It is believed that the ratio of cyclic photophosphorylation to Z-scheme photosynthesis changes in response to metabolic demands.How would this ratio in chloroplasts performing the following reaction compare to that in chloroplasts performing only the Calvin cycle? Calvin cycle + reduction of nitrite (NO₂^-)to NH₃ A)The ratio of cyclic photophosphotylation to Z-scheme is increased in chloroplasts performing the above reaction compared to those performing only the Calvin cycle B)The ratio of cyclic photophosphotylation to Z-scheme is decreased in chloroplasts performing the above reaction compared to those performing only the Calvin cycle C)The ratio of cyclic photophosphotylation to Z-scheme is depends primarily on the level of light available and would therefore not be altered by the above reaction D)The ratio of cyclic photophosphotylation to Z-scheme is depends primarily on the availability of plastocyanin and would therefore not be altered by the above reaction E)none of the above

Question

Quizplus · Accepted Answer

The reduction of nitrite in the above reaction requires electrons, which in turn could lead to a decrease in the availability of plastocyanin, a crucial electron carrier in the Z-scheme photosynthesis. This decrease in plastocyanin availability would lead to a decrease in the efficiency of the Z-scheme, and thus a decrease in the ratio of cyclic photophosphorylation to Z-scheme in chloroplasts performing the above reaction compared to those performing only the Calvin cycle.

It Is Believed That the Ratio of Cyclic Photophosphorylation to Z-Scheme