Revision: Biology and Human Welfare >> Strategies for Enhancement in Food Production Biology (Theory) ISC (Science) ISC Class 12 CISCE

The method of producing new crop varieties in which two or more plants of unlike genetical constitution are crossed together is known as hybridization.

The increased superiority of hybrids over their parents in terms of growth, yield, vigour and adaptability is called hybrid vigour.

Induced mutation is a mutation that is artificially produced using mutagenic agents.

'Ex vivo growth of cells or tissues in an aseptic and nutrient-rich medium’ is called tissue culture.

or

Tissue culture is the technique of growing plant cells, tissues or organs under controlled laboratory conditions for crop improvement.

A group of cells having the same origin, same structure and same function is called ‘tissue’.

Single Cell Protein is the microbial biomass obtained from bacteria, yeasts, fungi or algae and used as a source of protein for human food or animal feed.

Biofortification is the breeding of crop plants to increase their content of vitamins, minerals, proteins or healthy fats in order to improve human nutrition and public health.

Breeding between a superior male of one breed with a superior female of another breed is known as cross-breeding.

Apiculture is the rearing of honey bees for honey. It is called Beekeeping.

The rearing of honey bee to obtain honey and other commercially important products is known as apiculture or bee‑keeping.

Pisciculture (fishery) is the practice of breeding, rearing and harvesting fish in natural or artificial water bodies for food and other economic uses.

Pisciculture or Fish culture is the process of breeding and rearing fishes in ponds, reservoirs (dams), lakes, rivers, and paddy fields.

• Green Revolution refers to the collective methods used to obtain maximum agricultural yield from minimum land to overcome food scarcity caused by population explosion.
• Development of high-yielding dwarf varieties of wheat and rice, along with proper use of fertilizers, pesticides, and water management, greatly increased food grain production.
• Dr. Norman Borlaug and Dr. M. S. Swaminathan played key roles in the Green Revolution, supported by research institutes like IARI, New Delhi, and other national agricultural research centers.

• Selection is the oldest plant breeding method and involves choosing plants with desirable characters and eliminating undesirable ones.
• Domestication led to continuous improvement of crops, making cultivated plants very different from their wild ancestors.
• Human selection favored useful traits such as non-shattering ears in wheat and tightly embedded seeds in maize.
• Repeated selection over generations stabilized desirable characters while unwanted traits were gradually lost.
• Limitation of conventional breeding includes being time-consuming and restricted by natural crossing barriers, leading to the development of modern methods like mutation breeding, tissue culture, and genetic manipulation.

• Plant breeding for disease resistance develops crop varieties that can resist fungal, bacterial, and viral diseases.
• Resistance is achieved using methods like selection, hybridization, mutation breeding, and transfer of genes from resistant wild plants.
• This approach increases crop yield, reduces losses, and improves food production.

• Plant breeding for insect-pest resistance develops crop varieties that can withstand damage caused by insect pests.
• Resistance in plants occurs due to morphological, biochemical, or physiological traits such as hairy leaves, solid stems, or altered chemical composition.
• Resistance genes are obtained from cultivated varieties, germplasm collections, or wild relatives and introduced through selection and hybridization.

• Principle — Based on Totipotency — the ability of a single plant cell to grow, divide, and develop into a whole new plant.
• Explant — The part of the plant used in tissue culture (e.g., leaf, stem, root piece).
• Medium — Contains minerals, carbohydrates, proteins, fats, water, growth hormones, vitamins, and agar. MS medium is commonly used.
• Conditions — Aseptic, Temp: 18–20°C, pH: 5–5.8, with aeration for suspension culture.
• Steps in Order — Clean glassware → Prepare nutrient medium → Prepare explant → Inoculate in culture flask → Incubate (callus forms) → Subculture → Organogenesis → Hardening → Transfer to field.
• Types Based on Explant — Cell culture, Organ culture, Embryo culture.
• Types Based on In Vitro Growth — Callus culture uses a solid medium to form undifferentiated cells (callus) that can become organs/plantlets. Suspension culture uses a liquid medium constantly agitated by a shaker.

• Micropropagation – Rapid clonal multiplication of genetically identical plants (somaclones) in a short time; widely used for banana, potato, coconut and ornamentals.
• Production of disease-free plants – Virus-free plants are produced through shoot apical meristem culture, especially in banana, potato, sugarcane and citrus.
• Production of haploids – Anther and pollen culture produce haploid plants, helping in quick development of pure homozygous lines and reducing breeding time.
• Embryo rescue – Immature or aborting embryos from difficult crosses are cultured to obtain viable hybrid plants, especially in fruit crops.
• Induction and selection of mutants – Mutations are induced in cell cultures using chemicals, and useful resistant mutants are selected and regenerated.
• Somaclonal variation – Genetic variability produced during tissue culture is used to develop disease-resistant, early-maturing and high-yielding varieties.
• Protoplast technology and somatic hybridization – Fusion of protoplasts from different species enables transfer of useful genes beyond sexual compatibility barriers.

• Meaning — SCP is a crude or refined edible protein extracted from pure microbial cultures or dead/dried cell biomass. Its importance was first realised during World War I.
• Microorganisms Used — Fungi: Aspergillus niger, Trichoderma viride. Yeast: S. cerevisiae, Candida utilis. Algae: Spirulina, Chlorella. Bacteria: Methylophilus methylotrophus, Bacillus megasterium.
• Substrates Used — Microbes are grown on cheap/waste materials like sawdust, corn cobs, sugarcane molasses, agricultural waste, and even human & animal wastes.
• Nutritional Value — SCP contains 43–85% protein, vitamins (esp. Vitamin B complex), minerals, amino acids & fats. Used as a supplement in human and animal feed.
• Advantages — Fast multiplication of microbes → large biomass quickly. Can be genetically modified | Reduces pollution by using waste as substrate. Solves protein malnutrition.

• Meaning — Biofortification is the method of breeding crops for higher levels of vitamins, minerals and fats to improve nutritive value and overcome malnutrition.
• Methods — Achieved through conventional selective breeding or r-DNA technology. Nutrients can also be supplemented from outside.
• Objectives — Improving protein content & quality, oil content & quality, vitamin content, and micronutrient content & quality.
• Examples — Maize → 2x lysine & tryptophan, Wheat Atlas 66 → high protein, Rice → 5x more iron, Carrot & Spinach → more Vitamin A & minerals.
• IARI Contribution — Vitamin C-enriched bitter gourd and tomato were developed by IARI (Indian Agricultural Research Institute).

• Meaning — Artificial rearing of honey bees to obtain honey, wax, pollen, bee venom, propolis & royal jelly. Ancient cottage industry.
• 4 Species in India — Apis dorsata (rock bee), Apis florea (little bee), Apis mellifera (European), Apis indica (Indian). Mellifera & Indica = domesticated species.
• Requirements — Areas with shrubs, orchards & crops. Equipment: hive boxes, smoker, bee veil, gloves, uncapping knife, queen excluder.
• Management — Periodic inspection of cleanliness, queen activity, brood condition & water supply is necessary.
• Importance — Honey = nutritious + medicinal. Bees pollinate sunflowers, mustard, apples, mangoes, and citrus → increases crop productivity.

• Meaning — Dairying is the management of animals for milk and milk products for human consumption. It deals with increasing yield and improving quality of milk.
• Key Factor — Milk yield primarily depends on the quality of breeds — high-yielding potential combined with disease resistance.
• Breeds — Indian cow breeds: Sahiwal, Sindhi, Gir | Exotic breeds: Jersey, Brown Swiss, Holstein | Buffalo breeds: Jaffarabadi, Murrah, Nagpuri, Nili, Mehsana, Surati.
• Importance of Cattle — Provide milk, hides, horns, hooves, blood, fat. Bullocks used for ploughing, harrowing, threshing & transporting produce.
• By-products — Cattle dung used as fuel, biogas generation & manure. Livestock plays a significant role in Indian agriculture.

• India has one of the largest livestock populations in the world, with a major contribution from cattle and buffaloes to the rural and national economy.
• Proper cattle feeding includes roughage (fodder, hay, straw) and concentrates (oil cakes, grains, seeds) along with adequate water supply.
• Indian cattle breeds are hardy and disease-resistant and are classified as milch, draught and general utility breeds based on their use.
• Important indigenous milch breeds include Gir, Sahiwal and Red Sindhi, while Murrah is a well-known buffalo breed for high milk yield.
• Milk production has increased significantly through cross-breeding indigenous cattle with exotic breeds like Holstein-Friesian, Jersey and Brown Swiss.

• MOET (Multiple Ovulation and Embryo Transfer) is a technique used to rapidly improve the genetic quality and milk production of cattle.
• In this method, genetically superior cows are induced to produce multiple eggs (superovulation), which are fertilised and collected as embryos.
• The collected embryos are transferred into low-yielding cows (surrogate mothers) where they develop into healthy calves.
• Embryos can be frozen at very low temperatures (-196 °C) and stored for long periods for future use.
• MOET allows production of many superior calves from one cow in a year, making it faster and cheaper than natural breeding or importing cows.

• Meaning — Breeding & raising livestock to increase yield and improve desirable qualities (milk, meat, eggs).
• Inbreeding — Closely related individuals bred for 4–6 generations → increases homozygosity, eliminates harmful genes. Demerit: reduces fertility.
• Outbreeding — Unrelated animals, no common ancestor for 4–6 generations → removes inbreeding depression.
• Types of Outbreeding — Outcrossing (same breed), Crossbreeding (different breeds), Interspecific hybridisation (different species).
• Examples — Hisardale sheep = Bikaneri ewe × Marino ram | Mule = Horse × Donkey.
• Artificial Insemination (AI) — Semen from a superior male → frozen/preserved → injected into the female's genital tract.
• MOET — FSH given to cow → superovulation (6–8 eggs) → blastocysts (8–32 cell stage) transferred to surrogate mothers.

• Livestock development in India is managed by the Department of Animal Husbandry, Dairying & Fisheries to improve production and quality of livestock.
• Institutions like ICAR and NBAGR work for conservation, genetic improvement and scientific breeding of indigenous and exotic cattle breeds.
• Central Cattle Breeding Farms support artificial insemination, progeny testing and farmer training to enhance dairy productivity.
• Rapid growth of the dairy sector has made India the world’s largest milk producer with improved per capita milk availability.

• Meaning — Poultry includes domesticated birds (chicken, duck, turkey, fowl) raised for eggs and meat. Allied professions include feed, marketing, pharmaceuticals & equipment.
• Breeds by Origin — American: Plymouth Rock, New Hampshire, Rhode Island Red, Asiatic: Brahma, Cochin, Langshan, Mediterranean: Leghorn, Minorca, English: Australorp, Indian: Chittagong, Aseel, Kadaknath.
• Layers vs Broilers — Leghorn = best layer (eggs). Plymouth Rock, Rhode Island Red, Aseel, Brahma, Kadaknath = preferred broilers (meat).
• Farm Management — Requires disease-free breed, proper feed & water, hygiene, vaccination, ventilation, lighting, sanitation & culling.
• Poultry Diseases — Viral: Ranikhet, Bird flu, Bacterial: Pullorum, Cholera, TB, CRD, Fungal: Aspergillosis, Favus, Parasitic: Lice, Roundworm, Protozoan: Coccidiosis.

1. Incubation and brooding involve maintaining eggs under optimal conditions for hatching and caring for chicks for the first 4–6 weeks, either naturally or artificially.
2. Fowl housing must be clean, well-ventilated, dry and spacious, with separate arrangements for birds of different ages and proper methods like semi-intensive or intensive systems.
3. Balanced feed containing carbohydrates, proteins, fats, minerals and vitamins is essential for healthy growth, egg production and disease resistance.
4. Selection of breeds depends on purpose; indigenous breeds are hardy and disease resistant, while exotic and hybrid breeds are high egg and meat producers.
5. Disease management through proper hygiene, nutrition and timely vaccination is crucial, as viral diseases like Ranikhet can cause heavy mortality.

• Honey bees are social insects living in well-organised colonies consisting of queen, drone and worker bees.
• They live in hives made of wax with hexagonal cells used for storing honey and pollen and for rearing young ones.
• Apis indica is the best species for apiculture in India because it is gentle and highly efficient in honey production.

• Meaning — Branch of applied biology dealing with catching, processing, farming & marketing of fish, prawns, lobsters, oysters, mussels, crabs.
• Three Divisions — Inland (fresh water), Marine (sea water, 7500 km coastline), Estuarine (river meets sea, e.g., Sundarbans).
• Common Fish — Inland: Rohu, Catla, Mrigala | Marine: Bombay duck, Sardine, Mackerel, Pomfret.
• Fish Culture — Monoculture (1 species) or Polyculture (many species). Preservation: chilling, freezing, salting, canning, drying.
• By-products — Fish oil, fish meal, fertilisers, fish glue, isinglass → used in paints, soaps, medicines. Provides jobs & self-employment.

• India has great fisheries potential due to its long coastline of about 8,118 km and vast inland water resources, contributing significantly to food supply, employment, and nutrition.
• Fish production has increased more than six times since independence, supported by government programs like the Development of Fresh Water Aquaculture through Fish Farmers Development Agencies.
• Infrastructure development includes major and minor fishing harbours, fish landing centres, and subsidies for motorisation and improved fishing crafts to support poor fishermen.
• The establishment of the National Fisheries Development Board aims to boost fish production, promote the Blue Revolution, and increase fish exports and foreign exchange earnings.