Question

Carbon dioxide fixation is associated with _________.

• A. Kreb's cycle
• B. Glycolysis
• C. Calvin cycle
• D. Photorespiration

Answer 1

The correct option is C Calvin cycle

• Carbon dioxide ($C{O}_2$) fixation is the process of conversion of inorganic carbon dioxide into organic compounds.
• Krebs's cycle or citric acid cycle takes place to generate electron carriers which are used in the last step of cellular respiration.
• Glycolysis is a common pathway both in aerobic and anaerobic respiration, by which glucose converts into pyruvic acid.

• In Calvin cycle, there are three major phases that are carboxylation (carbon fixation), reduction and regeneration of RuBP.
• During carboxylation, $RuBP$ + $C{O}_2$ $\to$ $2$$\times$$(3-Phosphoglycericacid)$ carbon fixation takes place.

• Photorespiration or $C_2$ cycle takes place when there is a high concentration of oxygen molecules. It is a total wasteful process.

Hence, the correct answer is option C, i.e., Calvin cycle.