Question

How are the larger numbers of ATP and NADPH molecules used during the Calvin cycle consistent with the high value of glucose as an energy source?

Short answer

Glucose is the highly reduced form that is produced from the calvin cycle. It requires the consumption of larger numbers of ATP and NADPH molecules during this process.

Step-by-step solution

Description of the Calvin cycle

Calvin cycle is a similar mechanism to the citric acid cycle. The starting material that is involved in the reaction gets regenerated at the end of the reaction. Carbon fixation, reduction, and regeneration of RuBP are the steps involved in the Calvin cycle.

Description of steps involved in the Calvin cycle 

The carbon fixation step is in which the carbon dioxide gets converted to 3 phosphoglycerates. In the reduction phase, the 3-phosphoglycerate is converted into 1, 3 bisphosphoglycerate, which uses energy from ATP.

Electrons from NADPH are also utilized in this phase. In this step, glyceraldehydes-3-phosphates are formed from 1, 3 bisphosphoglycerate. Glucose and other carbohydrate molecules are synthesized from these molecules

Synthesis of glucose

The potential energy and reducing powers are required for the formation of a particular molecule. Here, the particular molecule is glucose. The glucose is formed by the reduction of a larger number of C-H bonds. These glucose molecules store the potential energy in its electron.

In the Calvin cycle, the glucose molecules are synthesized from the carbon dioxide, in which the carbon dioxide has to undergo a reduction reaction. This reduction process requires a larger amount of energy supplied by the ATP and NADPH molecules involved in the Calvin cycle.

Hence, ATP and NADPH are large molecules required to produce a huge amount of energy for the formation of glucose.