Passive Transport:This is the movement of substances across the cell membrane without the use of energy by the cell. It's like guests slipping past the bouncer when he's not looking.
Active Transport:This is when an input of energy is required to move materials through a cell membrane, often against their concentration gradient. It's like a VIP guest who gets escorted into the club regardless of how crowded it is inside.
Diffusion:This refers to the process by which molecules intermingle as a result of their kinetic energy of random motion. Imagine if everyone in the club started dancing and moving around, eventually, people would be spread out evenly throughout the dance floor.
