Zusammenfassung der Ressource
Movement of Substances
- Types
- Passive
- Does not require energy
- Move ↓ conc. gradient
- Eg.
- Diffusion
- Osmosis
- Active
- Requires energy
- Move against / up conc. gradient
- Diffusion
- NET movement of particles frm a region of HIGH conc. to LOW conc.
- Down conc. gradient
- Conc. gradient
- Diffeence in conc. btw 2 regions
- Steeper grad.
- ↑ rate of diffusion
- Factors affecting RATE
- Conc. gradient
- Steeper
- ↑ rate
- Temperature
- ↑
- ↑ energy level of molecules
- ↑ rate
- Size of particles
- ↓
- ↓ energy required to move particles
- ↑ rate
- Thickness of membrane
- Thin
- ↓ distance for particles to travel
- ↑ rate
- May be unapplicable
- Diffusion does not require a membrane
- Eg.
- Animal cells
- Partially permeable membrane
- Allow some substances through
- Eg.
- Lungs
- Alveolus separated frm capillaries by a thin membrane
- Diffusion
- Gas exchange across membrane
- Small intestines
- Epithelium of villus
- One-celled thick
- ↑ of diffusion
- Digested food molecules into bloodstream
- Practical Application
- Kidney Dialysis
- Diffusion
- Wastes products removed frm blood through artificial membrane in machine
- Blood cells & large molecules retained
- Osmosis
- NET movement of WATER molecules frm a region of ↑ WATER POTENTIAL to ↓ w.p
- Across a PARTIALLY PERMEABLE MEMBRANE
- Water potential
- Tendency for water molecules to move frm 1 place to other
- Eg.
- Dilute solution
- ↑ water molecules per unit vol than a concentrated soln
- Plants
- Tugor pressure