Answer:
Animalcule is an ancient term for all unicellular organisms, whether prokaryotes —such as bacteria—or eukaryotes, such as amoebas.
Step-by-step explanation:
Animalcule was the name of what we know today as microorganisms, a term used by van Leeuwenhoek in his observations under the microscope.
Single-cell organisms are those that —unlike multicellular organisms— do not need to join together to form tissues, but are simple organisms that can fulfill their functions independently. Single-cell organisms include:
- Bacteria and archaea, formed by prokaryotic cells.
- Protozoa, algae, and yeasts, which are unicellular but whose structure is eukaryotic.
The term animalcule previously included all these unicellular organisms, which have now been defined and classified, being called microorganisms or single-cell organisms.