Strategies for Enhancement in Food Production
Welcome to HSLC Guru! Here you will find detailed notes, summary, question answers, MCQs, fill in the blanks, true/false statements and a glossary for Class 12 Biology Chapter 9 — Strategies for Enhancement in Food Production, prepared strictly according to the ASSEB (Assam State School Education Board) syllabus. This chapter explains how scientific approaches in animal husbandry, plant breeding, tissue culture and single-cell protein production help meet the food demand of an ever-growing human population.
Summary
Animal Husbandry is the agricultural practice of breeding and raising livestock such as cattle, buffalo, sheep, goats, pigs, poultry birds and fishes. It deals with feeding, shelter, health care and improvement of these animals. Dairy farm management aims at increasing milk yield and ensuring quality milk through selection of high-yielding and disease-resistant breeds, scientific feeding, hygienic milking and regular veterinary care. Poultry farm management focuses on rearing domestic fowl for eggs and meat (broilers), with attention to breed selection, balanced feed, disease control and proper housing. Animal breeding aims to increase the yield of animals and improve desirable qualities. It includes inbreeding (mating of closely related animals of the same breed for 4-6 generations), which increases homozygosity but may cause inbreeding depression, and out-breeding, which is mating of unrelated animals.
Out-breeding has three forms — out-crossing (mating of animals of the same breed but having no common ancestors up to 4-6 generations), cross-breeding (mating of superior males of one breed with superior females of another breed; e.g., Hisardale sheep) and interspecific hybridisation (mating of male and female animals of two different related species; e.g., mule from horse and donkey). Controlled breeding uses artificial insemination and MOET (Multiple Ovulation Embryo Transfer Technology), in which a cow is administered FSH-like hormone to produce 6-8 eggs at a time. These eggs are fertilised by artificial insemination, and the early embryos are recovered and transferred to surrogate mothers. MOET has been successfully used in cattle, sheep, buffaloes, rabbits, etc.
Apiculture is bee-keeping for the production of honey, bee-wax and pollen; Apis indica is the most common species reared. Fisheries involve catching, processing and marketing of fish, prawns, crabs, lobsters, oysters, etc. It includes capture fishing (from natural water bodies) and aquaculture (controlled rearing). Aquaculture is of two types — marine (Hilsa, Sardine, Mackerel, Pomfret) and inland in fresh water (Catla, Rohu, Common carp). Pisciculture is the rearing of fishes in ponds and tanks. The Blue Revolution refers to the increase in the production of fish and other aquatic products through aquaculture. Ornamental fish like guppy, gold fish, angel fish are reared for decorative purposes and have economic value.
Plant breeding is the purposeful manipulation of plant species in order to create desired plant types better suited for cultivation, give better yields and resistant to pests and diseases. The main steps are — (1) Collection of variability/germplasm collection, (2) Evaluation and selection of parents, (3) Cross-hybridisation among the selected parents, (4) Selection and testing of superior recombinants, (5) Testing, release and commercialisation of new cultivars. Important applications include disease resistance (Himgiri wheat for rust resistance, Pusa Komal cowpea for bacterial blight), insect/pest resistance (Bt cotton, Pusa Sem 2, Pusa Sem 3 against jassids and aphids), improved yield (HYV — High Yielding Varieties giving rise to the Green Revolution in India under the leadership of Dr. M.S. Swaminathan) and biofortified food like Golden Rice rich in pro-vitamin A (β-carotene) and Atlas 66, an iron-rich wheat variety. Single Cell Protein (SCP) is microbial biomass like Spirulina (blue-green alga) and the bacterium Methylophilus methylotrophus, which provides a rich source of protein, vitamins, minerals and fats. Tissue culture exploits totipotency (capacity of a single cell to develop into a whole plant); micropropagation produces thousands of plantlets in a short duration; protoplast fusion gives rise to somatic hybrids (e.g., Pomato) and cybrids.
1 Mark Questions and Answers
Q1. What is animal husbandry?
Answer: Animal husbandry is the agricultural practice of breeding, rearing and caring for livestock and poultry to obtain food, fibre and other products.
Q2. Define inbreeding.
Answer: Inbreeding is the mating of more closely related animals of the same breed for 4-6 generations.
Q3. Expand MOET.
Answer: MOET stands for Multiple Ovulation Embryo Transfer Technology.
Q4. Name a disease-resistant variety of wheat.
Answer: Himgiri (resistant to leaf and stripe rust and hill bunt).
Q5. What is apiculture?
Answer: Apiculture is the rearing of honey bees on a large scale for obtaining honey, bee-wax and pollen.
Q6. Who is known as the father of Green Revolution in India?
Answer: Dr. M.S. Swaminathan.
Q7. What is Blue Revolution?
Answer: The increase in the production of fish and other aquatic products through aquaculture is called the Blue Revolution.
Q8. Name two examples of single-cell protein.
Answer: Spirulina and Methylophilus methylotrophus.
Q9. What is totipotency?
Answer: The capacity of a plant cell to generate a whole plant is called totipotency.
Q10. Name the species of honey bee most commonly reared in India.
Answer: Apis indica (also Apis mellifera).
2-3 Marks Questions and Answers
Q1. Differentiate between out-crossing and cross-breeding.
Answer: Out-crossing is the mating of animals of the same breed which have no common ancestors up to 4-6 generations on either side of the pedigree; it removes inbreeding depression. Cross-breeding is the mating of superior males of one breed with superior females of another breed to combine desirable qualities of both, e.g., Hisardale (sheep) and Karan Swiss (cattle).
Q2. What is interspecific hybridisation? Give an example.
Answer: Interspecific hybridisation is the mating of male and female animals of two different related species; the progeny may combine desirable features of both parents. Example — the mule, produced by crossing a male donkey and a female horse (mare).
Q3. Briefly explain MOET.
Answer: In MOET, an FSH-like hormone is given to a cow of high milk yield to induce follicular maturation and super-ovulation, producing 6-8 eggs instead of one. The cow is mated with an elite bull or artificially inseminated, and the embryos at the 8-32 cell stage are recovered non-surgically and transferred to surrogate mothers. The genetic mother is available for another cycle, allowing rapid multiplication of high-yielding animals.
Q4. Distinguish between capture fishery and aquaculture.
Answer: Capture fishery is the catching of fish from their natural habitats such as rivers, lakes, estuaries and oceans without rearing. Aquaculture is the production of useful aquatic plants and animals (fish, prawn, oyster, etc.) under controlled conditions in ponds, tanks or marine pens. Aquaculture allows planned and sustained yield, while capture fishery depends on natural availability.
Q5. What is biofortification? Give two examples.
Answer: Biofortification is the breeding of crops with higher levels of vitamins and minerals, or higher protein and healthier fats, to improve public health. Examples — (i) Golden rice, rich in pro-vitamin A (β-carotene); (ii) Atlas 66, a wheat variety with high protein and iron content.
Q6. What is single-cell protein? Why is it important?
Answer: Single-cell protein (SCP) is the protein extracted from cultivated microbial biomass such as Spirulina, Methylophilus methylotrophus, yeast and certain fungi. It is rich in protein, vitamins, minerals and fats, can be produced on industrial waste, requires very little land and time, and helps reduce environmental pollution while supplementing food and feed.
5-7 Marks Questions and Answers
Q1. Describe animal breeding and explain its different types.
Answer: Animal breeding aims to increase the yield of animals and improve their desirable qualities. The breeding strategies are of two main types — inbreeding and out-breeding. Inbreeding is the mating of more closely related animals of the same breed for 4-6 generations. It increases homozygosity, helps in evolution of pure lines and accumulation of superior genes; however, continued inbreeding may cause inbreeding depression — reduction in fertility and productivity. Out-breeding is the mating of unrelated animals and is of three types — (i) Out-crossing: mating of animals of the same breed without common ancestors up to 4-6 generations; the progeny is called an out-cross and helps overcome inbreeding depression. (ii) Cross-breeding: mating of superior males of one breed with superior females of another breed (e.g., Hisardale sheep — a cross between Bikaneri ewes and Marino rams). (iii) Interspecific hybridisation: mating of male and female of two different related species; e.g., mule from a male donkey and a female horse. Modern strategies also include controlled breeding using artificial insemination and MOET to multiply elite stocks rapidly.
Q2. What is plant breeding? Describe the main steps involved in a plant breeding programme.
Answer: Plant breeding is the purposeful manipulation of plant species to create desired plant types better suited for cultivation, with higher yield and resistance to biotic and abiotic stresses. The main steps are: (1) Collection of variability (germplasm collection) — gathering all the different wild varieties, species and relatives of the cultivated species which contain natural genetic variability. (2) Evaluation and selection of parents — the germplasm is evaluated and plants with desirable combination of characters are selected as parents and multiplied. (3) Cross-hybridisation among the selected parents — desired characters from two parents are combined by crossing; this is laborious and only one in few hundred crosses shows desirable combinations. (4) Selection and testing of superior recombinants — among the progeny of the hybrids, plants having the desired characters are selected and self-pollinated for several generations till they reach uniformity. (5) Testing, release and commercialisation of new cultivars — newly selected lines are evaluated for yield and other agronomic traits in research fields and farmers’ fields, then released as varieties.
Q3. Explain the role of plant breeding in disease resistance, insect resistance and improved yield with examples.
Answer: (a) Disease resistance — Several crops are damaged by fungal, bacterial and viral pathogens; resistant varieties have been bred through hybridisation and selection. Examples — Himgiri wheat (resistant to leaf and stripe rust and hill bunt), Pusa Komal cowpea (bacterial blight resistant), Pusa Swarnim mustard (white rust resistant). (b) Insect/pest resistance — Morphological features (hairy leaves, solid stems) and biochemical features (high aspartic acid, low nitrogen and sugar) confer resistance. Examples — Pusa Sem 2 and Pusa Sem 3 flat bean (resistant to jassids, aphids and fruit borers), Pusa Gaurav brassica (aphid resistant), Bt cotton developed through genetic engineering. (c) Improved yield — High Yielding Varieties (HYVs) of wheat (Sonalika, Kalyan Sona) and rice (IR-8, Padma, Jaya) developed in India ushered in the Green Revolution under the leadership of Dr. M.S. Swaminathan, making the country self-sufficient in food grain production.
Q4. What is tissue culture? Discuss its applications in crop improvement.
Answer: Tissue culture is the technique of growing plant cells, tissues or organs aseptically on a suitable nutrient medium under controlled conditions. It is based on the property of totipotency, the capacity of any plant cell to generate a whole plant. Applications include — (i) Micropropagation — production of thousands of plantlets in a very short duration; commercially used for tomato, banana, apple, orchids, etc. The plants produced are genetically identical to the original (somaclones). (ii) Production of disease-free (virus-free) plants by culturing meristem (apical/axillary), as the meristem is free from viruses; banana, sugarcane and potato have been recovered from infected plants this way. (iii) Somatic hybridisation — fusion of protoplasts of two different species/varieties produces hybrid protoplasts that grow into somatic hybrids (e.g., Pomato, a hybrid of tomato and potato). When only nucleus of one parent is combined with cytoplasm of another, cybrids are formed. (iv) Production of haploids through anther/pollen culture for rapid homozygous line development. (v) Cryopreservation of germplasm and synthesis of secondary metabolites.
Q5. Write a short note on apiculture and fisheries (capture, aquaculture, pisciculture).
Answer: Apiculture is the rearing of honey bees for the production of honey, bee-wax and pollen. The most common species reared in India is Apis indica. Bee-keeping requires knowledge of nature of bees, hive selection, catching swarms, management during seasons and handling of honey. It can be practised on land of little agricultural value and works well alongside agriculture, since bees are pollinators of many crops, and their activity actually increases crop yield. Fisheries is an industry devoted to the catching, processing and marketing of fish, molluscs and crustaceans. Capture fishing is the harvesting of fishes from natural water bodies, while aquaculture is the rearing of aquatic organisms under controlled conditions; it is divided into marine (Hilsa, Sardine, Mackerel, Pomfret) and inland/freshwater (Catla, Rohu, Mrigal, Common carp). Pisciculture is the rearing of fishes in ponds and tanks. The increase in fish production through aquaculture is referred to as the Blue Revolution. Besides edible fishes, ornamental fishes like guppy, gold fish and angel fish are reared for aquariums and provide good economic returns.
Multiple Choice Questions (MCQs)
Q1. The mating of more closely related animals of the same breed for 4-6 generations is called —
(a) Out-crossing (b) Cross-breeding (c) Inbreeding (d) Interspecific hybridisation
Answer: (c) Inbreeding.
Q2. Hisardale is a cross-breed of —
(a) Cattle (b) Sheep (c) Goat (d) Pig
Answer: (b) Sheep.
Q3. MOET stands for —
(a) Multiple Ovum Embryo Transfer (b) Multiple Ovulation Embryo Transfer (c) Mature Oocyte Embryo Technology (d) None of these
Answer: (b) Multiple Ovulation Embryo Transfer.
Q4. The species of honey bee most commonly reared in India is —
(a) Apis dorsata (b) Apis indica (c) Apis florea (d) Apis cerana
Answer: (b) Apis indica.
Q5. Father of the Green Revolution in India is —
(a) Norman Borlaug (b) M.S. Swaminathan (c) G.L. Chaddha (d) B.P. Pal
Answer: (b) M.S. Swaminathan.
Q6. Himgiri is a variety of which crop, resistant to —
(a) Rice — bacterial blight (b) Wheat — leaf and stripe rust (c) Cotton — boll worm (d) Mustard — white rust
Answer: (b) Wheat — leaf and stripe rust.
Q7. Golden rice is a biofortified variety rich in —
(a) Iron (b) Lysine (c) Pro-vitamin A (β-carotene) (d) Vitamin C
Answer: (c) Pro-vitamin A (β-carotene).
Q8. Spirulina is used as —
(a) Biofertiliser (b) Single-cell protein (c) Antibiotic source (d) Insecticide
Answer: (b) Single-cell protein.
Q9. Pomato is a —
(a) Sexual hybrid (b) Somatic hybrid (c) Cybrid (d) Mutant
Answer: (b) Somatic hybrid.
Q10. The increase in production of fish through aquaculture is called —
(a) Green Revolution (b) White Revolution (c) Blue Revolution (d) Yellow Revolution
Answer: (c) Blue Revolution.
Fill in the Blanks
Q1. The mating of unrelated animals of the same breed having no common ancestors is called __________.
Answer: Out-crossing.
Q2. __________ is a cross between a male donkey and a female horse.
Answer: Mule.
Q3. Bee-wax is obtained through __________.
Answer: Apiculture.
Q4. __________ is an iron-rich variety of wheat.
Answer: Atlas 66.
Q5. The capacity of a single plant cell to give rise to a whole plant is called __________.
Answer: Totipotency.
True or False
Q1. Inbreeding always increases the yield of animals.
Answer: False (continued inbreeding may cause inbreeding depression).
Q2. Hisardale is a cross-breed of cattle.
Answer: False (it is a cross-breed of sheep).
Q3. Catla and Rohu are inland freshwater fishes.
Answer: True.
Q4. Bt cotton has been developed through plant tissue culture.
Answer: False (it has been developed by genetic engineering).
Q5. Cybrids are hybrids in which the cytoplasm is from one parent and the nucleus from the other.
Answer: True.
Glossary
| Term | Meaning |
|---|---|
| Animal Husbandry | Agricultural practice of breeding and rearing livestock and poultry. |
| Inbreeding | Mating of closely related animals of the same breed for 4-6 generations. |
| Inbreeding Depression | Reduced fertility and productivity due to continued inbreeding. |
| Out-crossing | Mating of animals of same breed with no common ancestors up to 4-6 generations. |
| Cross-breeding | Mating of superior males of one breed with superior females of another breed. |
| Interspecific Hybridisation | Mating of male and female animals of two different related species (e.g., mule). |
| MOET | Multiple Ovulation Embryo Transfer Technology for rapid herd improvement. |
| Apiculture | Rearing of honey bees for honey, bee-wax and pollen. |
| Pisciculture | Rearing of fishes in ponds and tanks. |
| Aquaculture | Production of useful aquatic plants and animals under controlled conditions. |
| Blue Revolution | Increase in fish and aquatic produce through aquaculture. |
| Plant Breeding | Purposeful manipulation of plants to develop better cultivars. |
| Germplasm | Sum total of all alleles of all genes present in a crop and its wild relatives. |
| HYV | High Yielding Varieties of crops produced through breeding. |
| Green Revolution | Increase in food grain production in India led by Dr. M.S. Swaminathan. |
| Biofortification | Breeding crops with higher levels of vitamins, minerals, proteins or fats. |
| Golden Rice | Biofortified rice rich in pro-vitamin A (β-carotene). |
| Atlas 66 | Iron-rich and high-protein variety of wheat. |
| Himgiri | Wheat variety resistant to leaf and stripe rust and hill bunt. |
| Pusa Komal | Cowpea variety resistant to bacterial blight. |
| Bt Cotton | Genetically modified, insect-resistant variety of cotton. |
| Single Cell Protein | Protein obtained from microbes such as Spirulina and Methylophilus. |
| Totipotency | Capacity of a plant cell to develop into a whole plant. |
| Micropropagation | Production of many plantlets in short time through tissue culture. |
| Somatic Hybrid | Hybrid plant produced by fusion of somatic cell protoplasts (e.g., Pomato). |
| Cybrid | Hybrid cell containing nucleus of one species and cytoplasm of another. |