How to Use This Page
These are complete exercise solutions for Samacheer Kalvi 9th Science Chapter — Economic Biology. Solve each question yourself first, then verify your method and answer below. Focus on examples, classifications, and comparisons — these are the most frequently tested areas.
Key Concepts (Quick Recap)
- Economic biology: Study of organisms of commercial value — food crops, fibre crops, medicinal plants, livestock, poultry, fish, silkworms, honey bees.
- Crop improvement: Increasing yield through selection, hybridization, and biotechnology. Green revolution (food grains), white revolution (milk), blue revolution (fisheries).
- Animal husbandry: Scientific management of livestock for food (milk, meat, eggs), fibre (wool), and labour. Includes breeding, feeding, housing, and disease control.
- Poultry farming: Rearing domesticated birds (chicken, duck, turkey) for meat and eggs. Breeds: indigenous (Aseel, Chittagong) and exotic (Leghorn, Plymouth Rock).
- Sericulture: Rearing silkworms for silk production. Species: Mulberry silkworm (Bombyx mori), Eri, Tasar, Muga. Stages: egg → larva → pupa (cocoon) → adult moth.
- Aquaculture: Cultivation of aquatic organisms — fish (pisciculture), prawns, crabs, molluscs, seaweed. Types: freshwater, brackish water, marine.
- Beekeeping (Apiculture): Rearing honey bees for honey and wax. Species: Apis dorsata (rock bee), Apis florea (little bee), Apis indica (Indian bee), Apis mellifera (Italian bee).
- Sustainable agriculture: Farming that meets current food needs without compromising future productivity — organic farming, crop rotation, integrated pest management, water conservation.
I. Choose the Correct Answer
Q1. The high-yielding variety of wheat that contributed to the Green Revolution in India is: (a) IR-8 (b) Sonalika ✓ (c) CO-1 (d) Pokkali
Answer(b) ✓ — Sonalika and Kalyan Sona are high-yielding wheat varieties introduced during the Green Revolution. IR-8 is a rice variety.
Q2. Which revolution is associated with increased milk production? (a) Green revolution (b) Blue revolution (c) White revolution ✓ (d) Yellow revolution
Answer(c) ✓ — White revolution (Operation Flood) was led by Dr. Verghese Kurien and increased India's milk production through dairy cooperatives.
Q3. The scientific name of the mulberry silkworm is: (a) Antheraea paphia (b) Bombyx mori ✓ (c) Attacus ricini (d) Apis mellifera
Answer(b) ✓ — Bombyx mori is the mulberry silkworm, the most commercially important silk-producing species.
Q4. Which of the following is an indigenous breed of poultry? (a) Leghorn (b) Plymouth Rock (c) Aseel ✓ (d) Rhode Island Red
Answer(c) ✓ — Aseel is an indigenous Indian breed known for fighting ability. Leghorn, Plymouth Rock, and Rhode Island Red are exotic breeds.
Q5. Apiculture refers to: (a) Rearing of silkworms (b) Rearing of honey bees ✓ (c) Rearing of fish (d) Rearing of cattle
Answer(b) ✓ — Apiculture (api = bee, culture = rearing) is the rearing of honey bees for honey and beeswax.
Q6. Blue revolution is related to: (a) Milk production (b) Food grain production (c) Fisheries and aquaculture ✓ (d) Oilseed production
Answer(c) ✓ — Blue revolution refers to the increase in fish production through aquaculture and modern fisheries management.
Q7. The larval stage of a silkworm that spins the cocoon is called: (a) Caterpillar ✓ (b) Pupa (c) Imago (d) Nymph
Answer(a) ✓ — The caterpillar (larva) spins the silk cocoon. Inside the cocoon, it transforms into a pupa.
Q8. Which honey bee species is known as the rock bee? (a) Apis florea (b) Apis indica (c) Apis dorsata ✓ (d) Apis mellifera
Answer(c) ✓ — Apis dorsata is the rock bee, the largest Indian honey bee species, building large combs on tall trees and buildings.
Q9. Cross-breeding indigenous cattle with exotic breeds mainly aims to: (a) Increase draught power (b) Improve milk yield ✓ (c) Reduce fodder requirement (d) Increase body size only
Answer(b) ✓ — Cross-breeding (e.g., Jersey × Sahiwal, Holstein × Tharparkar) aims to combine the disease resistance of indigenous breeds with the high milk yield of exotic breeds.
Q10. The process of giving birth to young ones in cattle is called: (a) Lactation (b) Gestation (c) Parturition ✓ (d) Fertilisation
Answer(c) ✓ — Parturition is the act of giving birth. Gestation is the pregnancy period; lactation is milk production.
II. Fill in the Blanks
1. The Green Revolution was initiated by Dr. M.S. Swaminathan in India. 2. The high-yielding rice variety developed during the Green Revolution is IR-8. 3. White revolution is also called Operation Flood. 4. Bombyx mori feeds on mulberry leaves. 5. The largest species of honey bee in India is Apis dorsata (rock bee). 6. The rearing of silkworms for silk production is called sericulture. 7. Eri silkworm feeds on castor leaves. 8. The scientific name of the Indian honey bee is Apis indica. 9. Pisciculture is the rearing of fish. 10. Sustainable agriculture avoids excessive use of chemical fertilizers and pesticides.
III. True or False
1. Economic biology deals only with crop plants.
AnswerFalse — Correction: Economic biology covers both plants and animals of commercial importance, including livestock, poultry, fish, silkworms, and honey bees.
2. Bombyx mori is a mulberry silkworm.
AnswerTrue ✓
3. The cocoon of a silkworm is made of a single continuous silk thread.
AnswerTrue ✓ — A single cocoon yields approximately 1000–1500 metres of continuous silk filament.
4. Exotic breeds of poultry are always better than indigenous breeds.
AnswerFalse — Correction: Exotic breeds have higher egg/meat production but indigenous breeds like Aseel are more resistant to diseases and better adapted to local conditions.
5. Aquaculture includes only marine fish farming.
AnswerFalse — Correction: Aquaculture includes freshwater, brackish water, and marine cultivation of fish, prawns, crabs, molluscs, and seaweed.
6. Apis mellifera is an Indian honey bee species.
AnswerFalse — Correction: Apis mellifera is the Italian honey bee, introduced to India for higher honey yield. Apis indica is the Indian honey bee.
7. Sustainable agriculture promotes the use of chemical pesticides.
AnswerFalse — Correction: Sustainable agriculture promotes organic farming, bio-pesticides, and integrated pest management (IPM) to minimise chemical use.
8. Tasar silk is obtained from Antheraea paphia.
AnswerTrue ✓
IV. Match the Following
Set 1:
| Column I | Column II |
|---|
| 1. Green Revolution | (d) Food grain production |
| 2. White Revolution | (a) Milk production |
| 3. Blue Revolution | (e) Fisheries |
| 4. Yellow Revolution | (b) Oilseed production |
| 5. Golden Revolution | (c) Horticulture and honey |
Set 2:
| Column I | Column II |
|---|
| 1. Bombyx mori | (e) Mulberry silk |
| 2. Apis dorsata | (a) Rock bee |
| 3. Aseel | (c) Indigenous poultry breed |
| 4. Antheraea paphia | (d) Tasar silk |
| 5. Leghorn | (b) Exotic poultry breed |
V. Short Answers
Q1. Define economic biology.
Answer
Economic biology is the branch of biology that studies plants and animals of commercial importance to human beings. It covers food crops, fibre crops, medicinal plants, livestock, poultry, fish, silkworms, and honey bees, along with practices to improve their yield and quality.
Q2. What is crop improvement? Mention its objectives.
Answer
Crop improvement is the process of developing crop varieties with higher yield, better quality, and resistance to diseases and pests.
Objectives: (1) Increase yield per hectare, (2) Improve nutritional quality, (3) Develop disease and pest resistance, (4) Adapt crops to different climatic conditions, (5) Reduce maturation time.
Q3. Differentiate between indigenous and exotic breeds of poultry.
Answer
| Feature | Indigenous Breeds | Exotic Breeds |
|---|
| Origin | Native to India | Imported from other countries |
| Examples | Aseel, Chittagong, Busra | Leghorn, Plymouth Rock, Rhode Island Red |
| Egg production | Moderate | High |
| Disease resistance | High | Moderate |
| Body size | Small to medium | Large |
| Adaptability | Well adapted to local climate | Require controlled conditions |
Q4. What is sericulture? Name the types of silk.
Answer
Sericulture is the rearing of silkworms for the production of silk.
Types of silk in India: 1. Mulberry silk — from Bombyx mori (most common, ~80% of Indian silk) 2. Tasar silk — from Antheraea paphia ( tasar/teak silkworm) 3. Eri silk — from Attacus ricini (castor silkworm) 4. Muga silk — from Antheraea assama (Assam, golden silk)
Q5. What is aquaculture? Name two freshwater fish species cultured in India.
Answer
Aquaculture is the cultivation of aquatic organisms — fish, prawns, crabs, molluscs, and seaweed — under controlled conditions for food and commercial purposes.
Two freshwater fish species: (1) Catla (Catla catla), (2) Rohu (Labeo rohita).
Q6. List the factors essential for good animal husbandry.
Answer
1. Proper breeding (selection of high-yielding breeds) 2. Balanced and nutritious feed/fodder 3. Clean and ventilated shelter 4. Regular health monitoring and vaccination 5. Clean water supply 6. Proper waste management
VI. Detailed Answers
Q1. Explain the life cycle of a silkworm with a diagram description.
Answer
The silkworm undergoes complete metamorphosis with four stages:
1. Egg: Female moth lays 300–500 tiny eggs on mulberry leaves. Eggs hatch in 7–15 days depending on temperature. 2. Larva (Caterpillar): The larva hatches and feeds voraciously on mulberry leaves. It moults four times (five instar stages). The mature caterpillar is about 6–8 cm long. It then secretes a sticky fluid from its silk glands that hardens on contact with air, spinning a cocoon around itself. 3. Pupa: Inside the cocoon, the caterpillar transforms into a pupa. This is the stage from which silk is harvested — the cocoons are boiled to kill the pupa and unwind the silk thread. 4. Adult (Moth): The pupa develops into an adult moth that emerges from the cocoon. The moth mates, lays eggs, and the cycle repeats.
Q2. Describe beekeeping (apiculture). Name the species of honey bees found in India and their products.
Answer
Beekeeping (apiculture) is the rearing of honey bees in artificial hives for the production of honey and beeswax.
Honey bee species in India: 1. Apis dorsata (Rock bee) — largest, wild, builds combs on tall trees/buildings, yields the most honey per colony 2. Apis florea (Little bee) — smallest, wild, builds small combs on bushes 3. Apis indica (Indian bee) — medium-sized, can be domesticated 4. Apis mellifera (Italian bee) — introduced exotic species, high honey yield, most commonly reared in apiaries
Products of beekeeping: 1. Honey — natural sweetener, energy food, and medicine (antibacterial properties) 2. Beeswax — used in cosmetics, polishes, candles, and modelling 3. Royal jelly — nutritious secretion fed to queen larvae, used in health supplements 4. Propolis — resinous substance used to seal gaps, has antimicrobial properties 5. Venom — used in certain medical treatments (apitherapy)
Importance of beekeeping: Pollination by bees increases crop yield by 20–25% in many fruits and vegetables.
Q3. Explain the different types of aquaculture and their importance.
Answer
Types of aquaculture: 1. Freshwater aquaculture: Cultivation in ponds, tanks, lakes, and reservoirs. Major species: Catla, Rohu, Mrigal (Indian major carps), Common carp. 2. Brackish water aquaculture: Cultivation in estuaries and backwaters where river water mixes with seawater. Major species: Tiger shrimp (Penaeus monodon), mud crabs, grey mullet. 3. Marine aquaculture (Mariculture): Cultivation in coastal seawater. Major species: Seaweed, mussels, oysters, marine finfish.
Importance of aquaculture: 1. Provides high-quality protein-rich food (fish is a cheap protein source) 2. Generates employment in rural and coastal areas 3. Earns foreign exchange through seafood exports 4. Supplements declining capture fisheries 5. Integrated fish farming (fish + poultry + paddy) increases farm income 6. Blue revolution increased India's fish production significantly
Q4. Discuss sustainable agriculture and its practices.
Answer
Sustainable agriculture is the practice of farming that meets present food and fibre needs without compromising the ability of future generations to meet their own needs.
Key practices: 1. Organic farming: Avoiding synthetic fertilizers and pesticides; using compost, green manure, and bio-fertilizers. 2. Crop rotation: Alternating different crops on the same land to maintain soil fertility (e.g., legumes fix nitrogen, enriching soil for the next cereal crop). 3. Integrated Pest Management (IPM): Combining biological control (predators/parasites), mechanical methods, and minimal chemical use to control pests. 4. Water conservation: Drip irrigation, rainwater harvesting, mulching to reduce evaporation. 5. Bio-fertilizers and bio-pesticides: Using Rhizobium, Azotobacter for nitrogen fixation; neem-based pesticides instead of synthetic chemicals. 6. Vermicomposting: Using earthworms to convert organic waste into nutrient-rich compost. 7. Agroforestry: Growing trees along with crops to prevent soil erosion and improve biodiversity.
Benefits: Preserves soil health, reduces chemical residues in food, protects biodiversity, ensures long-term food security, and lowers farming costs.
Common Mistakes
1. Confusing revolutions — Green (food grains), White (milk), Blue (fisheries), Yellow (oilseeds), Golden (horticulture/honey). Each is specific. 2. *Calling Apis mellifera an Indian bee — It is the Italian bee, introduced to India for higher yield. Apis indica is the native Indian bee. 3. Equating aquaculture with pisciculture only — Aquaculture is broader; pisciculture is only fish farming. Aquaculture also includes prawns, crabs, molluscs, and seaweed. 4. Confusing Tasar and Eri silkworms — Tasar silkworm (Antheraea paphia) feeds on tasar/teak/arjun leaves; Eri silkworm (Attacus ricini*) feeds on castor leaves. 5. Saying sustainable agriculture means no chemicals at all — IPM allows minimal, targeted chemical use; the goal is reduction, not necessarily total elimination. 6. Forgetting pollination role of bees — Beekeeping is not just about honey; pollination by bees increases crop yields by 20–25%. 7. Writing "sericulture = silk production" without the worm name — Always specify the silkworm species and its host plant.
Exam Checklist
- [ ] Definitions: economic biology, crop improvement, animal husbandry, sericulture, aquaculture, apiculture, sustainable agriculture
- [ ] Revolutions and their leaders: Green (M.S. Swaminathan), White (Verghese Kurien), Blue, Yellow, Golden
- [ ] Silkworm life cycle (egg → larva → pupa → adult) and species–silk mapping (Mulberry, Tasar, Eri, Muga)
- [ ] Honey bee species (Apis dorsata, florea, indica, mellifera) and products (honey, wax, royal jelly)
- [ ] Indigenous vs exotic poultry breeds with examples
- [ ] Freshwater fish species (Catla, Rohu, Mrigal) and aquaculture types
- [ ] Sustainable agriculture practices (organic farming, IPM, crop rotation, vermicomposting)
- [ ] Cross-breeding objectives in cattle improvement
Internal Links
- [Economic Biology Chapter Guide](/school/tamil-nadu-state-board/class/9/science/economic-biology)
- [All Class 9 Science Solutions](/school/tamil-nadu-state-board/class/9/science/solutions)
- [Class 9 Science Subject Guide](/school/tamil-nadu-state-board/class/9/science)
