Imagine that a time traveler was able to successfully travel 2 billion years back in time and modified the environment so that photosynthesis and respiration were completely coupled (i.e., there was no "leakage" of products from respiration or photosynthesis). How would this affect Earth's present-day atmosphere, if at all?

Question

Quizplus · Accepted Answer

If photosynthesis and respiration were completely coupled, there would be no release of oxygen during photosynthesis or uptake of oxygen during respiration. This would result in a decreased atmospheric oxygen concentration over time. Carbon dioxide levels would also decrease as it would all be used up during the coupled process. However, the amount of carbon dioxide decrease would likely be offset by other geological processes so it is not likely to have a significant impact on the atmosphere.

Imagine That a Time Traveler Was Able to Successfully Travel