The radio labelled carbon in carbon dioxide supplied to potato plants in an experiment was seen in the tuber eventually. Trace the movement of the labelled carbon dioxide.

 |f a radio labelled carbon C™ in is supplied to patato plants while it’s carrying out photosynthesis in the presenceoflight, the CO2 will be fixed and form radioactive products of photosynthesis, i.e., glucose C614H1206.
This radioacative glucose is converted to sucrose which would again be radioactive due to transfer of C14 from previous sugar molecule. These sucrose molecules then move into pholem and transported to other parts of plant. 
Autoradiography technique detects the radioactive carbon (present in sugars) and traces the components and movement in the plant, i.e., through sieve tube channels of phloem from leaves (sources) to different parts (sink).