Question

What is a passive diffusion and how does it work?

Answer 1

Diffusion is defined as the migration of a chemical from a high-concentration area to a low-concentration area. Diffusion happens when particles in liquids and gases collide and spread out randomly. Diffusion is the mechanism through which chemicals flow into and out of cells in living things.

Complete answer:
Passive transport is a type of membrane transport in which chemicals are moved across cell membranes without the need of energy. Passive transport uses the second law of thermodynamics to drive the movement of substances across cell membranes rather than cellular energy, as active transport does. Fundamentally, chemicals obey Fick's first law and shift from a high-concentration area to a low-concentration area since this raises the overall system's entropy. The permeability of the cell membrane, which is determined by the organisation and properties of the membrane lipids and proteins, determines the rate of passive transport.
Simple diffusion, assisted diffusion, filtration, and/or osmosis are the four primary types of passive transport. The first and second laws of thermodynamics apply to passive transport.
Facilitated diffusion, also known as carrier-mediated osmosis, is the flow of molecules across the cell membrane via specific transport proteins implanted in the plasma membrane that actively accept or reject ions. The active transport of protons by H+ ATPases changes membrane potential, enabling more efficient passive transport of specific ions such as potassium down charge gradients via high affinity transporters and channels.

Note:
The passage of water molecules through a selectively permeable membrane is known as osmosis. The net transfer of water molecules from a solution with a high water potential to a region with a low water potential across a partially permeable barrier. Water will be drawn in by a cell with a lower negative water potential, although this is dependent on other parameters such as solute potential and pressure potential.