Apedia

A-Level Biology OCR A

Diffusion Multicellular Organisms Large Transport Slow Explain Meet

Diffusion alone cannot meet the demands of most multicellular animals because of their size, low SA:V ratio, and high metabolic rate; however, diffusion remains crucial at specialized exchange surfaces like alveoli and capillaries.

Diffusion alone is insufficient for most multicellular animals due to their large size, low SA:V ratio, and high metabolic activity; diffusion is still necessary at specialized exchange surfaces like alveoli and capillaries.

Front Explain why diffusion alone cannot meet the demands of most multicellular animals but state where diffusion is still necessary in these organisms.
Back Diffusion vs transport system:
  • Most multicellular organisms are too large for transport of substances by diffusion as the rate would be too slow due to the low SA:V ratio & large difusion distances
  • Multicellular organisms are also more metabolically active so large amounts of oxygen and food would need to be transported, constantly and diffusion is too slow for that
  • Diffusion occurs in specialised exchange surfaces in organisms such as alveoli and capillaries other than that, substnaces are transported by mass flow

Learn with these flashcards. Click next, previous, or up to navigate to more flashcards for this subject.

Next card: Mass define flow movement fluid bulk direction

Previous card: Supply organisms increase cells large diffusion explain meeting

Up to card list: A-Level Biology OCR A