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Improvement in crop variety - class-IX

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In breeding a new genetic variety of a crop by hybridisation, superior recombinants are self pollinated for several generations till they reach a state of 

  1. Uniformity

  2. Heterozygosity

  3. Homozygosity

  4. Both (1) and (3)


Correct Option: D
Explanation:

After the hybridization of two selected parent plant species, the recombinants with the desired combination of characters are selected. These hybrids are then self-pollinated for several generations so that they reach a state of uniformity or homozygosity so that the desired characters will not segregate in the progeny.

(Uniformity and Homozygosity are synonymous for the state of possessing two similar alleles for the same genes, one acquired from each parent.)
So, the correct answer is 'Uniformity' and 'Homozygosity'.

An improved insect resistant variety "Pusa Gaurav" is variety of _________

  1. Brassica

  2. Flat bean

  3. Cow pea

  4. Bhindi


Correct Option: A
Explanation:

Pusa Gaurav is an insect resistant variety of Mustard or Brassica that shows resistant against the aphids.

Hence, the correct answer is 'Brassica'

Calculate the amount of $(NH _4) _2SO _4$ in $'g'$ which must be added to $500ml$ of $0.2\,M\,NH _3$ to yield a solution of $pH=9.35$ given $p^{k _b} (NH _3)=4.74$.(Given $10^{-0.09}=0.812$)

  1. $8\,g$

  2. $5.36\,g$

  3. $4.55\,g$

  4. $4.0\,g$


Correct Option: A

How many documented varieties of Basmati rice are grown in india.

  1. $2,00,000$

  2. $50,000$

  3. $1000$

  4. $27$


Correct Option: D
Explanation:

(D) 27 varieties of documented basmatic rice are grown in India. It is known for excellent cooking and eating qualities and many improved varieties using plant breeding are developed which give tolerance to many disease or climate also increased yield.

The desired varieties of economically useful crops can be produced by_________

  1. Vernalisation

  2. Mutation

  3. Natural selection

  4. Hybridisation


Correct Option: D
Explanation:
  • The mating or crossing of two plants or lines of dissimilar genotype is known as hybridization. 
  • The chief objective of hybridization is to create genetic variation when two genotypically different plants are brought together in F1. Segregation and recombination produce many new gene combinations in F2 and the later generations, i.e., the segregating generations. 
  • The degree of variation produced in the segregating generations would, therefore, depend on the number of heterozygous genes in the F1 which in turn depends upon the number of genes for which the two parents differ. 
  • The aim of hybridization may be the transfer of one or few qualitative characters, the improvement in one or more quantitative characters, or use the F1 as a hybrid variety. 
  • Breeding new crops are important for ensuring food security by developing new varieties that are higher-yielding, resistant to pests and diseases, drought-resistant or regionally adapted to different environments and growing conditions.

Therefore, the correct answer is option D.

Classical plant breeding involves______________

  1. Crossing or hybridization of pure lines

  2. Artificial selection to produce plants with desired qualities

  3. Better yield, nutrition and resistance to disease

  4. All of the above


Correct Option: D
Explanation:

  • Processes like the crossing of plants that have a pure line character, selection of plants that have desirable qualities and their artificial selection, obtaining a better yield of crops to improve nutrition and resistance to diseases are all parts of plant breeding. 

So, option D is the correct answer.

Technology that involves purposeful manipulation of plant species for the development of high yielding and disease-resistant varieties are______________

  1. Green revolution

  2. Plant breeding and introduction

  3. Conventional plant breeding

  4. Hybridization and mutation breeding


Correct Option: D
Explanation:

  • Hybridization is defined as the process of interbreeding between two individuals of different plant species to obtain a hybrid that contains the genes of both the parent species due to genetic recombination. 
  • The process of developing a new variety by changing the genome through X-ray or UV radiation is known as mutation breeding. It is a quick method to obtain genetic variation. 
  • These are the two techniques that can be used for the development of the plant variety which gives high yield and resistance to diseases. 

Thus, the correct answer is option D. 

Method of preserving favourable variants and elimination of undesirable plants is termed as________

  1. Selection

  2. Hybrid

  3. Hybridization

  4. Somatic hybrids


Correct Option: A
Explanation:

  • The selection is the oldest method of plant breeding in which the two plants are selected on the basis of the superior characters. This method helps in the elimination of undesirable characters. The two plants are selected in order to preserve the favorable traits. This method involves the preservation of the plants which have superior characters. 
Thus, the correct answer is option A. 

Which of these is not a major group of activities for improving crop yield?

  1. Crop protection management

  2. Crop production management

  3. Crop variety improvement

  4. Crop transport management


Correct Option: D
Explanation:

Many different management programs are undertaken in order to improve the yield of the crop plants. The crop protection, production, and variety improvement are the management programs which help to enhance the yield of the crop. The transport management is not a part of crop yield increase. 

Thus, the correct answer is option D. 

The crosses are made between two different species of the same genus is known as

  1. Interspecific hybridization

  2. Intraspecific hybridization

  3. Intra-varietal hybridization

  4. None of the above


Correct Option: A
Explanation:
The crossing between two plants of different species to produce a new variety is called hybridization. Genetically modified crops can be produced by insertion of genes with desired traits by the process of hybridization.Crossing may be between two different varieties (intra-varietal cross breeding), between two different species of same genus (interspecific crossbreeding) and between different genera (intergeneric crossbreeding). The crossing between two species of same genus is known as interspecific cross breeding. 
Thus, the correct answer is option A. 

Choose the correct statement.

A) Hybridization is used to exploit and utilise the hybrid varieties.
B) Hybridization creates variation.

C) Hybridization leads to recombination of characters.

  1. Only A

  2. Only B

  3. Only C

  4. A, B and C


Correct Option: D
Explanation:

The crossing between genetically different plants to produce a new variety is called as hybridization. Genetically modified crops can be produced by insertion of genes with desired traits by the process of hybridization. The parents are allowed to perform hybridization and the offspring is known as the hybrid. The hybrid is allowed to self-pollinate in order to maintain a pure breed of the hybrid. The hybrid varieties are used for better crop production. There is the mating of two different plant species which results in genetic variation. There is the recombination of the characters of both the parent plants. 

Thus, the correct answer is option D. 

The trait which is accounted for hybridization is

  1. Resistance to diseases

  2. Productivity

  3. Tolerance to climatic condition

  4. All of the above


Correct Option: D
Explanation:

The crossing between two plants of different species to produce a new variety is called hybridization. The new plant which is produced is known as the hybrid which possesses superior characters of both the parent plants. The traits which are considered for hybridization are resistance to pests, insects and diseases, an increase in the productivity and high yielding, tolerance to adverse conditions, etc. The hybrid is called as hybrid vigor which has better characteristics when compared to the parental types. 

Thus, the correct answer is option D. 

Which of the following practices can be related to hybridisation?

  1. Segregation

  2. Recombination

  3. Variation

  4. All of the above


Correct Option: D
Explanation:

Hybrid plants can be developed by the breeding of the plants of different species. This is known as the process of hybridization. The parents are genetically different plants. There is segregation of the characters which results in the formation of offspring which have superior characters when compared to the parents. There is recombination which introduces certain new genes in the offspring. Due to genetic recombination, variations are produced. The offsprings are genetically different from the individual parents. 

Thus, the correct answer is option D. 

.......... is a sterile hybrid which spreads by rhizome division

  1. Iris albicans

  2. Evening primrose

  3. Tangelo

  4. None of the above


Correct Option: A
Explanation:

Hybrid plants can be developed by the breeding of the plants of different species. The parents are genetically different plants. Iris albicans is the sterile hybrid which is developed by breeding of two different species. This is known as interspecific hybridization. This is a sterile plant which spreads by rhizome division.

Thus, the correct answer is option A. 

Which of the following is not applicable to biological species concept?

  1. Hybridisation

  2. Reproductive isolation

  3. Natural selection

  4. Gene pool


Correct Option: A
Explanation:

Answer is option A i.e. "Hybridisation"
The biological species concept defines a species as members of populations that interbreed in nature. According to this concept, organisms belong to the same species if they can interbreed to produce viable, fertile offspring. Reproductive isolation, natural selection and gene pool are applicable to one species.
Hybridisation, on contrary, occurs due to process of combining two different species of organisms to create a hybrid.
Hence, "hybridisation" is not applicable to biological species concept.

Total number of meiotic division required for forming $100$ zygotes/ $100$ grains of wheat is?

  1. $100$

  2. $75$

  3. $125$

  4. $50$


Correct Option: C

Amber coloured Wheat produced from red coloured Mexican Wheat is

  1. Sharbati Sonora

  2. Pusa Lerma

  3. Both A and B

  4. Tanchung Native I.


Correct Option: C

Pulses usually lack amino acids

  1. Methionine and tryptophan

  2. Cysteine and methionine

  3. Cysteine and tryptophan

  4. Methionine and tryptophan.


Correct Option: B

Purity of seed is guaranteed by

  1. ICAR

  2. NBPGR

  3. National Seed Corporation

  4. All the above.


Correct Option: C

Assertion : Paraguay tea is obtained from Paullinia cupana

Reason :Tea is obtained from Camellia sinensis

  1. If both the assertion and the reason are true and the reason is a correct explanation of the assertion

  2. If both the assertion and reason are true but the reason is not a correct explanation of the assertion

  3. If the assertion is true but the reason is false

  4. If both the assertion and reason are false

  5. If the assertion is false but reason is true


Correct Option: E
Explanation:

Paraguay tea is obtained from leaves of evergreen tree Ilex paraguariensis

All the leaves are used. Tea is obtained from the leaves of Camellia sinensis of family Theaceae. 
So, the correct answer is 'If the assertion is false but reason is true'

Which of the following is an introduced variety of crop

  1. Soya Bean

  2. Sonora-64

  3. Tanchung native-1

  4. All the above.


Correct Option: D

The evolution of cultivated cotton is an example of _______________.

  1. Distant hybridization and polyploidy

  2. Diploidization of sterile $F _1$

  3. lntergeneric hybridization and polyploidy

  4. Interspecific hybridization and polyploidy


Correct Option: A

In crop improvement programmes, haploids are of  great importance because they ___________________.

  1. Grow better even under adverse climatic conditions

  2. Are useful in studies of meiosis.

  3. Have less requirement for energy inputs

  4. Give homozygous lines following diploidization


Correct Option: A

Match List-I(Transgenic variety of crop) with List-II(Trait for which gene has been incorporated) and select the correct answer using the given the lists.

List-I List-II
a. Seed link maixe $1$. Virus resistance
b. Rainbow papaya $2$. Herbicide resistance
c. Flavor Savr tomato $3$. Altered ripening
$4$. Insect resistance
  1. A-$2$, B-$1$, C-$3$

  2. A-$2$, B-$3$, C-$1$

  3. A-$4$, B-$3$, C-$1$

  4. A-$4$, B-$1$, C-$3$


Correct Option: A

Which of the following are required for the development of hybrid rice seed production?

  1. CMS line

  2. Maintainer

  3. Restorer

  4. Inbred line


Correct Option: A

Norine-$10$ is?

  1. Retrovirus causing enteritis

  2. Dwarfing gene in wheat

  3. Wheat variety resistant to black rust

  4. Fungicide


Correct Option: A

Triticale is the first man-made cereal crop. The combination of parents involved in its production is Tritium.

  1. Sorghum

  2. Barely

  3. Saccharin

  4. Rye


Correct Option: A

Find out the correct sentence.
(i) Hybridization means crossing between genetically dissimilar plants.
(ii) Cross between two varieties is called as inter specific hybridisation.
(iii) Introducing genes of desired character into a plant gives genetically modified crop.
(iv) Cross between plants of two species is called as inter varietal hybridisation.

  1. (i) and (iii)

  2. (ii) and (iv)

  3. (ii) and (iii)

  4. (iii) and (iv)


Correct Option: A
Explanation:

Hybridisation is defined as the process of interbreeding between two genetically divergent individuals or two individuals of different species. Therefore, the statement (i) is correct.
Interspecific hybridisation means cross mating between two different species but sharing same genera. For example, a cross breed between a lion and a tiger, they both are from same genus Panthera but different species. So the statement that cross between two varieties is called interspecific hybridisation is wrong.
I am a brinjal farmer, my brinjals are being infected by some beetles every year. I spend a huge sum of money on insecticides and pesticides to protect my crop. Then, a biotechnology company approaches me with a new strain or variety of brinjal plants which have the capability to produce a natural pesticide that makes it resistant to the beetles. My crop is not only saved, but  I also get good yield of brinjals now and earn a lot of money. I do not have to spend extra money on pesticides and insecticides. Basically, I got a brinjal plant with gene of desired character and got a desired genetically modified brinjal plants. Therefore, the statement (iii) is correct.
When the parent plants cross bred are from the same species, but of different variety is called intervarietal hybridisation. For example, a cross bred between two different varieties of wheat plant. They belong to the same species but they are of different variety. Therefore, the statement (iv) is wrong.
Hence, we can conclude that (i) and (iii) are correct statements.

The technique of combining of desirable characteristics in one plant and then multiplying such individual to the extent that it is easily available for common use of farmers is know as crop improvement.

  1. True

  2. False


Correct Option: A
Explanation:

The  method of altering the genetic pattern of plants to increase their value and utility for human welfare, is called crop improvement or plant breeding. It is a purposeful manipulation of plants to create desired plant types that are better suited for cultivation, give better yield and are disease resistant. iit is purely depends on domestication.

So the given statement is true.

In hybridisation the haploids combine the advantage of 

  1. Recombination

  2. Segregation

  3. Fixation

  4. All


Correct Option: A
Explanation:
During the process of hybridization, haploids combine together to reestablish the diploid condition and allow recombination.
So, the correct answer is 'Recombination'.

Recently there was a controversy regarding the plantation of

  1. Tamarindus

  2. Eucalyptus

  3. Acacia

  4. None of these


Correct Option: B
Explanation:
Controversy regarding the plantation of Eucalyptus was because of:
Environmental implications of eucalyptus plantations, it has allelopathy on ground vegetation, has a negative impact on biodiversity, exhausts soil from nutrients, has oil in its leaves and accumulated litter leads to forest fire hazards. It also exhausts groundwater and lowers the water table. 
So, the correct answer is 'Eucalyptus'.

Opuntia weed can be eradicated by  

  1. Gambusia

  2. cochineal insect

  3. grass carp

  4. both (a) and (b).


Correct Option: B
Explanation:

The cochineal insect are introduced into the (Opuntia) prickly pear. The insect destroy the weeds without harming the crop plants. Its one of the biological method as well.

What makes the bread soft and fluffy?

  1. Finely ground flour

  2. Alcohol given off during fermentation of sugar

  3. Carbon dioxide gas given off during fermentation of sugar

  4. Oxygen gas


Correct Option: C
Explanation:

Yeast ferments the sugar present in the dough into carbon dioxide. The ${ CO } _{ 2 }$ released from the yeast fills the dough and increases its volume. Once, the bread has baked, the heat causes the bubbles to break and makes the bread light and fluffy.

Triticale is a man-made cereal which has been developed through hybridization between_____________

  1. Wheat and oat

  2. Wheat and rice

  3. Wheat and gram

  4. Wheat and rye


Correct Option: D
Explanation:
  • Triticale is a man-made crop developed by crossing wheat and cereal rye. It is probably the only new man-made crop in commercial production. 
  • Triticale was found to be more efficient than wheat in utilizing and absorbing nitrogen from the soil. 
  • It also produces a 30% higher yield on acid soils and is superior to wheat on copper-deficient soil.

The main aim of plant breeding is_____________

  1. To produce improved varieties

  2. To make soil fertile

  3. To control pollution

  4. To become more progressive


Correct Option: A
Explanation:

  • Plant breeding aims to improve the characteristics of the plant so that they become more desirable agronomically and economically. 
  • Thus, the chief objective of plant breeding is to develop such improved varieties of crop plants that will be commercially successful. 

Therefore, the correct answer is option A.

Select the wrongly matched pair.

  1. Hybrid - Pure breeding progeny.

  2. Incomplete dominance - An exception to Mendelism

  3. Heredity - Transmission of characters from one generation to the next

  4. Allele - Alternate representation of a gene


Correct Option: A
Explanation:

Pure breeding varieties are the one that carries same allele for a particular character and pass the trait without change from one generation to next upon selfing (for example, pure breeding tall (TT) plant carries two copies of “T” allele). Hybrids are the one which carries contrasting allele of a particular gene e.g., hybrid tall plant’s genotype is “Tt”. Incomplete dominance refers to the conditions where none of factors of a gene is dominant; the phenotype of heterozygous dominant individual is blend of dominant and recessive traits. Thus, it is an exception to Mendel’s principle of dominance. Heredity is genetic transmission of characters from parent generation to progeny. Alternative forms of a gene are called alleles e.g., alleles for gene for plant height are “T” and “t”. Thus, the correct answer is option A.

The science of improving crop varieties is called as____________________

  1. Crop improvement

  2. Selection

  3. Introduction

  4. Plant breeding


Correct Option: D
Explanation:

  • Plant breeding is the art and science of changing the traits of plants in order to produce desired characteristics. 
  • Plant breeding can be accomplished through many different techniques ranging from simply selecting plants with desirable characteristics for propagation, to more complex molecular techniques. 
  • Plant breeding aims to improve the characteristics of the plant so that they become more desirable agronomically and economically. 
  • Thus, the chief objective of plant breeding is to develop such improved varieties of crop plants that will be commercially successful. 
  • Generally, a successful variety is one with a total balance of traits that makes it more profitable for growers. 
  • Quality characters vary from one crop to another, e.g., grain size, colour, milling and baking qualities in wheat (Triticum aestivum), cooking quality in rice (Oryza sativa), malting quality in barley (Hordeum vulgare), size, colour, and flavour of fruits, keeping quality of vegetables, protein content in cereals and legumes, lysine content in cereals, methionine and tryptophan contents in pulses, etc.

Therefore, the correct answer is option D.

The aim of plant breeding is to produce_____________

  1. Disease-free varieties

  2. High-yielding varieties

  3. Early-maturing varieties

  4. All of the above


Correct Option: D
Explanation:

  • Plant breeding aims to improve the characteristics of the plant so that they become more desirable agronomically and economically. 
  • Thus, the chief objective of plant breeding is to develop such improved varieties of crop plants that will be commercially successful. 

Therefore, the correct answer is option D.

The first artificial interspecific plant hybrid was produced by 

  1. Cotton Mather

  2. Joseph Koerauter

  3. Thomas Fairchild

  4. None of the above


Correct Option: C
Explanation:
The crossing between genetically different plants to produce a new variety is called as hybridization. Genetically modified crops can be produced by insertion of genes with desired traits by the process of hybridization. The first artificial interspecific type of hybridization was produced by Thomas Fairchild. The organism is known as Fairchild mule. This development was performed in the year 1717. 
Thus, the correct answer is option C. 

.......... is responsible for hybridization.

  1. Haploidy

  2. Polyploidy

  3. Seggregation

  4. None of the above


Correct Option: B
Explanation:

Presence of three or more sets of chromosomes in an organism is called polyploidy. It is often seen in plants and very rare in animals. It is caused due to the non disjunction of the sister chromatids during the recombination (at meiosis). It can be induced in plants and cell cultures with the help of some chemicals like colchicine. Polyploidy causes variation, as it adds new genomes into a species. It has been widely used in producing hybrids of wheat. Ploidy level also effects some characteristics of plants. For example, higher ploidy leads to the larger cell size. So, the correct answer is B.

In crop improvement programme, haploids are important because they

  1. Require one half of nutrients

  2. Are helpful in study of meiosis

  3. Grow better under adverse conditions

  4. Form perfect homozygous individuals on diploidisation.


Correct Option: D
Explanation:

In crop improvement programme, haploids are important because they form perfect homozygous lines. Homozygous are the pure line selection plants resulting from self pollination. In this way, considerable homozygosity is obtained. Haploids are those plants which possess a gametophytic number of chromosomes. Haploids are used in plant breeding, especially for the production of homozygous plants and in their studies in the detection of mutation.

So the correct answer is ' Form perfect homozygous individuals on diploidisation'

Genetic diversity in agricultural crops is threatened by -

  1. Introduction of high yielding varieties

  2. Intensive use of fertilizers

  3. Entensive intercropping

  4. Intensive use of biopesticides


Correct Option: A
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