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Method of plant breeding for crop improvement - class-IX

Description: method of plant breeding for crop improvement
Number of Questions: 59
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Tags: food production breeding and biotechnology biology cell biology and biotechnology strategies for enhancement in food production botany plant breeding
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The agriculture sector of India employs about

  1. $50$ percent of the population

  2. $70$ percent of the population

  3. $30$ percent of the population

  4. $60$ percent of the population


Correct Option: B
Explanation:

The agriculture sector of India employs about 70 percent of the population, in which 80% are rural population. The agriculture share in the GDP of India is 20.5 %.

So, the correct option is option B '70 percent of the population'.

Desired improved variety of economically useful crops are raised by

  1. Natural selection

  2. Hybridization

  3. Mutation

  4. Biofertilizer


Correct Option: B
Explanation:
Classical plant breeding includes hybridization (crossing) of pure lines, artificial selection to produce plants with desirable characters of higher yield, nutrition and resistance to diseases.  
The conventional method of breeding for disease resistance is hybridization and selection. 
Thus, the correct answer is option B.

Vegetable crop cultivation is known as

  1. Horticulture

  2. Sericulture

  3. Silviculture

  4. Apiculture


Correct Option: A
Explanation:

Horticulture has been defined as the agriculture of plants, mainly for food, materials, comfort and beauty. According to American horticulturist Liberty Hyde Bailey, "Horticulture is the growing of flowers, fruits and vegetables, and of plants for ornament and fancy." Hence, vegetable crop cultivation is known as Horticulture.

So, the correct answer is Horticulture'

Wide hybridisation has been used for producing

  1. Haploids

  2. Dihaploids from tetraploids

  3. Trihaploids from hexaploids

  4. All the above


Correct Option: D
Explanation:

Wide hybridization can be used to transfer the desirable variability. It is used for producing haploids, diploids from tetraploids and trihaploids from hexaploids.

So, the correct answer is 'All the above.'

First artificial hybrid was obtained by crossing sweet william and carnation in $1717$ by 

  1. G.J Mendel

  2. M.S Swaminathan

  3. P.Maheshwari

  4. Thomas Fairchild


Correct Option: D
Explanation:

A. G.J Mendal is known for his discovery of fundamental laws of inheritance.

B. M.S Swaminathan is responsible for introducing and further developing high-yielding varieties of wheat in India.
C. P. Maheshwari was the first person to to grow a plant after natural fertilization in a test tube containing artificial culture medium.
D. Thomas Fairchild was responsible for first artificial hybrid.
So, the correct answer is 'Thomas Fairchild'.

Totipotency is accurately defined as

  1. Regeneration

  2. Production of a plant from a part

  3. Induce roots

  4. Produce somatic embryo


Correct Option: B
Explanation:

Totipotency - The ability of cells such as an embryonic stem cell to differentiate into any type of body cell. Plant cells are also totipotent, which helps to explain why a graft of a plant can generate a whole new individual out of just a small branch cutting.
Totipotent cells can form all the cell types in a body, plus the extraembryonic, or placental, cells. Embryonic cells within the first couple of cell divisions after fertilization are the only cells that are totipotent. Pluripotent cells can give rise to all of the cell types that make up the body; embryonic stem cells are considered pluripotent. Multipotent cells can develop into more than one cell type, but are more limited than pluripotent cells; adult stem cells and cord blood stem cells are considered multipotent.

Norin-10 gene is

  1. Dwarf gene of rice

  2. Dwarf gene of wheat

  3. Dwarf gene of tomato

  4. Smut resistant gene of wheat


Correct Option: B
Explanation:

The Rht-B1b and Rht-D1b dwarfing genes were derived from Norin-10, which was a semi-dwarf variety bred in Japan and released in 1935 (Gale and Youssefian, 1985). Norin-10 was used in US breeding programs in the 1950s in order to improve lodging resistance in winter wheat, in which lodging was a serious problem when high rates of nitrogen fertilizers were applied. A selection from a cross of Norin-10 with the US variety, Brevor was particularly promising and was used by Borlaug in the development of the green revolution wheat varieties. Wheat Norin-10 is a semi-dwarf wheat cultivar with very large ears that was bred at an experimental station in Iwate Prefecture, Japan. Norin-10 helped developing countries, such as India and Pakistan, to increase the productivity of their crops from approximately 60% during the green revolution. Thus, the correct answer is option B.

Which of the following instrument can be used to record plant growth by seconds?

  1. Porometer

  2. Potometer

  3. Pressure bomb

  4. Crescograph


Correct Option: D
Explanation:

A crescograph is a device for measuring growth in plants. It was invented in the early 20th century by Sir Jagadish Chandra Bose. The Bose crescograph uses a series of clockwork gears and a smoked glass plate to record the movement of the tip of a plant (or its roots) at magnifications of up to 10,000. Marks are made on the plate at intervals of a few seconds, demonstrating how the rate of growth varies under varying stimuli. Bose experimented with temperature, chemicals, gases and electricity.

Thus, the correct answer is option D.

The aim of plant breeding programme is to produce 

  1. Disease-free varieties

  2. High-yielding varieties

  3. Early-maturing varieties

  4. All of the above


Correct Option: D

Which is not applicable to the biological species concept?

  1. Hybridization

  2. Natural population

  3. Reproductive isolation

  4. Gene Pool


Correct Option: A
Explanation:
The biological species concept defines a species as a members of populations that potentially interbreed in nature. The biological species concept explains species resemblance and how some differ from other species. Offspring has fusion of parent's genes. As the generation increases, the genes of different organisms are constantly shuffled around the species gene pool. The shared gene pool gives the species its identity. Genes are not transferred to other species and different species thus, take on a different phenotype. Interbreeding between species is prevented by isolating mechanisms. The biological species concept centers on this inability to successfully hybridize
 So, the correct answer is 'Hybridization'

Hybrid of maize is grown frequently because of 

  1. Good grain quality

  2. Good yield

  3. Higher starch content

  4. All of the above


Correct Option: B
Explanation:

Hybrid plants can be developed by the breeding of the plants of different species. The parents are genetically different plants. The hybrid of maize plant was developed in order to obtain higher yield. The plants with the trait of producing higher yield were crossed with the other plant with superior character. The number of grains in the plant and the number of fruits is counted to obtain a higher yield. 

Thus, the correct answer is option B. 

Crosses between the plants of the same variety are called as

  1. Interspecific

  2. Intervarietal

  3. Intravarietal

  4. Intergeneric


Correct Option: C
Explanation:

In intravarietal hybridization, the crosses are made between the plants of same variety. Thus, option C is correct.

Intervarietal hybridization is in which parents involved in hybridization belong to the same species. In crop improvement programme this type of hybridization is commonly used. E.g., crossing of two varieties of wheat or other crops. 
Interspecific hybrids are bred by mating two species, normally from within the same genus.
Hybrids between different genera (such as between sheep and goats) are known as intergeneric hybrids.

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:

The prime aim of plant breeding is to improve the characteristics of plants that they become more useful automatically and economically. Some of the objectives may be summarized as follows-
1. Higher yield: Higher yield of grain, fodder, fibre, sugar, oil etc.
2. Improved quality: The quality characters may vary from one crop to another, such as grain size, shape, colour, milling and backing quality of wheat, cooks quality in rice, malting in barley. Size shape and flavour in fruits and keeping quality of vegetables, protein contents in legumes, methionine and tryptophan contents in pulses etc.
3. Disease and pest resistance: Resistant varieties offer the cheapest and most convenient method of disease and pest control. They not only helps to increase the production but also stabilize the productivity.
4. Maturity duration: It permits new crop rotation and extends crop area. Thus breeding for early maturing varieties suitable for different dates of planting. This enables the farmer to take two-three crops in a year.
5. Agronomic characters: Three includes the characters, such as dwarf, profuse tillering, branching erect resistance and fertilizer responsiveness. Thus, option D is correct.

The process of removing stamens from the flower bud during hybridization is called as

  1. Crossing

  2. Selfing

  3. Emasculation

  4. Caping


Correct Option: C
Explanation:

Emasculation involves the removal of stamens from bisexual flowers of the female parents in order to avoid self-pollination in these flowers. It is done before the anthers are mature. If in a condition the female parent bears bisexual flowers, then elimination of anthers from the flower bud before the anther matures. This step is known as emasculation.  

Caping is the covering of flower for preventing cross pollination. Crossing refers to hybridization. Selfing occurs in bisexual flowers. 
Thus, the correct answer is option C.

Sugarcane breeding research institute (SBRI) is situated at

  1. Lucknow

  2. Coimbatore

  3. New Delhi

  4. Shimla


Correct Option: B
Explanation:

'Sugarcane Breeding Institute' is the sugarcane research and development institute located in Coimbatore, India. On the 1st day of April 1932, a sub-station of the 'Sugarcane Breeding Institute', Coimbatore (Tamil Nadu) was established at Karnal (Haryana) with funds provided by the then 'Imperial Council of Agricultural Research' (now the Indian Council of Agricultural Research abbreviated as ICAR). 

Thus, the correct answer is option B.

Mysore has one of the following institute

  1. National agricultural research institute

  2. Rice research institute

  3. Forest research institute

  4. Central food technology research institute


Correct Option: D
Explanation:

Central Food Technological Research Institute, is one of the laboratories of the Council of Scientific and Industrial Research located in Mysore, Karnataka. 

So the correct option is D.

Hexaploid or moderm wheat developed through ______________.

  1. Hybridomas

  2. Chromosome doubling

  3. Hybridisation

  4. Hybridisation and chromosome doubling


Correct Option: D

Majority of improved Indian Rice varieties have arisen from a cross between

  1. Oryza sativa indica $\times$ Oryza nivara

  2. Oryza sativa indica $\times$ O. sativa japonica

  3. O. sativa japonica $\times$ O. nivara

  4. O. rufipogon $\times$ O. nivara.


Correct Option: B

Aim of plant breeding is to

  1. Control pollution

  2. Keep soil fertile

  3. Produce improved varieties

  4. To maintain wild plants


Correct Option: C

Four inbred/pure lines of Maize are crossed. The cross is

  1. Double cross

  2. Dihybrid cross

  3. Tetrahybrid cross

  4. Tetraploid cross


Correct Option: C

A cybrid is hybrid carrying

  1. Genomes and cytoplams of two different plants

  2. Cytoplasms of two different plants

  3. Cytoplasms of two different plants but genome of one plant

  4. Genomes of two different plants

  5. Cytoplasms of several plants but genomes of two plants.


Correct Option: C

Branch of biology dealing with improvement of plant variety

  1. Eugenics

  2. Plant breeding

  3. Agrology

  4. Serendipity


Correct Option: B

From which technique, new and better varieties of crop plants are formed

  1. Selection

  2. Hybridisation

  3. Grafting

  4. Hybridisation followed by selection.


Correct Option: D

During hybridisation, offspring with hybrid vigour superior to both parents are self pollinated for a few successive generations to .............

  1. Retain their parental characters

  2. Remove their parental characters

  3. Get homozygosity

  4. Segregate characters.


Correct Option: C

During somatic hybridisation in plants

  1. Somaclones are produced in large numbers

  2. Apical meristems are cultured to get virus-free plant

  3. Cell walls and middle lamella are digested before fusing the cells

  4. Crop plants with higher levels of vitamins, proteins, and minerals are hybridised.


Correct Option: C

For hybridisation, which part is removed from bisexual flowers

  1. Stigma

  2. Stigma and style

  3. Anthers

  4. Ovary.


Correct Option: C

Consider the following statements: Hybrid plants can show.
a. Sterility
b. Mosaicism
c. Crossing over
d. Vigour
e. Homozygosis
Which of the statements are correct?

  1. $2, 3$ and $5$

  2. $2, 4$ and $5$

  3. $1, 2$ and $4$

  4. $1, 3$ and $4$


Correct Option: A

Plant breeders are interested in apomixes because it __________________.

  1. Improves seed-set

  2. Shortens the life cycle

  3. Yields clonal progeny

  4. None of these


Correct Option: A

A breeder crossed a pure bred all plant having white flowers to a pure bred short plant having blue flowers. He obtained $202\ F _{1}$ progeny and found that they are all tall having white flowers. Upon selfing there $F _{1}$ plants, he obtained a progeny of $2160$ plants. Approximately, how many of these are likely to be short and having blue flowers?

  1. $1215$

  2. $405$

  3. $540$

  4. $135$


Correct Option: D

Process of bringing wild species of plants under cultivation to suit human needs is called

  1. selection

  2. hybridization

  3. domestication

  4. cultivation


Correct Option: C
Explanation:
Domestication is the process where wild plant and animal species are adapted into the cultivation area for human use.
The species that are domesticated are used for food, work, medicine and various other uses.
Once the wild species are being domesticated they need to be raised and cared for by humans.
So, the correct option is 'domestication'

The main objective of plant breeding is to develop new crop varieties superior in all aspects as compared to the existing types.

  1. True

  2. False


Correct Option: A
Explanation:

Plant breeding is a method of altering the genetic pattern of plants to increase their value and utility for human welfare. 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. The main aim of plant breeding is to obtain higher yield, improved quality, resistance to pathogens and pests, etc.

So the given statement is true.

Which of the following variety of rice has been produced by the hybridisation of Oryza japonica and O. indices?

  1. Jagannath

  2. Aruna

  3. ADT-37

  4. Reimei


Correct Option: C
Explanation:

ADT-37 is an inter varietal cross between Oryza Japonica and Oryza Indices

Collection of genetic variability is required in plant breeding programme because

  1. It leads to inbreeding depression in hybrids

  2. It is the root of any breeding programme

  3. Diverse alleles in germplasm helps you to choose desirable charters

  4. Both (2) and (3)


Correct Option: D
Explanation:

Genetic variability is the cornerstone of breeding with the advent of molecular biology, traditional interspecific, intergenetic and plant type barriers to gene transfer have been removed. By isolating the gene for a particular trait and inserting it into a new host by a range of techniques the gene becomes a part of the host.DNA.

So, the correct option is 'Both (2) and (3)'.

"Bengal Desi" is a Hybrid variety of which of the following crops?

  1. Jute

  2. Cotton

  3. Sesame

  4. Gram


Correct Option: B

How many meiotic divisions are necessary for the formation of 100 grains of wheat?

  1. 100

  2. 125

  3. 25

  4. 50


Correct Option: B
Explanation:
For formation of 100 grains, 100 male gametes and 100 female gametes (eggs) are required. 100 male gametes are developed from 100 microspores (from 25 meiotic divisions) and 100 eggs are developed from 100 megaspores (from 100 meiotic division).
Hence, number of meiotic divisions necessary for 100 grains formation$ = 25 + 100 = 125$.

In high yielding hybrid crop varieties to exploit hybrid vigour, the farmers need to purchase fresh hybrid seed every year because 

  1. They are not allowed to grow their own seed.

  2. Hybrid vigour is lost due to inbreeding depression.

  3. It is cheaper to purchase fresh seed.

  4. Government has accepted Dunkel's proposals.


Correct Option: B
Explanation:

Hybrid vigour will be lost due to inbreeding depression. The increase in the level of production traits due to crossing is called hybrid vigour or heterosis. The term hybrid vigour points at the vigour, which is a real factor that can bee seen by the naked eye, in comparison to pure breeding. The other word heterosis is derived from heterozygosity and points toward the direction form where the effect arises. The direction of the effect of crossing is opposite the effect of inbreeding. Inbreeding depression is the reduced biological fitness in a given population as a result of inbreeding - ie., breeding of related individuals. Population biological fitness refers to its ability to survive and reproduce itself.

The first natural hybridization in corn was done by

  1. Cotton Mather

  2. Thomas Fairchild

  3. Joseph Koerauter

  4. None of the above


Correct Option: A
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 natural hybridization was recorded by Cotton Mather. This was observed and documented in corn in the year 1716. 

Thus, the correct answer is option A. 

Pomato is a hybrid of

  1. Potato

  2. Tomato

  3. Wheat

  4. Both A and B


Correct Option: D
Explanation:

  • The crossing between genetically different plants to produce a new variety is called hybridization.
  • Genetically modified crops can be produced by the insertion of genes with desired traits by the process of hybridization.
  • The plants of potato and tomato are the plants of the different genus. These plants are allowed to perform hybridization.
  • The resulting plant variety is known as pomato. Cherry-type tomatoes are grown on the climber while the potatoes are developed below the soil. 

Thus, the correct answer is option D. 

Which one is a plant wax?

  1. Lanolin

  2. Spermaceti

  3. Carnauba

  4. Petrolatum


Correct Option: C
Explanation:

Carnauba wax is made from the leaves of the palm tree. It is also known as palm wax. It is obtained from the leaves of the carnauba palm by collecting and drying them, beating them to loosen the wax, then refining and bleaching the wax.

So, the correct answer is 'Carnauba'.

Which of the following is a correct match between crop, variety and resistance to diseases?

  1. Crop - Wheat, Variety - Himgiri, Resistance to disease - White rust

  2. Crop - Brassica, Variety - Pusa Sadabahar, Resistance to disease - Black rot

  3. Crop - Cowpea, Variety - Pusa Komal, Resistance to disease - Bacterial blight

  4. Crop - Chilli, Variety - Pusa Swarnim, Resistance to disease - Chilly mosaic virus


Correct Option: A
Explanation:
A)Crop - Wheat, Variety - Himgiri, Resistance to disease - Leaf and stripe rust, hill blunt.
B)Crop - Brassica, Variety - Pusa swarnim, Resistance to disease - White Dust
C)Crop - Cowpea, Variety - Pusa Komal, Resistance to disease - Bacterial Blight
D)Crop - Chilli, Variety - Pusa Sadabahar, Resistance to disease - Chilly mosaic virus
So the correct option is 'Crop - Cowpea, Variety - Pusa Komal, Resistance to disease - Bacterial blight'


Which one of the following is not a fungal disease?

  1. Rust of wheat

  2. Smart of Bajra

  3. Black rot of crucifers

  4. Red rot of sugarcane


Correct Option: C
Explanation:
Black rot of Crucifers is not a fungal disease. it is a Bacterial Disease.

So, the correct answer is 'Black rot of crucifers'.

Which of the following is incorrectly matched?                         

  1. Disease - Black rot of crucifers; Causative Organism - Bacteria

  2. Disease - Brown rust of wheat; Causative Organism - Fungi

  3. Disease - Late blight of potato; Causative Organism - Virus

  4. Disease - Red rot of sugarcane; Causative Organism - Fungi


Correct Option: C
Explanation:

Late blight of potato is caused by Phytophthora infestans a oomycetae (fungi). Cool climate and wet weather help infection and spread, responsible for the irish famines in the nineties.

So, the correct answer is 'Disease - Late blight of potato; Causative Organism - Virus'

Use of certain chemicals and radiation to change the base sequence of genes of crop plants is termed

  1. recombinant DNA technology

  2. transgenic mechanism

  3. mutation breeding

  4. gene therapy


Correct Option: C
Explanation:

  • Mutation breeding is the process of exposing seeds to certain chemicals and radiation in order to generate mutants with desirable traits to bred with other cultivators. This will change the base sequence of genes of crop plants. In mung bean, resistance to yellow mosaic virus and powdery mildew were induced by mutations.
  • Recombinant DNA technology is the process of joining DNA molecules together from 2 different species that are inserted into a host organism to produce new genetic recombinations.
  • Transgenic mechanism is the mechanism of random integration of foreign DNA in transgenic animals.
  • Gene therapy is a therapeutic process of delivery of nucleic acid into a patient's cell as a drug to treat a disease.
So, the correct option is 'Option C' .

The hybrids are generally found to be superior to their parents, it is because of

  1. Homozygosity

  2. Hybrid vigour

  3. Parents are generally weak

  4. None of the above


Correct Option: B
Explanation:

Heterosis is also called as hybrid vigour. It is the increase in such characteristics as size, growth rate, fertility and yield of a hybrid organism over those of its parents. Plant and animal breeders exploit heterosis by mating two different pure-bred lines that have certain desirable traits. Because of this, hybrids are generally found to be superior to their parents. Thus, the correct answer is option B.

Mutation is a

  1. Radioactive mutagens

  2. Chemical mutagens

  3. Radiation mutagens

  4. Change in base sequence


Correct Option: D
Explanation:

 A mutation is a permanent change in the sequence of DNA. Mutations can be caused by external (exogenous) or endogenous (native) factors, or they may be caused by errors in the cellular machinery. Physical or chemical agents that induce mutations in DNA are called mutagens and are said to be mutagenic. Exogenous factors: environmental factors such as sunlight, radiation, and smoking can cause mutations. Endogenous factors: errors during DNA replication can lead to genetic changes as can toxic by-products of cellular metabolism.

IR-36 was developed through breeding of

  1. Six rice varieties and Oryza nivara

  2. 13 rice varieties and Oryza nivara

  3. Oryza sativa and O. indica

  4. Oryza indica and O. nivara


Correct Option: B
Explanation:

Gurdev S. Khush crossed 13 varieties of rice from Oryza nivara to develop IR - 36 which was resistant to grassy stunt virus.

Steps to be followed by a plant breeder to get disease-resistant crops are.

  1. Screening of germplasm for disease resistant varieties.

  2. Hybridisation of selected parents.

  3. Selection and evaluation of the hybrids.

  4. Testing and release of new varieties.


Correct Option: A

Most herbicide interfere with

  1. Water absorption

  2. Translocation of sugar

  3. Photolysis of water

  4. ${ CO } _{ 2 }$ absorption


Correct Option: C
Explanation:

Herbicides, also commonly known as weed killers, are pesticides used to kill unwanted plants. Selective herbicides kill specific targets, while leaving the desired crop relatively unharmed. Some of these act by interfering with the growth of the weed and are often synthetic mimics of natural plant hormones. A large number of different herbicide classes inhibit photosynthesis by binding to the quinone-binding protein, D-1, to prevent photosynthetic electron transfer. Mostly they interfere with photolysis of water. Thus, option C is correct. Herbicides does not interfere with water absorption, translocation of sugar and CO$ _{2}$ absorption. Thus, other options are wrong.

Virus free plant can be obtained through

  1. Grafting

  2. Callus culture

  3. Shoot tip culture

  4. Suspension culture


Correct Option: C
Explanation:

The shoot tip culture used for obtaining disease free plant without genetical changes. The plant which affected by any contaminant mostly by viruses have saved by shoot tip culture, because shoot tip of any affected plant is less or free from contamination (viruses, bacteria, fungus or others). Plant shoot tip are more efficient to cultivation or differentiation in-vitro because cells of them newly generated and healthy comparison to other parts. 

Thus, the correct answer is option C.

Plants show orange patch on infected plant parts

  1. Rust of wheat

  2. Smut

  3. Red rot

  4. All of the above


Correct Option: A
Explanation:

Rust of wheat is caused by fungus. Diseased plants show rust coloured orange patches on the infected plant part.

Himgiri developed by hybridisation and selection for disease resistance against rust pathogens is a variety of

  1. Wheat

  2. Chilli

  3. Maize

  4. Sugarcane


Correct Option: A
Explanation:

Himgiri is a wheat hybrid variety, which yields 26-30 qtls/ha. It is a disease resistance variety to stripe rust or yellow rust. This is Triticum aestivum species. The variety was developed by IARI. Thus, the correct answer is option A.

Breeding for disease resistance requires

  1. A good source of resistance

  2. Planned hybridisation

  3. Disease test

  4. All the above.


Correct Option: D

Match the columns:

I II
a Mutation breeding 1 Johannsen
b Inbreeding depression 2 Karpechenko
c Pureline selection 3 Darwin
d Intergeneric hybridization 4 Staddler
5 Shull
  1. a-4, b-2, c-5, d-1

  2. a-4, b-5, c-2, d-1

  3. a-4, b-5, c-1, d-2

  4. a-5, b-4, c-1, d-2.


Correct Option: C

The Ear cockier of wheat can be differentiated from Molya disease of wheat by the fact that in the former.

  1. Plants become dwarf, stem and leaves become twisted spike lets get distorted and grains get replaced by brown stony structures

  2. Plants become pale, leaves turn yellow with reddish lip, roots get matted and fail to ear

  3. Root tips swell and cyst adheres to roots that turn brown and fall

  4. Show hypertrophy of stern and leaves and roots swell


Correct Option: A

Which one of the following is the indigenous breed of chickens ?

  1. plymouth rock

  2. white leghorn

  3. aseel

  4. rhode island red


Correct Option: C
Explanation:

Aseel is a pure indigenous breed of chicken originated from India and Pakistan. They are used for cock fighting. They are very large breed of chicken from subcontinents. This breed is good in high yield of meat but it is not good for egg production. The average weight of cock varies from 4 to 5 kg and hens 3 to 4 kg. 

Which one of following breeds of cattle is a cross-breed and high milk yielding ?

  1. Sahiwal

  2. Karan-Swiss

  3. Tharparkar

  4. Jersey.


Correct Option: B
Explanation:

Karan Swiss is the hybrid variety and high milk yielding breed of cow. It is the hybrid breed of Taurine and Zebu. Taurine is used for milk production, while Zebu is used for flesh.

Which pathogen causes the blast disease of rice?

  1. Cercospora personata

  2. Pyricularia oryzae

  3. Xanthomonas citri

  4. Tungro virus


Correct Option: B
Explanation:
Blast disease in rice is caused by the fungus Magnaporthe oryzae which was earlier known as Pyricularia oryzae. Different parts of the plants are affected by the fungus. The blast can occur wherever blast spores are present. Rice can have blast in all growth stages. There are lesions formed on the leaf, panicle and neck region of the plant. There is great loss in yield due to this disease affecting the rice plants.
Thus, the correct answer is option B.
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