The diagram represents part of a plant cell identify the location in the plant cell where carbon dioxide fixation occurs

The location in the plant cell where carbon dioxide fixation occurs is the STROMA.

In the stroma are thylakoids stacked in grana where photosynthesis sits.In plants, algae, and cyanobacteria, carbohydrates are produced by a series of independent light reactions called the Calvin cycle, by fixing the carbon dioxide.
 The assimilation of CO2 is done in four main steps, the first three of which take place within the Calvin cycle:*CO2 fixation (carboxylation).*Carbon reduction fixed.*Regeneration of the CO2 acceptor.*Synthesis of sugars.