Find out how Melvin Calvin worked out the complete biosynthetic pathway for synthesis of sugar.

Explanation

Melvin Calvin used Chlorella as an experimental material and discovered the first stbale compound of phtosynthesis, i.e., 3- phosphyglyceric acid so as to trace the path of carbon by using a radioctive isotope of carbon `(C^(14))` and autoradiography technique.
He then, compared the radioactive compounds on the chromatogram as a result of which he found and concluded that the PGA (phosphoglyceric acid), as the first stable product of photosynthesis and gradually the other sugars including hexoses, teteoses and pentose etc.
Thus, he derive the pathway of `CO_(2)` fixation from these readioactive products (sugars) formed.