Classify these by the relation between subject and judgment:
“This tree bears fruit” — singular: one determinate tree.
“Human is a species” — natural: specieshood is attributed to the universal nature.
“Some trees bear fruit” — quantified: a specified portion of the class.
“Trees bear fruit” — indefinite: a claim about trees with no expressed quantifier.
Sentence length or word count is irrelevant. The key is whether the judgment concerns an individual, a nature, a stated range of individuals or an unstated range.