Multiple choice The main steps of photophosphorylation were discovered by: Arnon Blackman Hill Calvin Reveal answer Fill a bubble to check yourself A Correct answer Explanation Daniel I. Arnon discovered the main steps of photophosphorylation, including cyclic and non-cyclic photophosphorylation, in chloroplasts. Calvin worked out the carbon fixation pathway, and Blackman studied limiting factors in photosynthesis.