LIFE SCIENCE

Detailed explanation-1: -Microorganisms are single-celled organisms, such as a bacteria which cannot be seen with our naked eye.

Detailed explanation-2: -Bacteria are the smallest micro-organisms, ranging from between 0.0001 mm and 0.001 mm in size. Phytoplankton and protozoa range from about 0.001 mm to about 0.25 mm. The naked eye can see only the largest phytoplankton and protozoa. Most can only be seen under a microscope.

Detailed explanation-3: -Microorganisms are too minute in size to be seen by unaided eyes, hence are observed and studied using microscopes. Compound microscopes are commonly used in research labs and institutes to study microorganisms. They use glass lenses to bend and focus light rays and produce enlarged images of small objects.