Biology · Biological Classification · NEET
They are linked but not identical. The three-domain system is the higher grouping: Archaea, Bacteria, and Eukarya (three domains). When you split Kingdom Monera into Archaea and Bacteria, you now have SIX kingdoms instead of five. So the three-domain idea CREATES the six-kingdom system. NCERT says it plainly: the three-domain system divides Monera into two domains and leaves the eukaryotic kingdoms in the third domain, giving a six-kingdom classification.
Because archaebacteria and eubacteria are very different even though both are prokaryotes. Archaebacteria have a different cell wall and cell membrane structure that lets them live in extreme places (very salty, very hot and acidic, marshy gut). These deep differences suggest they separated very early in evolution. So scientists split Monera into Archaea and Bacteria. For NEET, remember: BOTH are still prokaryotes, but they go into two different domains.
Whittaker (1969) gave FIVE kingdoms: Monera, Protista, Fungi, Plantae, Animalia. The three-domain system came later and split Monera into Archaea and Bacteria. So Whittaker = 5 kingdoms. Three-domain = 6 kingdoms (Archaea, Bacteria, Protista, Fungi, Plantae, Animalia) grouped under 3 domains. The eukaryotic kingdoms are untouched; only Monera changes.
The three domains are: (1) Archaea (the archaebacteria), (2) Bacteria (the eubacteria or true bacteria), and (3) Eukarya (all eukaryotes: Protista, Fungi, Plantae, Animalia). Domain is a rank ABOVE kingdom. Memory line: 'A-B-E: Archaea, Bacteria, Eukarya.'
NCERT says you will learn it in detail in higher classes, so it is kept short. For NEET you must know these facts: it splits Monera into two domains, it makes a SIX-kingdom classification, and the three domains are Archaea, Bacteria and Eukarya. That level is enough to answer the questions NTA has asked.
Each of the following characteristics represents a Kingdom proposed by Whittaker. Arrange the following in increasing order of complexity of body organization. A. Multicellular heterotrophs with cell wall made of chitin. B. Heterotrophs with tissue/organ/organ system level of body organization. C. Prokaryotes with cell wall made of polysaccharides and amino acids. D. Eukaryotic autotrophs with tissue/organ level of body organization. E. Eukaryotes with cellular body organization.
Methanogens belong to
Which of the following are found in extreme saline conditions?
Try the real previous-year questions from this chapter — each with the answer and a full solution.
NCERT does not name the scientist and only says the system 'has been proposed.' For NEET, focus on WHAT it does: it splits Monera into two domains (Archaea and Bacteria) and gives a six-kingdom classification. Do not memorise a name NCERT does not give you.
After splitting Monera, the six kingdoms are: Archaebacteria (Archaea), Eubacteria (Bacteria), Protista, Fungi, Plantae and Animalia.
Yes. Domain is a rank above kingdom. Three domains (Archaea, Bacteria, Eukarya) sit above the six kingdoms.
Only Kingdom Monera. It splits into Archaea (archaebacteria) and Bacteria (eubacteria). All eukaryotic kingdoms stay together in the domain Eukarya.
Because Monera is divided into two kingdoms (Archaea and Bacteria). 4 eukaryotic kingdoms + 2 monera kingdoms = 6 kingdoms.
