Biology · Plant Kingdom · NEET
Numerical taxonomy is classification done with the help of computers. Every observable feature (character) of a plant is given a number or a code. All characters get equal weight, so hundreds of features can be handled together. The computer then groups plants by how many features they share. Because it uses numbers and computers, it is also called phenetics or Adansonian taxonomy. For NEET, just remember: numbers + codes + computer = numerical taxonomy.
Cytotaxonomy is classification based on cell (cyto = cell) information, mainly the chromosomes. It looks at chromosome number, chromosome size, and chromosome structure (like the shape and banding). Two plants that look similar may actually be different if their chromosome number is different. So cytotaxonomy helps separate or join species using cell-level, not just outer, features. NEET keyword to lock in: cyto = chromosome.
Chemotaxonomy is classification based on the chemical compounds (chemo = chemical) present in the plant. It uses chemical constituents such as alkaloids, proteins, amino acids, crystals (like raphides), and other secondary chemicals. Plants with similar chemistry are grouped together. Example type: using the presence of certain alkaloids or storage compounds to decide relationships. NEET keyword: chemo = chemical constituents.
Split each word. NUMERICAL comes from 'number' - features turned into numbers, run on a computer. CYTO means cell - so it is about chromosomes. CHEMO means chemical - so it is about chemical compounds. One line: Number - Cell - Chemical = Numerical, Cyto, Chemo. If a question mentions 'equal weight to all characters' or 'computers', pick numerical.
Classifying only by outer shape (morphology) can be misleading. Two plants can look alike but be genetically or chemically different, or look different but be closely related. Chromosomes (cytotaxonomy) and chemicals (chemotaxonomy) give hidden evidence about true relationships. Numerical taxonomy adds many features at once without bias. Together they make classification more accurate and reliable, which is why NEET calls them evidence used in modern classification.
No. Artificial, natural and phylogenetic systems are broad approaches. Numerical, cyto and chemotaxonomy are sources of evidence or techniques that feed into modern (mostly natural/phylogenetic) classification. They do not replace those systems; they strengthen them by adding cell, chemical and computer-based data. NEET may pair them, so keep the two ideas separate: systems vs evidence-tools.
Try the real previous-year questions from this chapter — each with the answer and a full solution.
Numerical taxonomy. Because it gives equal weight to all characters and groups plants by overall similarity using numbers and computers, it is also called phenetics or Adansonian taxonomy.
Yes. In numerical taxonomy every character gets the same weight, and hundreds of characters can be used at once. This is a common one-line NEET fact.
Chromosome number, along with chromosome size and structure. These help decide whether plants are the same or different species even when they look alike.
Number, Cell, Chemical. Numerical = number/computer, Cyto = cell/chromosome, Chemo = chemical compounds. Say it in that order and you will not confuse them.
They are mostly asked as definition-matching or 'which uses chromosomes/chemicals/computers' type questions in classification topics. Knowing the one-word keyword for each is enough to score.
