Transporting substances 🚕

• What are the three ways substances move in and out of cells?

  Diffusion,active transport, and osmosis.
• What is diffusion?

  Diffusion is the net movement of particles from an area of high concentration to an area of low concentration.
• What states does diffusion happen in?

  Liquids and gases.
• What type of process is diffusion?

  Passive process.
• How does diffusion work with the gradient?

  It goes down the gradient.
• What is active transport?

  Active transport is the net movement of particles from an area of low concentration to an area of high concentration through a partially permeable membrane.
• What type of process is active transport?

  It is an active process (hence the name having active in it.)
• How does active transport work with the gradient?

  It goes against the concentration gradient.
• Give an example of diffusion and active transport in the digestive system.

  When there is a higher concentration of nutrients in the gut than in the blood the nutrients diffuse naturally into the blood.

  Sometimes there is a lower concentration of nutrients in the gut than in the blood so active transport allows the nutrients to be taken into the blood.
• What is osmosis?

  Osmosis is the net movement of water particles from an area of high water potential (dilute) to an area of low water potential (concentrated) through a partially permeable membrane to achieve equilibrium.
• What are the steps to the osmosis potato sticks practical?

  1.Prepare sucrose solutions of different concentrations ranging from pure water to a very concentrated sucrose solution.

  2.Use a cork borer to cut a potato into same sized pieces (1cm)

  3.Divide cylinders into groups of three and measure mass of each group.

  4.Place one group in each solution and leave cylinders in solution for 40 minutes.

  5.Remove cylinders and pat dry gently with a paper towel to remove excess water and get accurate measurements.

  6.Weigh each group again and record results.
• What are the variables of this experiment?

  Independant: sucrose solution concentration

  Dependant: The percentage change in mass.

  Control: the size of the potato cylinders, the type of potatoes used, the amount of drying and the volume of solution.
• What is the calculation to work out percentage change in mass?

  final mass - initial mass divided by initial mass x 100