osmosis

• What is diffusion?


  Diffusion is the net movement of particles from an area of higher concentration to an area of lower concentration.
• How do oxygen and glucose molecules move into a cell?


  They diffuse down their concentration gradient into the cell.
• What is osmosis?


  Osmosis is the diffusion of water molecules across a partially permeable membrane.
• What is the definition of osmosis?


  Osmosis is the net movement of water molecules from a region of higher water concentration to a region of lower water concentration.
• What does the term "water concentration" refer to?


  Water concentration refers to the amount of water compared to other dissolved molecules like sugars or salts.
• What are solutes?


  Solutes are the molecules like sugars or salts that are dissolved in water.
• How does the concentration of solutes affect water concentration in a solution?


  • Higher solute concentration means lower water concentration.
  • Lower solute concentration means higher water concentration.
• If one beaker has one solute particle and another has three, which beaker has a higher solute concentration?


  The beaker with three solute particles has a higher solute concentration.
• What determines the concentration of water in a solution?


  The proportion of water compared to solutes determines the concentration of water.
• How does osmosis occur in relation to a cell's environment?


  • Water moves from an area of higher water concentration (outside the cell) to an area of lower water concentration (inside the cell).
  • This movement occurs across a partially permeable membrane.
• What is the water concentration inside a cell compared to its outside environment if the outside has almost pure water?


  The outside of the cell has a higher water concentration than the inside of the cell.
• What is the relationship between water concentration and solute concentration in the context of osmosis?


  Higher solute concentration corresponds to lower water concentration, driving osmosis.
• What is the aim of the osmosis required practical?


  To investigate the range of concentrations of salt or sugar solutions on the mass of plant tissue
• What is the procedure for the osmosis required practical?


  • Prepare samples of potatoes (or other plant tissue)
  • Place in different concentrations of sugar or sodium chloride solution
  • Measure mass and length before and after soaking
  • Calculate percentage change in mass
  • Plot, draw, and interpret graphs
• What should be done with the potato samples before and after soaking?


  Measurements of mass and length should be made
• How is the percentage change in mass of plant tissue calculated?


  By using the measurements of mass before and after soaking
• What should you do with the graphs after plotting them?


  Draw and interpret the graphs
• What is important to ensure when preparing potato samples?


  Samples should be prepared carefully and measurements recorded accurately
• How many different concentrations should be used in the practical?


  At least five different concentrations
• What is an example of a condition under which the experiment can be carried out?

  In a water bath at 30 °C for 30 minutes
• What should be measured carefully using appropriate equipment?

  Volumes of solutions and potato lengths
• What are the independent and dependent variables in this practical?

  • Independent variable: Concentration of salt or sucrose solution in mol dm³
  • Dependent variable: Mass and length of each potato cylinder before and after submersion
• How is the percentage change in mass and length calculated?


  Using the measurements taken before and after submersion
• What are the important control variables in this practical?

  • Type and volume of solute in solution
  • Temperature
  • Time