surface area to volume ratio

• What concept explains why multicellular organisms need exchange surfaces?

  Surface area to volume ratio
• Why do multicellular organisms require a transport system?

  To efficiently transport gases and nutrients
• What is the function of gills in fish?

  To transport gases into and out of fish
• How do molecules move in and out of cells?

  By diffusion
• What is the surface area to volume ratio of a single-celled organism like an amoeba?

  High surface area for its volume
• Why can single-celled organisms rely on diffusion?

  They have a high surface area to volume ratio
• How do you calculate the surface area of a cube with side length 1 mm?

  6 square mm
• What is the volume of a cube with side length 1 mm?

  1 cubic mm
• What is the surface area to volume ratio of a cube with side length 1 mm?

  6:1
• What is the surface area of a cube with side length 2 mm?

  24 square mm
• What is the volume of a cube with side length 2 mm?

  8 cubic mm
• What is the surface area to volume ratio of a cube with side length 2 mm?

  3:1
• What is the surface area to volume ratio of a cube with side length 3 mm?

  2:1
• What problem do multicellular organisms face regarding diffusion?

  Insufficient surface area for their volume
• How do animals solve the problem of gas exchange?

  By having specialized structures and transport systems
• How do fish obtain oxygen from water?

  Through gills as water flows over them
• What adaptations do gills have to increase diffusion rate?

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

  It ensures efficient oxygen uptake
• What are the adaptations of gills that enhance gas exchange?

  • Large surface area
  • Thin membrane for short diffusion pathway
  • Efficient blood supply to maintain concentration gradient
• What are the implications of a low surface area to volume ratio in multicellular organisms?

  • Insufficient diffusion for internal cells
  • Need for specialized exchange surfaces
  • Requirement for a transport system