Question

Organisms that are considered to be the most primitive organisms in the world are grouped under:
A. Kingdom Monera
B. Kingdom Protista
C. Kingdom Fungi
D. Kingdom Plantae

Answer 1

Hint: All living organisms are classified into some groups based on very basic and common characteristics. Organisms of each group are then further divided into some smaller groups. These smaller groups are based on more thorough similarities within each larger group. This grouping system makes it easier for the scientists to study a particular group of organisms. Characteristics such as reproduction, mobility, appearance and functionality are just a few ways through which living organisms are grouped together. These specialized groups are called together as the classification of living things. The classification of living things includes 7 levels.
These levels are kingdom, phylum, classes, order, families, genus and species.

Complete answer:
Kingdom Monera contains prokaryotic unicellular organisms like bacteria. These are the most primitive organisms with no membrane-bound organelles and no defined nucleus.
So, option A ‘Kingdom Monera’ is the right answer.
Option B - Kingdom Protista: Kingdom Protista includes all eukaryotes that are neither animals nor plants or fungi. Kingdom Protista is very dissimilar. It consists of both single-celled as well as multicellular organisms. They are eukaryotic organisms that means they have a well-defined nucleus.
As they have well defined nuclei, they can’t be the primitive organisms as we all know that the primitive cells were prokaryotic cells and they don’t have a well-defined nucleus.
So, Option B ‘Kingdom Protista’ is not the correct answer.
Option C - Kingdom Fungi: Fungi are eukaryotic organisms that include microorganisms like moulds, yeasts and mushrooms. These organisms are categorized under kingdom fungi. They are also eukaryotic organisms that means they have a well-defined nucleus.
As they have well defined nuclei, they can’t be the primitive organisms as we all know that the primitive cells were prokaryotic cells and they don’t have a well-defined nucleus.
So, Option C ‘Kingdom Fungi’ is not the correct answer.

Option D - Kingdom Plantae: All the plants are included in the Kingdom Plantae. They are eukaryotic, multicellular organisms. They are also eukaryotic organisms that means they have a well-defined nucleus.
As they have well defined nuclei they can’t be the primitive organisms as we all know that the primitive cells were prokaryotic cells and they don’t have a well-defined nucleus.
So, Option D ‘Kingdom Plantae’ is not the correct answer.

Note:
The easiest example of primitive organisms is Prokaryotes. In Prokaryotes all the essential purposes are carried out by a single cell. These organisms don’t have a membrane-bounded nucleus and other cell organelles. They experience asexual reproduction which is generally by binary fission. A team of researchers from the USA and Sweden announced that they have identified AEG within cyanobacteria which are supposed to be some of the most primitive organisms on Earth. Cyanobacteria occasionally appear as mats or scums on the surface of tanks and lakes during hot summer months.