High School

Which best represents an example of carbon fixation?

1) The conversion of 1,3-BPG into G3P.
2) The reduction of carbohydrates by NADPH.
3) The incorporation of CO₂ into organic molecules.
4) The oxidation of NADPH to form NADP.
5) The regeneration of RuBP.

Answer :

Final answer:

Carbon fixation is the conversion of inorganic carbon dioxide into organic compounds, which in the Calvin cycle of photosynthesis involves the enzyme RuBisCO converting CO2 to 3-PGA.

Explanation:

Carbon fixation refers to the process of converting inorganic carbon dioxide (CO2) into organic compounds within living organisms. The best example of carbon fixation is the incorporation of CO2 into organic molecules, as it is the initial step where CO2 is taken from the air and fixed into a stable organic compound. In the Calvin cycle of photosynthesis, this happens when CO2 is fixed by the enzyme RuBisCO to form 3-phosphoglycerate (3-PGA), which is then used to produce glyceraldehyde-3-phosphate (G3P) and eventually glucose.

Therefore, statement 3 accurately represents carbon fixation, as it is the direct conversion of CO2 into an organic compound through the Calvin cycle in plants.