Exchanging substances and exchange surfaces

• What are the three main factors that affect the movement of substances?

  Surface area to volume ratio, temperature, and concentration gradient
• How does surface area to volume ratio affect the rates of diffusion, osmosis, and active transport?

  A larger surface area to volume ratio increases the rates of these processes
• What happens to particle movement as temperature increases?

  Particles move faster as they gain more energy
• How does the concentration gradient affect the movement of substances in and out of a cell?

  Substances move faster if there is a higher concentration gradient
• What are the adaptations of exchange surfaces to maximize effectiveness?

  • Thin walls for short distance travel
  • Large surface area for more substance movement
  • Rich blood supply for quick exchange
  • Ventilation in gas exchange surfaces
• What is the primary function of the lungs?

  To transfer oxygen to the blood and remove carbon dioxide
• What are alveoli?

  Millions of tiny air sacs in the lungs where gas exchange occurs
• How are alveoli specialized for gas exchange?

  They have a large surface area, thin walls, moist lining, and good blood supply
• What happens to oxygen and carbon dioxide during gas exchange in the lungs?

  Oxygen diffuses into the blood, and carbon dioxide diffuses out of the blood
• What is the role of villi in the small intestine?

  To increase the surface area for the absorption of digested food molecules
• How do villi assist in the absorption of nutrients?

  They have a single layer of surface cells and a good blood supply
• Why is it beneficial for an exchange surface to be just one cell thick?

  It minimizes the distance substances must travel for exchange
• How are leaves adapted for efficient gas exchange?

  Leaves are broad, thin, have air spaces, and contain stomata
• What is the function of stomata in leaves?

  To allow gases like CO₂ and O₂ to diffuse in and out
• How do root hairs assist in water and mineral ion absorption?

  They increase surface area and facilitate osmosis and active transport
• Why does water move into root hair cells by osmosis?

  Because there is usually a higher concentration of water in the soil
• How do mineral ions enter root hair cells?

  Mineral ions move in by active transport
• What are the key adaptations of leaves for gas exchange?

  • Broad shape for large surface area
  • Thin structure for short diffusion distance
  • Air spaces for easy gas movement
  • Stomata for gas exchange and transpiration
• What are the adaptations of root hairs for water and mineral absorption?

  • Long "hairs" increase surface area
  • Microscopic size allows for more absorption
  • Osmosis for water uptake
  • Active transport for mineral ions