Beetroot cells are coloured red because they contain a red dye called anthocyanin

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Beetroot Experiment

Beetroot cells are coloured red because they contain a red dye called anthocyanin. In beetroot cells there red anthocyanin pigment occurs in the vacuoles. A membrane called the tonoplast surrounds each vacuole. The cytoplasm and vacuole is surrounded by the plasma membrane.

The function of a cell membrane is to control the movement of material into and out of the cell. The tonoplast does the same job for the vacuole.

The two main components of any membrane are proteins and fats. The anthocyanin can only be released and leak out of the cell if the membrane are broken or damaged. The anthocyanin diffuses out of cells.

Diffusion – gases move about at random and will move about at random and will move from where they are in high concentration to where they are in lower concentration.

Temperature has an affect on membranes. If the temperature is too hot the membrane changes shape, and makes holes it is damaged and the anthocyanin leaks out, the more damage the more leakage. If the temperature is too hot it denatures the proteins and enzymes.

The higher the temperature the more kinetic energy, the energy is given to the atoms and they begin to vibrate. They vibrate faster and faster and bang off each other, causing the structure to break. This allows the anthocyanin to leak out.

I predict that the higher the temperature the more damage done to the beetroot membranes. Therefore more anthocyanin will diffuse out of the beetroot cells therefore less transmission of light.

Factors we are planning to keep constant are:

  • Surface area of beetroot by using cork borer, measuring the diameter and length and keeping them the same.
  • Time spent in water bath. 1minute timed using stop watch.
  • Time spent in test-tube of distilled water. 20minutes timed using stop watch.
  • Volume of distilled water. 10mm measured using cylinder.
  • Use same colorimeter each time.
  • Use same filter in colorimeter.
  • Calibrated using same blank.
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Factors that will change:

  • Temperature. Range, 30, 40, 50, 60, 70, 80 ْْ
  • This gives a good range of temperatures for me to plot my graph from.
  • Repeat each temperature 3 times to increase reliability of results. Allow I would have liked to do more to make my results more reliable.
  • As we had limited and equipment we will use results from other members of the class to increase the reliability of the results.

I will measure the percentage transmission of light using a colorimeter.

Distilled water gives 100% transmission of light, the more dye there ...

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