What is the net outcome of the photorespiratory pathway in C_3...

In the photorespiratory pathway, RuBisCO binds with $O_2$ instead of $CO_2$, forming one molecule of phosphoglycerate and phosphoglycolate.

During this process, there is neither synthesis of sugars nor of ATP. Rather, it results in the release of $CO_2$ with the utilisation of ATP.

Therefore, the net outcome of photorespiration is the release of $CO_2$ and the consumption of ATP, making it a wasteful process.

Answer: Release of $\mathrm{CO}_2$ with the utilization of ATP