The Molecular Motion and Diffusion Quiz

Diffusion

• Random movement of molecules in a solution is described as Brownian motion.
• Dispersal of a dye in water is caused by the random movement of molecules, resulting in uniform distribution.
• Factors that affect the rate of dispersal of a dye in a solution include:
• Concentration gradient
• Temperature
• Surface area
• Shape and size of molecules
• Movement of molecules in biological systems can be observed through:
• Microscopy
• Dye dispersion
• Observation of cellular processes
• The ultimate goal of the net movement of molecules in a solution is to achieve equilibrium, where the concentration of molecules is uniform throughout the solution.

Factors Affecting Diffusion

• The rate of diffusion is NOT affected by the color of the dye.
• The primary determinant of a substance's direction of diffusion is the concentration gradient.
• In addition to the concentration gradient, the rate of diffusion is also determined by the:
• Temperature
• Surface area
• Shape and size of molecules

Cellular Membranes

• The main function of cellular membranes is to regulate the movement of molecules in and out of cells.
• The passive, directional movement of molecules is described as diffusion.