Hey sophmores! Mr. Landry tells us that you guys need to know diffusion, active transport and osmosis! So let's get started (:
Diffusion - Basically saying that particles are spread out evenly. Diffusion can be broken down into two things; simple and facilitated diffusion.
Both simple and facilitated diffusion move from HIGH to LOW concenctration and NO ENERGY is needed for these and are called passive transport because no energy is needed. Facilitated diffusion is different because it needs help, where as simple diffusion doesn't need help. The help comes from protein channels, they help move specific molecules across the cell membrane.
Alright, now it's time for Osmosis! Osmosis is basically diffusion of water. Osmosis also travels from HIGH to LOW concentration and no energy is needed still, so it is passive transport as well.
Now we need to cover Active transport. Active transport is where cells may have to move molecules AGAINST concentration gradient. So in other words in active transport the molecules more from LOW to HIGH concentration. Active transport does need energy (ATP) because it is moving from low to high concentration. Active transport uses a protein pump or proton pump.
Diffusion - High to low concentration and no energy is needed this is a passive transport.
Osmosis - Diffusion of water, high to low concentration, also passive transport because no energy is needed.
Active transport - Low to high concentration and energy IS NEEDED!