Roughly what proportion of the energy contained in glucose is extracted by the pathways of glucose catabolism in living systems?

1. Real cells are messier than an idealised pathway, since intermediates are drawn off for other uses. 2. Overall, in living systems, these pathways extract about 34 percent of the energy contained in glucose. 3. The remainder is not captured in adenosine triphosphate. 4. The word about matters, because the figure is an approximation rather than a fixed constant. _Source: OpenStax Biology (1st ed., CC BY 4.0), Ch 7 "Cellular Respiration", section 7.4 Oxidative Phosphorylation_