1. Passive Transport: This method doesn't require energy from the cell. It relies on the concentration gradient, meaning substances move from an area of high concentration to an area of low concentration. There are several types of passive transport:
* Simple Diffusion: Movement of small, non-polar molecules directly through the phospholipid bilayer.
* Facilitated Diffusion: Movement of larger or polar molecules aided by transport proteins embedded in the membrane.
* Osmosis: Movement of water across a selectively permeable membrane from a region of high water concentration to a region of low water concentration.
2. Active Transport: This method requires energy from the cell, typically in the form of ATP, to move substances against their concentration gradient, from an area of low concentration to an area of high concentration. It involves specific transport proteins called pumps that use energy to move molecules.
