Question

In the Calvin—Benson or C3 photosynthetic pathway, the enzyme rubisco catalyzes the reaction called

A) chemosynthesis.
B) carboxylation.
C) photoreduction.
D) respiration.

Answer 1

In the Calvin-Benson or C3 pathway, the enzyme rubisco catalyzes carboxylation, which is the first fixation stage of the Calvin cycle, leading to the synthesis of carbohydrates in plants.

Step-by-step explanation:

In the Calvin—Benson or C3 photosynthetic pathway, the enzyme rubisco catalyzes the reaction called carboxylation. This reaction occurs during the first stage of the Calvin cycle, known as fixation, where rubisco adds CO₂ to ribulose bisphosphate (RuBP), forming an unstable 6-carbon intermediate that immediately splits into two 3-carbon molecules of 3-phosphoglycerate (3-PGA). The Calvin cycle consists of three stages: fixation, reduction, and regeneration, and is essential for the synthesis of carbohydrates in plants.