Please refer to Strategies for Enhancement in Food Production Class 12 Biology notes and questions with solutions below. These revision notes and important examination questions have been prepared based on the latest Science books for Class 12. You can go through the questions and solutions below which will help you to get better marks in your examinations. We have provided the latest Class 12 Biology Notes and Questions for all chapters in your NCERT Class 12 Biology Book.
Class 12 Biology Strategies for Enhancement in Food Production Notes and Questions
Due to rapid increase in human population, increase in food production is the major necessity. Animal husbandry and plant breeding play a major role in increasing food production to meet the demand of ever increasing population.
ANIMAL BREEDING
- Animal husbandry is the science of systematic breeding and raising of domesticated animals as per human requirement.
- Animal breeding aims at increasing the yield of animals and improving the desirable qualities of the produce.
Dairy farm management
It is the management of animals for obtaining milk and other milk products for human consumption. It deals with processes and systems that increase yield and improve quality of milk. Dairy animals include cow, buffalo, goat etc.
Poultry farm management
Poultry is the class of domesticated fowl (birds) used for meat and eggs. They typically include chicken and ducks, and sometimes turkey and geese. Poultry birds exclusively grown for meat are called broilers (e.g., Plymouth Rock), layers are female fowls for egg production, cockerel is a young male fowl and rooster is a mature male fowl. Pullet is young hen of less than one year. Selection of disease free and suitable breeds, proper and safe farm conditions, proper feed and water, hygiene and health care are important components of poultry farm management.
Apiculture
- Apiculture or bee keeping is care and management of honey bees. Common species of honey bee are – Apis dorsata (rock bee), Apis indica (Indian bee), Apis florea (little bee), and Apis mellifera (Italian bee). All of them occur in nature as wild insects.
- However, because of their high economic importance, the honey-bees, especially, A. mellifera is domesticated, reared and bred in artificial hives.
- Honeybees also produce beewax, which finds many uses in industry, such as in the preparation of cosmetics and polishes of various kinds.
- Knowledge of the nature and habits of bees, selection of suitable location for keepingthe beehives, catching and hiving of swarms (group of bees), management of beehives during different seasons, and handling and collection of honey and beewax are important for successful bee keeping.
Sericulture
- Sericulture is the rearing of silkworms (i.e., production of cocoons) for commercial production of silk. though a number of silk producing species are known but only few species are used for sericulture like Bombyx mori, Antheraea paphia, Antheraea assama and Attacus ricinii.
- India is the fourth largest producer of raw silk in the world. Raw silk is used in many ways – in the manufacture of woollen and knitted garments, parachute components, fishing lines, elastic webs, bolting silk cloth used in milling and chemical industry, insulation coils of telephone and wireless receivers.
Fisheries
- Fishery is an industry devoted to the catching, processing or selling of fish, shellfish or other aquatic animals. A large section of our population is dependent on fish, fish products and other aquatic animals such as prawn, crab, lobster, oyster, etc., for food.
- Aquaculture is rearing and management of useful aquatic plants and animals like fish, oysters, mussels, prawns, etc. Pisciculture is rearing, catching and management of fish. This has led to the development and flourishing of the fishery industry, and it has brought a lot of income to the farmers in particular and the country in general.
- Fisheries are divided into two types -marine and freshwater.
Common edible fishes of India
PLANT BREEDING
- Plant breeding is the genetic improvement of the crop in order to create desired varieties of plant types that are better suited for cultivation, give better yields and are disease resistant.
- Classical plant breeding includes hybridisation (crossing) of pure lines, and selection of progeny plants to get plants with desirable characters of higher yield, nutrition and resistance to diseases.
- The development of several high yielding varieties of wheat and rice in the mid-1960s, as a result of various plant breeding techniques led to dramatic increase in food production in our country. This phase is often referred to as the Green Revolution.
- Conventional breeding is often constrained by the availability of limited number of disease resistance genes. Other breeding methods that are used are mutation breeding, selection amongst somaclonal variants and genetic engineering.
- It is possible to induce mutations artificially through use of chemicals or radiations (like gamma radiations), and selecting and using the plants that have the desirable character as a source in breeding-this process is called mutation breeding. In mung bean, resistance to yellow mosaic virus and powdery mildew were induced by mutations.
Breeding for improved food quality
- Breeding of crops with high levels of vitamins and minerals or higher protein and healthier fats is called biofortification and is the most practical aspect to improve the health of the people.
- Plant breeding is undertaken for improved nutritional quality of the plants with the objectives of improvement in : protein content and quality, oil content and quality, vitamin content and micronutrient and mineral content.
- Indian Agricultural Research Institute (IARI), New Delhi, has also developed many vegetable crops that are rich in minerals and vitamins.
SINGLE CELL PROTEIN (SCP)
- Conventional agricultural production of cereals, pulses, vegetables, fruits, etc., may not be able to meet the demand of food at the rate at which human and animal population is increasing.
- One of the alternate sources of proteins for animal and human nutrition is single cell protein (SCP). It is dried cell of microorganisms or microbes (algae, bacteria, actinomycetes and fungi) used as food.
- The term SCP does not indicate its actual meaning because the biomass is not only obtained from unicellular organisms but also from multicellular organisms.
- Microbes like Spirulina can be grown on waste water from potato processing plants (containing starch), straw, molasses, animal manure and even sewage, to produce food rich in proteins, minerals, fat, carbohydrates and vitamins.
- SCP is rich in high quality protein and is poor in fats.
- It has been estimated that a 250 kg cow produces 200 g of protein per day. In the same period 250 g of a microorganism like Methylophilus methylotrophus because of its high content of biomass production and growth, can produce about 25 tonnes of protein.
TISSUE CULTURE
- Plant tissue culture is an in vitro technique of maintaining and growing plant cells, tissues or organs aseptically on artificial medium in suitable containers under controlled environmental conditions. The part which is cultured is called explant.
- Cellular totipotency is the ability of a somatic cell/explant to produce the complete organism. The explants are treated with specific antimicrobial chemicals to make them free from microbes. Culture media containing inorganic salts, certain vitamins, sucrose (as a source of carbon and energy) and the desired growth regulators is provided that is required for the desired growth and development of the explants.
- Embryoids are nonzygotic or somatic embryolike structures which are produced by in vitro culture and have the ability to form full fledged plants.
- Producing thousands of plants through tissue culture is called micropropagation. Each of these plants will be genetically indentical to the original plant from which they are grown, i.e., they are somaclones. Many important plants like tomato, banana, apple, etc., have been produced on commercial scale using this method.
- Steps in micropropagation include initiation of culture from an explant on a suitable nutrient medium, shoot formation from the explant, rooting of in vitro developed shoots, hardening of plantlets and transplantation to fields.
- Depending upon the type of explant, tissue culture is called meristem culture, multiple shoot culture, anther/haploidculture, embryo culture, ovule culture, etc.
- On the basis of in vitro growth, plant tissue cultures are of two types, callus and suspension cultures.
- In callus culture, cell division in explant forms a callus. Callus is irregular unorganised and undifferentiated mass of actively dividing cells.
- A suspension culture consists of single cells or small groups of cells suspended in a liquid medium containing the auxin 2,4–D. Suspension cultures grow much faster than callus culture.
Protoplast culture and somatic hybridisation
- When a hybrid is produced by fusion of somatic cells of two varieties or species, it is known as somatic hybrid. The process of producing somatic hybrids is called somatic hybridisation.
- First, the cell wall of the plant cells are removed then the protoplasts of the two plants are brought in contact and made to fuse by means of electrofusion or chemicals like polyethylene glycol (PEG) and sodium nitrate. The fused protoplasts soon develop their own walls and then they are called somatic hybrid cells.
- Successful somatic hybrids have also been got from different species of Brassica, Petunia and Solanum. Pomato is somatic hybrid between potato and tomato that belong to two different genera.
- Protoplast technology has opened up avenues for development of hybrids of even asexually reproducing plants. Somatic hybrids may be used for the production of useful allopolyploids.
- Genetic mainipulations can be carried out more rapidly when plant cells are in protoplast state. New genes can be introduced (e.g., male sterility, herbicide resistance). Mutations will be easier.
