Tracer experiments

• Tracers:

  Tracing involves radioactively labelling carbon

  • Plants are provided with only radioactively labelled carbon dioxide and over time this is absorbed into the plant and used in photosynthesis to create sugars which all contain radioactively labelled carbon
• Tracers:

  • Once radioactively labelled carbon has been used in photosynthesis to create sugars which all contain radioactively labelled carbon:
  • Thin slices from the stems are then cut and placed on x-ray film that turns black when exposed to radioactive material
• Tracers:

  • When the stems are placed on the x-ray film the section of the stem containing the sugars turn black
  • This highlights where the phloem are and shows sugars are transported in the phloem
• Tracers: Tracing relies on autoradiography

  • The plant needs to be killed either freezing with liquid nitrogen or drying at 100 degrees
  • This ensures all water is evaporated but the plant does not burn
• Tracing experiments:

  • Relies on the substance taking up radioactively labelled carbon
  • This would then be used by the plant in photosynthesis to produce sugars which can then be tracked around the plant as they are translocated