one form
one found
one fourth
one fraction
one gene
one generation
one genotype
one genus
one grade

one group
one growing season
one habitat
one half
one hand
one hemisphere
one horse
one hospital
one host
one host species

one hour
one implant
one incident
one individual
one infection
one infusion
one injection
one instance
one institution
one intervention

one item
one job
one jurisdiction
one kind
one laboratory
one layer
one lesion
one level
one ligand
one line

one locality
one location
one locus
one male