Potato osmosis practical (B1) Flashcards
What is the independent variable?
The concentration of the solution
What is the dependent variable?
The percentage change in mass
Name 5 control variables
Length of potato
Diameter of potato
Volume of solution
Time potato is left in solution for
Temperature of solution
Give 3 ways to make the results accurate
Read the volume of the solution from the meniscus
Dab the potatoes dry before measuring the mass
Use a digital top pan balance
Name 1 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 the 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
How is the percentage change in mass calculated?
% change in mass=Change in mass/initial mass
Why 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 the possible variations of this method?
Using any other vegetable/plant tissue
Using any other food substance
Using a salt solution
