Question

Phosphoglyceric acid (PGA) is formed when carbon dioxide is fixed onto the 5C compound:

• A. adenosine monophosphate
• B. nicotinamide adenine dinucleotide phosphate
• C. ribulose bisphosphate
• D. adenosine triphosphate

Answer 1

The correct option is C ribulose bisphosphate

The Calvin cycle reactions can be divided into three main stages: carbon fixation, reduction, and regeneration of the starting molecule.
During carbon fixation. A carbon dioxide molecule combines with a five-carbon acceptor molecule, ribulose-1,5-bisphosphate (RuBP). This step makes a six-carbon compound that splits into two molecules of a three-carbon compound, 3-phosphoglyceric acid (3-PGA). This reaction is catalyzed by the enzyme RuBP carboxylase/oxygenase, or rubisco.