Q4
(a) What do you understand by water transport in xylem ? Explain the Cohesion-Tension theory. (20 marks) (b) How is the detailed record of relationship between the selected plants and their progenies maintained in the pedigree selection method ? Discuss the procedure for pedigree selection method, with the help of a simplified schematic diagram. (20 marks) (c) Describe the Indian Seeds Act, 1966. Also discuss the essential activities required for the success of seed industry in India. (10 marks)
हिंदी में प्रश्न पढ़ें
(a) जाइलम में जलाभिगमन (वाटर ट्रांसपोर्ट) से आप क्या समझते हैं ? संसर्जन-तनाव (कोहेशन-टेंशन) सिद्धांत की व्याख्या कीजिए। (20 अंक) (b) वंशावली चयन विधि में चयनित पौधों तथा उनकी संततियों के बीच संबंधों का विस्तृत ब्यौरा (रिकॉर्ड) कैसे बनाया रखा जाता है ? एक साधारण व्यवस्था आरेख की सहायता से वंशावली चयन विधि की प्रक्रिया की विवेचना कीजिए। (20 अंक) (c) भारतीय बीज अधिनियम, 1966 का वर्णन कीजिए। भारत में बीज उद्योग की सफलता के लिए आवश्यक गतिविधियों की भी चर्चा कीजिए। (10 अंक)
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.
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 'explain' demands clear causal reasoning and mechanistic clarity. Allocate approximately 40% of time/words to part (a) given its 20 marks and conceptual depth, 35% to part (b) for its procedural complexity and diagram requirement, and 25% to part (c). Structure: brief introduction linking water transport to seed quality; body with three clearly demarcated sections; conclusion integrating plant physiology with seed industry policy.
Key points expected
- Part (a): Define xylem water transport; explain transpiration pull, cohesion (hydrogen bonding between water molecules), adhesion (water-to-xylem wall), and tension (negative pressure); mention Dixon and Joly's theory with evidence from pressure bomb experiments
- Part (b): Define pedigree selection as progeny testing with ancestral records; explain maintenance of pedigree records (plant-to-row, head-to-row, individual plant selection); schematic showing F1 to F6+ generations with selection stages and record-keeping symbols
- Part (c): Outline Seeds Act 1966 provisions (seed certification, truth-in-labeling, establishment of Central Seed Committee and Certification Agencies); identify essential activities: breeder seed production, foundation and certified seed multiplication, seed testing infrastructure, and farmer-extension linkages
- Integration point: Link water stress tolerance (part a) to seed quality maintenance in breeding programs (part b)
- Policy connection: Connect Seed Act 1966 to subsequent Seed Policy 2002 and private sector participation in hybrid seed development
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 25% | 12.5 | Precisely defines cohesion-tension mechanism with correct terminology (transpiration stream, cavitation, xylem sap tension); accurately describes pedigree selection as cyclic progeny testing with correct generation notation (F1-F6); correctly identifies Seeds Act 1966 as regulatory framework preceding 1988 amendments | Basic definitions correct but confuses cohesion-adhesion roles or misrepresents pedigree selection as mass selection; mentions Seeds Act without specific provisions | Fundamental errors: describes root pressure as primary mechanism, confuses pedigree with bulk selection, or conflates Seeds Act with Plant Variety Protection Act |
| Quantitative reasoning | 15% | 7.5 | Cites quantitative parameters: xylem water potential values (-0.5 to -3.0 MPa), tension magnitudes (up to 3 MPa in tall trees); indicates selection intensity percentages in pedigree method (5-10% plants selected); mentions seed replacement rates or certification percentages under Seeds Act | Vague references to 'high tension' or 'few plants selected' without numerical grounding; no quantitative data on seed industry | No quantitative elements; purely descriptive without any measurable parameters |
| Indian context examples | 15% | 7.5 | Cites Indian research: Bose Institute work on plant water relations; mentions ICAR pedigree selection programs (e.g., wheat varieties like HD-2285, rice like IR-36 development); references State Seed Certification Agencies (e.g., Maharashtra, Karnataka) and NSC/SSC role; notes Seed Village Programme integration | Generic mention of ICAR or Indian agriculture without specific varieties, institutions, or regional seed programs | No Indian examples; uses only foreign crop varieties or completely omits national context |
| Diagram / process | 25% | 12.5 | Clear schematic for part (b) showing: parental lines, F1 hybridization, selfing generations F2-F6, selection symbols (check marks, crosses), plant-to-row testing, and final variety release; diagram properly labeled with generation notation and selection percentages; may include xylem vessel cross-section for part (a) | Rough flowchart without proper generation labels or selection symbols; diagram present but incomplete or poorly integrated with text | No diagram despite explicit requirement; or diagram completely uninterpretable with no labels |
| Policy / extension angle | 20% | 10 | Critically examines Seeds Act 1966 limitations (lack of PVP, weak enforcement) leading to 2002 Policy and PPV&FR Act 2001; discusses seed industry success factors: public-private partnership, seed village concept, seed bank networks, and climate-resilient variety development linking back to water stress physiology | Descriptive coverage of Seeds Act provisions without critical evaluation; lists success factors without integration with broader agricultural policy | No policy analysis; treats Seeds Act as isolated fact; no connection between seed industry and extension systems |
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