AP BIOLOGY

Detailed explanation-1: -Diffusion. Diffusion is a passive process of transport. A single substance tends to move from an area of high concentration to an area of low concentration until the concentration is equal across the space. You are familiar with diffusion of substances through the air.

Detailed explanation-2: -There are two main modes of transport of molecules across any biological membrane. These are passive and active transport. Passive transport, most commonly by diffusion, occurs along a concentration gradient from high to low concentration.

Detailed explanation-3: -Diffusion is the movement of molecules from an area of high concentration of the molecules to an area with a lower concentration. For cell transport, diffusion is the movement of small molecules across the cell membrane.

Detailed explanation-4: -In Passive transport, where the movement occurs without energy consumption, movement of fat-dissolvable and non-polar molecules follow simple diffusion. Diffusion of oxygen, carbon dioxide, fats occurs from the side with the higher concentration to the lower, until a balance is achieved.

Detailed explanation-5: -Passive transport occurs when substances cross the plasma membrane without any input of energy from the cell. No energy is required because the substances are moving from an area where they have a higher concentration to an area where they have a lower concentration.