RP3: Using a dilution Series to identify the water potential of plant tissue Flashcards
What are we investigating in this experiment
We are investigating the effect of different sucrose concentrations on the rate of osmosis in plant tissue
Describe the procedure
1: label a test tube with the sucrose concentration
2: pipette 10 cm³ of the sucrose solution into the test tube
3: Cut a cylinder of potato 3 cm in length on a white tile using the cork borer
4: Dry the potato cylinder on a paper towel
5: places cylinder on the electronic balance and record the mass
6: place the cylinder into the test tube
7: Record the final mass after certain amount of time
How do you calculate the mean change in mass of a potato cylindervat each of the sucrose concentrations
(mean difference in mass / mean initial mass) X 100
How do you plot a graph to show this information
Y axis: The mean percentage change in mass (grams)
X axis: sucrose concentration moldm3-1
Why is it important that the potato is dried before measuring the mass
because excess of water can add excess mass/weight onto the potato so we always lightly dry the potato sample with a paper towel. The added water could affect the initial mass reading therefore affecting the final mass reading
What does the term processed results mean
Smooth curve/we have calculator the main percentage change in mass (grams)
What does it mean when the curve crosses the X axes
this is the sucrose concentration does not affect the water potential of the potato cylinder
Why is the percentage change or the ratio of final to initial length or mass a better measurements and then simply a change in mass or length
because it gives a better spread of data/more accurate and it is a comparison between all of the lengths
because it also accounts for any slight differences in the initial mass.
Why is the rate of change determined from the initial part of the graph
Because it is the fastest and most constant part of the graph. It is the most accurate as it is the most linear.
