Q3
(a) What is clone ? What do you understand by clonal selection ? Describe the various steps involved in clonal selection. 15 (b) What do you understand by centre of origin ? Discuss the law of homologous series of variation. 15 (c) Describe self-pollination, cross-pollination and often cross-pollination. Discuss different mechanisms for facilitating self-pollination and cross-pollination. 20
हिंदी में प्रश्न पढ़ें
(a) क्लोन क्या है ? क्लोनीय चयन से आप क्या समझते हैं ? क्लोनीय चयन में सम्मिलित विभिन्न चरणों का वर्णन कीजिए । 15 (b) उत्पत्ति केन्द्र से आप क्या समझते हैं ? विचरण के संदर्भ में समजातीय श्रेणी (होमोलोगस सीरीज) नियम की चर्चा कीजिए । 15 (c) स्वपरागण, परपरागण तथा प्रायः परपरागण का वर्णन कीजिए । स्वपरागण तथा परपरागण को बढ़ावा देने वाली विभिन्न तंत्र प्रक्रियाओं की विवेचना कीजिए । 20
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 processes and concepts with clarity. Allocate approximately 30% time/words to part (a) on clonal selection, 30% to part (b) on centre of origin and Vavilov's law, and 40% to part (c) on pollination mechanisms given its higher mark weightage. Structure as: brief introduction defining key terms → systematic treatment of each sub-part with steps/processes clearly delineated → concluding synthesis on implications for crop improvement.
Key points expected
- Part (a): Definition of clone as genetically identical progeny derived from somatic cells; clonal selection as selection of superior genotypes from vegetatively propagated populations; detailed steps including selection of parental clone, clonal evaluation trials, and release of improved variety
- Part (b): Centre of origin as geographic area where plant species first developed distinctive properties; Vavilov's eight centres with Indian examples (Hindustan centre for rice, sugarcane); Law of homologous series explaining parallel variation patterns across related species
- Part (c): Clear distinction between autogamy (self-pollination), allogamy (cross-pollination), and facultative/often cross-pollination; mechanisms for self-pollination including cleistogamy, homogamy, and chasmogamy with adaptations; mechanisms for cross-pollination including dichogamy, self-incompatibility, male sterility, and floral adaptations
- Specific Indian crop examples: clonal selection in potato, sugarcane, citrus; centre of origin applications for indigenous crop diversity conservation; pollination mechanisms in rice, wheat, maize, sorghum, cotton
- Integration of genetic principles: maintenance of heterozygosity in clonal propagation, genetic diversity preservation through centre of origin understanding, and breeding system manipulation through pollination control
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 25% | 12.5 | Precise definitions of clone, clonal selection, centre of origin, and pollination types; accurate explanation of Vavilov's law with correct genetic basis; error-free description of pollination mechanisms with proper botanical terminology; correct sequence of clonal selection steps | Generally correct definitions with minor inaccuracies; basic understanding of Vavilov's centres but confused explanation of homologous series; adequate pollination descriptions but mixing up mechanisms; clonal selection steps present but incomplete or out of order | Fundamental conceptual errors such as confusing clone with pure line; incorrect or missing explanation of homologous series; conflation of self and cross-pollination mechanisms; omission of critical steps in clonal selection |
| Quantitative reasoning | 10% | 5 | Appropriate mention of genetic ratios where relevant (e.g., segregation patterns in clonal vs sexual reproduction); quantitative aspects of clonal evaluation trials; statistical basis of Vavilov's law; percentage-based classification of often cross-pollinating crops | Limited quantitative references; generic mention of trial replications without specifics; basic awareness that clonal populations show no segregation | No quantitative dimension; incorrect genetic ratios or complete absence of numerical reasoning where applicable |
| Indian context examples | 20% | 10 | Rich Indian examples: clonal selection success stories (Kufri potato varieties, Co sugarcane varieties); Hindustan centre specifics (rice, mango, sugarcane origin); Indian crop pollination biology (rice self-pollination, cotton often cross-pollinated, maize cross-pollinated); mention of NBPGR's role in germplasm conservation | Some Indian examples but limited or generic; mention of common crops without specific variety names; basic awareness of Indian centres of diversity | No Indian examples or inappropriate foreign-centric illustrations; failure to connect concepts to Indian agricultural reality |
| Diagram / process | 25% | 12.5 | Clear flow diagram of clonal selection steps; illustrative diagram of Vavilov's centres on world map; detailed floral diagrams showing dichogamy, herkogamy, or cleistogamy; schematic representation of pollination mechanisms; well-labelled process illustrations enhancing descriptive content | One or two simple diagrams present but lacking detail; basic flowchart without proper labelling; textual description substitutes for visual representation | No diagrams despite high suitability; poorly executed sketches that confuse rather than clarify; complete reliance on text for process descriptions |
| Policy / extension angle | 20% | 10 | Integration with Plant Variety Protection and Farmers' Rights Act; clonal selection's role in seed potato certification and virus indexing; centre of origin relevance to CBD and Nagoya Protocol on benefit sharing; pollination control in hybrid seed production (CMS lines in sorghum, rice); ICAR's network project on conservation of indigenous crop varieties | Brief mention of germplasm conservation or hybrid seed production without policy depth; generic reference to agricultural importance | No policy or extension dimension; failure to connect technical concepts to practical breeding programs or conservation efforts |
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