AP BIOLOGY

Detailed explanation-1: -Passive transport occurs when substances cross the plasma membrane without any input of energy from the cell. No energy is needed because the substances are moving from an area where they have a higher concentration to an area where they have a lower concentration. Water solutions are very important in biology.

Detailed explanation-2: -Passive transport is defined as movement of a solute from a region of high electrochemical potential on one side of the cell membrane to a region of lower electrochemical potential on the opposite side.

Detailed explanation-3: -There are three main types of passive transport: Simple diffusion – movement of small or lipophilic molecules (e.g. O2, CO2, etc.) Osmosis – movement of water molecules (dependent on solute concentrations) Facilitated diffusion – movement of large or charged molecules via membrane proteins (e.g. ions, sucrose, etc.)

Detailed explanation-4: -Some materials, like water and oxygen, can enter and leave cells without the cell needing to expend any energy. This is passive transport.