Q6
(a) Describe the development of female gametophyte in angiosperms with the help of suitable illustrations. (20 marks) (b) Give the botanical name, part used and ethnomedicinal importance of any three species each of Fabaceae, Euphorbiaceae and Liliaceae. (20 marks) (c) Define secondary metabolites. Explain their importance in taxonomy. (10 marks)
हिंदी में प्रश्न पढ़ें
(a) आवृत्तबीजी के मादा युग्मकोद्भिद के परिवर्धन का संयुक्त चित्र सहित वर्णन कीजिए। (20 अंक) (b) फेबेसी, युफोर्बिएसी तथा लिलिएसी, प्रत्येक के किन्हीं तीन पादपों का वानस्पतिक नाम, उपयोगी भाग तथा मानवजनित-औषधीय महत्व दीजिए। (20 अंक) (c) द्वितीयक उपापचयज को परिभाषित कीजिए। वर्गीकी में उनके महत्व को स्पष्ट कीजिए। (10 अंक)
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 coverage of developmental processes and factual information. Allocate approximately 40% of time/words to part (a) given its 20 marks and diagram requirement; 35% to part (b) for nine species with precise nomenclature; and 25% to part (c) for definition plus taxonomic applications. Structure: begin with (a)'s megasporogenesis and megagametogenesis with labeled diagrams, proceed to (b)'s tabular or bullet format for ethnomedicinal species, and conclude with (c)'s chemotaxonomic significance.
Key points expected
- Part (a): Megasporogenesis (functional megaspore formation from MMC via meiosis) and megagametogenesis (Polygonum-type monosporic 8-nucleate, 7-celled embryo sac development with precise cellular organization)
- Part (a): Labeled diagrams showing ovule structure, tetrad stage, and mature embryo sac with synergids, egg apparatus, antipodals, and central cell with polar nuclei
- Part (b): Fabaceae — three species with correct binomials (e.g., Glycyrrhiza glabra, Cassia fistula, Butea monosperma), specific plant part used, and documented ethnomedicinal use
- Part (b): Euphorbiaceae — three species with correct binomials (e.g., Euphorbia hirta, Ricinus communis, Jatropha curcas), specific plant part used, and documented ethnomedicinal use
- Part (b): Liliaceae — three species with correct binomials (e.g., Allium sativum, Aloe vera, Asparagus racemosus), specific plant part used, and documented ethnomedicinal use
- Part (c): Precise definition of secondary metabolites (non-essential, species-specific compounds like alkaloids, terpenoids, phenolics) distinguishing from primary metabolites
- Part (c): Taxonomic importance: chemotaxonomy, resolving phylogenetic relationships, species identification, and examples like benzylisoquinoline alkaloids in Papaveraceae or cardenolides in Asclepiadaceae
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 22% | 11 | For (a): accurate sequence of megasporogenesis and megagametogenesis with correct ploidy levels at each stage; for (b): correct family characteristics and pharmacological actions; for (c): precise distinction between primary and secondary metabolites with biochemical basis | Generally correct developmental sequence but minor errors in ploidy or cellular organization; some family characteristics confused; definition broadly correct but lacking biochemical precision | Fundamental errors in embryo sac development (e.g., confusing tetrasporic with monosporic), wrong family assignments, or conflating primary and secondary metabolites |
| Diagram / labelling | 18% | 9 | For (a): two clear, labeled diagrams (ovule with integuments/nucellus/micropyle; mature Polygonum-type embryo sac with all 7 cells and 8 nuclei distinctly marked); for (b) and (c): effective tables or structured formats enhancing readability | One adequate diagram with most structures labeled; some labels missing or misidentified; minimal visual organization for parts (b) and (c) | No diagrams despite explicit requirement, or diagrams with major structural errors; disorganized presentation without visual aids |
| Examples & nomenclature | 20% | 10 | For (b): nine species with correct binomial nomenclature (italicized genus and species, capitalized genus), authentic plant parts, and specific ethnomedicinal uses (e.g., A. racemosus roots as galactagogue); for (c): relevant chemotaxonomic examples from Indian flora | Most binomials correct but some formatting errors; plant parts generally accurate but ethnomedicinal uses generic; limited chemotaxonomic examples | Multiple incorrect scientific names, confused plant parts (e.g., using leaves instead of bark), vague or incorrect medicinal claims; no relevant examples for (c) |
| Process explanation | 22% | 11 | For (a): detailed chronological explanation of nuclear divisions, cellularization, and synergids/antipodal degeneration; for (b): clear connection between phytochemistry and therapeutic action; for (c): logical progression from definition to taxonomic applications | Basic developmental sequence described but lacking detail on nuclear migration or cell fate; medicinal uses stated without mechanism; adequate but pedestrian explanation for (c) | Disorganized or incorrect developmental sequence; mere listing without explanation of medicinal relevance; incoherent structure for (c) |
| Application / ecology | 18% | 9 | For (b): contextualization of ethnomedicinal knowledge in traditional Indian systems (Ayurveda, Siddha, tribal medicine) and conservation implications; for (c): sophisticated discussion of molecular systematics, co-evolution with herbivores, and bioprospecting significance | Some mention of traditional medicine systems; basic awareness that secondary metabolites aid classification; limited ecological or applied perspective | No connection to traditional knowledge systems or conservation; purely theoretical treatment without applied relevance; missing ecological context entirely |
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