Zoology 2025 Paper I 50 marks Describe

Q8

(a) What do you mean by infectious and communicable diseases? Mention the causative agent and means of spread of filaria. Also describe the symptoms, diagnosis, treatment and preventive measures of filaria. 20 (b) Give an illustrated account of carbon cycle with suitable diagram. 15 (c) Describe the phenomenon of sexual conflict and selfishness in studying animal behaviour with suitable examples. 15

हिंदी में प्रश्न पढ़ें

(a) संक्रामक एवं संचारणीय रोगों से आप क्या समझते हैं? फाइलेरिया के रोगकारक (कारक एजेंट) एवं प्रसार के तरीकों का उल्लेख कीजिए। फाइलेरिया के लक्षणों, निदान, इलाज एवं निवारक उपायों का भी वर्णन कीजिए। 20 (b) कार्बन चक्र का उपयुक्त रेखाचित्र सहित एक स्पष्टीकृत विवरण दीजिए। 15 (c) प्राणी व्यवहार के अध्ययन में यौन संघर्ष एवं स्वार्थ की परिघटना का उपयुक्त उदाहरणों सहित वर्णन कीजिए। 15

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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.

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How this answer will be evaluated

Approach

The directive 'describe' demands comprehensive coverage with factual precision across all three parts. Allocate approximately 40% of time/words to part (a) given its 20 marks, 30% each to parts (b) and (c). Structure: brief definitional opening for (a), then systematic treatment of filariasis; illustrated carbon cycle with clear biotic-abiotic compartments; and behavioural examples with evolutionary interpretation for (c). No conclusion needed—end with preventive/applied notes.

Key points expected

  • Part (a): Precise distinction between infectious (pathogen-caused) and communicable (transmissible between hosts) diseases; Wuchereria bancrofti, Brugia malayi, Brugia timori as causative agents with Culex/Anopheles/Mansonia vectors; clinical staging (asymptomatic microfilaraemia, acute lymphadenitis, chronic elephantiasis); diagnostic methods (night blood smear, ICT card test, USG for adult worms); DEC/albendazole/ivermectin treatment; MDA strategy under National Filaria Control Programme
  • Part (b): Complete carbon cycle diagram showing atmospheric CO2, producers (photosynthesis), consumers (respiration), decomposers, fossil fuels, and oceanic carbonate reservoir; quantification of pools and fluxes; mention of biological pump and anthropogenic perturbation
  • Part (c): Sexual conflict defined as antagonistic coevolution between sexes over optimal reproductive strategies; intralocus and interlocus conflict; selfish genetic elements (segregation distorters, meiotic drive); specific examples—Drosophila seminal fluid proteins, water strider (Gerris) coercive mating, bedbug traumatic insemination, stalk-eyed fly eye-span sexual selection
  • Part (c) continued: Evolutionary arms race and chase-away sexual selection; cost-benefit analysis for each sex; resolution mechanisms (sensory exploitation, cryptic female choice)
  • Integrated applied context: One Health approach for filaria; carbon sequestration relevance to climate policy; behavioural ecology implications for conservation breeding

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness22%11For (a): correctly distinguishes infectious vs. communicable with epidemiological nuance; accurate filarial species-vector associations and life cycle stages. For (b): correct stoichiometry and reservoir magnitudes. For (c): precise definitions of interlocus/intralocus conflict and selfish genetic elements without conflating with sexual selection.Basic definitions correct but conflates infectious/communicable or misses vector specificity; carbon cycle directionally accurate but pool sizes vague; sexual conflict described as mere 'competition' without genetic conflict mechanism.Fundamental errors—calls all infectious diseases communicable, wrong causative agent for filaria, reverses carbon cycle flows, or describes sexual conflict as cooperation.
Diagram / labelling18%9For (b): self-drawn carbon cycle with clear reservoirs (atmosphere, terrestrial biomass, soil, ocean, sediments), flux arrows with approximate magnitude labels, and biological/physical pumps distinguished. For (a): optional life cycle diagram of W. bancrofti with human-mosquito stages labelled. Diagrams integrated with text, not isolated.Carbon cycle diagram present but incomplete—missing oceanic or fossil fuel reservoirs, or arrows without directionality. No filarial life cycle. Diagrams mentioned but not actually drawn.No diagram for (b) despite explicit instruction; or diagram copied without understanding (e.g., nitrogen cycle labelled as carbon). Illegible or unlabelled sketches.
Examples & nomenclature20%10For (a): all three filarial species named with endemic regions (W. bancrofti—urban India; B. malayi—rural coastal); specific vectors (Culex quinquefasciatus, Mansonia spp.). For (c): minimum three specific taxa with mechanisms (Drosophila SP proteins, Gerris coercive mating, bedbug Cimex traumatic insemination or stalk-eyed flies).Generic 'mosquito' for vector without species; one or two behavioural examples without species names; 'elephantiasis' mentioned without specifying chronic lymphatic filariasis.No specific examples; vague 'some insects show conflict'; confuses filaria with other helminths; misspells key genera (Wuchereria, Brugia).
Process explanation22%11For (a): sequential staging of filarial disease (microfilaraemia → acute adenolymphangitis → chronic lymphoedema/elephantiasis/hydrocele) with immunological basis; diagnostic rationale for nocturnal blood collection. For (b): photosynthesis vs. chemosynthesis pathways, respiration vs. decomposition, and anthropogenic flux quantification. For (c): mechanistic explanation of how selfish genes spread and impose fitness costs.Lists symptoms and treatments without pathophysiological linkage; carbon cycle as linear not cyclical; describes behavioural outcomes without evolutionary process (e.g., 'males fight' without chase-away selection).Symptoms listed without staging; no explanation of why DEC works; carbon cycle described as 'plants eat CO2'; sexual conflict reduced to 'male dominance' without evolutionary framework.
Evolutionary / applied context18%9For (a): MDA strategy under NFCP/ELF elimination programme; triple drug therapy (IDA) pilot; vector control integration. For (b): carbon budget relevance to India's NDCs; blue carbon coastal ecosystems. For (c): evolutionary arms race and antagonistic coevolution; implications for speciation (reproductive isolation via sexual conflict).Generic prevention ('use mosquito net') without programme context; carbon cycle linked to 'global warming' without policy specifics; sexual conflict mentioned as 'evolution' without arms race dynamics.No applied context; no mention of elimination targets for filaria; carbon cycle without climate relevance; sexual conflict as static behaviour without evolutionary time dimension.

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