In a recent investigation, our Year 12 student, Ryunosuke Kusakari, sought to determine the water potential of beetroot, which is a measure of the potential for water to leave a solution.
Water Potential and Cells
- Water Movement: Water moves from areas of high water potential (more water, fewer solutes) to areas of low water potential (less water, more solutes) to reach equilibrium, or balance.
- Beetroot Cells: Beetroot cells have membranes that allow water to pass through but keep solutes inside. When you place the beetroot in different sucrose solutions, water will move in or out of the beetroot depending on the concentration of the solution compared to the concentration inside the beetroot cells.
How did you conduct your investigation?
“We investigated the water potential of beetroot by using a range of different water potential solutions, which were different known concentrations of sucrose, and submerging beetroot into each beaker.
“We measured the mass before and after submerging for 30 minutes, and found that the concentration of sucrose in the plant was between the 0.4M and 0.6M solutions.”
What did these changes show?
“The mass changes show how much the water moved in and out of the beetroot cells in order to reach equilibrium, and the concentration at which mass did not change show that the beetroot had the same water potential as the sucrose solution, so there was no concentration gradient and no movement of water across the plant cell membrane.”
What did you learn about water potential?
“I learnt about the effects of different water potential solutions on beetroot plant membranes, and concentrations of solutes in plant cells. I enjoyed seeing the red beetroot pigments sink or float in each solution depending on the concentrations of starch.”
How might you take your investigation further in future?
“A follow up experiment would be testing other plants to test for their water potentials, or animal cells to compare how differences in cell structures affect water potentials.”
Thank you Ryunosuke for sharing the results of your investigation with us so thoughtfully, and we look forward to hearing about your follow-up experiment.
