Strategies for Enhancement in Food Production Class 12 Important Questions and Answers Biology Chapter 9

Class 12 Biology Chapter 10 Important Questions Strategies for Enhancement in Food Production

Question 1.
A herd of cattle is showing reduced fertility and productivity. Provide one reason and one suggestion to overcome this problem. (All India 2017)
Answer:
The reduced fertility and productivity in a herd of cattle is may be due to inbreeding depression.
To overcome this problem, selected animals of the breeding population should be mated with unrelated superior animals of the same breed. This helps to restore the yield and fertility of cattle.

Question 2.
Mention the role of ‘genetic mother’ in MOET. (All India 2016)
Answer:
The genetic mother (cow) in MOET undergoes superovulation, i.e. production of 6-8 eggs per cycle instead of a single egg.

Question 3.
Suggest the breeding method most suitable for animals that are below average in milk productivity. All India 2016
Or
Write a professional approach at genetic level that can help the farmer to improve the milk yield of low milk producing cows in his farm. (Delhi 2013C)
Answer:
Outcrossing breeding is the most suitable method for the animals that are below average in milk productivity.

Question 4.
Mention the economic value of Apis indica. (Delhi 2015C)
Answer:
Apis indica is a common source of honey and wax 10. in apicultural practices, which are used in cosmetics, medicines, polishes, etc.

Question 5.
Write the name of the following
(i) The most common species of bees suitable for apiculture.
(ii) An improved breed of chicken. (All India 2012)
Answer:
(i) Apis indica is the most common species of bees for apiculture.
(ii) Leghorn is an improved chicken breed.

Question 6.
‘Artificial insemination helps overcome several problems of normal mating in the cattles’. Do you agree? Support your answer with any three reasons. (All India 2019)
Answer:
Yes , I do agree. Artificial insemination helps overcome several problems of normal mating in the cattle. The reasons to support the statement are as follows

Artificial insemination helps to overcome problems related to normal mating.
Semen can be transported very easily in frozen f j, form from one place to where female is housed and thus desirable matings are carried out.
Semen can be stored and frozen for the later use.

Question 7.
Why is cross-breeding in animals practiced? How is a breed Hisardale developed? (Delhi 2019)
Answer:
Cross-breeding helps to accumulate desirable qualities of two breeds into progeny or hybrid which is usually better than both the parents. Progeny may be used for commercial production.

A new sheep breed, Hisardale was developed in Punjab by crossing Bikaneri ewes and Marino Rams.

Question 8.
Write the steps in sequence as carried in multiple ovulation embryo transfer technology. (Delhi 2019)
Answer:
The steps involved in MOET are as follows

A cow is administrated with FSH-like hormones to induce follicular maturation and superovulation.
The cow produces 6-8 eggs instead of one egg, which they normally release per cycle. So, it is known as multiple ovulation.
A cow is then mated with an elite bull or artificially inseminated.
The fertilised eggs at 8-32 celled stages are recovered non-surgically and transferred to surrogate mother in which further development would take place.
The genetic mother can again be used for superovulation.

Question 9.
Give two reasons for keeping beehives in crop fields during flowering period. (Delhi 2016C)
Or
Why are beehives kept in a crop field during flowering period? Name any two crop fields where this is practised. (Delhi 2014)
Answer:
During flowering period, beehives are kept in a crop field, so as to increase the efficiency of pollination since bees act as major pollinators for many crops. It improves the yield and quality of honey as well as crops, as honeybees visit and collect nectar from a large number and variety of flowers.

The two crop-fields, where beekeeping is practised are those of Brassica and apple.

Question 10.
Differentiate between outbreeding and outcrossing. (Foreign 2015)
Answer:
The difference between outbreeding and outcrossing is
Outbreeding:
It is the breeding of unrelated animals, either of same breed or of different breed or even different species.

Outcrossing:
It refers to mating of animals within the same breed, but having no common ancestors on either sides of their pedigree upto 4-6 generations.

Question 11.
State the disadvantage of inbreeding among cattle. How it can be overcome? (Delhi 2014)
Answer:
Continued inbreeding among cattles reduces their fertility as well as productivity, resulting in inbreeding depression.

It can be overcome by a single outcross done by mating of cattle within the same breed, having no common ancestors of their pedigree upto 4-6 generations.

Question 12.
Explain the importance of inbreeding in cattle. (Delhi 2014C)
Answer:
The importance of inbreeding in cattle are

It increases homozygosity and evolves a pureline.
Accumulation of superior genes and elimination of less desirable genes by selection.

Question 13.
Differentiate between outcrossing and cross-breeding. Delhi 2018C. (All India 2014C)
Answer:
Differences between outcrossing and cross-breeding are

Outcrossing	Cross-breeding
It refers to the mating of animals within the same breed, but having no common ancestors on either sides of their pedigree upto 4-6 generations.	In this method, superior males of one breed are mated with superior females of another breed.
It helps to overcome inbreeding depression.	It develops new, stable and superior breeds.

Question 14.
Study the flow chart given below

(i) Identify the events that take place at stages ‘A’ and ‘B’ respectively.
(ii) State the importance of the technology explained above. (Foreign 2011)
Answer:
(i) A-The hormone induces follicular maturation and superovulation, i.e. production of 6-8 eggs per cycle.
B-Fertilised eggs are recovered and transferred to surrogate mother.

(ii) The technology is called MOET that is used to increase the herd size by mating high milk yielding breed of females with high quality meat yielding bulls.

Question 15.
How is a pureline in an animal raised? Explain. (Delhi 2011C)
Answer:
Pureline in an animal is raised by inbreeding as it increases homozygosity.

Mating of more closely related individuals within same breed for 4-6 generations is called inbreeding.
In this process, superior males and superior females of same breed are identified and mated in pairs.
The progenies obtained from such matings are evaluated and superior males and females among them are identified for further matings.

Question 16.
How does inbreeding depression set in? Mention the procedure you would suggest to reverse this. (All India 2011C)
Answer:
Inbreeding depression sets in when there is continued and close inbreeding. It reduces fertility and productivity of animals due to accumulation of recessive traits in successive generation. Whenever, this becomes a problem, selected animals of breeding population should be mated with unrelated superior animals of the same breed. This outcross helps in restoring fertility and yield and overcomes inbreeding depression.

Question 17.
Honey collection improves when beehives are kept in crop-fields during flowering season. Explain. (Delhi 2010)
Answer:
During flowering season, the honeybees visit a number of flowers in search of edible pollen and nectar. Since, they collect nectar from a large variety of flowers in a large amount, the honey collection improves both in quality and quantity.

Question 18.
Bee-keeping practice is a good income generating industry. Write the different points to be kept in mind for successful bee-keeping. Write the scientific name of the most common Indian species used for the purpose. (Delhi 2019)
Answer:
The important point that should be kept in mind for successful bee-keeping are

Knowledge of the nature and habits of bees.
Selection of suitable location for keeping the beehives.
Catching and hivingjaf swarms (group of bees).
Management of beehives during different seasons.
Handling and collection of honey and beeswax.

The most common species honeybee reared by bee-keepers in India is Apis indica (Indian bee).

Question 19.
Explain outbreeding, outcrossing and cross-breeding practices in animal husbandry. (2018)
Answer:
Outbreeding Breeding of unrelated animals via outcrossing or crossbreeding or interspecific hybridisation is called outbreeding. Thus, outbreeding in itself involves any of the three processes.
(i) Outcrossing The practice of mating of animals, within the same breed, but having no common ancestor on either sides of their pedigree upto 4-6 generations is called outcrossing. The offspring (result of mating) is known as outcross. It is known to be the best breeding method for animals that are below average in the production of milk and growth rate of beef (in cattle), etc. A single outcross may help to overcome inbreeding depression.

(ii) Cross-breeding The mating of superior males of one breed with the superior female of another breed is called cross-breeding. This is done to combine the desirable qualities of two breeds into a single individual. The hybrid progeny may be used for commercial production or they may be subjected to some form of inbreeding and selection.

This is to develop new stable forms that may be superior to the existing breeds, e.g. a new sheep breed, Hisardale was developed in Punjab by crossing two breeds, Bikaneri ewes and Marino Rams.

(iii) In interspecific hybridisation individuals of different species are crossed. Progeny may be of considerable economic value. However, such hybrids are usually sterile.
Example of interspecific hybridisation is a mule obtained by crossing of a male donkey with a female horse.

Question 20.
(i) What is inbreeding depression?
(ii) Explain the importance of ‘selection’ during inbreeding in cattle. (Delhi 2017)
Answer:
(i) Inbreeding is the crossing of closely related animals within the same breed for 4-6 generations. The continued inbreeding however reduces fertility and even the productivity, this is called inbreeding depression. Inbreeding is performed for developing a pureline and to express desirable superior genes.

(ii) Importance of ‘selection’ during inbreeding of cattle are as follows

By selection at every step, productivity of inbreed population is increased.
It helps in the accumulation of desired superior genes, so as to obtain more milk per lactation.
It helps in eliminating the less desirable genes from cattle population.
It helps to eliminate the harmful recessive genes.

Question 21.
(i) Name any two fowls other than chicken reared in a poultry farm,
(ii) Enlist four important components of poultry farm management. (Delhi 2016)
Answer:
(i) Geese and Turkeys are reared in a poultry farm.
(ii) The four important components of poultry farm management are

Selection of disease-free and suitable breeds.
Proper and safe conditions of farm.
Proper food (feed) and water should be provided.
Hygiene and healthcare of birds are mandatory.

Question 22.
Explain how and why controlled breeding experiment is carried out in cattle. (Delhi 2016C)
Answer:
Controlled breeding experiments are carried out in cattle using artificial insemination. In this procedure, the semen is collected from the desired male and is injected into the reproductive tract of the selected female by the breeder. The semen can be used immediately or can be frozen and used at a later date.

Controlled breeding experiments are carried out in cattle for the following reasons
(i) To increase milk production by cattle.
(ii) To increase growth rate in beef cattle.

Question 23.
What is inbreeding depression and how is it caused in organisms? Write any two advantages of inbreeding. (Delhi 2011)
Or
(i) Why is inbreeding necessary? Give two reasons.
(ii) What does continued inbreeding lead to? Outside (Delhi 2016C)
Answer:
(i) Inbreeding refers to mating between closely related individuals within the same breed for 4-6 generations.
Advantages of inbreeding are

It increases homozygosity and evolves a pureline.
Recessive genes are exposed by inbreeding, which can then be eliminated by selection.
It helps in accumulation of superior genes.

(ii) Inbreeding results in reduction of fertility and productivity, when continued for longer time. This is called inbreeding depression.

Question 24.
High yielding cattle is a good solution for food enhancement. How does the MOET technology help to increase the herd size? (Outside Delhi 2016C)
Or
(i) What is the programme called, that is involved in improving success rate of production of desired hybrid and herd size of cattle?
(ii) Explain the method used for carrying this programme for cows. (All India 2012)
Or
Describe the technology that has successfully increased the herd size of cattle in a short time to meet the increasing demands of growing human population. (All India 2011)
Answer:
MOET is Multiple Ovulation and Embryo Transfer.
Steps involved in MOET programme are

A cow is administrated with hormones having FSH-like activity to induce follicular maturation and superovulation.
The cow produces 6-8 eggs instead of one egg produced normally. This is known as multiple ovulation.
Mating is done either with an elite bull or artificial insemination is carried out.
When the fertilised eggs attain 8-32 celled stage, they are non-surgically removed and transferred to a surrogate mother. This is known as embryo transfer.
The genetic mother can be again superovulated.

Question 25.
Enlist the steps involved in inbreeding of cattle. Suggest two disadvantages of this practice. (Delhi 2015)
Answer:
Inbreeding refers to the mating between closely related individuals within the same breed for 4-6 generations.
The steps involved in inbreeding are as follows

Identifying superior males and superior females of the same breed.
Mating of the selected parents.
Evaluation of progeny obtained from the above mating to identify superior males and females among them. A superior female in case of cattle, is the cow or buffalo that produces more milk per lactation. A superior male is bull, which gives rise to superior progeny as compared to other males.

Two disadvantages of this practice are

Continued inbreeding reduces fertility and even productivity (inbreeding depression).
It leads to genetically similar individuals with little variations.

Question 26.
Enumerate any six essentials of good, effective dairy farm management practices. (All India 2015)
Or
Explain the efforts, which must be put in, to improve health, hygiene and milk yield of cattle in dairy farm. (Delhi 2010)
Answer:
Six essentials of good effective dairy farm management practices are

Selection of good breeds with high yield and resistance to the diseases.
Cattle should be housed-well, should have sufficient water and should be kept in disease-free conditions.
Cattle should be fed in scientific manner, with good quality and quantity of fodder.
Stringent cleanliness and hygiene of both the cattle and handlers is very important, while milking, storage and transport of milk.
Regular inspection and keeping proper records of all the activities of dairy farm is mandatory.
Regular visits of a veterinary doctor is necessary.

Question 27.
(i) Explain how to overcome inbreeding depression in cattle.
(ii) List three advantages of inbreeding in cattle.
(iii) Name an improved breed of cattle. (Delhi 2013)
Or
Mention and describe any three methods to overcome inbreeding depression in animal husbandry. (Delhi 2012c)
Answer:
(i) Inbreeding depression can be overcome by performing outcrossing, cross-breeding and interspecific hybridisation. For futher details,
Refer to Answer No. 19.
(ii) For advantages of inbreeding, Refer to Answer No. 23.
(iii) Hisardale

Question 28.
(i) Write the scientific name of most common species of honeybee reared,
(ii) Mention the kind of areas that are suitable for beekeeping practices.
(iii) Mention any two uses of bees wax. (Delhi 2011C)
Answer:
(i) Apis indica.
(ii) Beekeeping can be practiced in any area, where there are sufficient bee pastures of some wild shrubs, fruit, orchards and cultivated crops.
(iii) Beeswax is used in the preparation of cosmetics and polishes of various kinds.

Question 29.
What is “blue revolution’? Name two freshwater and two marine edible fishes. (All India 2011C)
Answer:
‘Blue revolution’ is the movement launched to increase the production of fish and fish products.
Freshwater fishes are Rohu and Catla.
Marine water fishes are Hilsa and Sardines.

Question 30.
List any three outbreeding practices carried out to breed domestic animals. Explain the importance of each one listed. (Delhi 2010C)
Answer:
Outbreeding refers to the crosses between different breeds.
Three major outbreeding practices carried out to breed domestic animals. Refer to Answer No. 19.

Question 31.
Differentiate between inbreeding and outbreeding in cattle. State one advantage and one disadvantage for each one of them. (Delhi 2013)
Or
(i) Inbreeding is advantageous as well as disadvantageous. Explain.
(ii) Differentiate between inbreeding and outbreeding. (Delhi 2010C)
Answer:
(i) Advantages of inbreeding are

It increases homozygosity to evolve a pureline.
Recessive genes are exposed by inbreeding, which are then eliminated by selection.
Superior genes can be accumulated by inbreeding and thereby eliminating undesirable genes.
By selection at every step, productivity of inbreed population is increased.

Disadvantage of inbreeding is that close inbreeding leads to the reduction of fertility and productivity. This is due to inbreeding depression.
Advantage of outbreeding It reduces the effect of inbreeding depression.
Disadvantage of outbreeding It leads to elimination of recessive characters, whereas desired combinations of characters may appear in low frequency.

(ii) Difference between inbreeding and outbreeding is
Inbreeding:
It refers to the mating of closely related individuals within the same breed for 4-6 generations.

Outbreeding:
It refers to breeding of unrelated animals either of the same breed with no common ancestor or between different breeds or different species.

Question 32.
(i) State the objective of animal breeding.
(ii) List the importance and limitations of inbreeding. How can the limitations be overcome?
(iii) Give an example of a new breed each of cattle and poultry. (All India 2014)
Answer:
(i) The main objective of animal breeding is to increase the yield of animals and improve the desirable and superior qualities in both the animals and their products.
(ii) Importance of Inbreeding Refer to Answer No. 12.
Limitations of Inbreeding The continued inbreeding in animals for subsequent generations reduces their fertility and productivity, resulting in condition called inbreeding depression. The inbreeding depression can be overcome by a single outcross, i.e. mating between animals of same breed having no common ancestors upto 4-6 generations.
(iii) An example of new breed of cattle is Hisardale and that of poultry is New Hampshire.

Question 33.
State the economic value of Saccharum officinarum in comparison to S. barberi. (All India 2015C)
Answer:

Saccharum barberi is grown in North India. It has poor sugar content and yield.
Saccharum officinarum grows in South India. It has thicker stems, more sugar content and yield. Thus, it is economically very valuable.

Question 34.
Write an alternate source of protein for animal and human nutrition. (All India 2014)
Answer:
Single cell protein, e.g. Spirulina derived from microbes acts as one of the alternate sources of protein for animal and human nutrition.

Question 35.
Identify the two correct statements from the following.
(i) Apiculture means apical meristem culture.
(ii) Spinach is iron enriched.
(iii) Green revolution has resulted in improved pulse yields.
(iv) Aphids cannot infest rapeseed mustard. (All India 2014C)
Answer:
The two correct statements identified are
(ii) Spinach is iron enriched.
(iv) Aphids cannot infest rapeseed mustard.

Question 36.
Name any two diseases the ‘Himgiri’ variety of wheat is resistant to. (All India 2013)
Answer:
Stripe rust and leaf rust are the two diseases to which ‘Himgiri’ variety of wheat is resistant.

Question 37.
Name the following
(i) The semi-dwarf variety of wheat, which is high-yielding and disease resistant.
(ii) Any one interspecific hybrid mammal. (Delhi 2012)
Answer:
(i) Sonalika and Kalyan Sona are the semi-dwarf varieties of wheat that are high-yielding and disease resistant.
(ii) Mule is an interspecific hybrid sterile mammal.

Question 38.
Write the names of the semi-dwarf and high-yielding rice varieties developed in India after 1966. (Delhi 2012)
Answer:
Jaya and Ratna are two semi-dwarf and high-yielding rice varieties developed in India after 1966.

Question 39.
Why is the South Indian sugarcane preferred by agriculturists? (Foreign 2012)
Answer:
The South Indian sugarcane has thick stems with high yield and sugar content that is why it is preferred by agriculturists.

Question 40.
State the importance of biofortification. (All India 2011)
Answer:
Biofortification improves the nutritional quality of food materials by breeding crops with higher vitamin, mineral or protein content. It is the most practical means to improve public health.

Question 41.
Explain the relevance of ‘totipotency’ and ‘somaelones’ in raising healthy banana plants from virus infected banana plants. (Delhi 2019)
Or
How is it possible to recover healthy banana plants from a diseased but desirable quality of banana plant? Explain? (Foreign 2012)
Answer:
The capacity to generate a whole plant from any cell/explant is called totipotency. By application of these methods, it is possible to achieve propagation of a large number of plants in very short duration. This method of producing thousands of plants through tissue culture is called micropropagation. Each of these plants will be genetically identical to the original plant from which they were grown also called somaclones.

Meristem (axillary and apical) remains free from pathogens due to the absence of vascular supply. Thus, meristematic tissues are used in recovering healthy plants from diseased plants. Many important food plants like banana, etc., have been produced on a commercial scale using this method.

Question 42.
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. (2018)
Answer:
The procedure that ensures retention of the desired characteristics repeatedly in large populations of future generations of the tomato crop is micropropagation.

Healthy explants are taken from the tomato plants and grown in sterile conditions in special nutrient medium. The tomato plants produced from tissue culture are genetically identical to the original plant from which they are grown, so they are called somaclones. Also, through micropropagation more number of tomato can be produced in a short time.

Question 43.
Why are microbes like Spirulina being produced on a commercial scale? Mention its two advantage. (2018C)
Or
‘Large scale cultivation of Spirulina is highly advantageous for human population.’ Explain by giving two reasons. (All India 2016)
Or
How does culturing of Spirulina solve the food problems of the growing population? (Foreign 2012)
Answer:
Large scale cultivation of Spirulina is highly advantageous as it can solve the food problems of growing human population because

Spirulina is a very fast, easily growing alga that can produce huge quantity of protein even in a small area of land.
These microbes grow on materials like waste water from potato processing plants, straw, molasses, animal manure and sewage. Utilisation of these may reduce environmental pollution.

Question 44.
In an agricultural field, there is a prevalence of the following organisms and crop diseases which are affecting the crop yield badly
(i) White rust
(ii) Leaf and stripe rust
(iii) Black rot
(iv) Jassids
Recommend the varieties of crops the farmer should grow to get rid of the existing problems and thus improve the crop yield. (Delhi 2017)
Answer:
Normal varieties of crops are prone to infection by various pathogens which lead to poor growth of crops. To get rid of existing problems, the farmers should grow improved hybrid varieties as these are mostly resistant to most pathogens and give higher yield.

Crop disease	Hybrid variety
(i) White rust	Pusa Swarnim
(ii) Leaf and stripe rust	Himgiri
(iii) Black rot	Pusa Shubhra
(iv) Jassids	Pusa Sem 3

Question 45.
By taking two examples explain how has biofortification helped in improving food quality. (Delhi 2017)
Answer:
Biofortification refers to methods of breeding crops with higher levels of vitamins, minerals and healthier fats to improve public health. Till now, many crops have been developed by this method in order to improve food quality. Some examples of crop varieties with improved nutrient contents are

Maize hybrids with increased amount of amino adds, lysine and tryptophan.
Atlas 66 is a wheat variety having a high protein content which has been used as donor for improving cultivated wheat.

Question 46.
Suggest four important steps to produce a disease resistant plant through conventional plant breeding technology. (All India 2016)
Answer:
The four important steps to produce a disease resistant plant through conventional plant breedhig technology are as follows

Selection and screening of germplasm for disease resistance.
Hybridisation of selected plants.
Selection and evaluation of hybrids.
Testing and release of new varieties into the market.

Question 47.
Identify A, B, C and D in the given table. (All India 2016)

Crop	Variety	Resistance to disease
A	Himgiri	Leaf mst
Cauliflower	Pusa Shubhra	B
Brassica	Pusa Swarnim	C
Cowpea	D	Bacterial blight

Answer:
A – Wheat
B – Black rot
C – White rust
D – Pusa Komal

Question 48.
Name any two common Indian millet crops. State one characteristic of millets that has been improved as a result of hybrid breeding, so as to produce high yielding millet crops. (Delhi 2015)
Answer:
Two common Indian millet crops are maize and jowar. Hybrid breeding has resulted in the production of high yielding millet varieties that are resistant to water stress.

Question 49.
Enumerate four objectives for improving the nutritional quality of different crops for the health benefits of the human population by the process of biofortification. (Delhi 2015)
Answer:
Four objectives for improving the nutritional quality of different crops for the health benefits of the human population by the process of biofortification are as follows

Improving protein content and quality.
Improving oil content and quality.
Improving vitamin content.
Improving micronutrients and mineral content.

Question 50.
How has mutation breeding helped in improving the production of mung bean crop? (Delhi 2015)
Answer:
Mutation breeding is a phenomenon by which genetic variation is achieved through changes in base sequences within the genes. This creates new characters or traits that are absent in parental generatiojLJt is the process of breeding by artificially inducing mutations using chemicals or radiations.

In mung bean, resistance to yellow mosaic virus and powdery mildew was introduced by this method.

Question 51.
(i) Why are the plants raised through micropropagation termed as somaelones?
(ii) Mention two advantages of this technique. (All India 2015)
Answer:
(i) The method of producing thousands of plants through tissue culture is called micropropagation. The plants produced through micropropagation are genetically identical to the original plant from which they are grown, so they are called as somaclones.

(ii) Advantages of micropropagation These are as follows

More number of plants can be produced in a short time.
Disease-free plants can be developed from diseased plants.
Seedless plants can be multiplied.

Question 52.
How can healthy potato plants be obtained from a desired potato variety which is virus infected? Explain. (Delhi 2014)
Or
A potato plant is infected with a virus. Name and explain a method to obtain virus-free potato plants from it. (2014C)
Answer:
The healthy potato plants can be obtained through meristem culture of virus infected plants. Meristematic tissues are free from virus and other infections. So, they are used as explants and cultured under in vitro conditions to produce new healthy plants, by micropropagation or tissue culture.

Question 53.
List two steps that are essential for carrying out artificial hybridisation in crop plants and why? (Foreign 2014)
Answer:
The two steps that are essential for carrying out artificial hybridisation in crop plants are given below

Emasculation It is the removal of anthers or stamens from bisexual flowers, in developing stage only.
Bagging The emasculated bisexual and unisexual flowers are covered with bag, i.e. butter paper, so as to prevent entry of any kind of unwanted pollens.

These steps are mandatory to prevent both self-pollination as well as unwanted cross-pollination.

Question 54.
How are biofortified maize and wheat considered nutritionally improved? (Foreign 2012)
Answer:
Biofortified maize variety has twice the amount of amino acids, lysine and tryptophan, as compared to normal varieties, while biofortified wheat variety is very rich in protein content.

Question 55.
Explain the advantage of cross-breeding of two species of sugarcane in India. (Delhi 2011)
Answer:
Sugarcane grown in North India, i.e. Sacchamm barberi had poor sugar content and low yield, while the sugarcane grown in South India, i.e. Saccharum officinarum had thicker stems and higher content of sugar, but it could not be grown in North Indian climatic conditions.

The hybrid produced by cross-breeding of these two species have the following desirable traits

High-yield
Thick stems
High sugar content
Ability to grow in North Indian sugarcane fields.

Question 56.
Explain ‘mutation breeding’ as a method of developing disease resistant crop plants. Give an example of a pulse crop where this technique has helped. (All India 2019)
Answer:
Mutation breeding involves inducing mutations artificially by using chemicals or radiations (e.g. gamma radiation).
It is carried out in the following steps

Inducing mutations in plants by various means.
Screening the plant for resistance.
Selecting the desirable plant for multiplication or for breeding.

In mung bean, resistance to yellow mosaic virus and powdery mildew were introduced by mutations.

Question 57.
Name the technique and the property of plant cells that can to grow somaclones of certain desired variety of apple. Explain how somaclones of apple can be obtained in the lab, so as to get the desired variety on a large scale. (All India 2019)
Or
How are somaclones cultured from explants in in vitro conditions? Why are somaclones so called? (All India 2019)
Answer:
Micropropagation is the technique of tissue culture that can help to grow somaclones. Somaclones cultured from explants are grown in following steps

The explant is grown in a petridish/test tube under sterile conditions in a special nutrient medium.
The medium must contain carbon source like sugpr, inorganic salts, vitamins, minerals, amino acids, growth regulators like auxins and cytokinins.
The-medium should be replaced regularly to restore nutrients in it.

Since, all plants produced by tissue culture are genetically identical to the original plant from which they are cultured, they are called as somaclones. Three food plants produced by micropropagation are tomato, banana, apple, etc.

Question 58.
(i) Write the desirable characters a farmer looks for in his sugarcane crop.
(ii) How did plant breeding techniques help North Indian farmers to develop cane with desired characters? (All India 2017)
Or
Plant breeding technique has helped sugar industry in North India. Explain how? (All India 2016)
Or
Name the prominent South Indian and North Indian species of sugarcane used for cross breeding. List the desired qualities of the hybrid that can be obtained from this cross. (Delhi 2013C)
Answer:
(i) The desirable characters a farmer looks for in his sugarcane crop are

High sugar content
High yield
Thick stems
Ability to grow all over India
Disease resistance

(ii) For breeding technique, Refer to Answer No. 23.

Question 59.
Differentiate between somaclones and somatic hybrids. Give one example of each. (All India 2016)
Answer:
The plants, which are genetically similar to the parent plant are called somaclones, e.g. banana, sugarcane, etc. The process of fusion of protoplast of somatic cells obtained from different varieties or species of a plant on a suitable nutrient medium in vitro to develop a hybrid, is known as somatic hybridisation.

The hybrids so produced are called somatic hybrids, e.g. Pomato is a somatic hybrid produced by the fusion of tomato and potato protoplasts.

Question 60.
(i) Write the two limitations of traditional breeding technique that led to promotion of micropropagation.
(ii) Mention two advantages of micropropagation.
(iii) Give two examples where it is commercially adopted. (All India 2016)
Answer:
(i) Limitations of traditional breeding technique These are as follows

The traditional breeding for developing disease resistant varieties is limited by the presence of small number of disease resistance genes in pre-existing varieties.
It is a time taking process to develop a disease resistant variety via traditional breeding. It may take several years to develop a new improved variety.

(ii) Advantages of micropropagation These are as follows

Micropropagation allows to produce large number of plants in short duration of time.
Each of the plant produced has the same genetic make up.

(iii) This technique is commerically adopted to produce banana and apple.

Question 61.
What is biofortification? Write its importance. Mention the contribution of Indian Agricultural Research Institute towards it with the help of two examples. (2018C, Foreign 2014)
Answer:
(i) Biofortification is the process of developing crops with higher content of protein, minerals, oils, carbohydrates, etc.
(ii) Importance of Biofortification: It provides the crops with higher levels of vitamins, minerals, proteins and healthier fats.
It helps in the improvement of public health.
(iii) LARI contributed towards biofortification by developing several vegetable crops rich in vitamins and minerals.
Two examples of such crops are

Vitamin-A enriched carrots and spinach.
Protein enriched beans.

Question 62.
Suggest and describe a technique through which a virus-free healthy plant can be obtained from a diseased sugarcane plant. (Delhi 2015C, All India 2014 C)
Or
Scientists have succeeded in recovering healthy sugarcane plants from a diseased one.
(i) Name the part of the plant used as explant by scientists.
(ii) Describe the procedure the scientists followed to recover the healthy parts.
(iii) Name the technology used for crop improvement. All Indig 2011
Answer:
The virus-free healthy sugarcane plant can be obtained through meristem culture of diseased plant; as meristematic tissues are free from viruses. They can be used as explants for micropropagation.

Steps in Meristem Culture

The shoot tip explants are grown in nutrient medium in either a test tube or a petridish, under aseptic/sterile in vitro conditions.
The nutrient medium should have carbon source, inorganic salts, vitamins, amino acids and growth regulators like auxin and cytokinin’in proper defined ratio.
The plantlets, thus obtained are later shifted to nurseries, under observation and finally to fields.

Question 63.
(i) Name the tropical sugarcane variety grown in South India. How has it helped in improving the sugarcane quality grown in North India?
(ii) Identify A, B and C in the following table. (Delhi 2014)

Crop	Variety	Insect Pests
Brassica	Pusa Gaurav	A
Flat bean	Pusa Sem 2, Pusa Sem 3	B
C	Pusa Sawani, Pusa A-4	Shoot and fruit borer

Answer:
(i) For sugarcane variety, Refer to Answer No. 23.

(ii) A- Aphids
B – Jassids, aphids and fruit borer
C – Okra

Question 64.
(i) Name the Indian scientist, whose efforts brought ‘Green Revolution in India’.
(ii) Mention the steps that are essentially carried out in developing a new genetic variety of crop under plant breeding programme. (Foreign 2012)
Answer:
(i) Dr. MS Swaminathan brought ‘Green Revolution’ in India.
(ii) The steps in developing a new genetic variety of crops are

Collection of genetic variability or germplasm.
Evaluation and selection of parents.
Cross hybridisation among the selected . parents.
Selection and testing of superior recombinant or hybrids.
Testing, release and commercialisation of new cultivars.

Question 65.
How can crop varieties be made disease resistant to overcome food crisis in India?
Name one disease resistant variety in India of
(i) Wheat to.leaf and stripe rust.
(ii) Brassica to white rust. (Delhi 2011)
Answer:
To overcome food crisis due to crop failure or disease, crop varieties that are disease resistant developed using following two techniques
(i) By conventional breeding techniques It includes

Screening the germplasm for the source of resistance.
Hybridisation of selected individuals.
Selection of hybrids.
Evaluation of hybrids.
Testing and release of the variety.

(ii) By mutation breeding It involves inducing mutations artificially and then using the plants that have the desirable character as a source of disease-resistance in breeding.

Himgiri wheat is resistant to leaf and stripe rust.
Pusa Swarnim (Karan Rai) is resistant to white rust.

Question 66.
Mention the property of plant cells that has helped them to grow into a new plant in in vitro conditions. Explain the advantages of micropropagation. (Delhi 2011)
Answer:
Plant cell has a property called ‘totipotency’ by which each plant cell or an explant can grow into a new plant under in vitro conditions.

Advantages of micropropagation These are as follows

Thousands of plants can be grown in a short period.
By culturing the meristems of virus infected plants, virus-free healthy plants can be raised.
Plants are genetically identical, so certain desirable characters can be continued through generations.
Hybrids can be produced by somatic hybridisation.

Question 67.
IAKI has released several varieties of crop plants that are biofortified. List three examples of such crops and their biofortifications. Foreign 2011
Answer:
Biofortified crops released by IARI are

Vitamin-A enriched carrots and spinach.
Iron and calcium enriched spinach.
Protein enriched beans.
Vitamin-C enriched bitter gourd and mustard.

Question 68.
(i) Mention the property that enables the explants to regenerate into a new plant.
(ii) A banana herb is virus-infected. Describe the method that will help in obtaining healthy banana plants from this diseased plant. (All India 2010)
Answer:
(i) Properties of explant, Refer to Answer No. 34.
(ii) Obtaining virus disease for plants. Refer to Answer No. 9.

Question 69.
With advancements in genetics, molecular biology and tissue culture, new’ traits have been incorporated into crop plants. Explain the main steps in breeding a new genetic variety of a crop. (All India 2014)
Answer:
The major steps in breeding a new genetic variety of a crop, Refer to Answer No. 32 (ii) and for detailed text, refer to page no. 246.

Question 70.
(i) Name the technology that has helped scientists to propagate on a large scale the desired crops in a short duration. List the steps carried out to propagate the crops by the said technique.
(ii) How are somatic hybrids obtained? (Delhi 2014)
Answer:
(i) Tissue culture is the technique that has helped scientists to propagate plants with desirable traits on a large scale, in short duration.
Since, large number of plants are propagated through this culture, it is also referred to as micropropagation. The steps involved in this technique are

Explants are derived from any part of plant (to be propagated), i.e. tips of carrot.
Explants are grown in sterile conditions in special nutrient medium to regenerate complete plants.
Nutrient media must contain a carbon source (such as sucrose), organic salts, vitamins, amino acids and phytohormones, i.e. auxin and cytokinin.
Hence, propagation is achieved for a large number of plants under in vitro conditions.
All the plants obtained by tissue culture are called somaclones, since they are genetically identical to each other as well as to their parent plant.

(ii) Somatic hybrids are obtained by the method of somatic hybridisation. In this method, the naked protoplasts of cells of two plants are hybridised. Protoplasts are isolated by dissolving cell wall and fused to get a hybrid protoplast. The fused nucleus is called • heterokaryon that grows further to form a a new plant. The plants thus formed are called somatic hybrids.

Question 71.
(i) What is plant breeding? List the two steps the classical plant breeding involves.
(ii) How has the mutation breeding helped in improving crop varieties? Give one example where this technique has helped.
(iii) How has the breeding programme helped in improving the public nutritional health? State two examples in support of your answer. (Delhi 2013)
Answer:
(i) Plant breeding involves the manipulation of plant’s genetic material,, so as to obtain a plant with desired characteristics. Classical plant breeding involves

crossing or hybridisations of purelines and
followed by artificial selection to produce plants with desirable plants of higher yield, nutrition and resistance to diseases.

(ii) For mutation breeding, Refer to Answer No. 18.

(iii) Breeding programmes help in improving public nutritional health via biofortification. It refers to the production of varieties with higher levels of nutritious substances,
e.g. Atlas-66-high protein content Maize hybrids-high lysine and tryptophan content.

Question 72.
More than 25% of human population is suffering from hunger and malnutrition. Do you think microbes can be helpful in overcoming this situation?
Answer:
Yes, microbes as Single Cell Protein (SCP) are helpful in overcoming this situation. They are a rich source of protein, e.g. Spirulina.

Question 73.
Mohan a big businessman, went to his village on Diwali holidays. He saw that there farmers are still using conventional plant breeding technique to increase the yield. He told them about plant tissue culture.
(i) What is plant tissue culture?
(ii) Name a method through which disease-free plants can be developed from a diseased plant.
Answer:
(i) Tissue culture is a technique in which any part of plant is grown in vitro under aseptic conditions to form a whole plant.
(ii) Meristem culture is the technique through which disease-free plants can be obtained from diseased plants.

Question 74.
Sohan is a small scale farmer and holds 3 acres of land. He would like to increase the yield in his farm. Harshit, a student of M.Sc. (Agriculture) advised him to go to the agricultural department centre of his locality to get high yielding variety of the crop. He also suggested Sohan to stop the use of chemical fertilisers.
(i) Explain the term high yielding variety.
(ii) Name two high yielding varieties of wheat.
(iii) What are the values shown by Harshit?
Answer:
(i) High yielding varieties are those varieties of crop plants which give better yield from the same resources than other varieties.
(ii) Sonalika and Kalyan Sona.

(iii) Harshit is helpful in nature. He uses his knowledge for the benefit of society.