3. Compare and contrast active transport to passive transport of diffusion of molecules across the cell membrane. You may use a diagram and/or an analogy to help? short explnation not a big one
In active transport, molecules move across the cell membrane against their concentration gradient, meaning they move from an area of lower concentration to an area of higher concentration. This process requires the input of energy in the form of ATP (adenosine triphosphate). Active transport is performed by specific carrier proteins or pumps embedded in the cell membrane, which actively pump molecules across the membrane. An analogy to active transport would be climbing a steep hill with the help of a rope and a pulley system, where the rope represents the carrier proteins and the input of energy is required to perform the uphill movement.
On the other hand, passive transport, also known as diffusion, occurs when molecules move across the cell membrane along their concentration gradient, from an area of higher concentration to an area of lower concentration. This process does not require energy input and is mainly driven by the random movement of molecules. Passive transport can occur through three main mechanisms: simple diffusion (small, nonpolar molecules crossing the lipid bilayer directly), facilitated diffusion (movement of larger or charged molecules facilitated by specific channel or carrier proteins), and osmosis (diffusion of water molecules across a selectively permeable membrane). An analogy to passive transport would be spices dispersing through the air in a kitchen, where the spices spread out from an area of higher concentration to an area of lower concentration without requiring external energy.
In summary, active transport requires energy and moves molecules against their concentration gradient, while passive transport occurs spontaneously without energy input and moves molecules along their concentration gradient.