Question

Ribulose-1-5-biphosphate carboxylase (Rubisco) "fixes" carbon dioxide into biomass in the vast majority of photosynthetic organisms on Earth. We can tell that it evolved before Earth was oxygenated because it is poorly suited to an oxygenated atmosphere.

A) What is one property of Rubisco that demonstrates that it is so poorly suited to an oxygenated atmosphere?

B) Why do organisms in the ocean use carbon concentration mechanisms when they use Rubisco?

Answer 1

Ans a) When oxygen and carbon molecule compete to bind to rubisco's active site , the oxygen binding , giving oxygenase reactions then decreases the carbon fixing efficiency by 50%

Ans b) phytoplanktons and few eukaryotic organisms in ocean environment are believed to be limited to diffusion of CO2 so they use certain mechanisms called as CCM (carbon concentration mechanism )