AP BIOLOGY

Detailed explanation-1: -Many things can diffuse. Odors diffuse through the air, salt diffuses through water and nutrients diffuse from the blood to the body tissues. This spread of particles through random motion from an area of high concentration to an area of lower concentration is known as diffusion.

Detailed explanation-2: -In the process of diffusion, a substance tends to move from an area of high concentration to an area of low concentration until its concentration becomes equal throughout a space.

Detailed explanation-3: -Facilitated diffusion is the transport of substances across a biological membrane from an area of higher concentration to an area of lower concentration with the help of a transport molecule. Since substances move along the direction of their concentration gradient, chemical energy is not directly required.

Detailed explanation-4: -Osmosis is a special type of diffusion, namely the diffusion of water across a semipermeable membrane. Water readily crosses a membrane down its potential gradient from high to low potential (Fig. 19.3) [4].