Question

Carbon fixation occurs in the second stage of photosynthesis, during the light-independent reactions of the Calvin cycle. In the first step of this cycle, the enzyme Rubisco adds CO2 to the energy-rich compound ribulose 1,5-bisphosphate, ultimately producing two molecules of 3-phosphoglycerate. In a culture of green alga that is carrying out photosynthesis in the presence of CO2 in the laboratory, what would happen to the levels of ribulose 1,5-bisphosphate and 3-phosphoglycerate in the minutes after the lights were turned off and the cultures were plunged into darkness

Answer 1

Ribulose 1,5-biphosphate will be depleted while 3-phosphoglycerate will accumulate.

Carbon fixation

The first step of the carbon fixation during which Rubisco adds CO2 to Ribulose 1,5-biphosphate to produce 2 molecules of 3-phosphoglycerate requires energy molecules from the light reaction.

In the subsequent steps, Ribulose 1,5-biphosphate is regenerated in a step that requires energy molecules from the light reaction.

Thus, in the first few minutes of turning off the light, the available energy molecule from the light reaction will be used up to produce 3-phosphoglycerate. However, the regeneration of Ribulose 1,5-biphosphate will become impossible.

More on carbon fixation can be found here: https://brainly.com/question/1219446

#SPJ12