Diffusion in Multicellular Organisms

• What is the role of root hair cells in plants?


  Root hair cells absorb water and mineral ions from the soil.
• Why do larger multicellular organisms have exchange surfaces and transport systems?

  Because diffusion, osmosis, and active transport cannot meet their needs due to their larger size.
• How do root hair cells increase their surface area?


  They have specialized structures with root hair projections.
• What is the role of the small intestine in the body?


  The small intestine is responsible for the absorption of digested food molecules into the bloodstream.
• How does the structure of the small intestine facilitate its function?


  It has a highly folded surface lined with specialized epithelial cells, which increases surface area and decreases diffusion distance.
• What is the gas exchange surface in humans called?


  The alveolus.
• What is the primary function of alveoli in the lungs?


  Gas exchange between air in the alveoli and the blood.
• How do alveoli maintain a concentration gradient for gas exchange?


  They have a moist lining and an excellent blood supply.
• What adaptations do fish gills have for gas exchange?

  Fish gills have filaments covered in lamellae and a dense capillary network.
• What is the role of stomata in leaves?


  Stomata allow air to circulate inside the leaf for gas exchange.
• How do stomata minimize water loss in plants?


  They are predominantly located on the lower side of the leaf.
• What are the key adaptations for efficient exchange in multicellular organisms?


  • Large surface area to increase transport rate
  • Thin barriers to provide short diffusion paths
  • Extensive blood vessel networks to reduce exchange distance
  • Well-ventilated gas exchange surfaces to maintain concentration gradients
• What is the misconception about the 'wall of the alveoli' and 'wall of the intestines'?


  They are made from animal cells, not cell walls.