AP BIOLOGY

Detailed explanation-1: -CO2 binds to RuBP in the key process called carbon fixation, forming two-three carbon molecules of phosphoglycerate. The enzyme that carries out this reaction is ribulose bisphosphate carboxylase/oxygenase, which is very large with a four-subunit and present in the chloroplast stroma.

Detailed explanation-2: -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-3: -Figure 5.15 The Calvin cycle has three stages. In stage 1, the enzyme RuBisCO incorporates carbon dioxide into an organic molecule. In stage 2, the organic molecule is reduced. In stage 3, RuBP, the molecule that starts the cycle, is regenerated so that the cycle can continue.

Detailed explanation-4: -The Calvin cycle has two parts. First carbon dioxide is ‘’fixed”. Then ATP and NADPH from the light reactions provide energy to combine the fixed carbons to make sugar.

Detailed explanation-5: -RuBP (ribulose 1, 5-biphosphate) is a five-carbon sugar which reacts with CO2 in the first step of the Calvin cycle for fixing carbon in photosynthetic systems. That reaction is catalyzed by the large enzyme rubisco .