Hundreds of individuals of a species have been observed and all are photosynthetic; therefore, the species is photosynthetic.
These organisms live in sunny parts of this area so they are able to photosynthesize.
If horses are always found grazing on grass, they can be only herbivores and not omnivores.
If protists are all single-celled, then they are incapable of aggregating.
If two species are members of the same genus, they are more alike than each of them could be to a different genus.