The net movement of particles from an area of higher concentration to their lower concentration
The energy for diffusion comes from the kinetic energy of molecules in random movement
Roothair cells have long and thin root hairs, epithelial cells have cilia, and red blood cells are biconcave to increase their surface area for absorption
Osmosis is the diffusion of water molecules from a dilute solution (high concentration of water) to a more concentrated solution (low concentration of water) across a partiallypermeable membrane
Diffusion occurs randomly at all times due to Brownian motion
Temperature and molecule movement
The higher the temperature, the faster molecules move as they have more energy, resulting in more collisions and therefore a faster rate of movement
Factors influencing diffusion
Temperature, distance, surfacearea to volume ratio
Concentration gradient
The greater the difference in concentration gradient, the faster movement across the membrane, leading to more random collisions
As cells grow in size, cell activity slows down, causing them to require a larger surface area to volume ratio to obtain enough nutrients
Diffusion helps living things to obtain nutrients, get rid of waste products, and carry out gaseous exchange for respiration
Diffusion is the random movement of particles in the direction of a concentration gradient
Diffusion occurs in various parts of the body such as the small intestine, mesophyll cells, blood capillaries, alveoli, etc.
The smaller the distance molecules have to travel, the faster the transport will occur
Diffusion is the movement of molecules from a region of higher concentration to a region of lower concentration
Molecules that diffuse down concentration gradient
Water
Oxygen
Carbon dioxide
Molecules moving out of cells can include digested food products like glucose, amino acids, fatty acids, glycerol, etc.
Diffusion, osmosis, and active transport are the main ways that molecules move into and through cell membranes
Blood capillaries and alveoli have walls which are only one cell thick to ensure the rate of diffusion across them is as fast as possible