Calvin discovered the ‘Calvin cycle’ by choosing a suitable organism to work with a single-celled alga called Cklorella, devising a claver piece of apparatus and by applying two carefully chosen techniques.
(i) The first technique he used was to track the path of carbon during photosynthesis by using a radioactive isotope, 14 C.
(ii) The second technique was two-dimensional paper chromatography. By this technique, the separated the substances, which the had extracted from the cells.
At the end, he was able to describe the sequence of compounds through which the carbon passed as it was converted from carbon dioxide to carbohydrate. He discovered that it was in fact a cycle of reactions, hence the name ‘Calvin cycle’.