Multiple choice Which enzyme is associated with the calvin cycle? Rubisco Oxygenase Carboxylase None of the above Reveal answer Fill a bubble to check yourself A Correct answer Explanation Rubisco (ribulose-1,5-bisphosphate carboxylase-oxygenase) is the key enzyme responsible for the first major step of carbon fixation in the Calvin cycle, where it attaches carbon dioxide to RuBP.