Which process is catalyzed by rubisco during the light-independent reactions of photosynthesis?

Rubisco is an enzyme that is active in the first phase of the calvin cycle. this phase is the carboxylation phase where rubisco catalyzes the attachment of a carbon dioxide molecule to a sugar called ribulose to from a 6-carbon intermediate. this intermediate then disintegrates almost immediately because it is very unstable and forms two identical 3-carbon molecules known as 3 phosphoglycerate molecules or 3pga. 3pga goes on into the second phase of the calvin cycle called the reduction phase.