Q8
(a) Explain the mode of action of organophosphate and Bacillus thuringiensis which are used in pest management. (20 marks) (b) What is phytochrome? Discuss its two forms and differentiate them. (20 marks) (c) Discuss the reasons for gap between production and consumption of cereals in the country. How can it be rectified? (10 marks)
हिंदी में प्रश्न पढ़ें
(a) नाशीजीव प्रबंधन में उपयोग में आने वाले ऑर्गेनोफॉस्फेट और बैसिलस थुरिंजिएंसिस की क्रियाविधि की व्याख्या कीजिए। (20 अंक) (b) फाइटोक्रोम क्या होता है? इसके दो रूपों एवं उनमें भिन्नता का वर्णन कीजिए। (20 अंक) (c) देश में अनाज की फसलों के उत्पादन एवं उपभोग में अंतर के कारणों की चर्चा कीजिए। इसको कैसे ठीक किया जा सकता है? (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 mechanisms and processes. Allocate approximately 40% of time/words to part (a) given its 20 marks, 35% to part (b) for its conceptual depth, and 25% to part (c). Structure: brief introduction acknowledging integrated pest management and food security context; body addressing each sub-part sequentially with clear sub-headings; conclusion synthesizing how scientific pest management and post-harvest interventions together ensure cereal security.
Key points expected
- Part (a): Organophosphates inhibit acetylcholinesterase enzyme leading to nerve impulse accumulation; Bt produces Cry proteins that bind to midgut epithelial receptors causing osmotic lysis in susceptible insects
- Part (a): Specificity differences—organophosphates are broad-spectrum neurotoxins affecting mammals/birds; Bt is target-specific with minimal non-target effects, making it compatible with IPM
- Part (b): Phytochrome as photoreversible chromoprotein with phytochromobilin chromophore; Pr (red-absorbing, 660nm, biologically inactive) and Pfr (far-red absorbing, 730nm, active form) with photoconversion mechanism
- Part (b): Physiological roles—seed germination, shade avoidance, photoperiodism/flowering; differential table contrasting absorption peaks, stability, dark reversion, and biological functions
- Part (c): Production-consumption gap drivers—post-harvest losses (FCI estimates 10-15%), distribution inefficiencies, MSP vs market price distortions, changing dietary preferences, export-import imbalances
- Part (c): Rectification strategies—improved storage (PUSA bin, hermetic storage), FCI decentralization, NFSA targeting, value addition/processing infrastructure, crop diversification incentives
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 25% | 12.5 | Precise biochemical mechanisms: acetylcholinesterase inhibition and synaptic transmission disruption for organophosphates; Cry protein structure, receptor binding, and pore formation for Bt; accurate phytochrome photoconversion kinetics and physiological role specificity; correct identification of gap drivers without conflating production deficits with distribution failures | General description of toxicity and biological control without molecular detail; basic Pr/Pfr distinction without photoconversion explanation; generic mention of 'wastage' without distinguishing harvest, storage, and consumption losses | Confusion between organophosphates and organochlorines; describing Bt as chemical pesticide rather than biological agent; equating phytochrome with chlorophyll; attributing gap solely to low production without structural analysis |
| Quantitative reasoning | 15% | 7.5 | Specific wavelengths (660nm/730nm) for phytochrome forms; approximate quantum efficiency or photostationary state ratios; current cereal production figures (~230-240 MT), buffer stock norms (41 MT), actual losses (~16% per PHL Committee), import dependency for specific cereals | Round-number estimates for production; general awareness that losses exceed 10%; qualitative mention of wavelength differences without specific values | No quantitative data; incorrect orders of magnitude; confusing area under cultivation with production volumes |
| Indian context examples | 20% | 10 | Bt cotton adoption in India (95%+ area) and associated controversies; specific organophosphate poisoning incidents (Kerala endosulfan, Punjab monocrotophos); FCI storage capacity constraints and decentralized procurement (DCP) states; NFSA coverage and exclusion errors; Operation Greens or PM-FME scheme relevance | Generic mention of Green Revolution states; awareness that Bt cotton is widely grown; general reference to PDS without specificity | No Indian examples; using exclusively Western agricultural systems; irrelevant examples from non-cereal crops |
| Diagram / process | 20% | 10 | Clear synaptic transmission diagram showing acetylcholinesterase function and organophosphate blockade; Bt toxin mode of action flowchart (solubilization, processing, binding, pore formation); phytochrome photoconversion cycle diagram with wavelength arrows; post-harvest loss chain diagram from farm to plate | Simple block diagrams without molecular detail; basic Pr/Pfr interconversion sketch; list format for loss points without visual flow | No diagrams where clearly needed; incorrect or misleading diagrams; diagrams without labeling or explanation in text |
| Policy / extension angle | 20% | 10 | IPM promotion through SAFAL, APMC reforms for better price realization; FCI restructuring recommendations (Shanta Kumar Committee); buffer stock policy rationalization; crop diversification incentives in Punjab-Haryana; integration of Bt with refuge strategy and resistance management protocols | Generic mention of IPM and PDS improvement; awareness of FCI issues without specific reform proposals | No policy recommendations; purely technical answer without institutional or governance dimensions; outdated or irrelevant policy references |
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