Question

The first stable product of CO₂ fixation in sorghum is

• A. Pyruvic acid
• B. Succinic acid
• C. Oxaloacetic acid
• D. Phosphoglyceric acid

Answer 1

The correct option is C

Oxaloacetic acid

The correct option is C.

The explanation for the correct option:

1. The first stable product formed in Sorghum which is a C₄ plant is Oxaloacetic corrosive.
2. A membrane-bound enzyme complex called oxaloacetate decarboxylase catalyzes the biotin-dependent pyruvate formation process along with the extrusion of a sodium ion across the cytoplasmic membrane.
3. This results in the accumulation of a sodium gradient that can be used by a sodium-dependent ATP synthase to produce ATP.

The explanation for the incorrect options:

Option A:

1. Pyruvic acid is a 2-oxo monocarboxylic acid.
2. It is formed during the process of glycolysis.
3. It acts as a substrate and a cofactor.

Option B:

1. Succinic acid is an alpha, omega-dicarboxylic acid formed in the middle of the citrus cycle.

Option D:

1. 3-Phosphoglyceric corrosive (3PG, 3-PGA, or PGA) is the form of 3-phosphoglycerate or glycerate 3-phosphate (GP or G3P).
2. This acts as a substrate in glycolysis and the Calvin cycle.

Final answer: The first stable product of CO₂ fixation in sorghum is oxaloacetic acid.