osmosis

osmosis

1. the net movement of water from a dilute solution to a more concentrated solution through a partially-permeable membrane

   • the partially peremeable membrane
     • Eg: water particles can move through pores in membrane but sugar particles (big) cant move through
     • allows water molecules through
     • stops solute molecules because they are too large

2. red blood cell in dilute solution - the cell would burst

   • red blood cell in concentrated solution - cell would shrink
     • in a plant the cell would swell in dilute solution but not burst as it has a cell wall for protection

3. Active transport

   • root hair cells have large surface area
   • cells need to transport substances in and out
     • (in) eg oxygen by diffusion for respiration from an area where theres a high concentration to lower concentration down a concentration gradient
       • eg water by osmosis( can be in or out depending on concenration of the solutions inside and outside of the cell
     • (in) glucose for respiration can go in by diffusion but we need active transport which requires energy ( can be moving against a concentration gradient )
   • The movement of particles/ions/molecules from an area of low concentration to an area of high concentration (against a concentraion gradient) energy from respiration is required
     • substances are sometimes absorbed against a concentration gradient - in the opposite direction to normal disrtibution
       • This requires energy from respiration.known as active transport
   • allows cells to absorb sugar ions that pass through cell membranes from very dilute solutions
     • plants absorb ions from very dilute solutions in the soil by active transport
     • in humans,sugar can be absorbed from the intestine and from the kidney tubules by active transport

4. concentration gradient is the region where the concenration of a substance varies from higher to lower

   • eg water moves from the soil into the plantsa root hair cells by osmosis along a concentration gradient

5. cell membrane controls particles that pass through as they have speacialised molecules to allow certain substnces through

6. sports drinks

   • blood sugar (glucose) needed for respiration that releases energy
     • sweat - lose lots of water and mineral ions like sodium and potassium . if there are not enough mineral ion the cells work inefficiently
     • the sugar used to relase energy during exerise
   • sports drinks can replace water, mineral ions and sugar