Question

During Calvin cycle the total number of $C{O_2}$, ATP and NADPH molecules utilised and glucose, ADP and NADP molecules generated is
A. 31
B. 36
C. 61
D. 67

Answer 1

Hint:- The Calvin cycle creates three carbon sugars which are used to generate glucose and starch. The Calvin cycle is a dark cycle and occurs in the absence of light. The different stages of the Calvin cycle include carbon fixation, reduction and regeneration.

Complete answer:
Calvin cycle occurs in plants in the absence of light. Calvin cycle occurs in three steps- fixation, reduction and regeneration. To start the cycle, energy resources are required. These energy resources are met by ATP and NADPH present in the plant cells which are derived from the sun’s energy. Calvin cycle uses these energy molecules to convert three molecules of carbon dioxide to one molecule of the three-carbon sugar.
In the Calvin cycle, three molecules of carbon dioxide and water are converted into one molecule of glyceraldehyde. During this process, six atoms of oxygen are formed which are released into the atmosphere for the organism to use for respiration. In the first stage of the cycle, fixation of carbon dioxide occurs, as it is converted from an inorganic molecule to an organic molecule. This stage also witnesses the initiation of light independent reactions. In the second stage of the cycle, reduction occurs. ATP and NADPH are used to reduce 3-PGA into G-3-P, and the conversion of ATP and NADPH to ADP and $NAD{P^ + }$occurs.
The last stage of the cycle is the regeneration stage where RuBP is regenerated so that more carbon dioxide molecules can be fixed in the plants. In this cycle, 6 molecules of carbon dioxide, 18 molecules of ATP and 12 molecules of NADPH are utilized and the generation of one molecule of glucose, 18 molecules of ADP and 12 molecules of NADP takes place. This results in a total 67 molecules.

So, the correct answer is Option D.

Note:- The Calvin cycle occurs in the absence of sunlight and presence of carbon dioxide, which is present during the night time. The plant takes in carbon dioxide through the stomata of the cells. The products formed during this cycle are then used up in the light reaction.