Question

Domain Eukarya includes how many kingdoms (with respect to the six kingdom system)?
A. Two
B. Three
C. One
D. Four

Answer 1

Hint: The members of domain eukarya called the eukaryotes have membrane bound organelles. It was given by Carl Woese. The system of classification includes Archaebacteria, Eubacteria, Protista, Fungi, Animalia and Plantae.

Complete answer: Aristotle was the earliest once that attempted a more scientific classification.
Later it was linnaeus, who classified species in two kingdom systems of classification which include Plantae and Animalia. This system did not distinguish between prokaryotes and eukaryotes unicellular and multicellular organisms and photosynthetic and non- photosynthetic organisms. A need was felt wherein classification was done on morphology, other methods of reproduction and more.
Classification systems had undergone several changes over time. Though the plant and animal kingdom have been a constant under all different systems. Six kingdom classification was given by Carl Woese which includes Archaebacteria, Eubacteria, Protista, Fungi, Animalia and Plantae.
Archaebacteria are single- celled prokaryotes which are bacteria that are found in most harsh habitats such as extreme salty areas, hot springs and marshy areas. They differ from bacteria as they have different cell wall structure and this is responsible for their survival in extreme conditions.
Eubacteria or we call them "true bacteria" are prokaryotes. They are characterised by rigid cell walls and if motile, a flagellum. They are responsible for fixing atmospheric nitrogen in specialised cells called heterocysts. Chemosynthetic autotrophic bacteria oxidises various nitrates, ammonia and uses the energy being released for ATP production. Some of these causes damage to human beings, crops, farm etc.
Euglenoids are freshwater organisms found in stagnant water. They are called eukaryotic because of membrane bound organelles found in them. Instead of a cell wall, they contain a protein rich layer called pellicle which makes them flexible. They are photosynthetic in the presence of sunlight and deprived of it they act as heterotrophs by predating on other organism.
Fungi are eukaryotic with great diversity in morphology and habitat. Some of these are used to make bread and beer. They are cosmopolitan and usually grow in air, water and soil. They prefer to grow in warm and humid places.
Plantae includes all eukaryotic chlorophyll containing organisms. Few members are partially heterotrophic. Plant cells have eukaryotic structure with prominent eukaryotic cell structure.
Animalia are characterised by heterotrophic, eukaryotic organisms that are multicellular and lack cell walls. They are dependent on plants for energy as well as food. Their mode of nutrition is holozoic - by ingestion of food. They follow up a distinct growth pattern and grow up into adults in definite shape and size.

So, the correct answer is option D, four.

Note: Eukarya is the only domain that contains multicellular and visible organisms. In biology, the second largest taxonomic hierarchy is domain. Traditionally, we used six kingdom classification to distribute the organism in different phyla. Carl segregated them in three domains that have been evolved from a common ancestor called as progenote.