Question

Unicellular eukaryotic organisms are included in:
a. Monera
b. Protista
c. Fungi
d. Plantae

Answer 1

Hint: The organisms in which have well defined nuclei but have a very simple one cell structure.

Complete step-by-step answer:
Kingdom Protista is known as the kingdom in which all the organisms survive with a single cell that is unicellular and the cell has a well defined nucleus in which the genetic material is placed.

Additional Information:
1. Kingdom Monera includes all bacteria. Bacteria are unicellular prokaryotic organisms and they lack membrane-bound organelles.

2. Kingdom Protista:
All single-celled eukaryotes are included in the
Kingdom Protista, protists are further divided into Chrysophytes, Dinoflagellates, Euglenoids, Slime moulds and Protozoans. Most protists are primarily aquatic. This kingdom acts as a connecting link between prokaryotes and the others dealing with plants, animals and fungi. Since they are eukaryotes, the protist cells’ nucleus has a well defined nucleolar membrane and the cells contain membrane-bound organelles. For the purpose of locomotion some have flagella or cilia. Asexual and sexual reproduction are both seen in protists. Sexual reproduction involves zygote formation, and asexual reproduction includes binary fission multiple fission and budding.

3. Chrysophytes: They are available in freshwater as well as in marine waters. These are microscopic plankton the free float in water and are food for small fish. Most of the chrysophytes can perform photosynthesis and are called phytoplankton, the ones who cannot photosynthesize are called zooplankton. Chrysophytes are composed of diatoms that have a soapbox like cell wall structure. The cell walls of these organisms are embedded with silica and are considered indestructible.

4. Dinoflagellates: they are marine photosynthetic organisms. They appear in a variety of colors like yellow, green, brown, blue or red. The colors of these organisms depend on the pigments present in their cells. The dinoflagellate cell is protected by a cell wall that has stiff cellulose plates on the outer surface. Locomotion is brought about by the presence of two flagella which are longitudinally and transversely present.

5. Euglenoids: These organisms are majorly found in freshwaters and stagnant water. The euglenoid cell is protected by a protein-rich layer called pellicle which makes their body flexible. Locomotion is carried out by flagella, they have two, one short and one long. They can be called facultative heterotrophs, in the presence of light they can produce their own food but in the absence of food they can act as heterotrophs and consume nutrition by predating on smaller organisms. The photosynthetic pigments present in these cells are similar to higher plants.

6. Slime Moulds: The mode of nutrition in these organisms is saprophytic. Their body moves over decaying materials and continuously engulfs organic material. They aggregate as plasmodium under suitable conditions. Plasmodium may grow and spread over a large area of several feet. To survive unfavorable conditions, the plasmodium body differentiates and forms spore-bearing fruiting bodies. These spores are highly resistant and continue the species in extreme environments, they germinate when conditions are favorable again.

7. Protozoans: They are usually heterotrophs and survive by predating or as parasites. They are believed to be a primitive link that evolved into animals. There are four major groups of protozoans, amoeboid protozoans, flagellated protozoans, ciliated protozoans, and sporozoans.

So, the correct answer is Protista.

Note: Protists are known to be the connecting links and the common ancestors to plants and animals, the proof of this belief is plant-like protists and animal-like protists.