9

Q1. Give four examples of microorganisms which help in the production of single cell protein.

Solution

Spirulina maxima, Methylophilus methylotrophus, Candida utilis and Paecilomyces variotii are helpful for production of single cell protein.

Q2. Probiotics are

• 1) Food allergens
• 2) Cancer-inducing microbes
• 3) Safe antibiotics
• 4) Live microbial food supplements

Solution

Probiotics are live microorganisms which are available commercially as dietary supplements. They are called ‘good bacteria’.

Q3. 2,4-D is a

• 1) Auxin
• 2) None of the above
• 3) Cytokine
• 4) Gibberellin

Solution

2,4-D is an auxin which is used to induce shoot growth.

Q4. To obtain disease-free plants through tissue culture techniques, the best method is

• 1) Anther culture
• 2) Protoplast culture
• 3) Meristem culture
• 4) Embryo rescue

Solution

Meristems are virus-free, and they are cultured on a suitable medium of shoot apical meristems to obtain virus-free plants.

Q5. The species of Saccharum originally grown in India was

• 1) S. munja
• 2) S. boulardii
• 3) S. barberi
• 4) S. officinarum

Solution

Saccharum barberi and Saccharum officinarum were crossed to obtain sugarcane varieties having desirable qualities. Saccharum barberi was grown in north India but had poor sugar content and yield.

Q6. Triticum aestivum, the common bread wheat, is

• 1) Diploid with 14 chromosomes
• 2) Tetraploid with 28 chromosomes
• 3) Triploid with 21 chromosomes
• 4) Hexaploid with 42 chromosomes

Solution

Triticum aestivum is the major breed of wheat containing six homologous sets of chromosomes and 42 chromosomes in total.

Q7. High milk-yielding varieties of cows are obtained by

• 1) Use of surrogate mother
• 2) Artificial insemination
• 3) Super ovulation
• 4) All of the above

Solution

High milk-yielding varieties of cows are obtained by the techniques of super ovulation, artificial insemination and use of surrogate mother.

Q8. Which chemical is used for induction of polyploidy?

• 1) Colchicine
• 2) IAA
• 3) Cytokinin
• 4) Nitrous acid

Solution

An organism having more than two sets of chromosomes is polyploid. It can be artificially induced by application of colchicine.

Q9. The substance used in the tissue culture medium for the induction of shoots in the callus is

• 1) Cytokinin
• 2) IAA
• 3) GA₃
• 4) ABA

Solution

Shoots are regenerated by keeping the callus cultures on a cytokinin-rich medium. The callus develops shoot buds which grow into a stem and leaves.

Q10. Honey is

• 1) Basic when freshly produced
• 2) Acidic
• 3) Alkaline
• 4) Neutral

Solution

Honey is acidic in nature with a pH of 2.5 to 4.

Q11. The production of new characteristics by introducing new genes and altering the genome is called

• 1) Gene manipulation
• 2) Totipotency
• 3) Genetics
• 4) Splicing

Solution

The alteration of the structure of genetic material or the genome in a living organism by the introduction of new genes is called gene manipulation.

Q12. Most cultivated plants are

• 1) Haploids
• 2) Autopolyploids
• 3) Allopolyploids
• 4) Aneuploids

Solution

An organism which has more than two sets of chromosomes per cell is called a polyploid, and this condition is known as polyploidy. Allopolyploids are the common type in plant breeding. They are developed through hybridisation between two species followed by doubling of chromosomes.

Q13. Yeast is used in the industrial production of

• 1) Butanal
• 2) Tetracycline
• 3) Ethanol
• 4) Citric acid

Solution

Yeast is used in the production of ethanol, as it ferments sugars to release ethanol as a by-product.

Q14. Haploid plants are preferred over diploids for mutation studies, because in haploids

• 1) Induction of mutation is easy.
• 2) Dominant mutations are expressed easily.
• 3) Culturing of plants is easy.
• 4) Recessive mutations express immediately.

Solution

Haploid plants are preferred over diploids for mutation studies, because in haploids, even recessive mutations express immediately as other dominant alleles are not present to mask the effect.

Q15. Single cell protein refers to

• 1) Proteins extracted from a single cell
• 2) A specific protein extracted from a pure culture of a single type of cells
• 3) Sources of mixed proteins extracted from pure or mixed culture of organisms or cells
• 4) A specific protein extracted from a single cell

Solution

The cells from microorganisms such as bacteria and yeasts are extracted from pure or mixed culture, and they are sources of mixed proteins.

Q16. Micropropagation is the

• 1) Propagation of plants in vitro
• 2) Propagation of cells in vitro
• 3) Propagation of microbes in vitro
• 4) Growing of plants on a small scale

Solution

Micropropagation is an in vitro tissue culture technique which produces several plants for rapid vegetative multiplication of ornamental plants and fruit trees.

Q17. Why is vivipary an undesirable character for annual crops?

• 1) Seeds exhibit long dormancy.
• 2) It adversely affects the fertility of the plant.
• 3) It reduces plant vigour.
• 4) Seeds cannot be stored under normal conditions for the next season.

Solution

Seeds of viviparous plants develop on the plant itself. Hence, the seeds cannot be stored for a long time.

Q18. The scientific process by which crop plants are enriched with certain desirable nutrients is called

• 1) Breeding
• 2) Crop protection
• 3) Biofortification
• 4) Bioremediation

Solution

Breeding of crops with higher levels of vitamins and minerals or higher protein and healthier fats is called biofortification.

Q19. Somaclonal variation can be obtained by

• 1) Application of colchicine
• 2) Hybridisation
• 3) Irradiation with gamma rays
• 4) Tissue culture

Solution

The genetically identical plants developed from any part of a plant by tissue culture are called somaclones. Through micropropagation, plants are produced which will be genetically identical to the original plant.

Q20. The technique of obtaining a large number of plantlets by the tissue culture method is called

• 1) Micropropagation
• 2) Plantlet culture
• 3) Macropropagation
• 4) Organ culture

Solution

The best way to obtain bacteria- and virus-free plants is through cloning or micropropagation. Micropropagation is the growing of plants from seeds under hygienic conditions in a laboratory. Through micropropagation, vast quantities of strong and healthy plantlets are produced.

Q21. To meet the demands of society, the in vitro production of a large number of plantlets in a short duration practised in the floriculture and horticulture industry is called

• 1) Somaclonal variation
• 2) Somatic hybridisation
• 3) Hybridoma technology
• 4) Micropropagation

Solution

In the floriculture and horticulture industry, several plants are produced in vitro under aseptic conditions in a nutrient medium. This process is called micropropagation. Small-sized explants are used for rapid vegetative multiplication of ornamental plants and fruit trees.

Q22. Which of the following microbes is used as a single cell protein?

• 1) Candida utilis
• 2) All of the above
• 3) Chaetomium cellulolyticum
• 4) Brevibacterium sp.

Solution

Some of the microbes used as SCPs are Bacteria - Brevibacterium sp. Yeast - Candida utilis Fungi - Chaetomium cellulolyticum

Q23. Ajmalicine is obtained from

• 1) Atropa
• 2) Papaver
• 3) Curcuma
• 4) Sarpagandha

Solution

Ajmalicine is obtained from Sarpagandha or Rauwolfia serpentina.

Q24. MOET is a method of

• 1) Birth control in humans
• 2) Hybridisation in cattle
• 3) Cloning in sheep
• 4) Fish cultivation

Solution

MOET stands for Multiple Ovulation Embryo Transfer Technique which is a process of hybridisation to overcome the low success rate of artificial or natural cross-breeding experiments.

Q25. How are somaclones cultured from explants in in vitro conditions? Why are somaclones so called?

Solution

The explant from the plant is grown in a culture medium which is rich in inorganic nutrient, vitamins and growth regulators such as auxins and cytokinins. This method of producing plants through tissue culture is called micropropagation. The plants produced from the original plant are genetically identical, so they are called somaclones.

Q26. Which one of the following is an American poultry breed?

• 1) Aseel
• 2) Australorp
• 3) Rhode Island Red
• 4) Minorca

Solution

Rhode Island Red is a breed of chicken which was developed in Rhode Island in the United States. The Australorp is a chicken breed of Australian origin. The Minorca is a breed of chicken which originated in Spain. Aseel is a breed of chicken which originated from Sindh province in Pakistan.

Q27. New varieties of plants are produced by

• 1) Mutation and selection
• 2) Selection and hybridisation
• 3) Introduction and mutation
• 4) Introduction and selection

Solution

New varieties of plants have an improvement in genetic characteristics in plant breeding. So classical plant breeding includes hybridisation of pure lines and artificial selection to produce plants with desirable characters.

Q28. Explain the process of emasculation and bagging of flowers. State their importance in breeding experiments.

Solution

(i) The removal of anthers from the flower bud before the anther splits apart in bisexual flowers is called emasculation. It is done by using a pair of forceps. (ii) The emasculated flower is covered with a bag of suitable size, generally made of butter paper to prevent contamination of its stigma with unwanted pollen. This process is called bagging.   To obtain superior varieties, artificial hybridisation is one of the major approaches of crop improvement programmes. It is important that only the desired pollen grains are used for pollination and the stigma is protected from contamination.

Q29. At cryopreservation of germplasm, biological activity

• 1) All of the above
• 2) Cell division stops
• 3) No genetic change occurs
• 4) Essentially ceases

Solution

Cryopreservation refers to the storage of cells and tissues (germplasm) at a temperature of −196 degree centigrade of liquid nitrogen. Biological activity stops during cryopreservation, resulting in stopping of cell division and no genetic change.

Q30. Genetic diversity in agricultural crops is threatened by

• 1) Introduction of high-yielding varieties
• 2) Extensive use of fertilisers
• 3) Intensive use of biopesticides
• 4) Extensive intercropping

Solution

Genetic diversity in agricultural crops is the most important step in biodiversity conservation. So the use of fertilisers and pesticides does not have an impact on diversity, but the introduction of high-yielding varieties causes a decline in genetic diversity of crops.

Q31. The biggest constraint of plant breeding is

• 1) Trained manpower
• 2) Transfer of genes from unrelated sources
• 3) Infrastructure
• 4) Availability of the desirable gene in the crop and its wild relatives

Solution

There cannot be any transfer of genes from unrelated sources; this is the biggest limitation in plant breeding.

Q32. Most of our crop plants are

• 1) Mixed genotype
• 2) Allopolyploids
• 3) Autopolyploids
• 4) Heterozygous

Solution

Most of our crop plants are autopolyploid in origin.

Q33. Germplasm includes

• 1) All of the above
• 2) Wild and obsolete plants
• 3) Varieties which are no more in cultivation
• 4) Cultivated improved varieties

Solution

A germplasm is a collection of genetic resources for an organism. It includes cultivated improved varieties, wild and obsolete plants and those varieties which are no more in cultivation.

Q34. Emasculation is required for

• 1) Pure lines
• 2) Natural hybridisation
• 3) Selective hybridisation
• 4) Self-pollination

Solution

Emasculation involves the removal of stamens from bisexual flowers of the female parents to avoid self-pollination in these flowers. It is done before the anthers mature. Because selective hybridisation produces hybrids with desired characteristics to produce the next generation, emasculation is required. 

Q35. Write four objectives of animal breeding. 

Solution

Four objectives of animal breeding are (i) To produce more milk-yielding cows with longer lactation period. (ii) To produce pure lines through inbreeding. (iii) To combine good characters of different breeds or species of animals to produce cross-breeds. (iv) To produce animals of higher physical strength.

Q36. In cattle, when a cow of good breed is stimulated to produce a large number of eggs, it is called

• 1) In vitro fertilisation
• 2) Induction
• 3) Artificial insemination
• 4) Superovulation

Solution

In superovulation, a cow of good breed is stimulated to produce a large number of eggs by injecting gonadotropic hormones such as FSH and LH. A healthy female cow can produce up to 6 to 8 eggs per cycle instead of one egg per cycle.

Q37. The drug used for deworming poultry birds is

• 1) Antihistamine
• 2) Antibiotic
• 3) Antiviral
• 4) Antihelminthic

Solution

Antihelminthic drugs are medicines which rid the body of parasitic worms in the affected poultry. 

Q38. Protoplast is

• 1) Another name for protoplasm
• 2) A plant cell
• 3) A plant cell without a cell wall
• 4) An animal cell

Solution

The plant cells without cell wall are called protoplasts. Protoplasts are used for tissue culture by fusion of protoplasts in a solution of polyethylene glycol or sodium nitrate.

Q39. What are the physical barriers of a cell in the protoplast fusion experiment? How are the barriers overcome?

Solution

The cell wall is an important physical barrier in the protoplast fusion technique of tissue culture. The barriers can be overcome by treatment of enzymes such as hemicellulase, cellulose and pectinase which digest the cell wall and release the protoplast surrounded by the cell membrane.

Q40. Hybrid vigour is due to

• 1) Homozygosity
• 2) Linkage
• 3) Heterozygosity
• 4) Emasculation

Solution

Increased heterozygosity is the underlying factor which causes hybrid vigour. The hybrid is superior to both the parents.

Q41. Which is the breeding season for camels?

• 1) July to September
• 2) November to March
• 3) May to August
• 4) March to May

Solution

Camels breed in winter from November to March.

Q42. Name two growth regulators commonly used in plant tissue culture.

Solution

2,4-dichlorophenoxy acetic acid (2,4-D) and benzylaminopurine (BAP) are two growth regulators which are used in plant tissue culture. 

Q43. Give a brief account of tissue culture. Also give the advantages of micropropagation.

Solution

The production of whole plants from an explant by growing them on a suitable culture medium under sterile conditions in vitro is called tissue culture. The culture medium must be rich in vitamins, nutrients and growth regulatory hormones such as auxins and cytokinins. The plants which are produced by micropropagation are genetically identical and constitute somaclones.   The advantages of micropropagation are (i) Healthy disease-free plants can be grown by meristem culture. (ii) Somatic hybrids can be produced by tissue culture.

Q44. Pathogen-free plants are obtained from

• 1) Root culture
• 2) Shoot meristem culture
• 3) Seeds
• 4) Embryo culture

Solution

Meristems are virus-free, and they are cultured on a suitable medium for shoot apical meristems to obtain virus-free plants.

Q45. Describe the technology which has successfully increased the herd size of cattle in a short time to meet the increasing demands of growing human population.

Solution

Multiple Ovulation Embryo Transfer Technology (MOET) has successfully increased the herd size of cattle. The cow is administered with follicle-stimulating hormone (FSH) to induce follicular maturation and superovulation to produce 6 to 8 eggs. It is then mated or artificially inseminated. The fertilised eggs are recovered non-surgically and transferred to a surrogate mother, where they develop into an improved variety.

Q46. Which of the following is not used for surface sterilisation of an explant, which is used for plant tissue culture?

• 1) Sodium hypochlorite
• 2) UV radiation
• 3) Clorox water
• 4) Methiolate

Solution

An explant which is used for plant tissue culture is surface sterilised by chemicals such as Clorox water, sodium hypochlorite, calcium hypochlorite or methiolate. UV radiation cannot be used for surface sterilisation as it can induce mutations in the explant.

Q47. (i) What are the features of plants which will prevent insect and pest infestation? (ii) Name a man-made cereal and where it is used.

Solution

(i) The features of plants which will prevent insect and pest infestation are (a) Turning flowers nectarless. (b) To have intensive hair on the above ground parts of plants. (c) Toxins released by plants. (ii) A man-made cereal is Triticale, and it is used as fodder.

Q48. What is dedifferentiation and redifferentiation?

Solution

Dedifferentiation is a process where the mature cells are transformed to meristematic cells leading to the formation of a callus. Redifferentiation is the development of entire plants from the cells of a callus.

Q49. The process of bringing wild species of plants under cultivation to suit human needs is called

• 1) Cultivation
• 2) Hybridisation
• 3) Domestication
• 4) Selection

Solution

To adapt (an animal or plant) to life in intimate association with and to the advantage of humans is called domestication. 

Q50. The term 'totipotency' refers to the capacity of a

• 1) Seed to germinate
• 2) Cell to enlarge in size
• 3) Bud to generate a whole plant
• 4) Cell to generate a whole plant

Solution

When we take any part of a plant to develop a new embryoid, it has the capacity to generate a whole plant which is called cellular totipotency.

Q51. Triticale is produced by the crossing of

• 1) Wheat and barley
• 2) Wheat and rye
• 3) Wheat and maize
• 4) Rye and maize

Solution

Triticale is a hybrid of wheat (Triticum turgidum) and rye (Secale cereale). Triticale is the first man-made crop derived by crossing wheat and rye.

Q52. Somaclonal variation appears in plants

• 1) Transformed by recombinant DNA technology
• 2) Raised in tissue culture
• 3) Growing in polluted soil or water
• 4) Exposed to gamma rays

Solution

The genetically identical plants developed from any part of a plant by tissue culture are called somaclones. Through micropropagation, plants are produced which will be genetically identical to the original plant.

Q53. Which one of the following is an indigenous breed of chickens?

• 1) Rhode Island Red
• 2) White Leghorn
• 3) Aseel
• 4) Plymouth Rock

Solution

Aseel is a naturally occurring breed of chicken because it provides a high yield of flavoured meat and has high immunity against common diseases.

Q54. Select the viral disease of cattle:

• 1) Anthrax
• 2) Aspergillosis
• 3) Tuberculosis
• 4) Foot and mouth disease

Solution

Foot and mouth disease is a viral disease which is caused in cattle, pigs and sheep.   Anthrax is a bacterial disease caused by Bacillus anthracis which affects both humans and cattle.   Aspergillosis is a fungal disease in cattle which affects both respiratory system and excretory system.   Tuberculosis, specifically bovine tuberculosis, is a bacterial disease in cattle.

Q55. Name the Japanese cytologist who cultured anthers for the first time.

• 1) Sumuki
• 2) Yabuta
• 3) Shimakura
• 4) Hannig

Solution

In 1934, the Japanese cytologist Shimakura initiated in vitro culture of the anther to study the physiology of meiosis.

Q56. Haploid plantlets can be produced by

• 1) Embryo culture
• 2) Meristem culture
• 3) Cotyledon culture
• 4) Pollen culture

Solution

Haploid plants can be produced from both male and female gametes. The anther produces pollens. When the anther is cultured on a suitable medium, it produces haploid plants and is called anther or pollen culture.

Q57. The most likely reason for the development of resistance against pesticides in insect-damaged crop is

• 1) Acquired heritable changes
• 2) Genetic recombination
• 3) Directed mutations
• 4) Random mutations

Solution

Due to random mutations, crops infected by insects show resistance to pesticides.

Q58. What is inbreeding in plants? What happens to the recessive alleles in this process? 

Solution

The process of mating more closely related plants within the same breed is called inbreeding. The recessive alleles become homozygous and express themselves. These are then eliminated by selection.

Q59. The percentage of proteins in fish meal is

• 1) 15-20%
• 2) 40-50%
• 3) 55-70%
• 4) 25-50%

Solution

There are several by-products provided by pisciculture, such as liver oil which contains vitamins, fish meal which contains 55-70% proteins and fish protein concentrate which contains about 80-90% proteins.

Q60. State any one significance of interspecific hybridisation in plants.

Solution

It is important for breeding disease-resistant plant varieties.

Q61. What is single cell protein? Give any two points of significance of such a protein?

Solution

The biomass obtained from microorganisms which can be treated or processed in the industry to be used as food for human beings is called single cell protein. Two points of significance of single cell protein are (i) It provides a protein-rich diet. (ii) It helps to minimise environmental pollution.

Q62. Why does the pure line represent the progeny of homozygous plants?

Solution

Self-pollinated crops gradually become homozygous. Best homozygous individuals can be isolated from such crops. Pure lines are then produced by selection.

Q63. A collection of all the alleles of all the genes of a crop plant is called

• 1) Somaclonal collection
• 2) Protoplasm collection
• 3) Germplasm collection
• 4) Herbarium

Solution

Germplasm refers to the hereditary material transmitted to the offspring through the germ cells. It is the total content of genes. It serves as the raw material for the breeder to develop different crops.

Q64. Which one of the following species of bees is used for the commercial production of honey?

• 1) Apis florea
• 2) Apis mellifera
• 3) Apis indica
• 4) Apis dorsata

Solution

Apis mellifera produces a large yield of honey because of prolific egg production, less swarming and good defence mechanism.

Q65. Which of the following terms is used to describe the component isolated from a plant for in vitro culturing in the specific medium?

• 1) Synthetic seeds
• 2) Callus
• 3) Explant
• 4) Embryoid

Solution

The part of the plant which is taken out and grown in a test tube under sterile conditions in a special nutrient media is called an explant.

Q66. Norman Borlaug, known as 'Father of the Green Revolution', had developed a new cultivated variety of

• 1) Sugarcane
• 2) Rice
• 3) Paddy
• 4) Wheat

Solution

Norman Borlaug along with M. S. Swaminathan, who introduced the Green Revolution in India, developed a new cultivated variety of wheat.

Q67. What is the economic value of Spirulina? 

Solution

Spirulina are grown on a large scale to serve as a good source of protein called single cell protein. It also serves as food rich in minerals, vitamins, fats and carbohydrates.

Q68. Define the terms somatic embryos and somatic hybrids. 

Solution

The embryos which develop from somatic cells of a callus culture are called somatic embryos. Fusion of two somatic cells of different varieties is called somatic hybrids.

Q69. Cattle feed should contain

• 1) None of these
• 2) Concentrate
• 3) Both of these
• 4) Roughage

Solution

Cattle feed constitutes two major components such as roughage and concentrate. Roughage contains large amount of fibres which include hay and fodder that are much needed for cattle. Concentrate is also an important feed for cattle which is a mixture of cereals such as maize, oat and jowar that are moistened in water. These are rich in proteins and other nutrients.

Q70. Somatic hybridisation can be done by

• 1) Haploid anther
• 2) Pollen culture
• 3) Cell culture
• 4) Protoplast fusion

Solution

When a hybrid is produced by the fusion of somatic cells of two species, it is known as a somatic hybrid, and the process of producing somatic hybrids is called somatic hybridisation. This is achieved by protoplast fusion which involves the fusion of protoplasts in a polyethylene glycol (PEG) or sodium nitrate solution.

Q71. Spirulina is a rich source of

• 1) Protein
• 2) Vitamins
• 3) Minerals
• 4) All of the above

Solution

Spirulina is a blue-green alga which is the primary source protein for animal and human nutrition. Spirulina is called single cell protein (SCP).

Q72. State the importance of biofortification. 

Solution

The main importance of biofortification is the nutritional quality which is better improved due to breeding of crops.

Q73. An explant is a

• 1) Part of the plant
• 2) Dead plant
• 3) Part of the plant which expresses a specific gene
• 4) Part of the plant used in tissue culture

Solution

The explant is a part of the plant which is taken out and cultured and grown in a test tube under sterile conditions in special nutrient media.

Q74. Monosomy and trisomy can be represented as

• 1) 2n − 1, 2n − 2
• 2) 2n, 2n + 1
• 3) 2n + 1, 2n + 3
• 4) 2n − 1, 2n + 1

Solution

Monosomy is the presence of only one chromosome (instead of the typical two in humans) from a pair. Hence, it is denoted as 2n − 1.  Trisomy is the presence an extra chromosome (instead of the typical two in humans) from a pair giving 3. Here, it is denoted as 2n + 1. 

Q75. What is Triticale?

• 1) It is a modified form of wheat.
• 2) It is an intergeneric hybrid.
• 3) It is a new plant produced by selection.
• 4) It is a wild ancestral wheat.

Solution

An intergeneric hybrid is a cross between plants in two different genera in the same family. Triticale is a hybrid of wheat (Triticum turgidum) and rye (Secale cereale).

Q76. Pebrine is a disease of

• 1) Lac insect
• 2) Fish
• 3) Silk worm
• 4) Honey bee

Solution

Pebrine is a disease which affects silk worms.

Q77. (i) What is the difference between inbreeding and heterosis. (ii) What is inbreeding depression?

Solution

(i) The cross between two individuals of a species which are related by descent is called inbreeding, whereas the cross between two unrelated individuals or species which may develop an improved hybrid is called heterosis. (ii) The loss of fertility and productivity due to continuous inbreeding, especially close inbreeding, is called inbreeding depression.

Q78. What is somatic hybridisation? Explain the various steps involved in the process. Mention any two uses of somatic hybridisation.

Solution

The process of fusion of protoplasts of somatic cells obtained from different varieties or species of plant on a suitable nutrient medium in vitro to develop a somatic hybrid is called somatic hybridisation. Various steps involved in somatic hybridisation are (i) Single cells are isolated from a single plant. (ii) The cell walls are digested by enzymes such as pectinase and cellulose to liberate the protoplasts. (iii) Naked protoplasts surrounded only by plasma membranes are isolated. (iv) The isolated protoplasts are fused to obtain hybrid protoplasts under sterile conditions in a nutrient medium. (v) The hybrid protoplasts are cultured in a suitable media to form new plants. Two uses of somatic hybridisation are (i) Somatic hybrids may be produced. (ii) Healthy plants can be recovered from diseased plants.

Q79. Explain the efforts which must be put in to improve health, hygiene and milk yield of cattle in a dairy farm.

Solution

The efforts are as follows: (i) The cattle in the dairy farm must be housed and fed properly. (ii) Cleanliness should be maintained in the milking area. (iii) The health of the dairy cattle should be of utmost importance, and a veterinary doctor must visit regularly. (iv) Regular inspections of the farm, maintaining records, identification and rectification of problems should be done along with maintaining precautionary measures. (v) High-yielding and disease-resistant breeds can be selected to maximise benefits.

Q80. (i) What is plant breeding? List the two steps which classical plant breeding involves. (ii) How has mutation breeding helped in improving crop varieties? Give one example where this technique has helped. (iii) How has the breeding programme helped in improving public nutritional health? State two examples in support of your answer.

Solution

(i) Plant breeding is the manipulation of plant species to create desired plant types which are better suited for cultivation, give better yields and are disease resistant. Classical plant breeding involves the following steps: (a) Hybridisation of pure lines (b) Artificial selection to produce plants with desirable traits (ii) Inducing mutation in plants helps in producing desirable genes for disease resistance. Plants having desirable genes can either be multiplied directly or can be used in breeding. For example, in mung bean, resistance to yellow mosaic virus and powdery mildew were induced by mutations. (iii) Biofortification is the technology which has helped in improving public nutritional health by breeding crops with higher levels of vitamins and minerals or higher protein and healthier fats. In biofortification, protein, oil, vitamin, micronutrient and mineral content and their qualities are improved. For example, (a) Maize hybrids with more quantity of amino acids such as lysine and tryptophan were developed. (b) To increase wheat cultivation, an improved variety, Atlas 66, has been used as the donor for having a high protein content.

Q81. In an autoclave, materials are sterilised by heating at

• 1) 180°C for 15-20 minutes
• 2) 120°C for 30-60 minutes
• 3) 180°C for 30-60 minutes
• 4) 120°C for 15-20 minutes

Solution

In an autoclave, materials are sterilised by heating at 120°C for 15-20 minutes.

Q82. IARI has released several varieties of crop plants which are biofortified. Give three examples of such crops and their biofortification.

Solution

(i) IARI released Vitamin A-enriched carrots, spinach and pumpkin. (ii) Vitamin C-enriched bitter gourd, mustard and tomato. (iii) Iron- and calcium-enriched spinach.

Q83. The main sugar present in honey is

• 1) Ribose
• 2) Dextrose
• 3) Laevulose
• 4) Maltose

Solution

Honey is produced by worker bees. It is formed of laevulose (42%), dextrose (23%), maltose (10%), enzymes and pigments (25%), minerals, vitamins and water (19%).

Q84. What is interspecific hybridisation? Give one example of a crop in which it is practised and mention one advantage derived from it. 

Solution

The cross between two individuals of different species of the same genus is called interspecific hybridisation.   Resistance to yellow mosaic virus in Okra plant (Abelmoschus esculentus) was transferred from a wild species and resulted in a new variety of Abelmoschus esculentus called Prathani Kranti.   One advantage is that a disease-resistant variety is obtained.

Q85. Mule is an example of

• 1) Out-breeding
• 2) Inbreeding
• 3) Cross-breeding
• 4) Interspecific hybridisation

Solution

Breeding which involves the interbreeding of male and female animals of different species is called interspecific hybridisation.   Mules are interspecific hybrids produced by a cross between male donkey and female horse.

Q86. (i) Mention the property which enables explants to regenerate into a new plant. (ii) A banana herb is virus-infected. Describe the method which will help in obtaining healthy banana plants from this diseased plant.

Solution

(i) The property which enables the explants to regenerate into a new plant is called totipotency.   (ii) Healthy banana plants can be obtained from diseased plants by meristem culture. We select the apical and axillary meristem because it is free of virus. The meristem is taken out and is cultured in vitro by micropropagation in which virus-free plants are produced.

Q87. The following is used to get a desired breed of plants:

• 1) Inbreeding
• 2) Tissue culture
• 3) Genetic engineering
• 4) Ikebana

Solution

Genetic engineering is a process in which the genetic makeup of cells is altered by deliberate and artificial means. This process involves the transfer or replacement of genes to create recombinant DNA. So, to get the desired breed of plants, genetic engineering technology is used.

Q88. The term totipotency was coined by

• 1) Maheshwari
• 2) Guha
• 3) Gottlieb Haberlandt
• 4) Shimakura

Solution

The term totipotency was coined by Gottlieb Haberlandt. He put forth the idea that every plant cell is totipotent, i.e. capable of giving rise to an entire new plant.

Q89. How can pollen grains of wheat and rice which tend to lose viability within 30 minutes of their release be made available months later for breeding programmes? 

Solution

The pollen grains can be cryopreserved (storing in liquid nitrogen at −196°C.)

Q90. (i) Give two important contributions of Dr M. S. Swaminathan. (ii) Interspecific crosses are rare in nature and intergeneric crosses are almost unknown. Why?

Solution

(i) Two important contributions of Dr M. S. Swaminathan are  (a) Development of high-yielding varieties in rice. Example: Basmati rice  (b) Development of light-coloured wheat variety of Sharbati Sonora and Pusa Lerma from red-coloured Mexican wheat by gamma irradiation. (ii) Unrelated chromosomes in interspecific crosses and intergeneric crosses differ considerably and fail to pair during gametogenesis.

Q91. In a tissue culture medium, the embryoids formed from pollen grains is due to

• 1) Cellular totipotency
• 2) Test tube culture
• 3) Organogenesis
• 4) Double fertilisation

Solution

Plant tissue culture is a technique of maintaining and growing plant cells in a nutrient medium. So, when we take any part of a plant to develop a new embryoid, it has the capacity to generate a whole plant which is called cellular totipotency.

Q92. What is meant by the term ‘breed’? What are the objectives of animal breeding? 

Solution

The group of animals having same ancestry characters, general appearance and size is called ‘breed’. They have been developed as a result of animal breeding which aims at increasing the yield of animals and improving the desirable qualities of the progeny.

Q93. Rohit is a milkman. He asked his father that he has heard about high-milk-yielding cows but has no idea from where he can procure such a variety of cow. Rohit’s father, being an agricultural scientist, solved his son’s problem. Based on the above passage, answer the following questions: (i) What is artificial insemination? (ii) Name two superior varieties of cows. (iii) How did Rohit’s father help him?

Solution

(i) The collection of semen from the desired male parent and its injection into the reproductive tract of the selected female is called artificial insemination. (ii) Two superior varieties of cows are Jersey and Holstein. (iii) Rohit’s father advised him to get his cows artificially inseminated.

Q94. Which of the following is a mismatch? 

• 1) Pila globosa - Pearl
• 2) Kenia lacca - Lac
• 3) Bombyx mori - Silk
• 4) Apis indica - Honey

Solution

Pearl is obtained from Pinctada vulgaris (pearl oyster).

Q95. (i) Name the chemical used for doubling the chromosome number. (ii) Name the improved variety of wheat which was developed through hybridisation that took 12 years.

Solution

(i) Colchicine is used for doubling the chromosome number. (ii) HUW 468 is an improved variety of wheat which took 12 years to develop through hybridisation.

Q96. Give an example of a somatic hybrid produced.

Solution

Pomato is a somatic hybrid of potato and tomato.

Q97. Scientists have succeeded in recovering healthy sugarcane plants from a diseased one. (a) Name the part of the plant used as explants by scientists. (b) Describe the procedure which scientists follow to recover healthy plants. (c) Name the technology used for crop improvement.          

Solution

(a) The stem of Saccharum barberi and Saccharum officinarum is used as explants by scientists. (b) Under aseptic conditions, the explant is grown in a nutrient medium. The tissue proliferates to form undifferentiated mass. This mass is transferred to a medium containing growth hormones. (c) The technology used for crop improvement is plant breeding. 

Q98. List any four components of poultry farm management.

Solution

Four important components of poultry farm management are (i) Selection of disease-free and suitable breeds (ii) Proper and safe farm conditions (iii) Proper feed and water (iv) Hygiene and health care

Q99. Describe two main components of cattle feed.

Solution

Two main components of cattle feed are roughage and concentrate. Roughage includes the straw of cereals such as wheat, rice and jowar. Sudan grass and Napier grass are common fodder grasses which are highly nutritive but contain less minerals and proteins. Concentrate is also an animal feed which is rich in proteins and minerals. It is obtained from cottonseeds, oil cakes and cereal grains.

Q100. What is the main difference between layers and broilers? 

Solution

Layers are egg-laying birds, whereas broilers are meat-yielding birds.

Q101. Why is the Italian bee preferred for beekeeping rather than the Indian bee? 

Solution

The Italian bee (Apis mellifera) is docile, less swarming and produces a high yield of honey.

Q102. Expand SCP and PEG. What are their uses?

Solution

SCP stands for Single Cell Protein. Single cell protein is rich in protein and helps to reduce environmental pollution. PEG stands for Polyethylene Glycol. In protoplast fusion, the protoplasts are fused in a solution of polyethylene glycol and allowed to grow in a culture medium which gives rise to the callus.