AP BIOLOGY

Detailed explanation-1: -This is a type of passive transport in which molecules that cross the cell membrane move quickly due to the presence of specific permeases in the membrane. Facilitated diffusion occurs only in the direction of a concentration gradient and does not require metabolic energy.

Detailed explanation-2: -Osmosis is the diffusion of water through a semipermeable membrane according to the concentration gradient of water across the membrane. Whereas diffusion transports material across membranes and within cells, osmosis transports only water across a membrane and the membrane limits the diffusion of solutes in the water.

Detailed explanation-3: -Water crosses cell membranes by passive transport and by secondary active cotransport along with ions.

Detailed explanation-4: -The movement of molecules across a membrane without the input of energy is known as passive transport. When energy (ATP) is needed, the movement is known as active transport. Active transport moves molecules against their concentration gradient, from an area of low concentration to an area of high concentration.

Detailed explanation-5: -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.