NCERT Solutions for Class 12 Science Biology Chapter 9 - Strategies For Enhancement In Food Production

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The chances of contacting bird flu from a properly cooked chicken are negligible because proper cooking above 70°C inactivate/kill the virus in the egg as well as in the meat.

Hence, the correct answer is option (d).

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A group of animals that are related by descent and are similar in most characters like general appearance, features, size, configuration etc. are said to belong to a breed.

Hence, the correct answer is option (a).

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Inbreeding increases homozygosity, i.e. state of possessing two identical alleles one inherited from each parent. It helps in evolving a pureline of breed.

Hence, the correct answer is option (d).

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Sonalika and Kalyan Sona are outstanding semi-dwarf varieties of wheat possessing amber grains and good yield potential.

Hence, the correct answer is option (a).

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Black rot of crucifers is not a fungal disease. It is caused by bacteria Xanthomonas campestris.
Hence, the correct answer is option (c).

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In virus infected plants, the meristematic tissues in both apical and axillary buds are free of virus because the multiplication of meristematic cells is faster than replication of viruses.

Hence, the correct answer is option (c).

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Rice is grown in some south Indian states twice a year. The agronomic feature that makes this possible is early yielding rice variety.

Hence, the correct answer is option (c).

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A sugarcane farmer will look for thick stem, long internodes, high sugar content and disease resistance. Saccharum barberi and Saccharum officinarum are being used to develop such combinations.

Hence, the correct answer is option (a). 

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Many fungal, bacterial and viral pathogens harm the yield of cultivated crop species. Fungicides and antibiotics are chemicals that kill pathogenic fungi and bacteria respectively.

Hence, the correct answer is option (b).

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Mutation breeding is a process to induce mutations artificially in crop plants through the use of chemicals or radiations (like gamma radiations) and then selecting and using those plants that have a desirable character as a source in breeding.
Hence, the correct answer is option (c).

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Biofortification is the process of breeding crops with higher levels of vitamins and minerals or higher protein and healthier fats. It is the most cost-effective method to promote public health.
Hence, the correct answer is option (c).

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Totipotency is the capacity of a cell or an explant to grow into a whole plant. Explant is any part of plant taken out and grown in test tube.

Hence, the correct answer is option (a).

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Isolated protoplasts (surrounded by plasma membranes) from two different types can be combined to produce hybrid protoplasts that develop to generate a new plant. Cellulase, hemicellulase, and pectinase which dissolve the cell wall are the enzymes required to obtain wall free or naked protoplasts. Polyethene glycol (PEG) and sodium nitrate, which induce fusion, are used create somatic cell hybrids. Chemofusion and electrofusion are used in protoplast fusion.

Hence, the correct answer is option (d).

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Any part of the plant taken out and grown in a test tube under sterile conditions in a special nutrient media is called an explant. A whole plant can be generated from an explant.

Hence, the correct answer is option (c).

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Breeding is often constrained by the availability of limited number of disease resistance genes that are present and identified in various crop varieties or wild relatives.
Hence, the correct answer is option (a).

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Essential amino acids are amino acids that the body does not synthesize and must obtain from outside sources. Tryptophan and lysine are essential amino acids.


Hence, the correct answer is option (c).

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Micropropagation is propagation of plants in vitro to achieve a large number of pants in very short durations. This results in genetically identical plants and is widely used in forestry and floriculture.

Hence, the correct answer is option (b).

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A protoplast is a plant, bacterial or fungal cell whose cell wall is completely removed using either mechanical or enzymatic means. 

Hence, the correct answer is option (c).

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The cell wall of plant cells consists of pectin and cellulose which can be removed by enzymes cellulase, hemicellulase, pectinase to obtain wall-free or naked protoplasts.

Hence, the correct answer is option (c).

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Hilsa, sardines, mackerel and pomfrets are some marine fishes while Catla, Rohu and Common Carp are fresh water fishes.

Hence, the correct answer is option (b).

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Wax is an apiculture product that is used in cosmetics and polishes. Honey is a highly nutritive food and also found in medicines. Royal jelly is used an antioxidant. Propolis is an anti-inflammatory product.

Hence, the correct answer is option (c).

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India and China have more than 70% of the world's livestock population but they only contribute 25% of global farm products that means productivity per unit is very low.
 
Hence, the correct answer is option (d).

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India's agriculture sector employs over 60% of the population. India is mainly an agricultural country. India produces various crops like wheat, rice, pulses and spices on a large-scale.

Hence, the correct answer is option (d).

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Agriculture accounts for approximately 33% of India's GDP. Agriculture is rapidly increasing its contribution to the country's national wealth.

Hence, the correct answer is option (b).

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A germplasm collection is a collection of all the alleles of all the genes in a crop plant. It serves as the raw material for the breeder to develop different crops.

Hence, the correct answer is option (a).

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Millions of chicken were killed in West Bengal, Assam, Odisha and Maharashtra because they were found to be infected with H₅N₁ virus, which the casual organism of bird flu.

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Moong varieties resistant to yellow mosaic virus and powdery mildew have been developed using gamma rays. It proves that treatment of gamma rays in agriculture for crop improvement is safe for humans.

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Inbreeding results in loss in fertility and vigour because the recessive alleles tend to get together and express harmful effects in the progeny.

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Collection and preservation of all the different wild varieties, species and relatives of the cultivated species is important for effective exploitation of natural genes available in the population. Sources of resistant genes may be cultivated varieties, germplasm collections of the crop or wild relatives.

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Triticale is a man-made cereal. It was developed by crossing Triticum aestivum which is a wheat and Secale cereale which is a european rye.

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ans

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(a) Mating of closely related individuals within the same breed is called inbreeding.
(b) Mating of animals of same breed but having no common ancestors on either side for 4-6 generations is called outbreeding.
(c) Mating of animals of two different species is called interspecific hybridisation.
(d) Breeding of animals belonging to different breeds is called cross-breeding.

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Consumption of food deficient in nutrients particularly micronutrients, proteins and vitamins is called 'hidden hunger'.

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Plants obtained by protoplast culture are called somatic hybrids because they are formed by the fusion of isolated protoplasts from two different varieties of plants, each having a desirable character, to obtain a hybrid protoplast which can be further grown to form a plant.

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The ability of protoplasts obtained from two different cells to fuse and form a hybrid protoplast is called protoplast fusion.

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Meristems have the capacity to divide continuously throughout their life. Their walls are thin and elastic to facilitate the division, hence are suitable for tissue culture. Permanent cells lose their ability to divide and their walls are thick. They have to dedifferentiate to divide, hence are not easier to culture.

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Single cells proteins are proteins obtained from unicellular organisms. Spirulina is one such unicellular microbe, so proteins synthesized by Spirulina are called single cell proteins.

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The person with allergies to pulses is advised to take spirulina because 
i) It could substitute protein rich pulses.
ii) It is rich in β-carotene and antioxidants that help in improving allergic symptoms.

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Aquaculture is the culturing of aquatic plants and animals in freshwater bodies.
Examples:
Finfish - Carp, Catfish
Shellfish - Shrimps, Oysters

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Veterinary doctor has to ensure proper and safe farm conditions to keep the animals disease-free and treat them properly if diseased.

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No, it is not wrong to call plants obtained through micropropagation clones because each of these plants will genetically identical to each other and the parent plant.

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Somatic hybrids are formed by the fusion of two somatic cells whereas hybrid is produced by the fusion of two gametes. Sexual reproduction is necessary to produce a conventional hybrid but is not necessary to produce somatic hybrid.

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Removal of stamens from the bisexual flower that is used as a female parent in plant hybridisation is called emasculation. This is done to avoid unwanted self-pollination. This has to be done at bud condition before the anthers dehisce. 

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The limitations of plant hybridisation are -
(1) Availability of limited number desirable traits (such as disease resistance).
(2) Compatibility of parents.

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Two different male and female species are mated in the interspecific crossing. The so formed progeny will be infertile. This type of cross is rare in nature.
In inter-generic crossing, the crossing is done between male and female of two different genera which are completely impossible.

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Aquaculture is the culture of all aquatic plants and animals while Pisciculture is the culture of just fishes to obtain fish products.

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Dr. M.S. Swaminathan is known as the "Father of Green Revolution" in India. He developed high yielding varieties of wheat in India.
He is an advocate of moving India to sustainable development.

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The desirable trait can be different for different plants. For example,
Resistance to pathogens causing yellow mosaic virus and powdery mildew in moong bean, are desirable traits.

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The following aspects are required to be considered:-
(i) Good breeds with high yielding potential combined with disease resistance should be selected.
(ii) Feeding of cattle should be done in scientific manner with good quality and quantity of fodder.
(iii) Proper hygienic conditions, are most important while milking, storage and transport of milk and its products. 
(iv) Cattle and handler should be kept in clean hygienic condition.
(v) Animal shed should be kept clean, away from dirt and pollution.
(vi) Regular visit by veterinary doctor with proper record is needed.

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The H₅N₁ virus is an Influenza virus that occurs mainly in birds. Globalisation is the major environmental issue that plays a large role in the advancement of the H₅N₁ avian influenza virus. Migrating from one place to another is an important cause of globalisation, so the chance of spreading of infectious disease is increased. Virus transfers from unhealthy to healthy human at very fast rate.

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The term blue revolution refers to the remarkable emergence of aquaculture (related to aquatic plants and animals). There was a wide increase in the production of aquatic organisms and their products. Aquaculture refers to all forms of active culturing of aquatic animals (including fish) and plants, occuring in marine, brackish or freshwater.

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Agriculture or bee keeping is culturing and maintenance of beehives for the commercial production of honey and wax. The beehives when kept in the fields of sunflower, brassica, apple and pear, increase the efficiency of pollination of flowering plants and improve the yields as pollination increases the seed production. On the other hand, it also increases the honey production.

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Both of the challenges can be addressed through biofortification, which is a method of breeding crops to include more vitamins, minerals, proteins, and lipids, among other nutrients. It also raises food quality. 

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Multiple Ovulation Embryo Transfer Technology (MOET) is employed in animal husbandry to increase the rate of fertilisation during artificial insemination. 

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The collection of genes is known as germplasm. The collection of plants or seeds having all alleles for all genes in a given crop is known as germplasm collection. 
Benefits-
(a) It maintains diversity. 
(b) The genes can be used in future when needed. 

Answer:

The improved characteristics of wheat that helped India to achieve green revolution are-
(a) Semi-dwarf nature 
(b) High-yield
(c) Early maturity 
(c) Disease resistance
(d) Quick yield

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Features of plants that will prevent insect and pest infestation-

• Growth of hair-like structure on aerial parts of plants
• Production of nectarless flower
• Secretion of insect killing chemicals

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Due to the ability of dedifferentiation and becoming meristematic again, plants can be cultured in vitro. It is the ability of the cells to lose as well as reverse the ability of differentiation. This property is absent in animal cells, hence they cannot be cultured easily.

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An artificially prepared growth medium is known as culture medium. The growing cell needs a variety of nutrients, chemicals, growth regulators, and dietary supplements, all of which are present in this medium. The soil is the naturally occurring medium because it contains all the minerals, nutrients, decomposers, water, and other elements necessary for the growth of organisms.

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Since differentiated cells can be used to produce any type of tissue, the dedifferentiation of plant cells is crucial in plant tissue culture. The differentiation process can be reversed by the plant cells.

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Through the process of tissue culture, we can produce thousands of plants of the same type with a single cell. The growth of these plants occurs in a specialised nutritional medium that contains a carbon source, inorganic salts, amino acids, vitamins, and other growth regulators under sterile circumstances. Each of these plants are known as somaclones as they are genetically identical to the original plant from which they were grown.

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 Plants raised through tissue culture are genetically identical to the original plant and that is why they are known as clones of the parent plant. They are utilised for maintaining a desirable trait of parents.

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The newly selected lines are assessed for their production as well as additional agronomic characteristics like quality, disease resistance, etc. These crops are grown in research fields and their performance is evaluated under ideal fertilizer application, irrigation, and other crop management practices. This crop is then grown by farmers at several locations, for at least three growing seasons. The crop is evaluated by comparing with the best available local crop cultivar (which acts as a reference).

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Stress is any adverse effect on the plant that results from a biotic or abiotic factor. It affects the growth and development of the plant. Different types of stress in plants include cold, pests, diseases, drought, and salinity.

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The intentional breeding of plants or animals by humans to produce desired products is known as the artificial selection of organisms. 
The process of natural selection takes place without human intervention. Nature always favours the creature that can adapt to its surroundings and change over time. This is known as the process of natural selection.
Natural selection is the key mechanism of evolution, it determines the heritable traits of a population over time.

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The term "pureline" refers to a breed or strain of plants and animals with homozygous alleles and similar characters over various generations. In animal husbandry, purelines are produced by mating animals of the same breed repeatedly for four to five generations.

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In the protoplast fusion experiment, cell wall acts as the physical barrier. It can be digested using certain enzymes, such as, cellulase, pectinase, lipase etc. which ultimately liberates the protoplasm of the cell. 

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Biofortification involves the breeding of crops to increase their nutritional value. Golden rice, vit A enriched carrot, maize hybrid, Atlas 66 (wheat variety) are a few biofortified crops. They have high nutrient content. They are also used to control nutrient-deficient diseases such as malnutrition.

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Steps Involved in Breeding a New Genetic Variety of a Crop

• Collection of genetic variability

  • Genetic variability is availed from the wild relatives of the crop.

  • Hence, all the wild varieties and relatives of the crop are collected and preserved.

  • The natural genes available in a population are utilised by this method.

  • Entire collection of plants/seeds (wild types/relatives) of the given crop, which has all the diverse alleles for all genes, is called germplasm collection.

• Evaluation and selection of parents

  • From the available genetic variability, the germplasm is analysed and evaluated to identify the plants with desirable traits.

• Crop hybridisation among selected parents

  • Two selected parents are crossed (hybridised). This facilitates the combination of desired traits from two different plants.

  • Pollen grains from one plant are dusted over the stigma of the other plant.

• Selection of superior recombinants

  • Among the hybrid progeny, those plants are selected which have the desired character combination.

  • Careful scientific evaluation of progeny is required for selection.

  • This step yields the plant that is superior to both the parents.

• Testing, release and commercialisation

  • Selected yields are evaluated for traits like quality, disease resistance, insect resistance, etc.

  • These crops are grown in research fields and their performance is recorded under ideal conditions.

  • This crop is then grown by farmers at several locations, for at least three growing seasons.

  • The crop is evaluated by comparing with the best available local crop cultivar (which acts as a reference).

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(a) The meat consumed by humans is obtained from animals such as goats, chicken, cows, etc., so the demand for cereals increased and the diet shifted from grains to meat.
(b) This is known as single cell protein, which means that microbes are used as a source of protein. Microorganisms, despite being very small, are capable of producing tonnes of proteins due to their higher rates of biomass production. They generate a significant amount of protein in small duration. It is a high-yielding, less time-consuming approach.

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Advantages of tissue culture method over conventional method of plant breeding-
(1) Used to produce disease-free plants
(2) Only viable method of regenerating genetically modified plants
(3) Plants can be produced throughout the year
(4) High volume and large scale propagation method
(5) Rare and endangered plant species can be multiplied 

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Through the following modern techniques, animal and plant breeding can be alleviated-
(a) Single cell protein (SCP)- Single-cell protein means that microbes are used as a source of protein. Microorganisms, despite being very small, are capable of producing tonnes of proteins due to their higher rates of biomass production.
(b) Tissue culture- Tissue culture is the process of developing a complete plant from a part of a plant. The plant part is called an explant. Explants can be grown in sterile conditions in special nutrient media to regenerate complete plants. Nutrient media contain a carbon source (such as sucrose), inorganic salts, vitamins, amino acids and phytohormones. Hence, propagation is achieved for a large number of plants in a short duration. This process is called micropropagation, also known as clonal propagation.
(c) Biofortification- It involves the breeding of crops to increase their nutritional value. It is a strategy for dealing with micronutrient deficiencies in developing countries.
(d) Multiple Ovulation Embryo Transfer (MOET)- Using this technique, high milk-yielding breeds of females and lean meat-yielding bulls have been bred successfully. 

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Apiculture is the practice of bee-keeping. It includes maintenance of beehives for production of honey. Honey has a high nutritive value and medicinal value. Honeybees also produce beeswax that is used in the preparation of polishes and cosmetics. 
Bees are good pollinators so beekeeping in crop fields during the flowering season boosts pollination effectiveness and yield, which is advantageous for both crop and honey production. Effective pollination increases seed production, which ultimately increases the crop of plants.

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(a) In ​mutational breeding, genetic variations are created, which result in the creation of traits not found in the parental type.
Mutations are induced with the help of mutagens (like chemicals) or irradiation. The plants in which the desired character (in this case, the desired resistance) has come through mutation are selected. Resistance to yellow mosaic virus and powdery mildew in mung beans were induced by mutations. 
(b) Plant breeding is the purposeful manipulation of plant species in order to create desired plant types which are better suited for cultivation, give better yields, and are disease resistant. This technology has made us self-sufficient in food production. 

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Tissue culture is the process of developing a complete plant from a part of a plant. The plant part is called an explant. Explants can be grown in sterile conditions in special nutrient media to regenerate complete plants. Nutrient media contain a carbon source (such as sucrose), inorganic salts, vitamins, amino acids and phytohormones. Totipotency is the concept that refers to a plant's capacity to produce its entire body from a single cell. Totipotency facilitates the growth of countless genetically identical plants. This large scale production of plants is known as micro-propagation.

Answer:

Following are three options to increase food production-
(a) Single cell protein (SCP)- Single-cell protein means that microbes are used as a source of protein. Microorganisms, despite being very small, are capable of producing tonnes of proteins due to their higher rates of biomass production.
(b) Tissue culture- Tissue culture is the process of developing a complete plant from a part of a plant. The plant part is called an explant. Explants can be grown in sterile conditions in special nutrient media to regenerate complete plants. Nutrient media contain a carbon source (such as sucrose), inorganic salts, vitamins, amino acids and phytohormones. Hence, propagation is achieved for a large number of plants in a short duration. This process is called micropropagation, also known as clonal propagation.
(c) Multiple Ovulation Embryo Transfer (MOET)- Using this technique, high milk-yielding breeds of females and lean meat-yielding bulls have been bred successfully. 

Demerits-
(a) The genetic diversity reduces in the process of tissue culture. 
(b) The procedure of Single-cell protein is very costly process. 
 (c) The success rate of Multiple Ovulation Embryo Transfer Technology low and it is also a high-cost method.