Surface Area to Volume Ratio

• Why do multicellular organisms require exchange surfaces and a transport system?

  Due to their low surface area to volume ratio
• What is the surface area to volume ratio?

  It compares the surface area of an object to its volume
• Why does the surface area to volume ratio decrease as organisms get larger?

  Because volume increases faster than surface area
• What problem do multicellular organisms face regarding gas exchange?

  Insufficient diffusion for cells deep inside
• How do animals solve the problem of gas exchange?

  By having specialized structures and transport systems
• What do fish use to obtain oxygen from water?

  Gills
• How does oxygen-rich water flow in fish?

  It passes into the mouth and over gills
• What adaptations do gill filaments have for gas exchange?

  Large surface area, thin membrane, efficient blood supply
• Why is a high concentration gradient important for diffusion in gills?

  It ensures efficient oxygen uptake into the blood
• What are the adaptations of gill filaments that enhance gas exchange?

  • Large surface area
  • Thin membrane for short diffusion pathway
  • Efficient blood supply to maintain concentration gradient
• How does the surface area to volume ratio affect multicellular organisms?

  • Larger organisms have lower ratios
  • Diffusion becomes insufficient for internal cells
  • Requires specialized structures for gas exchange