Key Terms:

• Solution - homogenous mixture of two or more substances

• Solute - A substance which is dissolved

• Solvent - the substance in which a solute is dissolved

• Intracellular fluids - fluids found within a cell

• Extracellular fluids - fluids found outside of a cell

• Diffusion - the movement of molecules in solution from areas of high concentration to areas of lower concentration

• Concentration gradient - the change in molecular density over a given area

• Simple diffusion - small polar molecules pass through a selectively permeable membrane without assistance from areas of high concentration to areas of lower concentration

• Facilitated diffusion - large, charged molecules pass through specialized channels from areas of high concentration to low concentration

• Active transport - Molecules are moved through channels against the concentration gradient using ATP as the energy source for transport.

• Osmosis - describes the movement of water molecules across a selectively permeable membrane

• Tonicity - describes the solute differences between solutions and determines the net direction of water molecule movement

• Hypertonic - A solution with a higher solute concentration than the solute concentration on the opposite side of the permeable membrane. Hypertonic Solution has a lower percentage of water than solute.****

• Hypotonic - A solution with a lower solute concentration than the solue concentration on the opposite side of the permeable membrane. Hypotonic Solution has a higher percentage of water than solute

• Isotonic - A solution with equal solute concentration on both sides of the permeable membrane.

• In osmosis, water flows from - hypotonic to hypertonic solutions

• Water potential - The tendency of water to leave one place in favor of another.

• Water always moves - from an area of higher water potential to an area of lower water potential

• The more negative the water potential - the higher the concentration of solutes in the system

• Crenate - shrink

• In most biological systems cells are - hypertonic and extracellular water flows into them

• Lyse - burst

• What happens to cells placed in pure water - they lyse due to the increase of pressure from water moving in

Exercise 1

Part I

1. Lymphocyte - Appears dark purple and enlarged with a purple halo

2. Neutrofil - Appears light purple with three dark purple spots inside

3. Hypotonic red blood cell - Appears uniform purple with no ‘donut’ visible.

4. Hypertonic red blood cell - Appears irregular in shape, non-circular

5. Isotonic red blood cell - Uniform in shape, circular with clear ‘donut’ shape visible

Part II - Blood Cells in Distilled Water

• Majority of cells appear hypotonic and enlarged with few appearing to have a regular shape.

Part III - Blood Cells in 0.9% salt solution

• Majority of cells appear to have regular shape with no defects present.

Part IV - Blood cells in 12.5% salt solution

• Cells appear to be severely damaged showing no uniform shape and signs of hypertonicity