Describe the effects of an increase in oxygen pressure on the dark reactions of photosynthesis.

Thelight-dependent reaction and the light-independent reaction are two types of reactions that convert light energy to chemical energy. Calvin's cycle, also known as the CBB (Calvin-BensonBassham) cycle, is a series of processes that take place in the stroma of the chloroplast. It is also known as the dark reaction because it is a light-independent reaction.

The ambient carbon dioxide is fixed with Ribulose 1,5-bisphosphate to form two three-carbon molecules in Calvin's cycle. To make another sugar, one of the three-carbon compounds is reduced. RuBisCo catalyzes a reaction between carbon dioxide and Ribulose 1,5 -bisphosphate (RuBP), forming a six-carbon compound that is then instantly converted into two three-carbon compounds and 3-phosphoglyceric acid in the first step of Calvin's cycle (3-PGA). Carbon fixation is the name for this process.

That’s why when the oxygenase activity of RuBP carboxylase-oxygenase increases, the efficiency of fixation may decrease.