Surface Area to Volume Ratio

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

  To facilitate gas exchange due to size
• What is the role of gills in fish?

  To transport gases into and out of fish
• How does the surface area to volume ratio affect diffusion in single-celled organisms?

  Higher ratio allows efficient diffusion of molecules
• What are the adaptations of gills in fish for gas exchange?

  • Large surface area from filaments
  • Thin membrane for short diffusion pathway
  • Efficient blood supply to maintain concentration gradient
• What problems do multicellular organisms face regarding gas exchange?

  • Insufficient surface area for volume
  • Cells far from surface cannot get enough oxygen
  • Need for specialized structures for gas exchange
• How do animals solve the problem of gas exchange?

  • Special structures like lungs for gas exchange
  • Transport systems to carry gases throughout the body