Question

"The first event in the Calvin cycle is the attachment of carbon dioxide to the five-carbon RuBP molecule, which: is a reaction assisted by large quantities of RuBP carboxylase enzyme.

A True
B False"

Answer 1

The statement is true, as RuBisCO catalyzes the attachment of CO₂ to RuBP, initiating the fixation stage of the Calvin cycle, which eventually leads to the synthesis of glucose.

Step-by-step explanation:

The statement, “The first event in the Calvin cycle is the attachment of carbon dioxide to the five-carbon RuBP molecule, which is a reaction assisted by large quantities of RuBP carboxylase enzyme,” is True. The enzyme responsible for this reaction is called ribulose-1,5-bisphosphate carboxylase/oxygenase (RuBisCO). This attachment is known as carbon fixation, which is the first of three stages in the Calvin cycle: fixation, reduction, and regeneration. During the fixation stage, CO₂ combines with RuBP to form a six-carbon intermediate, which immediately splits to form two three-carbon molecules, namely 3-phosphoglycerate (3-PGA).

The efficiency of carbon fixation by RuBisCO is crucial as it sets the stage for the production of glucose and other carbohydrates essential for the plant's energy needs and growth.