Effect of temperature on the permeability of the plasma-membrane


  • Small equal sized pieces of beet root tissue are cut with the help of a cork-borer and thoroughly washed with distilled water.
  • Each of these pieces is placed in a separate test tube containing water at different temperature e.g., 0°C, 10°C, 20°C, 30°C, 40°C, 60°C, 70°C, and 80°C.
  • The experiment is kept for an hour or so and colouration of the water is observed.
  • KAfter sometime it is observed that the water in those test tubes which were kept at lower temperature, room temp, or slightly higher temp remain colourless while the water in test tubes kept at higher temperatures (e.g. 600, 700 and 800 C) becomes red coloured.
  • Add two drops of safranin stain in the watch glass to stain the peel.
  • The low temperature water remains colourless and the intensity of red colour increases with the increase in temperature.
  • The red colour is due to the diffusion of the anthocyanin pigments from the cell sap into the water.
  • The higher temperature kills the cell due to which semi permeable nature of cell membrane is lost and the membrane becomes permeable.