Zoology 2022 Paper II 50 marks Describe

Q4

(a) What is fossil? Describe the origin and evolution of horse based on the fossil records. 20 (b) Define variation. Describe different types of variations and their role in evolution. 15 (c) What is biodiversity? Describe the major types of biodiversities found in nature. 15

हिंदी में प्रश्न पढ़ें

(a) जीवाश्म क्या होता है? जीवाश्म प्रमाणों पर आधारित घोड़े के उद्भव एवं विकास का वर्णन कीजिए। 20 (b) विभिन्नता को परिभाषित कीजिए। विभिन्न प्रकार की विभिन्नताओं और विकास में उनकी भूमिका का वर्णन कीजिए। 15 (c) जैव-विविधता क्या है? प्रकृति में पायी जाने वाली जैव-विविधताओं के प्रमुख प्रकारों का वर्णन कीजिए। 15

Evaluate your answer to this question → See all 2022 Zoology questions

Directive word: Describe

This question asks you to describe. The directive word signals the depth of analysis expected, the structure of your answer, and the weight of evidence you must bring.

See our UPSC directive words guide for a full breakdown of how to respond to each command word.

How this answer will be evaluated

Approach

The directive 'describe' demands detailed, systematic exposition of phenomena with appropriate examples. Structure your answer with a brief introduction defining key terms, then allocate approximately 40% of content to part (a) on horse evolution given its 20 marks, 30% each to parts (b) and (c). For (a), trace the chronological lineage from Eohippus to Equus with morphological changes; for (b), classify variations and link to natural selection; for (c), define biodiversity and elaborate on genetic, species and ecosystem levels with Indian examples. Conclude by synthesizing how fossil evidence, variation and biodiversity together illuminate evolutionary processes.

Key points expected

  • Part (a): Definition of fossil (remains/traces of prehistoric organisms preserved in sedimentary rocks) and chronological description of horse evolution through Hyracotherium/Eohippus → Mesohippus → Merychippus → Pliohippus → Equus with specific morphological changes (dental evolution from browsing to grazing, limb elongation, reduction of toes from 4/3 to 1)
  • Part (a): Mention of Gobi Desert (Mongolia) and Siwalik Hills (India) as important fossil sites; reference to Cope's Law or evolutionary trends observed (increase in body size, hypsodonty, reduction of lateral digits)
  • Part (b): Definition of variation as differences among individuals of same species; classification into continuous/discontinuous (qualitative/quantitative), somatic/germinal, heritable/non-heritable variations
  • Part (b): Role of variation in evolution: raw material for natural selection, basis of adaptability, source of polymorphism; connection to mutation, recombination, gene flow and genetic drift as sources
  • Part (c): Definition of biodiversity as variety of life at genetic, species and ecosystem levels; mention of CBD definition or Edward O. Wilson's concept
  • Part (c): Detailed description of three major types: genetic diversity (within species, e.g., rice varieties in India), species diversity (species richness and evenness, e.g., Western Ghats hotspot), ecosystem diversity (biomes, e.g., Himalayas to coral reefs)
  • Part (c): Indian examples: mention of biodiversity hotspots (Himalaya, Western Ghats, Indo-Burma, Sundaland), endemic species (Nilgiri tahr, lion-tailed macaque), or Project Tiger/elephant conservation relevance
  • Synthesis across parts: brief connection showing how fossil records demonstrate evolutionary change, variation provides mechanism, and biodiversity represents outcome of evolutionary processes

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness20%10Precise definitions for all three parts: fossils as preserved remains/traces with modes of preservation; variation as phenotypic/genotypic differences with correct classification; biodiversity encompassing genetic, species and ecosystem levels. No conflation of terms (e.g., does not confuse variation with mutation alone).Generally accurate definitions with minor errors (e.g., incomplete fossil definition missing trace fossils; variation definition lacking distinction between heritable/non-heritable; biodiversity limited to species count only).Vague or incorrect definitions (e.g., fossils as 'old bones' only; variation equated solely with mutation; biodiversity confused with 'number of animals'); significant conceptual confusion between parts.
Diagram / labelling15%7.5Clear evolutionary lineage diagram for horse showing temporal progression with geological epochs (Eocene to Pleistocene); OR comparative skeletal/foot structure diagrams showing toe reduction and dental changes; properly labelled with scientific names and time scale.Basic diagram attempted for horse evolution but lacking proper geological time scale or incomplete labelling; OR describes diagrams in text without actual drawing.No diagram despite clear need for visual representation; OR completely incorrect/misleading diagram (wrong sequence, mislabelled structures).
Examples & nomenclature20%10Accurate scientific nomenclature throughout: Eohippus/Hyracotherium, Mesohippus, Merychippus, Pliohippus, Equus with correct geological periods; specific Indian biodiversity examples (Western Ghats, Himalayan species, endemic flora/fauna); fossil sites (Siwalik Hills, Gobi Desert); variation examples (industrial melanism, sickle cell trait).Most names correct but some errors (e.g., skips intermediate forms in horse lineage; generic biodiversity examples without Indian specificity; limited variation examples).Incorrect scientific names, wrong sequence of horse evolution, no Indian examples for biodiversity, or completely missing nomenclature despite question demands.
Process explanation25%12.5Detailed chronological narrative for horse evolution explaining adaptive significance of each change (grazing adaptation, cursorial locomotion for open plains); clear mechanism of how variation generates evolutionary change (natural selection acting on heritable variation); ecosystem functioning linking biodiversity levels.Lists evolutionary stages or variation types without explaining processes; superficial treatment of how variation leads to evolution; descriptive rather than explanatory approach to biodiversity.Merely enumerates terms without process explanation; no understanding of adaptive significance; confuses cause and effect in evolutionary mechanisms.
Evolutionary / applied context20%10Synthesizes across parts: shows how fossil evidence (a) demonstrates evolutionary trends, variation (b) provides raw material, and biodiversity (c) represents current evolutionary legacy; mentions conservation implications (CBD, Aichi targets, India's Biological Diversity Act 2002); references contemporary relevance (climate change impacts on biodiversity, evolutionary medicine).Brief mention of conservation or evolutionary significance without integration; treats parts as isolated segments without cross-referencing.No applied or contemporary context; purely academic treatment without relevance to current biodiversity crisis or conservation needs; fails to connect the three sub-parts thematically.

Practice this exact question

Write your answer, then get a detailed evaluation from our AI trained on UPSC's answer-writing standards. Free first evaluation — no signup needed to start.

Evaluate my answer →

More from Zoology 2022 Paper II