What did studies unexpectedly show about the acceptor molecule in the 'dark reaction'?

Step-by-step solution

Let us now ask ourselves a question that was asked by the scientists who were struggling to understand the ‘dark reaction’. How many carbon atoms would a molecule have which after accepting (fixing) CO2 , would have 3 carbons (of PGA)? The studies very unexpectedly showed that the acceptor molecule was a 5-carbon ketose sugar – ribulose bisphosphate (RuBP) . The scientists took a long time and conducted many experiments to reach this conclusion. They also believed that since the first product was a C3 acid, the pri