Class 12 VBQs Biology Strategies for Enhancement in Food Production
Very Short Answer Type Questions
Question. State the economic value of Saccharum officinarum in comparison to S. barberi.
Answer : Saccharum officinarum has higher sugar content and thicker stem, whereas Saccharum barberi is inferior in sugar content and yield.
Question. State the importance of biofortification.
Answer : Biofortification is the breeding of crops for improvement of nutritional quality.
It is used to improve protein content and quality, to improve oil content and quality, to improve vitamins, etc.
Question. Name any two diseases the ‘Himgiri’ variety of wheat is resistant to.
Answer : (i) Leaf and stripe rust.
(ii) Hill bunt.
Question. Name the semi-dwarf variety of wheat which is high yielding and disease resistant.
Answer : Sonalika and Kalyan-sona are the high yielding and disease resistant varieties of wheat.
Short Answer Type Questions
Question. Suggest four important steps to produce a disease resistant plant through conventional plant breeding technology.
Answer : Steps for producing disease resistant plants are :
(i) Screening of germplasm (for resistance source).
(ii) Hybridization of selected parents.
(iii) Selection and evaluation of hybrids.
(iv) Testing and release of new varieties.
Detailed Answer :
The important steps involved in conventional plant breeding technology are :
(i) Selection of parent plants with desired combination of characters.
(ii) Cross hybridisation among the selected parents.
(iii) Selection of superior hybrids.
(iv) Testing, release and commercialisation of new cultivars.
Question. How has mutation breeding helped in improving the production of mung bean crop ?
Answer : Mutation breeding has helped in improving the moong bean crop by producing its disease resistant varieties against yellow mosaic virus /powdery mildew. In mutation breeding, the mutations are induced artificially through the use of chemicals or radiations (like gamma rays) followed by selecting and using the plants that have desirable characters as a source in breeding.
Question. Enumerate four objectives for improving the nutritional quality of different crops for the health benefits of the human population by the process of ‘‘Biofortification’’.
Answer : Biofortification involves the breeding of crops to increase their nutritional value. The objective for biofortification are as follows :
(i) To improve protein content and quality.
(ii) To improve oil content and quality.
(iii) To improve vitamin content.
(iv) To improve micronutrients and mineral contents.
Question. To reduce the percentage of population suffering from hunger and malnutrition, microbes are grown on a large scale to act as food supplements. Mention any two microbes used as food supplement and suggest their role.
Answer : The two microbes used as food supplement are Spirulina and Methylophilus.
Spirulina : Produces large quantities of food rich in protein, minerals, fats, carbohydrates and vitamins. Methylophilus methylotrophus—
250 gm of this microorganism produces 25 tonnes of protein per day.
Question. (i) ‘‘Fortification of crops is the need of the hour.’’
Give two reasons.
(ii) Select one fresh-water and one marine fish from the following : Prawn; Catla; Mackerel; Lobster.
Answer : (i) To improve the nutritional quality in order to improve public health / to prevent malnutrition.
(ii) Fresh water : Catla, Marine Fish : Mackerel.
Detailed Answer :
(i) With the ever increasing population of the world, the enhancement of food production by fortification of crops has become a major necessity. Further, keeping in view the present public health and hygiene and also the problem of malnutrition it is necessary to improve the nutritional quality which can be achieved by fortification of crops.
Question. Life style diseases are increasing alarmingly in India. We are also dealing with large scale malnutrition in the population. Suggest a process by which we can address both these problems. Give any three examples to support your answer.
Answer : Biofortification
a) Enhancing food quality with respect to protein- Maize hybrids that had twice the amount of the amino acids, lysine and tryptophan, compared to existing maize hybrids were developed. Or Wheat variety, Atlas 66, having a high protein content has been used as a donor for improving cultivated wheat.
Or Protein enriched beans- broad, lablab, French and garden peas. (Any one)
b) Vitamin enriched- Vitamin A enriched Carrots, Spinach, Pumpkin Or Vitamin C enriched bitter gourd, bathua, mustard, tomato.
c) Enrichment of Micro Nutrient and Mineral content- Iron and calcium enriched spinach and bathua.
Question. (i) Why are the plants raised through micropropagation termed as somaclones ?
(ii) Mention two advantages of this technique.
Answer : (i) Genetically identical.
(ii) Large number of plants in short duration, virus free plants.
Detailed Answer :
(i) The plants obtained by micropropagation are called somaclones because they are genetically identical to each other as well as to parent plant.
(ii) Advantages :
(a) It helps in the propagation of a large number of plants in a short span of life.
(b) It helps in the production of healthier plants that are disease and pest resistant.
Question. You have obtained a high yielding variety of tomato.
Name and explain the procedure that ensures retention of the desired characteristics repeatedly in large populations of future generations of the tomato crop.
Answer : Tissue culture / micropropagation / somaclonal propagation / apomixis.
(a) Explant / any part of plant taken out and grown (in a test tube / vessel).
(b) under sterile condition.
(c) in special nutrient medium (containing carbon source / sucrose, inorganic salt / vitamins /amino acids and growth regulator).
Question. How are biofortified maize and wheat considered nutritionally improved ?
Answer : Biofortified maize and rice are quite rich in amino acids and proteins. Biofortified maize contains twice the amount of amino acids like lysine and tryptophan as compared to existing varieties and biofortified wheat, which has increased amount of protein.
Question. A sugarcane has been affected by virus. How can a virus free cane developed from it ?
Answer : Virus free sugarcane can be developed by tissue culture technique. The meristematic regions of a plant are generally free from virus. Healthy and virus free sugarcane plants can by developed by this technique using meristems as explants.
Procedure : Explants obtained from the meristem apical or young axillary buds or from nodes near the stem apex are taken and surface sterilized by 0.5% sodium hypochlorite and then seeded over the nutrient agar medium enriched with cytokinin under aseptic conditions. After incubation for a few days under optimal conditions the explants give rise to shoots. These shoots are cut into nodal segments of 2-3 cm which are then transferred into a medium containing extra auxin for promoting root formation. This results in the development of a number of plantlets, which are then transferred to fields.
Question. (i) Write two limitations of traditional breeding technique that led to promotion of micropropagation.
(ii) Mention two advantages of micro-propagation.
(iii) Give two examples where it is commercially adopted.
Answer : (i) Failed to keep pace with demand, failed to provide fast and efficient system of crop improvement.
(ii) Large number of plants can be developed in a short duration / production of genetically identical plants / somaclones / healthy plants can be recovered from diseased plants.
(iii) Tomato / banana / apple.
Detailed Answer :
(i) Two limitations of traditional breeding that led to promotion of micro-propagation are :
(a) It failed to fulfil the demand.
(b) It failed to provide an efficient and fast crop improvement system.
(ii) Two advantages of micro-propagation are :
(a) It helps in the propagation of a large number of plants in a short span of time.
(b) It leads to the production of healthier plantlets, which exhibit better disease resistant powers.
(iii) Micro-propagation technology is adapted in the commercial production of many important food plants such as tomato, apple and banana.
Question. (i) Name the tropical sugar cane variety grown in South India. How has it helped in improving the sugar cane quality grown in North India ?
(ii) Identify ‘a’, ‘b’ and ‘c’ in the following table :
Answer : (i) Saccharum officinarum, crossed with, North Indian variety (Saccharum barberi) to increase
(ii) (a) Aphids
(b) Jassids / aphids / fruit borer
(c) Okra (Bhindi)
Question. How can crop varieties be made disease resistant to overcome food crisis in India ? Explain. Name one disease resistant variety in India of :
(i) Wheat to leaf and stripe rust.
(ii) Brassica to white rust.
Answer : The crop varieties can be made disease resistant so as to overcome food crisis in India by usual and conventional methods of breeding or mutation breeding for disease resistance by hybridization and selection. The various sequential steps of this programme are screening germplasm for resistance sources, hybridization of selected parents, selection and evaluation of the hybrids and testing and release of new varieties // mutation breeding. It is possible to induce mutations artificially through use of chemicals or radiations (like gamma radiations) and selecting and using the plants of desirable character as a source in breeding. Selection amongst somaclonal variants / Genetic engineering.
(i) Variety of wheat resistant to leaf and stripe rust is Himgiri.
(ii) Variety of Brassica resistant to white rust disease is Pusa swarnim / Karan rai.
Detailed Answer :
A wide range of fungal, bacterial and viral pathogens affect the yield of cultivated crops. Disease resistant can be provided by conventional breeding, mutational breeding or genetic engineering.
(i) Conventional breeding: It includes the basic steps of screening, germplasm, hybridisation, selection, testing and release.
(ii) Mutational breeding: In this method, genetic variations are created, which then result in the creation of traits not found in the parental type.
(iii) Genetic engineering: Certain wild varieties have disease- resistant characteristics but they are low yielding, Disease- resistant genes from such varieties are introduce in high- yielding varieties through recombinant DNA technology.
One disease resistant variety in India is:
(a) Himgiri (b) Pusa swarnim
Question. IARI has released several varieties of crop plants that are biofortified. Give three examples of such crops and their biofortifications.
Answer : The biofortified crops released by IARI are :
(i) Carrots enriched with Vitamin A.
(ii) Bittergourd-rich with Vitamin C.
(iii) Spinach enriched with calcium and iron.
Question. (i) Write the desirable character a farmer looks for in his sugarcane crop.
(ii) How did plant breeding techniques help north Indian farmers to develop cane with desired characters ?
Answer : (i) High yield, thick stem, high sugar content, ability to grow in their areas.
(ii) By crossing Saccharum officinarum / South Indian variety having desired characteristics with Saccharum barberi / north Indian low yield variety.
Question. GM plants are useful in many ways. How would you convince farmers to grow GM plants on their field ? Explain giving three reasons.
Answer : Make crop more tolerant to abiotic stresses / Reduce reliance on chemical pesticides / Help to reduce post harvest loses / Increase efficiency of mineral usage / Enhance nutritional value of food.
GM plants refers to genetically modified plants, plants in which foreign genes have been introduced through genetic engineering methods.
Growing plants GM plants (approved by government) has various benefits
i. the GM cotton, is not only pest resistant but also requires less water. Such Bt Cotton crop farming gives very good produce.
ii. Post harvest losses are reduced, examples in flavr savour tomato, where the plant is introduced with delayed ripening gene.
iii. Crops with increased nutritional value like golden rice will have high vitamin A content.
iv. Crops are more resistant to abiotic stress such as, cold, drought, salt and heat.
v. Increased efficiency of mineral usage by plant prevents early exhaustion of soil fertility.
vi. herbicide resistance and disease resistance
Question. What is single cell protein ? Give its importance and two examples of SCP.
Answer : Single cell protein is the large quantities of biomass produced by culturing single type of cells or microorganisms, which serve as food specially rich in protein, fats, carbohydrates, minerals and vitamins.
(i) It serves as rich source of protein in human diet.
(ii) It reduces pressure on agricultural production system for the supply of protein requirement.
(iii) It helps in reducing environmental pollution.
(a) Spirulina–a cyanobacterium or blue green algae.
(b) Methylophilus methylotrophus–a bacterium.