Background Information:
Osmosis is the movement of solvent molecules across a partially permeable membrane. They move from a region of low concentration (hypotonic) to a region of high concentration (hypertonic). The rate of osmosis across a eukaryotic cell membrane can be affected by different factors; including temperature, concentration gradient, water potential and the surface area for osmosis to occur and pressure exerted on either side of the semi-permeable membrane.
A potato (Solanum Tuberosum) contains 92% water, which is an osmotically active component. The precise osmotic potential of sweet potatoes is however unknown.
The osmotic potential of sucrose is know to be at 20 oC, the osmotic potential of sucrose is 2.436 MPa2. The rate of osmosis will be calculated by measuring the percentage change in mass of a piece of potato, that has been submerged in a specific concentration of sucrose over a 94 h period.
Research Question:
What is the effect of sucrose concentration on the rate of osmosis across a potato (Solanum Tuberosum) cell membrane?
Hypothesis:
If the sweet potato cytoplasm is hypotonic relative to the sucrose solution, then water will move from the potato into the sucrose solution, resulting in a decrease in mass.
If the potato cytoplasm is hypertonic relative to the sucrose solution, then water will move from the sucrose solution into the potato, resulting in an increase in mass of the sweet potato.
Variables: Independent | Concentration of sucrose solution: 1.0 M0.8 M0.6 M0.2 M | Dependent | Rate of osmosis, indicated by change in mass of sweet potato (±0.01 g)/time (94h ±0.001h) | Controlled | Temperature Water potentialPressure exerted on either side of cell membrane | Uncontrolled | Surface area for