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B2.1.2—Lipid bilayers as barriers


Here are experiments our science specialists have selected to support this IB* topic.

Chemistry of Membranes

Experiment #4 from Investigating Biology through Inquiry

In the Preliminary Activity, you will use a spectrophotometer to measure color changes due to the release of betacyanin caused by the damage to beet cell membranes by a 30% 2‑propanol solution. Isopropyl alcohol is another name for 2‑propanol.

After completing the Preliminary Activity, you will first use reference sources to find out more about biological membranes before you choose and investigate a researchable question. Some topics to consider in your reference search are:

  • biological membranes
  • vacuole
  • tonoplast
  • betacyanin
  • lipids
  • lipid solubility
  • 2‑propanol
  • alcohols

The Effect of Alcohol on Biological Membranes

Experiment #8 from Biology with Vernier

In this experiment, you will

  • Use a Colorimeter to measure the color intensity of beet pigment in alcohol solutions.
  • Test the effect of three different alcohols on membranes.
  • Test the effect of different alcohol concentrations on membranes.

Educational Standard
International Baccalaureate (IB) 2025
B Form and function
Level of organization
2 Cells
B2.1 Membranes and membrane transport
Standard level and higher level

* The IB Diploma Program is an official program of the International Baccalaureate Organization (IBO) which authorizes schools to offer it. The material available here has been developed independently of the IBO and is not endorsed by it.