Improvement in Food Resources – Case-based Questions with Answers
Class 9 • Biology
Chapter 7: Improvement in Food Resources — 20 Case-Based Questions & Answers
Instructions: Read each short case and answer the questions. Answers are concise, NCERT-focused and ideal for classroom discussion or board exam preparation. Use them to practise application of concepts from Chapter 7: Improvement in Food Resources.
Case 1: A farmer who used the same crop on his field for three consecutive seasons notices increasing pest damage and declining yields.
Q1: Explain the likely cause and suggest two measures the farmer can implement to restore productivity.
A1: Repeated monoculture leads to pest build-up and nutrient depletion. Measures: (1) Practice crop rotation or intercropping to break pest life cycles and restore soil fertility; (2) Use resistant varieties and integrated pest management (IPM) — biological control, cultural practices and targeted pesticides only when necessary.
Note: Crop rotation also improves soil nutrients by alternating legumes with cereals.
Case 2: Seeds of two wheat varieties — one certified high-yielding, one saved from last year — are available to a farmer. He wants quick good yields.
Q2: Recommend which seed to use and justify your answer. Mention any pre-sowing step to improve success.
A2: Use the certified high-yielding variety for reliable higher yield and disease resistance. Also perform seed treatment (with recommended fungicide/insecticide) to protect against seed-borne pathogens and improve germination.
Note: Saved seed might carry diseases or have lower vigour if not selected properly.
Case 3: A vegetable field has uneven water distribution; some patches are waterlogged while others show wilting.
Q3: Identify two probable causes and propose irrigation methods to correct this problem.
A3: Causes: poor leveling and unsuitable irrigation method (e.g., flood irrigation on uneven land). Solutions: (1) Level the field to ensure uniform water spread; (2) Adopt sprinkler or drip irrigation to provide uniform controlled water delivery and reduce waterlogging.
Note: Drip irrigation also conserves water and reduces disease incidence by keeping foliage dry.
Case 4: A paddy field shows patches where seedlings are stunted and display yellow leaves early in the season.
Q4: Suggest diagnostic checks and two corrective measures.
A4: Check for waterlogging, nutrient deficiency (especially nitrogen), and pest/disease symptoms. Corrective measures: (1) Test soil and apply appropriate fertiliser (e.g., nitrogen) as per recommendation; (2) Ensure proper drainage or adjust irrigation; if disease/pests present, use IPM measures.
Note: Yellowing from uniform deficiency usually indicates nutrient shortage; patchy symptoms may suggest disease.
Case 5: A cooperative notices increased costs from chemical fertilisers and wishes to maintain yields sustainably.
Q5: Propose an integrated nutrient strategy they can adopt and its benefits.
A5: Adopt Integrated Nutrient Management (INM): combine organic manures (FYM/compost/green manure) with targeted chemical fertilizers based on soil tests, and include biofertilisers (Rhizobium, Azotobacter). Benefits: reduced fertiliser cost, improved soil structure, sustained fertility, and better long-term yields.
Note: Soil testing guides precise fertiliser application and avoids overuse.
Case 6: A farm experiences bird damage to ripening grains every season.
Q6: Suggest three practical measures to reduce bird losses without harming bird populations.
A6: (1) Use physical deterrents — bird nets or scare devices (reflective tapes, scarecrows with variation); (2) Harvest timely or stagger planting to avoid peak vulnerability; (3) Grow sacrificial crops/alternate feeding areas to divert birds away from main crop. These are non-lethal methods conserving biodiversity.
Note: Avoid indiscriminate poisoning which harms ecosystems.
Case 7: A dairy farmer wants to increase milk yield of his herd over two seasons.
Q7: Recommend a short-term and a long-term plan covering nutrition and breeding.
A7: Short-term: Improve nutrition — balanced rations with adequate energy, protein, minerals, and clean water; ensure deworming and vaccination. Long-term: Implement selective breeding or cross-breeding with high-yielding breeds, adopt artificial insemination (AI) for superior sire genes, and maintain records to select best performers.
Note: Proper housing/hygiene also reduces mastitis and improves yields.
Case 8: A smallholder practices monoculture of a vegetable and faces soil-borne disease recurring every year.
Q8: Explain why disease recurs and suggest cultural practices to manage it.
A8: Continuous monoculture builds up soil-borne pathogen populations specific to that crop. Management: rotate crops with non-host species, practice sanitation (remove infected debris), use resistant varieties where available, and solarise or treat soil if feasible. Combine with organic amendments to boost soil microbial antagonists.
Note: Crop rotation reduces pathogen carryover and improves soil health.
Case 9: Farmers complain of declining fish production in community ponds despite similar stocking.
Q9: Identify possible reasons and suggest management improvements.
A9: Possible reasons: poor water quality (low dissolved oxygen), overstocking, inadequate feed or disease. Improvements: test and manage water quality (aeration), adjust stocking density, provide balanced feed and pond preparation (liming, removal of predators), and practice disease prevention through biosecurity and healthy fingerlings.
Note: Integrated fish farming can improve input efficiency.
Case 10: A farmer uses high doses of pesticides but still sees pest resurgence annually.
Q10: Explain why this might happen and recommend IPM steps to break the cycle.
A10: Overuse of pesticides can kill natural enemies and cause pest resistance, leading to resurgence. IPM steps: monitor pest levels, conserve/promote natural predators (biocontrol), use pheromone traps, adopt cultural controls (timing, sanitation), apply selective pesticides only when thresholds are exceeded, and rotate chemical classes to avoid resistance.
Note: Farmer education on pesticide judiciousness is critical.
Case 11: A cooperative wants to improve seed availability to member farmers with limited funds.
Q11: Suggest an economically viable approach to ensure access to quality seed.
A11: Form a seed bank or community seed production initiative—multiply certified seeds locally during season, store properly, and distribute at subsidised rates. Train farmers in seed selection and storage; partner with government schemes for seed subsidies. This reduces dependency on commercial seed purchases.
Note: Proper storage prevents loss of seed viability.
Case 12: After heavy rains, a farmer observes increased fungal diseases in his crop.
Q12: Explain environmental factors favouring fungal outbreaks and recommend preventive measures.
A12: High humidity, prolonged leaf wetness and moderate temperatures favour fungal growth and spore germination. Preventive measures: ensure proper plant spacing for air circulation, avoid overhead irrigation or water at times that allow foliage to dry, apply disease-free seeds, use resistant varieties, and employ timely fungicide sprays as part of IPM when necessary.
Note: Field hygiene and removal of infected debris reduce inoculum sources.
Case 13: A student preparing for exams must demonstrate how to reduce post-harvest losses of grains at village level.
Q13: List three simple, low-cost methods to reduce post-harvest losses in grains.
A13: (1) Dry grains thoroughly to safe moisture (sun-drying on clean platforms); (2) Use clean, rodent-proof storage (elevated bins or sealed containers) and practice periodic inspection; (3) Use simple solar dryers or improved storage sacks (hermetic bags) to reduce insect and fungal damage.
Note: Cleanliness during threshing and handling reduces contamination risk.
Case 14: An entrepreneur wants to start a small poultry unit but is concerned about disease risks.
Q14: Advise on two housing and two health-management practices to minimise disease outbreaks.
A14: Housing: provide well-ventilated, dry, easy-to-clean coops with adequate space and proper drainage. Health management: implement vaccination schedules (e.g., for Newcastle, Marek's), regular deworming, and strict biosecurity (restrict visitors, disinfect footwear/equipment).
Note: Early detection and isolation of sick birds limit spread.
Case 15: A farmer uses chemical fertiliser excessively and notices patches of scorched crops.
Q15: Explain the cause and recommend corrective steps and long-term prevention.
A15: Excess fertiliser (especially urea or salts) can cause fertiliser burn due to high salt concentration and osmotic stress. Immediate corrective step: flush soil with water if possible to leach excess salts; apply organic matter to buffer soils. Long-term: adopt soil testing to apply recommended doses, integrate manures with fertilisers, and use split applications timed to crop needs.
Note: Over-fertilisation also causes environmental pollution (nitrate leaching).
Case 16: A village cooperative plans to adopt organic farming on marginal lands to earn premium prices.
Q16: Outline a transition plan (3 steps) and mention one potential economic challenge.
A16: Transition plan: (1) Phase out synthetic chemicals and start building soil fertility with compost and green manures; (2) Implement IPM and biological pest controls; (3) Obtain organic certification and develop market linkages for premium sale. Economic challenge: initial yield drop and certification costs may reduce short-term income; market access and premiums are required to offset this.
Note: Farmer training and cooperative marketing mitigate risks.
Case 17: A student wants to model the effect of irrigation on yield in a small experiment.
Q17: Suggest a simple experimental design and two variables to measure.
A17: Design: Grow identical crop plots with varying irrigation regimes (e.g., no irrigation, weekly, drip). Keep other factors constant (same seed, fertiliser, spacing). Measure variables: (1) plant growth/yield per plot, (2) soil moisture content or water used per plot to calculate water-use efficiency. Analyse results to relate irrigation frequency/method to yield and efficiency.
Note: Replicates improve experiment reliability.
Case 18: A farmer wants to adopt a high-yielding variety (HYV) but worries about seed cost every year.
Q18: Explain why HYV seeds are often bought each season and suggest an alternative strategy to reduce costs.
A18: Many HYVs (especially F1 hybrids) lose hybrid vigour in saved seed generations, so farmers buy fresh F1 seeds annually. Alternative: use improved open-pollinated varieties (OPVs) that allow seed saving, or join cooperatives to bulk-purchase certified seed, or invest in community seed production to lower costs.
Note: Seed choice depends on economics and desired traits.
Case 19: After introducing a new pesticide, beneficial ladybird beetles decline while pest populations later increase.
Q19: Explain ecological reason for this observation and suggest sustainable pest control steps.
A19: Non-selective pesticide killed natural enemies (ladybirds), removing biological control and allowing pest resurgence. Sustainable steps: use selective pesticides, promote biological control (release/ conserve predators), use cultural practices, and monitor before chemical application as part of IPM.
Note: Encourage biodiversity to stabilise pest populations.
Case 20: A farmer cooperative wishes to reduce post-harvest grain losses and improve marketability.
Q20: Suggest a low-cost post-harvest strategy and one value-addition that can increase farmer income.
A20: Strategy: implement community-level clean drying platforms and hermetic (airtight) storage bags to reduce insect/fungal losses. Value-addition: small-scale processing like milling and packaging graded flour or pulses with labelling to fetch better prices and open new markets.
Note: Collective action reduces individual costs and improves bargaining power.