AP BIOLOGY

Detailed explanation-1: -A CO2start text, C, O, end text, start subscript, 2, end subscript molecule combines with a five-carbon acceptor molecule, ribulose-1, 5-bisphosphate (RuBP). This step makes a six-carbon compound that splits into two molecules of a three-carbon compound, 3-phosphoglyceric acid (3-PGA).

Detailed explanation-2: -In the Calvin cycle, carbon dioxide (CO2) molecules are fixed to sugar with the help of an enzyme called RuBisCO. RuBisCO is short for ribulose-1, 5-biphosphate carboxylase/oxygenase.

Detailed explanation-3: -RuBP stands for ribulose bisphosphate, it’s a 5 carbon compound involved in the Calvin cycle, which is part of the light-independent reactions of photosynthesis. Atmospheric CO2 is combined with RuBP to form a 6 carbon compound, with the help of an enzyme (biological catalyst) called RuBisCo.

Detailed explanation-4: -ATP is also used in the regeneration of RuBP. Figure 5.15 The Calvin cycle has three stages. In stage 1, the enzyme RuBisCO incorporates carbon dioxide into an organic molecule.

Detailed explanation-5: -Stage 1: Fixation RuBP has five atoms of carbon, flanked by two phosphates. RuBisCO catalyzes a reaction between CO2 and RuBP. For each CO2 molecule that reacts with one RuBP, two molecules of 3-phosphoglyceric acid (3-PGA) form. 3-PGA has three carbons and one phosphate.