Question

The first stable compound formed during the photosynthesis of $C_3$ plants is

• A. Phosphoglyceric acid.
• B. Starch.
• C. Pyruvic acid.
• D. Ribulose diphosphate.

Answer 1

The correct option is A Phosphoglyceric acid.

The $C_3$ plants are called so because the first stable product of photosynthesis in these plants is a three carbon atom containing compound 3- phosphoglyceric acid (3 PGA). This compound is produced by carbon dioxide fixation reaction catalyzed by ribulose 1, 5 bisphosphate carboxylase/ oxygenase (RUBISCO) enzyme, which carboxylates one molecule of five carbon atom containing compound ribulose 1, 5 bisphosphate (RUBP) into two molecules of three carbon atom containing compound 3 PGA.