Osmosis And Diffusion Lab Report

Diffusion is the molecular net movement from a higher concentration to a lower concentration. For instance, when a person is smoking, the smoke diffuses into the air. The molecules in the smoke, released from the cigarette, travel through the air. Here is how it occurs. When molecules are close enough, they collide with each other, their kinetic energy changes. Due to the direct relationship between diffusion and molecular kinetic energy, the molecules move away from the point of the collision as their kinetic energy is redirected. Therefore, molecules always tend to distribute themselves throughout the area they stay. It continues until dynamic equilibrium is reached, that is, no net movement happens. Molecules at that time are still in motion, but the amount of molecules moving in one direction equals to the amount of molecules moving in the other direction.
There are three types of solutions to diffusion: isotonic, hypertonic, or hypotonic. When the solutions have the same concentration of solutes, they are isotonic. When the solutions differ in their solute concentration, the solution with more solute is hypertonic to the other solution. The solution that has less solute is hypotonic
to the other solution.
Osmosis is a special kind of diffusion, which is the water through a selectively permeable membrane. A selectively permeable membrane is that the membrane only allows certain molecules through. Water molecules travel from the area of high water concentration to the area of low water concentration.
Osmosis has a major effect on living cells because it is rare that organisms live in external environment with solute concentrations that exactly match their internal environment.
Cells must move materials through membranes in order to maintain homeostasis. The cellular environment is aqueous, indicating that the solutes dissolve in the solvent, water. When a cell is hypertonic, or hypotonic, to its surroundings, it tries to make concentration of solution inside and outside itself equal. However, the solutes are too big to pass the cell membranes without the help of channel proteins, or transport proteins. Water may freely pass through the membrane by osmosis, which requires no energy. Thus, the cell starts to take in, or release, water until it is isotionic to its
surroundings.
If a cell is hypertonic to its external environment, water goes into the cell, causing cell to expand. If this happens in an animal cell, the cell bursts, or cytolizes. So, being hypertonic is extremely dangerous for animal cells. On the other hand, if it is in a plant cell, the cell wall can keep the cell together, preventing the cell to burst.
If a cell is hypotonic to its external environment, water goes into its surroundings, making cell to shrink. In animal cells, the cells lose shape and support as well as shrivel up. If it is in plant cells, the plants wilt.