 The basal metabolic rate of an organism is the measure of the amount of energy consumed by all of these chemical reactions.A striking feature of metabolism is the similarity of the basic metabolic pathways among vastly different species.For example, the set of carboxylic acids that are best known as the intermediates in the citric acid cycle are present in all known organisms, being found in species as diverse as the unicellular bacterium "Escherichia coli" and huge multicellular organisms like elephants.