Q.The taxonomy which involves the similarities and dissimilarities among the immune system of different taxa is termed as

Step 1. Spot the key term. The question asks specifically about a taxonomic approach built on the 'immune system' - that is the language of serology, the study of antigen-antibody (serological) reactions.

Step 2. Match to the chapter's definition. Serotaxonomy (also called immunotaxonomy or systematic serology) classifies very similar plants by comparing differences in the proteins they contain, using antigen-antibody reactions raised against a known taxon - precisely a study of immune-system-based similarity and dissimilarity between taxa (e.g. the reassignment of Phaseolus aureus and P. mungo to the genus Vigna, supported by serological evidence).

Step 3. Eliminate the distractors. Chemotaxonomy (a) uses biochemical constituents broadly (starch, oils, proteins) but is not specifically about immune/antigen-antibody reactions; Molecular systematics (b) uses DNA/RNA sequence data, not antibodies; Numerical taxonomy (d) refers to statistical clustering on many characters, unrelated to immunology and not part of this chapter's terms.

Map the phrase 'immune system' directly to serology/antigen-antibody reactions, the defining feature of serotaxonomy.

• Confusing serotaxonomy with chemotaxonomy because both are 'biochemical' - chemotaxonomy is broader and not immunology-specific
• Selecting molecular systematics, which is DNA-based, not antibody-based