Final answer:
The organism most likely to be located at the apex of the pyramid of biomass is an apex predator or top predator.
Step-by-step explanation:
Organisms located at the apex of the pyramid of biomass are typically top predators or apex predators. These organisms occupy the highest trophic level in the food chain and have the least biomass. This means that they have the lowest amount of living tissue compared to other organisms in the ecosystem.
For example, in a terrestrial ecosystem, a top predator like a lion or a tiger would be located at the apex of the pyramid of biomass. In an aquatic ecosystem, a top predator like a shark or a killer whale would be located at the apex.
Therefore, the organism most likely to be located at the apex of the pyramid of biomass is an apex predator or top predator.