what are the rolse of RuBP and Rubisco in the production of sugars?

Answer 1

Rubisco binds RuBP and carbon dioxide and links the two together. The products of this reaction are 2 3-carbon sugars. Those can eventually be converted into glucose and made into all carbon compounds in the plant.

Rubisco is responsible for "fixing" carbon. That is, it is the enzyme that converts carbon dioxide into an organic compound. Every carbon atom in your body was at some point the carbon in a molecule of CO2 that was fixed by some plant somewhere...