Write your answer in about 150 words for each of the following : 10×5=50

(a) Describe the requirement of proteins for the initiation of transcription in an eukaryote. 10

(b) What is modern concept of gene ? Describe the test of allilism with suitab

Question

Write your answer in about 150 words for each of the following : 10×5=50

(a) Describe the requirement of proteins for the initiation of transcription in an eukaryote. 10

(b) What is modern concept of gene ? Describe the test of allilism with suitable example. 10

(c) Define mimicry. Discuss the types of mimicry with suitable examples. 10

(d) Describe the use of molecular techniques in animal taxonomy. 10

(e) What is cladistics ? Discuss the international code of biological nomenclature. 10

UPSC Answer Check · Accepted Answer

The directive 'describe' demands systematic, detailed exposition of processes, concepts and mechanisms across all five sub-parts. Allocate approximately 30 words per sub-part (150 words total), spending roughly equal time on each since all carry equal marks. Structure each sub-part as: definition/core concept → key components/process steps → specific example/conclusion. For (a) focus on transcription factors and PIC assembly; (b) cover split gene concept and cis-trans test; (c) define mimicry then classify with Indian examples; (d) list molecular markers and their taxonomic applications; (e) define cladistics then outline ICZN principles.
- (a) Eukaryotic transcription initiation: RNA Pol II, general transcription factors (TFIID/TBP, TFIIA, TFIIB, TFIIE, TFIIF, TFIIH), promoter elements (TATA box, Inr, DPE), formation of pre-initiation complex (PIC), role of activators and co-activators
- (b) Modern gene concept: split gene/introns-exons, overlapping genes, alternative splicing; Test of allelism: cis-trans test (complementation test), Benzer's rII locus work in T4 phage, distinction between cis and trans configurations
- (c) Mimicry definition: resemblance of one species to another for protection/advantage; Types: Batesian (palatable mimics unpalatable, e.g., Papilio polytes mimicking unpalatable Euploea), Müllerian (mutually unpalatable, e.g., Danaus and Euploea), aggressive (e.g., anglerfish), automimicry
- (d) Molecular techniques in taxonomy: DNA barcoding (COI gene), RFLP, RAPD, AFLP, microsatellites, DNA-DNA hybridization, phylogenetic analysis using mitochondrial and nuclear genes, resolving cryptic species (e.g., Indian biodiversity assessments)
- (e) Cladistics: phylogenetic systematics based on shared derived characters (synapomorphies), construction of cladograms; ICZN: binomial nomenclature, principle of priority, type specimens, publication requirements, mandatory Latinization, rules for naming higher taxa

Dimension	Weight	Max marks	Excellent	Average	Poor
Concept correctness	25%	12.5	Demonstrates precise understanding across all sub-parts: correctly identifies all six GTFs for (a), distinguishes modern gene features from classical bead theory for (b), accurately defines mimicry types with correct biological mechanisms for (c), names appropriate molecular markers with their specific taxonomic utilities for (d), and correctly defines cladistics as synapomorphy-based while citing valid ICZN principles for (e)	Shows generally correct concepts with minor errors: misses 1-2 GTFs or confuses promoter elements, presents basic gene definition without modern features, describes 2 mimicry types with minor confusion, lists molecular techniques without clear taxonomic application, defines cladistics loosely and mentions 2-3 ICZN rules	Contains fundamental conceptual errors: confuses prokaryotic and eukaryotic transcription, presents obsolete bead theory as modern concept, conflates mimicry types or gives incorrect examples, confuses molecular techniques with clinical diagnostics, defines cladistics as traditional taxonomy, shows ignorance of nomenclatural rules
Diagram / labelling	15%	7.5	Includes at least 2 well-drawn, properly labelled diagrams: e.g., PIC assembly on promoter for (a), cis-trans configurations for (b), or a cladogram structure for (e); diagrams enhance explanation and contain accurate anatomical/genetic labels	Includes 1 diagram with basic labelling, or mentions diagrams descriptively without drawing; labels are present but incomplete or slightly misplaced	No diagrams attempted despite clear visual potential in multiple sub-parts, or diagrams are drawn without any labels, or diagrams are biologically inaccurate/misleading
Examples & nomenclature	20%	10	Provides specific, accurate examples for each applicable sub-part: Indian butterfly examples for mimicry (Papilio polytes, Danaus genutia), T4 phage rII locus for allelism test, COI barcoding for taxonomy, cites actual ICZN articles or type specimen concepts; nomenclature follows binomial conventions throughout	Gives generic or partially correct examples: mentions 'butterfly' without species names, refers to 'phage experiments' without specifying Benzer/T4, lists molecular techniques without species-level applications, mentions priority principle without elaboration	Examples are missing, invented, or biologically incorrect: cites non-mimetic species as mimics, confuses experimental systems, gives examples from plant taxonomy for animal molecular techniques, shows no awareness of binomial nomenclature conventions
Process explanation	20%	10	Presents clear, stepwise mechanistic explanations: sequential assembly of PIC with factor functions for (a), experimental procedure of cis-trans test with interpretation for (b), evolutionary mechanism and selection pressures for each mimicry type for (c), methodological workflow from DNA extraction to phylogenetic inference for (d), character analysis and tree construction steps for (e)	Describes processes in general terms without clear sequence: lists factors without assembly order, mentions test without experimental logic, describes mimicry appearances without evolutionary mechanism, lists techniques without workflow, defines cladistics without methodology	Process descriptions are absent, fragmented, or backwards: confuses initiation with elongation, cannot explain test interpretation, describes mimicry as 'looking similar' without selection context, presents molecular data as phenotypic traits, confuses cladistics with phenetics
Evolutionary / applied context	20%	10	Explicitly connects concepts to evolutionary biology and practical applications: discusses co-evolutionary arms race in mimicry, conservation genetics and cryptic species resolution for molecular taxonomy, evolutionary implications of gene structure for (b), phylogenetic systematics replacing phenetics, stability and universality principles of ICZN for global biodiversity documentation	Makes passing reference to evolution or application without development: mentions 'evolution' in mimicry without mechanism, notes 'conservation' for molecular techniques without specificity, acknowledges cladistics as 'modern' without evolutionary basis	Completely misses evolutionary and applied dimensions: treats all concepts as static facts, no mention of selection pressures, co-evolution, conservation relevance, or why cladistics/ICZN matter for modern biology

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