Botany 2023 Paper I 50 marks 150 words Compulsory Explain

Q1

Answer the following questions in about 150 words each: (a) What are prions? How do they differ from viruses? Mention few diseases caused by prions in animals and human beings. (10 marks) (b) What is parasexuality in fungi? Explain the mechanism of parasexual cycle. What are the applications of parasexuality? (10 marks) (c) State the distinguishing features of Cyanophyceae. Discuss the phylogeny and affinities of Cyanophyceae with other groups. (10 marks) (d) Discuss the distribution of different modern species of Cycas found in India. Enumerate the fern characters observed in Cycas. (10 marks) (e) State the principles of International Code of Botanical Nomenclature. How are Operational Taxonomic Units (OTUs) used in numerical taxonomy? (10 marks)

हिंदी में प्रश्न पढ़ें

निम्नलिखित में से प्रत्येक प्रश्न का उत्तर लगभग 150 शब्दों में दीजिए : (a) प्रियोन्स क्या हैं? ये वाइरस से कैसे भिन्न हैं? पशुओं और मनुष्यों में प्रियोन्स द्वारा होने वाली कुछ बीमारियों का उल्लेख कीजिए। (10 अंक) (b) कवक में पैरासेक्सुअलिटी क्या है? पैरासेक्सुअल चक्र की प्रक्रिया की व्याख्या कीजिए। पैरासेक्सुअलिटी के अनुप्रयोग क्या हैं? (10 अंक) (c) साइनोफाइसी के विशिष्ट लक्षणों को बताइए। साइनोफाइसी की अन्य समूहों के साथ वंशावली और बंधुताओं पर चर्चा कीजिए। (10 अंक) (d) भारत में पाई जाने वाली साइकस की विभिन्न आधुनिक जातियों के वितरण पर चर्चा कीजिए। साइकस में प्रेक्षित फर्न वाले लक्षणों का परिगणन कीजिए। (10 अंक) (e) अंतर्राष्ट्रीय वानस्पतिक नामकरण संहिता के सिद्धांतों को बताइए। संख्यात्मक वर्गिकी में ऑपरेशनल टैक्सोनोमिक इकाइयाँ (ओ. टी. यू.) किस प्रकार प्रयोग में लाई जाती हैं? (10 अंक)

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Directive word: Explain

This question asks you to explain. 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

This multi-part question requires explaining five distinct botanical concepts within strict 150-word limits per part. Allocate approximately 30 words to each component within a sub-part: for (a) define prions, contrast with viruses, and list diseases; for (b) define parasexuality, outline the parasexual cycle mechanism, and state applications; for (c) list distinguishing features of Cyanophyceae and discuss phylogenetic relationships; for (d) describe Indian Cycas distribution and enumerate fern characters; for (e) state ICBN principles and explain OTU usage in numerical taxonomy. Prioritize precision over elaboration, use scientific terminology correctly, and include relevant examples for each part.

Key points expected

  • (a) Prions: proteinaceous infectious particles lacking nucleic acid; contrast with viruses (presence/absence of genetic material, replication mechanism); diseases: Creutzfeldt-Jakob disease, Kuru, BSE (mad cow disease), Scrapie
  • (b) Parasexuality: genetic recombination without meiosis and sexual reproduction; mechanism: heterokaryosis → nuclear fusion → mitotic crossing over → haploidization; applications: industrial strain improvement in Penicillium, Aspergillus
  • (c) Cyanophyceae features: prokaryotic, absence of membrane-bound organelles, presence of phycocyanin, heterocysts in Nostoc, Anabaena; phylogeny: considered most primitive photosynthetic organisms, bridge between bacteria and algae
  • (d) Indian Cycas species: C. circinalis (Western Ghats), C. beddomei (Andhra Pradesh), C. pectinata (Northeast), C. rumphii (Andaman); fern characters: circinate vernation, megasporophylls resembling pinnate leaves, leaf traces
  • (e) ICBN principles: priority, typification, binomial nomenclature, Latin diagnosis; OTUs: operational taxonomic units used in numerical taxonomy for phenetic classification based on overall similarity, computer-assisted analysis

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness25%12.5Accurately defines prions as protein-only infectious agents without nucleic acids; correctly identifies parasexuality as genetic recombination independent of meiosis; precisely describes Cyanophyceae as prokaryotic oxygenic phototrophs; correctly classifies Cycas as gymnosperm with pteridophytic ancestry; accurately states ICBN principles including priority and typificationBasic definitions present but with minor errors (e.g., confusing prions with viroids, incomplete parasexuality mechanism, vague prokaryotic/eukaryotic distinction for Cyanophyceae, incomplete ICBN principles)Fundamental conceptual errors (e.g., stating prions contain RNA, describing parasexuality as sexual reproduction, classifying Cyanophyceae as eukaryotic algae, missing key ICBN principles)
Diagram / labelling10%5Includes clear schematic of parasexual cycle showing heterokaryon formation, nuclear fusion, and haploidization; or labelled diagram of Cyanophyceae cell structure (thylakoid arrangement, heterocyst); or Cycas megasporophyll with circinate vernationSimple unlabelled diagram or incomplete labelling; mentions diagram needed but not drawn; confusing representation of cycle stagesNo diagrams where essential (especially for parasexual cycle mechanism); or completely incorrect diagrams that misrepresent structures
Examples & nomenclature20%10Specific disease examples: Creutzfeldt-Jakob disease, Kuru (human), BSE, Scrapie (animals); Indian Cycas species with locations: C. circinalis (Western Ghats), C. beddomei (Seshachalam hills), C. pectinata (Meghalaya); correct binomial nomenclature format; specific fungal genera for parasexuality applicationsGeneric examples without specificity (e.g., 'mad cow disease' without BSE), incomplete Indian species list, minor nomenclature errors (lowercase genus, missing italics indication)Incorrect or no examples; wrong disease associations; no Indian Cycas species mentioned; serious nomenclature violations
Process explanation25%12.5Clear stepwise parasexual cycle: plasmogamy → heterokaryosis → karyogamy (diploid nucleus) → mitotic crossing over → haploidization; prion replication via protein misfolding and templating; OTU construction and similarity matrix in numerical taxonomy; phylogenetic positioning of Cyanophyceae via endosymbiotic theorySequence present but steps unclear or out of order; incomplete explanation of prion propagation; vague description of numerical taxonomy proceduresNo sequential logic; confused mechanism description; missing critical steps in any process; failure to explain how OTUs function in practice
Application / ecology20%10Parasexuality applications: strain improvement for antibiotic production (Penicillium chrysogenum), industrial enzyme production; Cyanophyceae ecological significance: nitrogen fixation in rice fields (Nostoc, Anabaena), bloom formation and toxicity; Cycas conservation status (C. beddomei endangered); ICBN practical importance in avoiding nomenclatural confusionGeneric applications mentioned without specificity; incomplete ecological roles; missing conservation or industrial relevanceNo applications or ecological context; irrelevant or incorrect applications attributed to wrong organisms

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