Which two levels of ecological organization include members of only a single species?

There are six levels of ecological organization, listed from the smallest to the largest, they are: organism, population, community, ecosystem, biome and biosphere.
The two levels which are made up of members of only a single species are ORGANISMS and POPULATION. Organism refers to any individual living thing while population refers to a group of individual species that live in a specific area at a particular time.

The name of the element is  technetium (tc)