transport in & out of cells

• examples:
  • O2 & CO2 into gas exchange in lungs, gills & plant leaves
  • urea from cell into plasma for excretion 
  • food molecules from s.intestine into blood
• affecting factors:
  • concentration gradient
  • temp
  • surface area of membrane
• Adaptations:
  • large surface area
  • thin surface -> short distance to diffuse
  • moist surface so substances go across cell membrane faster
  • ANIMALS; rich blood supply keeps concentration gradient
  • ANIMALS; ventilation happens to speed up gaseous exchange

• diffusion of water from dilute to concentrated 
  • goes through partially permeable membrane
• KEEP INMIND THE POTATO-OSMOSIS PRACTICAL.

ACTIVE TRANSPORT; 

• moves substances against concentration gradient -> from low to high
• needs energy from respiration
• lets mineral ions to be absorbed into plant root hairs from dilute solutions into soil
• lets sugar molecules to be absorb from low concentration in gut into blood