Q5
Write short notes on the following in about 150 words each: 10×5=50 (a) Biodiversity hot spots (b) Navigation in birds (c) Sickle cell anaemia (d) Circadian rhythms (e) Biome
हिंदी में प्रश्न पढ़ें
निम्नलिखित में से प्रत्येक पर लगभग 150 शब्दों में संक्षिप्त टिप्पणी लिखिए : 10×5=50 (a) जैव विविधता अधिदेशल (b) पक्षियों में पथ-संचालन (नैविगेशन) (c) दार (हँसिया) कोशिका अरक्तता (d) दिवसीय लय (e) जीवोम
Directive word: Write short notes
This question asks you to write short notes. 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 'write short notes' demands concise, information-dense responses for each sub-part with equal weightage (10 marks each). Allocate approximately 150 words and 10-12 minutes per sub-part. Structure each note with a precise definition, 2-3 key features/mechanisms, and one relevant example. No elaborate introduction or conclusion is needed; prioritize factual accuracy and technical terminology over narrative flow. For (a) and (e), emphasize geographical distribution and conservation significance; for (b) and (d), focus on physiological mechanisms; for (c), integrate molecular genetics with disease ecology.
Key points expected
- (a) Biodiversity hotspots: Definition by Myers (1988), criteria (≥1,500 endemic vascular plants, ≥70% habitat loss), mention of Himalaya and Western Ghats as Indian hotspots, conservation significance
- (b) Navigation in birds: Sun compass, star compass, magnetic compass (magnetite-based), olfactory maps, integration of multiple cues with example of Arctic tern or Indian homing pigeon studies
- (c) Sickle cell anaemia: Molecular basis (Glu→Val substitution at β6 position), HbS polymerization under hypoxia, heterozygote advantage/malaria resistance, distribution in Indian tribal populations (Saurashtra, Nilgiris)
- (d) Circadian rhythms: Endogenous oscillators (suprachiasmatic nucleus), zeitgebers (light, temperature), molecular clock mechanism (Clock/Bmal1, Per/Cry feedback loops), chronobiology applications
- (e) Biome: Definition as major ecological unit, distinction from ecosystem, classification by Whittaker (temperature-precipitation matrix), Indian examples (tropical thorn forest, montane forests), climate-vegetation coupling
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 20% | 10 | All five sub-parts demonstrate precise, error-free definitions: hotspots meet Myers' dual criteria; bird navigation distinguishes compass vs. map mechanisms; sickle cell specifies β-chain mutation; circadian rhythms correctly identify SCN as master pacemaker; biome distinguishes from ecosystem level | Most definitions are correct but some imprecision exists: vague hotspot criteria, conflated navigation mechanisms, incomplete molecular description of HbS, missing SCN identification, or biome/ecosystem confusion | Multiple conceptual errors: incorrect hotspot criteria, confused navigation mechanisms with migration, wrong amino acid substitution, circadian conflated with circannual rhythms, biome treated as synonym for ecosystem |
| Diagram / labelling | 15% | 7.5 | At least two relevant, well-labelled diagrams: for (c) showing HbS polymerization/deoxygenated sickle RBC; for (d) feedback loop of molecular clock or SCN location; OR for (b) magnetic inclination compass; clear anatomical/structural labels | One diagram attempted with partial labelling, OR two diagrams with minor errors in structure; acceptable but not fully explanatory of the mechanism | No diagrams despite clear visual potential in 3-4 sub-parts, OR diagrams present but fundamentally incorrect (e.g., normal RBC labelled as sickled, wrong brain region for SCN) |
| Examples & nomenclature | 20% | 10 | Specific, geographically accurate examples: for (a) names 2 Indian hotspots (Western Ghats, Eastern Himalaya, Indo-Burma); for (b) cites specific species (Arctic tern, bar-tailed godwit); for (c) mentions Indian tribal groups; for (e) specifies Indian biomes; correct scientific nomenclature throughout | Generic examples provided (e.g., 'rainforest' for hotspot, 'pigeons' for navigation) without specificity; OR Indian examples missing where clearly applicable; some nomenclature errors | No specific examples, OR factually wrong examples (e.g., Sunderbans as hotspot, which is actually included in Indo-Burma); invented or misspelled scientific terms |
| Process explanation | 25% | 12.5 | Clear mechanistic explanations: for (b) how magnetic, solar and stellar cues integrate; for (c) polymerization kinetics and RBC sickling cascade; for (d) transcription-translation feedback loop with time delays; for (a/e) ecological processes driving endemism | Processes mentioned but described superficially or sequentially without causal linkage; missing key steps in molecular or physiological mechanisms | No process explanation, OR confused cause-effect relationships (e.g., malaria causes sickle cell mutation rather than selecting for it); teleological explanations |
| Evolutionary / applied context | 20% | 10 | Explicit evolutionary reasoning: for (c) balanced polymorphism and heterozygote advantage with malaria; for (a/e) hotspot vulnerability from Pleistocene refugia and anthropogenic pressure; for (d) adaptive significance of circadian entrainment; for (b) evolutionary optimization of multi-cue systems; conservation applications | Brief mention of evolutionary or applied significance without elaboration; OR applied context present but evolutionary mechanism missing | No evolutionary or applied context; OR Lamarckian or incorrect evolutionary explanations; purely descriptive treatment of all sub-parts |
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