Biology · Biological Classification · NEET
Aristotle. Before him, people grouped organisms just by usefulness (food, shelter, clothing), not by science. Aristotle was the earliest to use a more scientific basis. He used simple morphological (body-shape) characters. For NEET, remember: Aristotle = first scientific attempt.
He classified plants into three groups: trees, shrubs, and herbs. He divided animals into two groups: those with red blood and those without red blood. This is a very common one-mark NEET fact, so memorise both splits exactly.
Linnaeus. The two kingdoms were Plantae (all plants) and Animalia (all animals). It was developed in Linnaeus' time. This system was simple but it mixed very different organisms together, which is why it later failed (see the next concept).
R.H. Whittaker, in 1969. His five kingdoms are Monera, Protista, Fungi, Plantae, and Animalia. Year 1969 and the name Whittaker are both directly asked in NEET, so keep them together.
Five criteria: (1) cell structure, (2) body organisation, (3) mode of nutrition, (4) reproduction, and (5) phylogenetic (evolutionary) relationships. Note: presence of a flagellum is NOT one of the criteria. NEET 2026 asked this exact point.
The Three-Domain system (six-kingdom idea). It splits Kingdom Monera into two domains and keeps the other eukaryotic kingdoms in the third domain. NCERT says you learn it in detail in higher classes, so for NEET just know it exists and divides Monera.
The main criteria used for Five Kingdom Classification proposed By R.H. Whittaker (1969) included: A. Cell structure B. Body organization C. Presence of flagellum D. Reproduction E. Phylogenetic relationships. Choose the correct answer from the options given below:
Try the real previous-year questions from this chapter — each with the answer and a full solution.
No. Aristotle did not use the word 'kingdom'. He only split plants into trees, shrubs, herbs and animals into red-blood vs non-red-blood groups. Kingdoms as a rank came later with Linnaeus (two kingdoms).
Both ideas are linked to Linnaeus. Here we focus on the Two Kingdom system (Plantae and Animalia) developed in his time. His binomial naming system is studied in the 'Living World' chapter.
Because the criteria (rules) used for grouping kept changing. As scientists learned about cell type, nutrition, and evolution, old groups were broken up and remade. This is why the same organism can sit in different kingdoms in different systems.
Only lightly. Know that it was proposed after Whittaker, splits Monera into two domains, and leads to a six-kingdom idea. NCERT says details come in higher classes, so deep study is not required.
Use A-L-W: Aristotle (scientific start, no kingdoms), Linnaeus (2 kingdoms), Whittaker (5 kingdoms in 1969). The kingdom count rises 0, 2, 5.
