Biology Beetroot Practical.

The investigation into the effect of temperature on cell membrane permeability in beetroot cells.

- Beetroot contain betalin pigments which give the tissue a dark red colour. This pigment is contained in the cell vacuole (membrane bound organelle containing water and enzymes). If the membrane becomes damaged- the pigment can leak out of the cells by diffusion therefore the amount of betalin leaking out can be seen as an indicator of damage to the cell membrane.

Independant Variable: Temperature at which the beetroot discs were incubated.
Dependant Variable: Percentage of absorbance at 520 nm of the beetroot pigment solution.

The relationship between the amount of pigment released and the temperature.

- The higher the temperatre, the greater the amount of pigment released from the tissues.
This is because increasing temperature gives the phospoholipid molecules more kinetic energy so they move faster. They move much more than previously, distrupting the cell surface membrane and membrane of the vacuole, leaving temporary gaps in the membrane through which the pigment molecules pass, making the membranes leaky. The protein molecules too vibrate more as the temperature increases, this may lead to them coming apart and losing their shapes therefore leaving gaps in the cell membrane and increasing the permeability of the cell membrane.

Also, increasing temperature increases the rate of diffusion as the betalin molecules are given more kinetic energy to try to leave the membrane…