis Exocytosis the movement of large particles into a cell. Both require energy therefore are considered ACTIVE TRANSPORT. The movement of large particles out of the cell Vesicle – a sac that forms from pieces of the cell membrane. Carry the particles