Question

Are prokaryotes single-celled?

Answer 1

Hint: Protists are unicellular in nature but can also be found as a colony of cells. Most of them are found in the damp and moist areas, water, terrestrial environments, or even as parasites. They are generally aquatic in nature and are found within the soil.

Complete answer
Unicellular organisms are the organisms having a single cell. The protists are the eukaryotic unicellular organisms that do not include any plant, animal, or fungus. Whittaker in his five-kingdom classification grouped them under a different kingdom. Protists are mostly unicellular organisms but a few like kelp are the multicellular protists. Through the single-cell and with the simplest mechanism these organisms are able to survive throughout their life. They are the independent completely developed unicellular organisms that do not depend upon others for their basic requirements and perform all the functions and life processes to survive.
This group shows the process of symbiosis with their other members. For example, kelp (seaweed) are the multicellular protist that lives in symbiotic association with the otters they protect otters from predators and keep them safe in their thick kelp while the otters eat sea urchins that attacks the kelp as the prey.
Their modes of nutrition are both autotrophic or heterotrophic. Those organisms that can male their own food are called autotrophic organisms while those organisms that are dependent on others for food and nutrition are called heterotrophic organisms.
The nucleus present in them is prominent. Its nucleus is enclosed in a nuclear membrane. The nucleus is composed of DNA along with histone proteins. They constitute cell organelles. They produce fruiting bodies by the production of spores. Their cells are motile for some part of their life cycle. Their life cycle is complex consisting of both sexual and asexual phases. Examples are amoeba, Paramecium, Euglena, etc.

Note:
Parasitism is also observed in protists. In humans sleeping sickness is caused by species like Trypanosoma protozoa. Protists exhibit locomotion through cilia and flagella while a few of them consist of pseudopodia for locomotion. Protista reproduces by asexual means under severe conditions while the sexual method of reproduction is extremely rare.