Topic 1 biology

• Diffusion


  Particles spread out and move from areas of high concentration to areas of low concentration
• Particles move down the concentration gradient on their own</b>
• As temperature increases


  The rate of diffusion increases
• Equilibrium


  The state where the concentration of particles is the same everywhere
• Diffusion is one of the most important processes in biology as it helps maintain balance
• Cell membrane


  Semi-permeable - allows some things to pass through but not others
• Concentration


  The amount of a substance dissolved in a given volume of solution
• If there is a low concentration of glucose inside a cell


  There is a high concentration of water
• If there is a high concentration of glucose outside the cell


  Water will move out of the cell to balance the concentrations
• Osmosis


  The movement of water across a semi-permeable membrane to balance concentrations
• Overwatering plants can cause their cells to become turgid and explode
• Drinking too much water can cause cells, including in the brain, to swell and become turgid, which can be fatal
• Drinking too little water causes cells to become dehydrated and flaccid
• Potato osmosis experiment


  Cut equal-sized potato cylinders

  2. Weigh the cylinders

  3. Place in solutions of different glucose concentrations

  4. Weigh the cylinders again after time

  5. Calculate percentage change in mass

  6. Plot a graph to find the glucose concentration where no change occurred
• Independent variable


  Concentration of solution
• Dependent variable


  Percentage change in mass of potato cylinders
• Controls


  Same size and shape of cylinders, temperature, volume of solutions, time
• Active transport


  The movement of molecules across a cell membrane against the concentration gradient, using energy
• Active transport is especially important for plants to absorb minerals from soil