Answer:
The organisms that harness non-biological energy and convert it to biologically relevant/useful energy are called __autotrophos or producers_. The organisms that consume these are called _herbivores_ (it should end in -ores) which occur at the __second_ trophic level. The number of trophic levels that any ecological system will primarily dependent on the _consumer_ organisms.
Step-by-step explanation:
In the trophic web occurs energy transference through organisms occupying different levels in the chain. Each level feeds on the preceding one and becomes food for the next one. The first link is occupied by autotroph organisms, which are the producer. The following links are the consumers: herbivores are primary consumers and feed on producers. Carnivores are secondary consumers and feed on herbivores, and so on. The last links are the decomposers, microorganisms that act on dead animals degrading organic matter.
Every link has an effect on the superior links and the immediately anterior link, meaning that whenever one of the links changes, the other ones will be affected.
Autotrophs or producers synthesize inorganic substances, such as light, and turn them into organic matter according to their own needs. These organisms are photoautotrophs, such as plants, or chemoautotrophs. They occur at the first trophic level.
Heterotrophs are those incapable of producing their own organic matter, so they feed on producers, depending on them to get proteins and energy. In the trophic chain, heterotrophic organisms occupy the first, second, or third consumer level, after producers. These animals can be herbivorous, carnivorous, omnivorous, hematophagous, ichthyophagous, and etcetera. All of them depend on autotrophic organisms.
In the particular case of herbivores, they occur at the second throphic level feeding on producers and being eaten by carnivores.
In general, most trophic chains are composed of 4 or 5 levels, depending on the number of consumers present, and the energy transference between levels.