Question

In $C_3$ plants, the first stable product formed during the dark reaction is

• A. Phosphoglyceraldehyde.
• B. Malic acid.
• C. Oxaloacetic acid.
• D. 3-phosphoglyceric acid.

Answer 1

The correct option is D 3-phosphoglyceric acid.

The dark reaction of $C_3$ plants is also called as Calvin cycle, which occurs in three stages-
1. Carboxylation- In this step ribulose 1,5 bis phosphate (RUBP) is carboxylated to generate 3-phosphoglyceric acid (PGA). 3-PGA is the first stable product of dark reaction.
2. Reduction- The 3PGA is reduced to phosphoglyceraldehyde.
3. Regeneration- In this step RUBP used up in first step is regenerated using phosphoglyceraldehyde.