University:
California State University, Northridge
Course:
BIOL 322 |Evolutionary Biology
Academic year:

2023
Views:

46

Pages:

3
Author:

kundgetanufv

LAB 4 Title: Osmosis- Movement of Water Across a Selectively Permeable Membrane Purpose: In this simulation, you will examine osmosis using thistle tubes that are fitted with membranes over their large, open ends, and record changes in volume of water moved by water. Materials: - 10% corn syrup - 20% corn syrup - 30% corn syrup - Distilled water - Selectively permeable membrane - Beaker - Thistle tube Methods: Phase 1: 10% Corn syrup 1. Attach selectively permeable membrane to bottom of thistle tube 2. Add 10% corn syrup to thistle tube 3. Add distilled water to beaker 4. Wait 10 minutes to measure volume of liquid inside tube. Record data. Phase 2: 20% Corn syrup 1. Attach selectively permeable membrane to bottom of thistle tube 2. Add 20% corn syrup to thistle tube 3. Repeat steps 3 and 4 in Phase 1. Phase 3: 30% Corn syrup 1. Attach selectively permeable membrane to bottom of thistle tube 2. Add 30% corn syrup to thistle tube 3. Repeat steps 3 and 4 in Phase 1. Observations: I observed how much water has gone up into the tube in each trial, and recorded the amount of water (mL) in the data table below. Left thistle tube is placed in a solution of 10% corn syrup concentration, middle 20%, and right 30%. Analysis: The 10% corn syrup had the least amount of water (3 mL) drawn up into the thistle tube whereas the 30% had the highest amount (12 mL). 20% had 7 mL of water in the thistle tube. Conclusion: Osmotic pressure is influenced by changes in nonpermeable solute concentration, where higher nonpermeable solute concentration increases the amount of water that will cross the membrane. Therefore, more water is drawn up into the thistle tube with higher concentrations of corn syrup. The more concentrated the water is with the corn syrup, the more water will diffuse into the corn syrup solution in order to reach equilibrium between the concentrations- inside and out of the selectively permeable membrane. That is why there was the most visible action of osmosis in the 30% thistle tube to balance out the concentrations.