movement of substances (chapter 2)

concentration gradient definition

concentration gradient is the difference in concentration between two regions

• steeper gradient → faster rate of diffusion

diffusion definition

diffusion is the net movement of particles from a region where they are of a higher concentration to a region where they are of lower concentration, that is, down a concentration gradient

factors affecting rate of diffusion

• diffusion distance → shorter diffusion distances, less time is needed for substances to travel, diffusion rate is higher

• surface area-to-volume ratio →the greater the surface area-to-volume ratio of a cell, the higher the rate at which substances move in and out of it

osmosis definition

osmosis is the net movement of water molecules from a region of higher water potential to a region of lower water potential, through a partially permeable membrane

active transport definition

active transport is the process in which energy is used to move the particles of a substance across a membrane against oils concentration gradient , from a region where the particles are of a lower concentration to a region where they are of higher concentration