Transport and exhcnahe

• Urea Is a waste product what does it diffuse out of cells into?

  Blood
• Why does urea diffuses

  • Urea particles cam pass through cells membrane
  • High concentration of urea in body cells than in blood
• After urea diffuses from blood where does it go?

  Travels to kidneys then removed in urine
• What substances need to be moved out of organisms?

  Water, dissolved food molecules, mineral ions
• Larger objects the smaller it's?

  Surface to volume area ratio
• Why do single celled organism have large surface to volume ratio

  Molecules can diffuse and take in all substances they need or get rid of waste products
• Multicellular organism have small surface area to volume ratio so they can't rely on diffusion have to use  adaptations
• Exchange surfaces are adapted to increase rate of diffusion
• Exchange surface has larger surface area soo

  Increase amount of particles that can diffuse at same time
• Exchange surfaces have thin membrane soo

  Gives molecules shorter distance to travel
• Exchange surfaces have good blood supply and well ventilated soo

  Maintained larger concentration gradient for fast rate of diffusion