Question

The first stable compound of the Calvin cycle is

• A. 3 C compound called 1,3-Biphosphoglycerate
• B. 3 C compound called 3-Phosphoglycerate
• C. 3 C compound called 3-Phosphoglyceraldeyde
• D. 3 C compound called pyruvate

Answer 1

Answer: (B)

The first step of the Calvin Cycle is when RuBP combines with $C{O}_2$ to form a 6 carbon unstable compound in the presence of enzyme RubisCO. This 6 carbon compound spontaneously forms two molecules of 3C compound called phosphoglyceric acid, which is the first stable compound of the Calvin cycle. Hence, it is also called $C_3$ cycle.