Answer :
Final answer:
RuBisCO substrates include CO2, O2, and RuBP. RuBisCO functions as a carboxylase when catalyzing the reaction with CO2 and as an oxygenase with O2 during photorespiration. Therefore, the correct answer is c. CO2, O2 and RuBP.
Explanation:
The substrates of the enzyme ribulose-1,5-bisphosphate carboxylase/oxygenase, commonly referred to as RuBisCO, are CO2 (carbon dioxide), O2 (oxygen), and RuBP (ribulose bisphosphate). RuBisCO catalyzes the first major step of carbon fixation in the Calvin cycle, which is the addition of CO2 to RuBP, leading to the formation of two molecules of 3-phosphoglycerate (3PG). However, RuBisCO also binds to O2 in a process known as photorespiration, which rather produces 2-phosphoglycolate and 3PG.
This makes RuBisCO both a carboxylase and an oxygenase because it can catalyze two different types of reactions depending on whether the substrate is CO2 or O2. Hence, the answer to the question 'Which of the following is/are rubisco substrates?' would be c. CO2, O2 and RuBP, as all are substrates that engage with RuBisCO during photosynthesis.