NCERT Exemplar for Class 12 Biology Chapter-9 (Book Solutions)

Multiple Choice Questions

1. The chances of contacting bird flu from a properly cooked (above 100°C) chicken and egg are: 

(a) very high 

(b) high 

(c) moderate

(d) none 

Ans: (d) none 

Explanation: When chicken is correctly cooked, it aids in the destruction of the bird flu virus.

2. A group of animals which are related by descent and share many similarities are referred to as: 

(a) breed 

(b) race 

(c) variety 

(d) species 

Ans: (a) breed 

Explanation: Race is a social group with no biological significance. In the case of plants, variety is utilized. A species is a valid taxonomic group. A breed is a pseudo-taxonomic group within a species.

3. Inbreeding is carried out in animal husbandry because it: 

(a) increases vigor 

(b) improves the breed

(c) increases heterozygosity

(d) increases homozygosity 

Ans: (d) increases homozygosity 

Explanation: Increased homozygosity aids in the preservation of a pure line of breed.

4. Sonalika and Kalyan Sona are varieties of: 

(a) wheat 

(b) rice

(c) millet

(d) tobacco 

Ans: (a) wheat 

5. Which one of the following is not a fungal disease?

(a) Rust of wheat

(b) Smut of Bajra 

(c) Black rot of crucifers 

(d) Red rot of sugarcane 

Ans: (c) Black rot of crucifers

Explanation: The black rot of crucifers is a bacterial infection.

6. In virus-infected plants the meristematic tissues in both apical and axillary buds are free of virus because: 

(a) the dividing cells are virus resistant 

(b) meristems have antiviral compounds

(c) the cell division of meristems are faster than the rate of viral multiplication 

(d) Viruses cannot multiply within meristem cell (s). 

Ans: (c) the cell division of meristems is faster than the rate of viral multiplication.

Explanation: Meristematic cells are not impacted by viruses due to their rapid rate of reproduction. 

7. Several South Indian states raise 2-3 crops of rice annually. The agronomic feature that makes this possible is because of

(a) shorter rice plant 

(b) better irrigation facilities 

(c) early yielding rice variety 

(d) disease-resistant rice variety. 

Ans: (c) early yielding rice variety 

Explanation: Rice is grown in some South Indian states twice a year. The early producing rice variety is the agronomic trait that makes this possible.

8. Which one of the following combinations would a sugarcane farmer look for in the sugarcane crop? 

(a) Thick stem, long internodes, high sugar content and disease resistant 

(b) Thick stem, high sugar content and profuse flowering 

(c) Thick stem, short internodes, high sugar content, disease-resistant

(d) Thick stem, low sugar, content, disease-resistant 

Ans: (a) Thick stem, long internodes, high sugar content and disease resistant.

Explanation: A sugarcane farmer would strive for a sugarcane crop with thick stems, long internodes, high sugar content, and disease resistance.

9. Fungicides and antibiotics are chemicals that: 

(a) enhance yield and disease resistance 

(b) kill pathogenic fungi and bacteria, respectively 

(c) kill all pathogenic microbes 

(d) kill pathogenic bacteria and fungi respectively. 

Ans: (b) kill pathogenic fungi and bacteria, respectively 

Explanation: (b) Antibiotics and fungicides are substances that kill harmful fungus and bacteria.

10. Use of certain chemicals and radiation to change the base sequences of genes of crop plants is termed: 

(a) recombinant DNA technology

(b) transgenic mechanism 

(c) mutation breeding 

(d) gene therapy. 

Ans: (c) mutation breeding 

Explanation: Mutation breeding is the process of changing the base sequences of genes in crop plants using chemicals and radiation. Mutations can be artificially produced with the use of chemicals or radiations such as gamma rays. Mutations in the mung bean induced resistance to yellow mosaic virus and powdery mildew.

11. The scientific process by which crop plants are enriched with certain desirable nutrients is called:

(a) crop protection 

(b) breeding 

(c) bio-fortification 

(d) bioremediation. 

Ans: (c) bio-fortification

Explanation: Bio-fortification is the most cost-effective way to promote public health. Breeding crops with higher levels of vitamins and minerals, or higher protein and better fats, is used in bio-fortification. In the year 2000, maize hybrids with twice the level of the amino acids lysine and tryptophan were discovered (MALT). Atlas 66 (Wheat variety) has been utilized as a donor for upgrading grown wheat due to its high protein content. Iron-fortified rice has more than 5 times the amount of Fe. 

12. The term ‘totipotency’ refers to the capacity of a:

(a) cell to generate whole plant 

(b) bud to generate whole plant 

(c) seed to germinate 

(d) cell to enlarge in size. 

Ans: (a) cell to generate whole plant 

Explanation: Cellular totipotency refers to an explant's or any cell's ability to create a whole plant. All plant cells exhibit cellular totipotency. F.C. Steward proved cellular totipotency.

13. Given below are a few statements regarding somatic hybridization. Choose the correct statements. 

(i) protoplasts of different cells of the same plant are fused 

(ii) protoplasts from cells of different species can be fused

(iii) treatment of cells with cellulase and pectinase is mandatory

(iv) the hybrid protoplast contains characters of only one parental protoplast. 

(a) (i) and(iii) 

(b) (i) and (ii)

(c) (i) and (iv) 

(d) (ii) and (iii) 

Ans: (d) (ii) and (iii) 

Explanation: 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. Polyethylene glycol (PEG) and sodium nitrate, which induce fusion, are used to create somatic cell hybrids (protoplast hybrids). Chemo Fusion and electrofusion are used in protoplast fusion.

14. An explant is: 

(a) dead plant 

(b) part of the plant 

(c) part of the plant used in tissue culture 

(d) part of the plant that expresses a specific gene. 

Ans: (c) part of the plant used in tissue culture 

Explanation: An explant is a plant component that is utilized in tissue culture.

15. The biggest constraint of plant breeding is: 

(a) availability of desirable gene in the crop and its wild relatives 

(b) infrastructure 

(c) trained manpower 

(d) transfer of genes from unrelated sources. 

Ans: (a) availability of desirable gene in the crop and its wild relative's 

Explanation: There is sufficient infrastructure for the purpose, and there is no shortage of trained labor due to thousands of years of farming experience.

16. Lysine and tryptophan are: 

(a) proteins 

(b) non-essential amino acids

(c) essential amino acids

(d) aromatic amino acids. 

Ans: (c) essential amino acids 

Explanation: Essential amino acids are amino acids that the body does not make and must obtain from outside sources. Tryptophan and Lysine are necessary amino acids.

17. Micro-propagation is: 

(a) propagation of microbes in vitro 

(b) propagation of plants in vitro 

(c) propagation of cells in vitro 

(d) growing plants on a smaller scale. 

Ans: (b) propagation of plants in vitro 

Explanation: Option 'd' is wrong because a smaller scale can refer to a little flower pot. Because microbes and cells are small enough to grow in vitro, choices a and c are erroneous.

18. Protoplast is:

(a) another name for protoplasm 

(b) an animal cell 

(c) a plant cell without a cell wall 

(d) a plant cell. 

Ans: (c) a plant cell without a cell wall 

Explanation: Assume we grabbed a plant cell and digested its cell wall using specialized digestive enzymes. After the cell wall is removed, the cell is referred to as a 'Protoplast.' The protoplast is made up of cytoplasm and plasma membrane, but no cell wall. Whereas cytoplasm is a fluid-like liquid found within the plasma membrane that contains nutrients, biomolecules, and all cell organelles. These cell organelles include mitochondria, ribosomes, the endoplasmic reticulum, the Golgi complex, the nucleus, and others. The nucleus is the biggest cell organelle in eukaryotic creatures such as plants and animals. As a result, the previous explanation supports Option C, i.e., Protoplast is a single wall-less cell.

19. To isolate protoplast, one needs: 

(a) pectinase 

(b) cellulase 

(c) both pectinase and cellulase 

(d) chitinase. 

Ans: (c) both pectinase and cellulase 

Explanation: Cellulase, hemicellulase, and pectinase, which dissolve the cell wall, are the enzymes required to obtain wall-free or naked protoplasts.

20. Which one of the following is a marine fish: 

(a) Rohu 

(b) Hilsa

(c) Catla 

(d) Common Carp. 

Ans: (b) Hilsa 

Explanation: Rohu, Catla, and Common carp are freshwater fish. 

21. Which one of the following products of apiculture is used in cosmetics and polishes:

(a) honey

(b) oil 

(c) wax

(d) Royal jelly 

Ans: (c) wax

Explanation: Wax is an apiculture product that is used in cosmetics and polishes.

22. More than 70 percent of the livestock population is in

(a) Denmark

(b) India 

(c) China

(d) India and China. 

Ans: (d) India and China. 

Explanation: India and China are home to more than 70% of the world's cattle population, but they only contribute 25% of global farm products (means productivity per unit is very low).

23. The agriculture sector of India employs: 

(a) 50 percent of the population 

(b) 70 percent of the population 

(c) 30 percent of the population 

(d) 60 percent of the population. 

Ans: (d) 60 percent of the population. 

Explanation: India's agriculture sector employs over 60% of the population.

24. 33 percent of India’s (Gross Domestic Product) comes from

(a) Industry 

(b) Agriculture 

(c) Export 

(d) Small-scale cottage industries.

Ans: (b) Agriculture 

Explanation: Agriculture contributes 33 percent of India's GDP, and agriculture is rapidly increasing its contribution to the country's national wealth. As a result, 'Option B' is the correct answer.

25. A collection of all the alleles of all the genes of a crop plant is called:

(a) germplasm collection 

(b) protoplasm collection

(c) herbarium 

(d) somaclonal collection 

Ans: (a) germplasm collection 

Explanation: A germplasm collection is a collection of all the alleles of all the genes in a crop plant.

Very Short Answer Type Questions

1. Millions of chickens were killed in West Bengal, Assam, Odisha, and Maharashtra recently. What was the reason?

Ans: Millions of chickens were murdered (culled) in West Bengal, Orissa, and Maharashtra after the H5N1 virus, the cause of Bird Flu, was discovered infected.

2. Can gamma rays used for crop improvement programmes prove to be harmful for health? Discuss. 

Ans: Moong varieties resistant to yellow mosaic virus and powdery mildew have been developed using this strategy. This is strong proof that using Gamma rays for agricultural enhancement is safe for humans. 

3. In animal husbandry, if two closely related animals are mated for a few generations, it results in loss of fertility and vigor. Why is this so? 

Ans: Inbreeding depression, which results from many generations of inbreeding, causes a reduction of fertility and vitality. 

4. In the area of plant breeding, it is important not only to preserve the seeds of the variety being cultivated but also to preserve all its wild relatives. Explain with a suitable example. 

Ans: The preservation of seeds from cultivated and wild types aids in the creation of a good germplasm collection. Wheat, rice, and maize cultivars with high yields and disease resistance have been developed through plant breeding. This may be achievable as a result of improved germplasm collection.

5. Name a man-made cereal? Trace how it was developed and where is it used? 

Ans: Triticale was the earliest cereal created by humans. It's a cross between wheat and rye. It was first bred in a laboratory in Scotland and Sweden in the late 1800s. It blends wheat's yield potential and grain quality with rye's resistant characteristics. It is mostly used as a source of feed.

6. Fill in the blanks

Ans: I. Cellulase; II. Somatic hybridization; III. Pomato; IV. Somatic hybrid

7. A few statements are given below followed by a set of terms in a box. Pick the correct term and write it against the appropriate statement

(a) Mating of closely related individuals within the same breed 

(b) Mating of animals of the same breed but having no common ancestors on either side for 4-6 generations 

(c) Mating of animals of two different species 

(d) Breeding of animals belonging to different breeds

(i) Crossbreeding (ii) Interspecific hybridization (iii) Outbreeding (iv) Outcrossing (v) Inbreeding 

Ans: (a) Mating of closely related individuals within the same breed→ (v)Inbreeding

(b) Mating of animals of the same breed but having no common ancestors on either side for 4-6 generations →(iv) Outcrossing

(c) Mating of animals of two different species  →(ii)  Interspecific hybridization

(d) Breeding of animals belonging to different breeds→(i)  Crossbreeding

8. What is meant by ‘hidden hunger’? 

Ans: Many folks are able to obtain a good that is solely composed of carbohydrates. Other nutrients, such as protein, vitamins, and minerals, are not available to these people. This is referred to as 'hidden hunger.' 

9. Why are plants obtained by protoplast culture called somatic hybrids? 

Ans: The fusion of two protoplasts from distinct plants is known as protoplast culture. This is then permitted to generate a plant that combines the best qualities of both plants. Because somatic cells are employed, these plants are referred to as somatic hybrids.

10. What is protoplast fusion? 

Ans: Protoplast fusion occurs when the protoplast of two plants are fused together. It is made possible by using an appropriate enzyme to dissolve the cellulose.

11. Why is it easier to culture meristems compared to permanent tissues? 

Ans: Meristem cells have the ability to divide, but cells in permanent tissues do not. As a result, meristems are easier to cultivate than permanent tissues.

12. Why are proteins synthesized from Spirulina called single-cell proteins? 

Ans: Spirulina is a single-celled algae. As a result, the protein produced by it is known as single-cell protein. 

13. A person who is allergic to pulses was advised to take a capsule of Spirulina daily. Give the reasons for the advice. 

Ans: Spirulina is a high-protein food that provides all necessary amino acids. Spirulina has a considerably greater protein content than pulses. As a result, it may be a superior source of protein, particularly for individuals who are allergic to pulses.

14. What is aquaculture? Give an example of an animal that can be multiplied by aquaculture. 

Ans: Aquaculture is the practice of farming aquatic animals and plants. Pisciculture is a type of aquaculture. Aquaculture can be used to multiply prawns. 

15. What are the duties of a veterinary doctor in the management of a poultry farm? 

Ans: In the management of a poultry farm, a veterinary doctor is responsible for the following tasks: 

(a) Consistent inspection to ensure a disease-free environment. 

(b) Provide a nutritious diet for the birds. 

(c) Maintain clean and sanitary enclosures

16. Would it be wrong to call plants obtained through micro-propagation as ‘clones’? Comment. 

Ans: It is determined by the source of the gene pool. A clone is a plant that is created from a single plant using micro-propagation. If a plant is created by blending genes from other plants, it cannot be a clone. 

17. How is a somatic hybrid different from a hybrid? 

Ans: A somatic hybrid is created from somatic cells, whereas a conventional hybrid is created through gamete fusion. Sexual reproduction is required to create a conventional hybrid but is not required to create a somatic hybrid.

18. What is emasculation? Why and when is it done? 

Ans: Emasculation is the expulsion of anthers from a flower. This is achieved by using scissors or another appropriate instrument to remove the anthers.

19. Discuss the two main limitations of the plant hybridization programme. 

Ans: The following are the two main limits of the plant hybridization programme: 

1. Germplasm collection: Cultivators and agricultural scientists must have seeds from both present cultivated varieties and wild variants. This can be a time-consuming process. 

2. Selection and Testing: Before being released for commercial production, a hybrid variety must be tested for all possible environmental elements such as climate, soil type, flood, drought, and so on. This is a time-consuming operation as well.

20. Interspecific crosses are rare in nature and intergeneric crosses almost unknown. Why? 

Ans: Interbreeding is a significant condition for any species' members. If two individuals are unable to reproduce, they cannot be classified as belonging to the same species. As a result, interspecific crosses are uncommon in nature. For intergeneric crossovers, certain logic applies. The fundamental reason is that different organisms' cells have varying numbers of chromosomes. As a result, two gametes with differing numbers of chromosomes cannot create a viable zygote. However, artificial hybridization is commonly utilized to establish interspecific and intergeneric crosses, particularly for the production of superior plant varieties.

21. Differentiate between pisciculture and aquaculture.

Ans:

22. Give two important contributions of Dr. M. S. Swaminathan. 

Ans: Dr. M. S. Swaminathan made the following two significant contributions:

(a) Played a key role in launching India's Green Revolution.

(a) Started the "Lab to Land" program to ensure India's food security. 

23. The term ‘desirable trait’ can mean different things for different plants. Justify the statement with suitable examples. 

Ans: The following examples will assist to demonstrate this:

(a) While thick and tall stems are preferred in sugarcane, dwarf stems are ideal in rice plants.

(b) While more leaves are desired in spinach, this may not be the case with the mustard plant.

Short Answer Type Questions

1. You are planning to set up a Dairy Farm. Describe the various aspects you would consider before you start the venture. 

Ans: Before beginning the venture, the following factors must be considered: 

1. Breed Selection: The breed should be capable of producing a high milk output. It should be resistant to a variety of ailments. 

2. Cattle Shed Construction: Cattle sheds should be well ventilated and have plenty of natural light. Water should be able to drain quickly due to the slope of the floor. 

3. Fodder Availability: Fodder should have both mass and required nutrients. 

4. Veterinary Doctor Availability: A veterinary doctor should be nearby so that correct medical care for cattle can be assured in times of need.

2. It is said that diseases are spreading faster due to globalization and the increased movement of people. Justifying the statement by taking the example of the H5N1 virus. 

Ans: The H5N1 virus is an influenza virus subtype. Avian influenza, sometimes known as bird flu, is caused by this virus. This illness began in South East Asia and quickly spread to the rest of the world. The spread of this illness to many other nations was facilitated mostly by international chicken commerce. This demonstrates that globalization and greater human travel have aided in the spread of illnesses.

3. Explain the concept of the Blue Revolution. 

Ans: The term "blue revolution" refers to the extraordinary rise of aquaculture as a significant and highly productive agricultural sector. It aims to achieve economic prosperity for the country and its fishers and farmers, as well as to contribute to food and nutritional security by utilizing water resources to their full potential for fisheries development in a sustainable manner while keeping bio-security and environmental concerns in mind. It promotes aquaculture in India. Aquaculture encompasses all forms of active culturing of aquatic animals and plants in marine, brackish, and freshwater.

4. A farmer was facing the problem of low yield from his farm. He was advised to keep a beehive in the vicinity. Why? How would the beehive help in enhancing yield? 

Ans: It appears that the farm's low output was caused by a lack of sufficient pollinators. We know that pollination is critical for seed generation in a variety of crops. Insects play a crucial role in pollination, and bees pollinate a wide range of plant species. Keeping a beehive near the farm will aid in optimal crop pollination throughout the flowering stage. This will eventually aid in increasing farm productivity. Furthermore, the farmer's revenue will be supplemented by the sale of honey and beeswax.

5. Lifestyle diseases are increasing alarmingly in India. We are also dealing with large-scale malnutrition in the population. Is there any method by which we can address both of these problems together? 

Ans: A lack of a well-balanced diet is the root cause of lifestyle diseases and malnutrition. A person who consumes a high-carbohydrate, high-fat diet while ignoring protein, vitamins, and minerals is more prone to develop lifestyle diseases. Malnutrition occurs as a result of a shortage of most nutrients in the diet. One approach to addressing these issues is to ensure the availability of all types of food (in terms of available nutrients). Another approach could be to use biofortification to increase the availability of all nutrients in food. 

6. How can we improve the success rate of fertilization during artificial insemination in animal husbandry programs? 

Ans: MOET is an excellent approach for increasing the success rate of artificial insemination in animal husbandry. MOET stands for Multiple Ovulation Embryo Transfer Technology. In this program, a cow is administered a hormone that works in the same way as FSH (Follicle Stimulating Hormone). This causes hyper ovulation in the cow, and the cow produces six to eight eggs in an ovulation cycle instead of the usual one egg each ovulation cycle. After that, the animal is artificially inseminated. Zygotes are allowed to grow to cell stages ranging from 8 to 32. After that, the embryo is transferred to a surrogate mother in order to produce a healthy calf. This method increases the success rate of artificial insemination.

7. What is meant by germplasm collection? What are its benefits? 

Ans: The preservation of seeds from cultivated and wild types aids in the creation of a good germplasm collection. The following are some of the advantages of germplasm collection.

1. This aids in the preparation of a big pool of favorable traits in a plant species.

2. This aids in the right selection of appropriate traits during a hybridization procedure.

3. This aids in mixing the best of developed and wild plant varieties.

8. Name the improved characteristics of wheat that helped India to achieve the green revolution. 

Ans: The improved wheat features that aided India's green revolution were as follows:

1. Semi-dwarf Plants: Dwarf plants use the majority of their resources to produce a greater number of grains.

2. High Yield: The new varieties may provide a higher yield in terms of wheat production per acre.

3. Disease Resistance: The new plants were resistant to a wide range of diseases that afflicted older wheat cultivars.

4. Quick Yield: The new types matured harvests in a short period of time.

9. Suggest some of the features of plants that will prevent insect and pest infestation.

Ans: Some of the characteristics of plants that help to keep insects and pests at bay are as follows:

(a) Hairy leaves are thought to be resistant to pest assault; for example, jassids do not attack cotton, and the leaf beetle does not attack wheat.

(b) Wheat's solid stem renders it resistant to stem sawfly.

(c) Cotton cultivars that lack nectar do not attract bollworms.

(d) Maize's high aspartic acid, low nitrogen, and sugar content confer resistance against maize stem borers.

10. It is easier to culture plant cells in vitro as compared to animal cells. Why? 

Ans: Plant cells can be cultured in vitro more easily than animal cells. The reasons behind this are as follows:

(a) Meristems are found in plants, and their cells are constantly divided. After a certain age, the majority of cells in animals stop dividing. In an adult mammal, cell division is primarily used for repair.

(b) Plant tissues de-differentiate in response to stress, while animal tissues do not.

11. The culture medium (nutrient medium) can be referred to as a ‘highly enriched laboratory soil. Justify the statement. 

Ans: Soil is a water and nutrient reservoir for plants. Similarly, culture media serves as a reservoir for water and nutrients for plants that are grown on it. Many nutrients may be lacking, and the soil may have a higher or lower nutrient concentration. In culture media, on the other hand, all of the required nutrients are provided as needed. As a result, the culture medium is more nutrient-dense for plants. Because of these factors, culture media is sometimes referred to as "highly enriched laboratory soil."

12. Is there any relationship between dedifferentiation and the higher degree of success achieved in plant tissue culture experiments? 

Ans: Meristematic tissue cells, as we know, differentiate and lose their proliferative potential in order to form permanent tissue. Plants, on the other hand, have the unusual capacity to flip between permanent and meristematic tissue as needed. This is referred to as dedifferentiation. Many plant tissues can undergo cell division to create new components due to their predisposition for dedifferentiation. Plant tissue testing is more successful as a result of these capabilities.

13. “Give me a living cell of any plant and I will give you a thousand plants of the same type” Is this only a slogan or is it scientifically possible? Write your comments and justify them. 

Ans: Tissue culture, we know, has made it feasible to grow a new plant from any portion of an existing one. Explants are small piece of a plant that is used to grow a plant through tissue culture. As a result, a single plant cell can theoretically be used to create a thousand plants of the same species.

14. What is the difference between a breed and a species? Give an example for each category.

Ans: 

15. Plants raised through tissue cultures are clones of the ‘parent’ plant. Discuss the utility of these plants. 

Ans: Tissue-cultured plants have the following advantages: 

(a) A large number of clones can be grown in a shorter amount of time.

(b) Tissue culture makes it simple to pick desirable traits.

(c) This procedure can be used to create somatic hybrids.

(d) Tissue culture can be used to create high yield cultivars.

(e) A diseased plant can be recovered into a healthy plant.

16. Discuss the importance of testing new plant varieties in a geographically vast country like India. 

Ans: India is a huge country with many attractions. Different soil types and weather conditions may be found throughout the country.A crop variety must be able to deliver good results in all regions of India in order to be successful throughout India. As a consequence, new plant varieties are evaluated in simulated habitats that mimic the country's various climatic conditions and soil types. Only if a crop variety passes this test is it declared ready for market introduction.

17. Define the term ‘stress’ for plants. Discuss briefly the two types of stress encountered by plants. 

Ans: A plant must interact with a variety of biotic and abiotic stimuli on a regular basis. A plant may be stressed as a result of several circumstances. The following are two types of stress that plants frequently face:

1. Environmental Stress: Unfavorable conditions, such as salinity, dryness, and severe temperatures, cause environmental stress. Many crop plants are unable to withstand high salinity, drought, or temperature extremes.

2. Biotic Stress: Insects and pests are examples of biotic stresses. Weeds can also cause biotic stress in plants. While pests and insects cause direct damage to plants, weeds compete for resources such as sunlight, nutrients, and water.

18. Discuss natural selection and artificial selection. What are the implications of the latter on the process of evolution? 

Ans: Natural Selection: Nature picks creatures with desirable characteristics, as the term implies. Organisms that are better adapted to adapt to changing environmental conditions can produce more progenies and carry on their lineage.

Artificial Selection: Humans are the ones who bring about artificial selection. Humans have been selectively breeding numerous plants and animals with the purpose of gaining benefits from them. In the evolution process, artificial selection plays a significant role. Artificial selection has given birth to many plant species and animal breeds. Take, for example, wild cabbage, which has long been subjected to artificial selection. Cauliflower, broccoli, cabbage, and other vegetables are the consequence of wild cabbage being selectively bred.

19. Discuss briefly how pure lines are created in animal husbandry. 

Ans: In-breeding is used to establish pure lineages. In-breeding refers to the practice of breeding closely related individuals. For this aim, a superior male and superior female are chosen and mated. Superior males and females are chosen from the next generation to continue the process. To achieve a pure line, this process is repeated for 4 to 5 generations. Inbreeding increases homozygosity, allowing for the production of pure lines. This approach, however, has a serious flaw: inbreeding depression.

20. What are the physical barriers of a cell in the protoplast fusion experiment? How are the barriers overcome? 

Ans: The physical barrier that can inhibit protoplast fusion is the cell wall. Cellulase, an enzyme, aids in the breakdown of the cell wall, which is composed of cellulose. The protoplast is subsequently fused via electrical and chemical processes.

21. Give a few examples of biofortified crops. What benefits do they offer to society?

Ans: Examples of biofortified crops: maize, wheat, rice, bathua, spinach, and legumes are available. Fortified maize hybrids contain double the amount of amino acids, fortified wheat varieties have a high protein level, and fortified rice has a high iron content. 

Crops that have been biofortified have the following advantages: Biofortified crops hold a lot of promise for society. These are especially beneficial for persons who may be, experiencing 'hidden hunger.' Many poor people only get enough food to survive.

However, they do not get the majority of the nutrients from their meal. As a result, malnutrition and associated disorders are common among these people. Anemia, night blindness, rickets, and other diseases are widespread among the impoverished. These issues can be solved by giving these persons biofortified meals.

Long Answer Type Questions

1. You are a Botanist working in the area of plant breeding. Describe the various steps that you will undertake to release a new variety. 

Ans: To introduce a new crop variety, the following processes must be taken:

1. Variability Collection: The most crucial aspect of every breeding effort is genetic variability. Seeds of current cultivated kinds, as well as seeds of wild plant varieties, are collected for this purpose. From the standpoint of increased productivity, already developed varieties would provide a variety of attractive characteristics. From the standpoint of stress resistance, wild varieties will provide beneficial characteristics.

2. Parent Selection and Evaluation: Germplasm is analyzed in order to create a list of desirable characteristics. Pure lines are created by selecting varieties that meet the majority of the criteria.

3. Selected Parent Cross Hybridization: After the previous stage, selected parent cross-hybridization is performed. Cross-hybridisation has a poor success rate since only a few individuals in the next generation demonstrate all of the required characteristics. As a result, this is a time-consuming process. Only a few hundred or thousands of crosses contain the desired combination.

4. Selection and Testing of Superior Recombinants: To develop pure lines, crosses with desirable combinations are selected and self-pollinated for numerous generations.

5. Testing and Release: Agriculture involves a variety of applications and is carried out in a variety of climates and soil types. This is especially true in a country as large as India. Once a pure line of plant with acceptable characteristics has been obtained, it is grown in a variety of simulated circumstances to determine its viability in the real world. When a variety passes this test, it is ready for market release.

2. (a) The shift from grain to meat diets creates more demands for cereals. Why? 

Ans: We know that 90% of the biomass consumed by an organism at a specific trophic level is used for its own needs, leaving just 10% accessible for the creature at the next trophic level. So, in order to generate 1 kilogramme of meat, 3 to 10 kg of grains must be spent on cattle. This demonstrates that a change from grain to meat diets increases demand for grains.

(b) A 250-kg cow produces 200 g of protein per day but 250 g of Methylophilus Methylotrophus can produce 25 tons of protein. Name this emerging area of research. Explain its benefits. 

Ans: This new area of study is known as single-cell proteins (SCP). When bacteria, fungus, and algae decompose organic molecules, single-cell proteins are generated. The protein composition of the single-cell protein is quite high. The following are the advantages of this procedure:

• Increased protein production per unit biomass.

• Improved solar energy use per unit area

• This is a non-harmful process for the environment.

• The land need is minimal.

• Production is not affected by seasonal or climatic changes.

• This might aid in addressing the issue of food security.

3. What are the advantages of tissue culture methods over conventional methods of plant breeding in crop improvement programmes? 

Ans: In crop improvement programmes, tissue culture has the following advantages over traditional plant breeding methods: Any portion of the parent plant can be used to create a new plant. Hundreds of plants can be grown from a single tiny tissue. Producing a new generation takes a short amount of time, therefore this procedure is faster than the traditional method. Because offspring are clones of parent plants, producing pure lines takes less time. It is not necessary to wait for four to five generations to achieve this. This method does not necessitate any land. As a result, this method uses fewer resources than traditional methods. This procedure can be used to rescue healthy plants from damaged plants. As a result, creating disease-resistant plants is simple with this strategy. 

4. ‘Modern methods of breeding animals and plants can alleviate the global food shortage’. Comment on the statement and give suitable examples. 

Ans: This is an accurate statement: contemporary ways of growing animals and plants can help to solve the worldwide food shortfall. When we compare the position of food security during World War II to the current situation, we can conclude that food security is considerably better in modern times than it was previously. This may have been achievable due to improved plant and livestock types. Food processing and food preservation technology have also had a part in this, albeit only to a limited extent. Here are a few instances to demonstrate this:

Prior to the 1950s, India had to rely on wheat imports from the United States to satisfy its needs. Following the Green Revolution, numerous improved wheat types were introduced, which aided in improving farm productivity. Wheat output climbed from 11 million tons to 75 million tons between 1960 and 2000. Rice output climbed from 35 million tons to 89 million tons within the same time period. At the moment, India is not only a food-sufficient country, but it also exports a large portion of its food grain output.

The introduction of hybrid cow breeds propelled India to the forefront in milk production.

Because of improved poultry farming procedures, the majority of Indians now have access to chicken and eggs as part of their normal diet.

Significant advancements have also occurred in the field of pisciculture. This has increased the revenue of fishermen while also increasing the availability of fish around the country.

5. Does apiculture offer multiple advantages to farmers? List its advantages if it is located near a place of commercial flower cultivation. 

Ans: Farmers can benefit from apiculture in a variety of ways. The following are some of the benefits of having an apiary near a commercial flower farm:

1. Flowers will provide plenty of nectar for bees. This will make it easier for them to make a greater batch of honey. The amount of beeswax produced will likewise rise dramatically.

2. Bees play a vital role in pollination. They will aid in the enhancement of floral production. This will assist the gardener in increasing his revenue from flower sales.

3. This will also aid in increasing flower supply for the perfume business.

4. Many medicinal medicines contain essential oils derived from a variety of flowers. As a result, greater flower cultivation will also help this activity.

6. Answer the following: 

(a) Mutations are beneficial for plant breeding. Taking an example, justify the statement. 

Ans: A mutation is a change in a gene's base sequence that can be caused by modifying the base sequence. The use of appropriate technologies, such as Gamma radiation, can be used to cause mutation in plants. Through mutational breeding, many disease-resistant plant variants can be obtained. Mung bean resistance to yellow mosaic virus and mildew, for instance, might be achieved by mutational breeding.

(b) Discuss briefly the technology that made us self-sufficient in food production. 

Ans: Plant breeding has enabled humanity to become food self-sufficient. Plant breeding uses a variety of strategies to generate high-yielding, disease-resistant cultivars of diverse crops. Because of diverse plant breeding procedures, improved varieties of rice, wheat, maize, and other crops might be generated in India. Because of the Green Revolution, many technologies that existed but were not widely used may be adopted by more farmers. Irrigation, herbicides, and synthetic fertilizers are only a few examples.

Irrigation Projects: The Green Revolution would be doomed if massive irrigation projects were not properly implemented. Irrigation canals were fed by a number of multipurpose dams. Punjab is an excellent example of a state that has benefited from a well-developed canal network. 

Pesticides: During the Green Revolution, pesticides were utilized more extensively. This resulted in a large increase in farm productivity. 

Synthetic Fertilizers: While manure is beneficial, synthetic fertilizers produce more dramatic benefits. To accommodate the demand, the government built a slew of fertilizer plants. Farmers were granted fertilizer subsidies in order to boost farm production.

7. Discuss how the property of plant cell totipotency has been utilized for plant propagation and improvement 

Ans: In the 1950s, scientists discovered that an explant could be utilized to develop a whole plant. Explant is a term that refers to any component of a plant that has been grown in a test tube under sterile conditions using a specific nutritional mix. Totipotency is the ability of a cell to create a whole organism. Using this feature, it is possible to develop a large number of plants in a short period of time. This function necessitates the presence of a carbon source in the nutritional medium, such as sucrose. There should also be inorganic salts, vitamins, amino acids, and plant hormones present. This method is used to grow clones of the parent plant. Somaclones is a phrase used to describe them. Many desired features can be integrated into the progeny using this technology and a combination of genetic engineering. This method can be used to propagate healthy plants from faulty plants. Virus-free plants can be easily created with this method. This method has been used to cultivate bananas, sugarcane, potatoes, and other plants.

8. What are three options to increase food production? Discuss each giving the salient features, merits, and demerits. 

Ans: The following methods can be used to boost food production: 

1. Through the Introduction of Improved Crop Varieties: This can be accomplished by selective breeding of plants to incorporate desirable traits in a specific plant. 

Merits: Many new wheat, rice, and maize types were introduced. After the Green Revolution was implemented in India, this helped to greatly improve wheat and rice production. Because of high producing and disease resistant plant types, per acre yield rose. 

Demerits: Selective breeding can occasionally generate an annoying weed that is difficult to eradicate. Some plant mutations have the potential to be extremely hazardous to humans.

2. Via Enhancing Irrigation Infrastructure: Water is essential for plants, and crops require a lot of it to thrive. Rice plants, for example, require so much water that they are submerged for most of the cropping season. 

Merits: Improved irrigation facilities have aided crop output in numerous areas. Because of improved irrigation facilities, farmers in various states (such as Punjab and Haryana) have prospered.

Demerits: Water resources are overexploited as a result of intensive irrigation. Because of heavy irrigation, the water table has dropped dramatically in several locations. Many areas are experiencing a lack of drinking water as a result of this. Dam construction has a negative impact on the environment. 

3. Using Synthetic Fertilizers: Plants absorb a large number of minerals from the soil. As a result, after a few farming cycles, the soil has lost most of its nutrients. Soil needs to be replenished with nutrients by some manner. The quickest method to accomplish this is to use synthetic fertilizers.

Merits: Synthetic fertilizers aid in the rapid replenishment of soil nutrients. 

Demerits: Synthetic fertilizers release a number of hazardous substances into the soil. Groundwater pollution results as a result of this. As a result of bioaccumulation, hazardous compounds accumulate in the human body.

NCERT Biology Chapter 9 for Class 12

The NCERT Biology Chapter 9 for Class 12 relates to the adoption of Strategies for boosting the production of food. The different principles are applied in plant breeding and animal husbandry which contributes immensely to the growth of food production. There are modern techniques such as tissue culture and embryo transfer that play a crucial role in the enhancement and boosting of food production. This chapter covers all the details, techniques, and strategies related to the enhancement of food production.

The Exemplar is the model set of questions related to a specific subject that provides the students with the essential practice and helps them with the revision of their concepts. The exercise questions with solutions provided by Vedantu for the Class 12 Biology Exemplar for Chapter 9 offers the students an amazing insight into the different terms as well as concepts and equips them with crucial information that goes a long way in helping them prepare for the exams.

Solutions to NCERT Exemplar

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