What are microorganisms?

Microorganisms are defined as small living things that can only be seen under a microscope. This definition encompasses a wide variety of organisms, including bacteria, viruses, fungi, and protozoa. The key feature that defines microorganisms is their microscopic size, which differentiates them from larger, visible life forms.

Understanding that microorganisms can be beneficial or harmful is critical in areas such as nursing and healthcare. For instance, beneficial bacteria play essential roles in processes like digestion and immunity, while pathogenic microorganisms can cause diseases. This broad definition helps to clarify the diversity of microorganisms and their various roles in our environment and health.

In contrast, large visible organisms refer to creatures that can be seen without a microscope, which does not fit the definition of microorganisms. The notion of pathogenic viruses only and only harmful bacteria is too restrictive, as it ignores the vast majority of microorganisms that are not harmful and includes beneficial species. Therefore, considering all these aspects, small living things is indeed the comprehensive answer for what microorganisms are.