Forms of transport

• Diffusion is the movement of particles from an area of high to low concentration until they are evenly distributed and occur in both liquid and gas
• Osmosis is the movement of water molecules across a partially permable membrane from a region of higher water concentration to a region of lower water concentration
• Partially permible mebrane only allow tiny particles to pass through it
• Water movies into a cell by osmosis and the water moves through a partially permible mebrane
• A solution is fomred when a solute dissolves into a solvent


  solute+solvent=solution
• less water=concentrated
• more water=diluted
• hypertonic


  water moves out causing cells to shrink
• Isotonic

  balanced amount of water in and out of a cell
• Hypotonic


  too much water causing cell to swell but NOT burst
• water in cells

  
• Carbin dioxide diffuses from the air into leaves through tiny pores calls Stomata. Carbon dioxide is needed for Photosynthesis. Oxygen diffuses out of the leaf. The leaves have large surafce area therefore increasing rate of diffusion
• Nutrients move across the small intestine into the blood stream by diffusion where they are transported to the cells. The small intestine has a fingerlike projection called 'Villi' to increases surface area, which increases the rate at which nutirents are absorbed into the blood stream
• Red blood cells have a large surface area allowing oxygen to easily diffuse into the cells to carry out respiration
• Alveioli are air sacs inside the lungs, which have a large surafce area allowing oxygen to diffus quickly into bloodstream
• Active Transport: The movement of ions from an area of low concentration to an area of high concentration against their concentration gradient using energy
• Active Transport allows sodium and potassium ions to be transported acroos the membrane of the nerve cell
• Glucose is transported from the lumen of the small intestine by active transport
• Mineral ions are transported from soil to root hair cells by active transport
• Osmosis practicle

  1. measure identical potatoe cylinders
  2. place potatoe in different concentration of sugar/salt solution
  3. leave them all in the same amount of time
  4. take them out and pat them dry and weigh them again
  5. if mass increases then water has been taken in by osmosis
  6. if mass decreases then water has been taken out by osmosis
• Errors with potatoe practicle

  amount of patting on the potatoe meaning cylinder will have excess water and give a higher mass
• Errors with potatoe practicle

  if room is at room temp then the temp might increase causing fluid to evaporate causing fluid to become more concentrated