Which sugar is generated through the Calvin cycle?
a. Glucose
b. Fructose
c. G3P
d. ATP
e. The Calvin cycle does not generate sugars
The correct answer and explanation is:
The correct answer is c. G3P (Glyceraldehyde-3-phosphate).
The Calvin cycle, also known as the Calvin-Benson cycle, is part of the photosynthesis process in plants. It occurs in the stroma of the chloroplasts and is responsible for fixing carbon dioxide into organic molecules. The main product of the Calvin cycle is G3P, a three-carbon sugar, which plays a crucial role in the synthesis of glucose and other carbohydrates.
During the cycle, carbon dioxide is fixed by an enzyme called RuBisCO and is combined with a five-carbon sugar called ribulose bisphosphate (RuBP). This results in an unstable six-carbon compound, which immediately splits into two molecules of 3-phosphoglycerate (3-PGA). Through a series of reactions, ATP and NADPH, produced during the light-dependent reactions of photosynthesis, are used to convert 3-PGA into G3P. For every three molecules of carbon dioxide that enter the cycle, six molecules of G3P are produced. However, only one G3P molecule exits the cycle to be used in the synthesis of glucose or other carbohydrates.
G3P is vital because it serves as the precursor to glucose and other sugars. It can be combined to form fructose-6-phosphate, which is then used to produce glucose. However, ATP and fructose are not directly generated by the Calvin cycle itself; they either serve as energy sources or intermediates in the process.
In summary, the Calvin cycle does not directly produce glucose or fructose, but it generates G3P, which is the building block for glucose synthesis and other carbohydrates.