RP3-investigating water potential

Question 1

what occurs when plant tissue is placed into hypotonic solution

Answer 1

-water moves into the plant tissue via osmosis, causing the plant tissue to increase in mass

Question 2

what occurs when plant tissue is placed into hypertonic solution

Answer 2

-water moves out of plant tissue via osmosis, causes the plant to shrivel and lose mass.

Question 3

why are the potato disks left in the solution for 20 mins

Answer 3

to allow time for osmosis until plant tissue reaches equilibrium with the surrounding solution

Question 4

outline the procedure of investigating osmosis using potato tissue

Answer 4

-make a simple dilution of 1M of sucrose solution for 5 concentrations then add 5cm3 to each test tube
-cut potatoes into equal chips then weigh
-place a chip in each test tube and leave for 20 mins
-take them out, dry with paper towel and re-weigh
-calculate percentage change in mass

Question 5

why is percentage change used rather than change in mass

Answer 5

-potato chips may not all have same starting mass
-percentage change allows for comparison

Question 6

what is indicated by the x-intercept on the graph of percentage change in mass against concentration

Answer 6

-the concentration that is isotonic to the solution

Question 7

what are the control variables in investigating osmosis

Answer 7

-length of time in solution
-volume of solution
-size of potato chips