Diffusion

Define diffusion as the spreading of particles from higher to lower concentration.

Identify substances transported by diffusion (oxygen, carbon dioxide, urea).

Explain how concentration gradient, temperature, and surface area affect the rate of diffusion.

Calculate and compare surface area to volume ratios.

Explain the need for exchange surfaces and transport systems in multicellular organisms.

Describe adaptations of the small intestine, lungs, gills, roots, and leaves for exchanging materials.