The ans op B 2 carboxylation coz sorghum and maize are c4 plants and in c4 2 carboxylation takes place

Number of Carboxylation Reactions in Photosynthesis in Plants like Sorghum and Maize

There are two carboxylation reactions that occur during the process of photosynthesis in plants like Sorghum and Maize. These reactions are essential for the fixation of carbon dioxide (CO2) into organic molecules.

1. Primary Carboxylation Reaction:
The primary carboxylation reaction is the first step in the process of photosynthesis. It involves the fixation of CO2 into a 5-carbon molecule called ribulose-1,5-bisphosphate (RuBP). This reaction is catalyzed by the enzyme known as ribulose-1,5-bisphosphate carboxylase/oxygenase (Rubisco). Rubisco adds one molecule of CO2 to one molecule of RuBP, resulting in the formation of two molecules of 3-phosphoglycerate (3-PGA).

2. Secondary Carboxylation Reaction:
The secondary carboxylation reaction is a series of enzymatic steps that occur in the Calvin cycle, which is the second phase of photosynthesis. In this reaction, the two molecules of 3-PGA produced during the primary carboxylation reaction are further converted into glyceraldehyde-3-phosphate (G3P) molecules. This conversion requires the input of ATP (adenosine triphosphate) and NADPH (nicotinamide adenine dinucleotide phosphate) produced during the light-dependent reactions of photosynthesis.

Explanation:
- The primary carboxylation reaction is the initial step in photosynthesis, where CO2 is fixed into an organic molecule.
- This reaction occurs in the stroma of the chloroplasts, where Rubisco is localized.
- Rubisco is the most abundant enzyme on Earth and plays a crucial role in carbon fixation.
- The secondary carboxylation reaction takes place in the stroma as well, specifically during the Calvin cycle.
- The Calvin cycle is a series of enzymatic reactions that occur after the primary carboxylation reaction.
- During the Calvin cycle, ATP and NADPH produced during the light-dependent reactions are utilized to convert 3-PGA into G3P.
- G3P is a key intermediate in the production of glucose and other organic molecules.
- The overall purpose of these carboxylation reactions is to convert CO2 into organic compounds that can be used by the plant for growth, energy production, and other metabolic processes.

In conclusion, the number of carboxylation reactions in photosynthesis in plants like Sorghum and Maize is two. The primary carboxylation reaction fixes CO2 into RuBP, while the secondary carboxylation reaction converts 3-PGA into G3P during the Calvin cycle. These reactions are vital for the production of organic molecules and energy in plants.