Question

How many major types of cells are involved in the CO2 fixation process in C3 plant

Answer 1

C3 carbon fixation is the most common of three metabolic pathways for carbon fixation in photosynthesis, along with C4 and CAM. This process converts carbon dioxide and ribulose bisphosphate (RuBP, a 5-carbon sugar) into two molecules of 3-phosphoglycerate through the following reaction:

CO2 + H2O + RuBP → (2) 3-phosphoglycerate

This reaction occurs in all plants as the first step of the Calvin–Benson cycle. (In C4 and CAM plants, carbon dioxide is drawn out of malate and into this reaction rather than directly from the air.)

Answer 2

Answer:

   Photorespiration is a wasteful pathway that occurs when the Calvin cycle enzyme rubisco acts on oxygen rather than carbon dioxide.

   The majority of plants are C3\text C_3C3​start text, C, end text, start subscript, 3, end subscript plants, which have no special features to combat photorespiration.

   C4\text C_4C4​start text, C, end text, start subscript, 4, end subscript plants minimize photorespiration by separating initial CO2\text {CO}_2CO2​start text, C, O, end text, start subscript, 2, end subscript fixation and the Calvin cycle in space, performing these steps in different cell types.

   Crassulacean acid metabolism (CAM) plants minimize photorespiration and save water by separating these steps in time, between night and day.

Explanation: