The Calvin Cycle is Essentially

Question

The Calvin cycle is essentially
A) started by the oxygen capture by Rubisco.
B) a reductive pentose phosphate cycle.
C) the reductive, or reverse, tricarboxylic acid cycle.
D) a pathway to synthesize fatty acids but not sugars.
E) a pathway that is used only when light is present.

Accepted Answer

The Calvin cycle is a reductive pentose phosphate cycle that occurs in the chloroplasts of photosynthetic organisms. It is responsible for the fixation of carbon dioxide into glucose and other sugars. The cycle is initiated by the capture of carbon dioxide by the enzyme Rubisco. This process occurs in the stroma of chloroplasts and doesn't require light to occur. Therefore, option E is incorrect. The Calvin cycle doesn't synthesize fatty acids but synthesize sugars, so option D is also incorrect. The reverse tricarboxylic acid cycle is involved in carbon fixation in bacteria, but not in plants. Hence, option C is also incorrect.