RP: osmosis (B.3) (B.43)

• what is the independent variable?

  The concentration of the solution
• what is the dependent variable?

  The percentage change in mass
• 5 Control variables

  1)Length of potato 2)diameter of potato 3)volume of solution 4)time potato is left for 5)temperature of solution
• 3 ways to make the results accurate

  1)read the volume of the solution from the meniscus 2)Dab the potato dry before measuring the mass 3)use a digit top pan balance
• Name one risk and precaution

  Risk = cutting yourself with the potato borer Precaution = push the borer down towards the desk not upwards
• what is the purpose of distilled water?

  to act as a control to compare your results to
• how is the concentration inside the tissue estimated?

  plot a graph of concentration against % change in mass and find where the line of best fit crosses 0%
• how is the percentage change in mass calculated?

  % change in mass = change in mass/initial mass
• what is percentage change calculated rather than just the change?

  The potato may be slightly different sizes and shapes to begin with
• why does the tissue increase in mass?

  water has entered the tissue by osmosis in more dilute solutions
• how can you tell if there has been an increase in mass?

  The % change in mass +ve
• why does the tissue decrease in mass?

  water has left the tissue by osmosis in more concentrated solutions
• how can you tell if there has been a decrease in mass?

  The % change in mass is -ve
• what does no change in mass mean?

  the concentration of the solution is the same as the concentration inside the tissue
• what are possible variations on this method?

  1)Using any other vegetable/plant tissue 2)Using any other food substance 3)using a salt solution