2.49: Understand Why Simple, Unicellular Organisms can Rely on Diffusion for Movement of Substances In and Out of the Cell

DIFFUSION: Net Movement of Particles Down the Concentration Gradient (High Concentration to Low Concentration)

UNICELLULAR ORGANISMS: Organisms made of a Single Cell. E.g, Bacteria, Fungus, Yeast

UNICELLULAR ORGANISMS AND DIFFUSION:

UNICELLULAR ORGANISMS RELY ON DIFFUSION

Diagram Showing the Relation of Size and Surface Area to Volume Ratio

EXPLANATION: Unicellular Organisms Relies on Diffusion to Move Substances Into and Out of Cells It has a Large Surface Area to Volume Ratio as they are Small (As Size Increases, Surface Area to Volume Ratio Decreases) as they Only have One Cell so has a Efficient Rate of Diffusion So Relies on Diffusion to Transport it with Necessary Substances that it Needs Quickly through the Membrane such as Oxygen and Glucose

COMMON FEATURES OF EXCHANGE SURFACES: Thin Cell Walls Distance of Diffusion is Short so Efficient Rate of Diffusion Large Surface Area to Volume Ratio Mostly Single Celled Organisms as they are Long, Thin, Flat or Folded Moist Substances can Easily Diffuse through Membrane