Biotechnological Applications in Agriculture Questions in English

(B) The correct answer is $B$.
"Crown gall" is a plant disease characterized by the formation of tumors or galls.
It is caused by the soil-borne bacterium $Agrobacterium \ tumefaciens$.
This bacterium transfers a segment of its $DNA$, known as $T-DNA$, into the plant cell, which leads to uncontrolled cell division and gall formation.

(B) In $1970$,the Southern Corn Leaf Blight epidemic occurred in the United States. This devastating outbreak was caused by the fungus $Helminthosporium$ $maydis$ (also known as $Bipolaris$ $maydis$). The epidemic resulted in the destruction of approximately $50\%$ of the maize crop in the $USA$,leading to significant economic losses. Therefore,the correct option is $B$.

(C) $Bt$ in "$Bt$-cotton" refers to the bacterium $Bacillus$ $thuringiensis$, not just a general term for biotechnology. Thus, option $A$ is incorrect.
Somatic hybridization involves the fusion of protoplasts, not complete plant cells (which include cell walls). Thus, option $B$ is incorrect.
$Hirudin$ is an anticoagulant protein originally found in leeches. Its gene has been transferred into $Brassica$ $napus$ (rapeseed) to produce it in seeds. Thus, option $C$ is correct.
$Flavr$ $Savr$ tomato was engineered to have delayed ripening by inhibiting ethylene production, not enhancing it. Thus, option $D$ is incorrect.

(B) terminator gene is a genetic modification technology that renders seeds sterile.
This means that plants grown from these seeds will produce seeds that are incapable of germinating in the next generation.
This technology is primarily used to prevent the unauthorized reuse of patented seeds by farmers,effectively terminating the seed's ability to germinate.

(C) Induced mutagenesis is a technique used in plant breeding to create genetic variation.
Gamma rays,specifically those emitted from $Cobalt-60$,are the most commonly used ionizing radiations for inducing mutations in crop plants because they have high penetrating power and effectively cause $DNA$ damage leading to mutations.
Therefore,the correct option is $C$.

(D) . Transgenic plants are those plants in which a foreign gene (transgene) has been introduced and stably integrated into the host $DNA$ using genetic engineering techniques. This allows the plant to express new traits derived from the donor organism.

(B) Genetic engineering is the process of manipulating the genetic material of an organism to introduce desirable traits.
Recombinant $DNA$ technology is the primary method used to introduce novel genes into plants.
In this process,a gene of interest is isolated and inserted into a vector,which then transfers the gene into the plant cells to create transgenic plants.

(B) The correct answer is $B$.
In India,$Bt$ cotton is the only transgenic crop that has been approved for commercial cultivation.
It was introduced in March $2002$ by the Maharashtra Hybrid Seeds Company $(MAHYCO)$ in collaboration with the American company Monsanto.

(D) The term $Bt$ in $Bt-cotton$ stands for the bacterium $Bacillus$ $thuringiensis$.
This bacterium produces specific insecticidal proteins that are toxic to certain insect pests,such as lepidopterans,coleopterans,and dipterans.
These genes have been incorporated into cotton plants through genetic engineering to provide resistance against pests,thereby reducing the need for chemical insecticides.

(B) $Agrobacterium \text{ tumefaciens}$ is a soil bacterium that naturally infects a wide variety of dicot plants.
It contains a $Ti$ (Tumor inducing) plasmid which can be modified to act as a vector for delivering genes of interest into plant cells.
Due to its natural ability to transfer $DNA$ into the host plant genome, it is the most widely used tool for the genetic transformation of crop plants in genetic engineering.

(B) Insect-resistant transgenic cotton,commonly known as $Bt$ cotton,is produced using genetic engineering techniques.
This process involves the insertion of a specific $DNA$ segment (the $cry$ gene) derived from the soil bacterium $Bacillus$ $thuringiensis$.
This gene encodes for a toxic protein that kills specific insect pests,such as bollworms,when they ingest the plant tissue.

(A) In genetic engineering,the $Promoter$ is a $DNA$ sequence that initiates the transcription of a particular gene.
It acts as a regulatory switch that determines when,where (in which tissue),and at what level a transgene will be expressed.
While enhancers can increase the rate of transcription,the $Promoter$ is the fundamental element required to direct the tissue-specific expression of the transgene.

(A) Transgenic plants,such as $Bt$ cotton,are genetically modified to express specific genes (like the $cry$ gene from $Bacillus$ $thuringiensis$) that produce insecticidal proteins. These proteins make the plants resistant to specific pests,thereby reducing the need for chemical pesticides.

(B) herbicide is a chemical substance used to kill or inhibit the growth of unwanted plants (weeds).
$A$. Allethrin is a synthetic pyrethroid used as an insecticide.
$B$. Triazine is a class of chemical compounds,many of which are widely used as herbicides.
$C$. Aldrin is an organochlorine insecticide.
$D$. $BHC$ (Benzene Hexachloride) is a well-known organochlorine insecticide.
Therefore,Triazine is the correct answer.

(A) Sporeine (derived from $Bacillus \text{ } thuringiensis$) produces crystal proteins that are toxic to specific insects. When ingested, these crystals are solubilized in the alkaline $pH$ of the insect's midgut. The activated toxin binds to the surface of the midgut epithelial cells, creating pores that cause cell swelling and lysis, thereby inhibiting ion transport and leading to the death of the insect.

(C) Transgenic crops are plants that have been genetically modified to express desirable traits, such as resistance to pests, diseases, or herbicides.
Tobacco $(Nicotiana \, tabacum)$ was one of the first plants to be genetically engineered for herbicide tolerance (specifically resistance to glyphosate).
Therefore, tobacco is a well-known example of a transgenic crop developed for herbicide tolerance.

(B) The correct answer is $B$. Transgenic crops are genetically modified organisms that contain genes from other species to provide desirable traits such as pest resistance. $A$ well-known example is the transgenic tomato,which has been engineered to be resistant to hornworm larvae.

(A) Thurioside is a proteinaceous toxin produced by the bacterium $Bacillus$ $thuringiensis$ $(Bt)$.
It acts as an insecticide by killing specific insect larvae that ingest it,as the toxin becomes active in the alkaline $pH$ of the insect gut.

(A) $BT$ cotton is a genetically modified organism $(GMO)$ created by introducing the $cry$ genes from the bacterium $Bacillus$ $thuringiensis$ into the cotton plant.
These $cry$ genes encode for crystal proteins ($Cry$ proteins) that are toxic to specific insect pests,such as lepidopterans (tobacco budworm,armyworm),coleopterans (beetles),and dipterans (flies,mosquitoes).
When these insects ingest the plant tissue,the alkaline $pH$ of their gut activates the toxin,leading to the formation of pores in the midgut epithelium,which causes cell swelling,lysis,and eventually the death of the insect.
Therefore,$BT$ cotton is specifically engineered for resistance against insect pests.

(C) The Lal Bahadur Shastri Biotechnology Centre is a prominent research facility located in New Delhi,India. It is associated with the Indian Agricultural Research Institute $(IARI)$,which plays a crucial role in agricultural biotechnology research and development.

(B) Anand Chakrabarty is a renowned scientist known for his work in genetic engineering.
He developed a genetically modified bacterium,specifically a strain of $Pseudomonas$ $putida$,which is capable of breaking down crude oil.
This bacterium was engineered to degrade hydrocarbons,making it highly effective for the bioremediation of oil spills in marine environments.
Therefore,his contribution to biotechnology is primarily associated with the removal of oil pollution.

(A) The primary objective of biotechnology in agriculture is to enhance crop productivity and sustainability. One of the most significant applications is the development of genetically modified $(GM)$ crops that are resistant to pests,such as $Bt$ cotton. This reduces the reliance on chemical pesticides,lowers production costs,and minimizes environmental impact.

(D) $Bt$ transgenic plants are genetically modified crops that express insecticidal proteins derived from the bacterium $Bacillus$ $thuringiensis$.
These plants are created using recombinant $DNA$ technology to introduce specific genes into the plant genome.
$Bt$ crops are widely known and used,such as $Bt$ cotton and $Bt$ brinjal,which provide resistance against specific insect pests.
Therefore,the statement that 'No such plant is known' is false.

(D) The tumour-inducing $(Ti)$ plasmid is found in the soil bacterium $Agrobacterium$ $tumefaciens$.
This bacterium is known as a natural genetic engineer because it can transfer a specific segment of its $DNA$, known as $T-DNA$, into the genome of host plants, causing the formation of tumours (crown galls).
In biotechnology, scientists have modified this $Ti$ plasmid to remove its pathogenic genes while retaining its ability to transfer foreign genes into plant cells, making it an essential tool for creating transgenic plants.

(B) In genetic engineering,the expression of a transgene is controlled by regulatory sequences known as promoters.
These $DNA$ sequences are located upstream of the gene of interest and provide the binding site for $RNA$ polymerase and other transcription factors.
By using tissue-specific promoters,scientists can ensure that the transgene is expressed only in the desired target tissue,thereby achieving precise control over the genetic modification.

(B) $Bacillus\, thuringiensis$ $(Bt)$ is a soil bacterium that produces insecticidal proteins (Cry proteins).
Scientists have incorporated the genes encoding these proteins into crop plants,such as cotton,corn,and brinjal,to create $Bt$ crops.
These genetically modified plants are resistant to specific insect pests,effectively acting as bio-pesticidal plants.
Therefore,$Bt$ strains are used to design bio-pesticidal plants.

(A) Antisense technology is a method used to block the expression of a specific gene.
It involves the introduction of an antisense $RNA$ molecule,which is complementary to the $mRNA$ sequence of the target gene.
When this antisense $RNA$ binds to the target $mRNA$,it forms a double-stranded structure,preventing the translation of the $mRNA$ into a protein.
Thus,the expression of the specific gene is effectively silenced or inhibited.

(B) Diuron is a well-known herbicide derived from urea. It is commonly used for the control of weeds in various crops such as tea,cotton,and tobacco. Urea-based herbicides act by inhibiting photosynthesis in the target weeds.

(B) The first transgenic plant developed was tobacco $(Nicotiana tabacum)$.
It was genetically engineered to contain a gene for herbicide resistance (specifically resistance to the herbicide $kanamycin$ or $glyphosate$ in various experimental contexts).
Therefore, the correct answer is herbicide resistance.

(D) Transgenic Basmati rice is a genetically modified variety developed to provide specific nutritional benefits. The most notable example of such biofortified transgenic rice is 'Golden Rice',which is engineered to produce high levels of beta-carotene,a precursor to Vitamin $A$. Therefore,it is characterized by high yield and being rich in Vitamin $A$.

(A) The $Cry$ gene is isolated from the soil bacterium $Bacillus$ $thuringiensis$ $(Bt)$.
This bacterium produces insecticidal crystal proteins (Cry proteins) during a particular phase of their growth.
These proteins contain toxic insecticidal proteins which kill certain insects such as lepidopterans,coleopterans,and dipterans.
Therefore,the correct answer is $Bacillus$ $thuringiensis$.

(C) The first transgenic plant to be successfully produced was tobacco $(Nicotiana \, tabacum)$.
This milestone was achieved in $1983$ by researchers who introduced an antibiotic resistance gene into the tobacco plant using $Agrobacterium \, tumefaciens$ as a vector.
Therefore, the correct option is $C$.

(C) $Bt-$ cotton is a genetically modified organism $(GMO)$ produced by introducing the $cry$ genes from the bacterium $Bacillus$ $thuringiensis$ into the cotton plant.
These $cry$ genes encode for insecticidal proteins that are toxic to specific insect pests.
Specifically, $Bt-$ cotton is engineered to be resistant to lepidopteran pests, which include tobacco budworm and armyworm, and coleopteran pests, but it is most famously known for its resistance to $Bollworms$ $(Helicoverpa$ $armigera)$.
Therefore, the correct option is $C$.

(D) The primary objective of developing herbicide-resistant $GM$ crops is to allow farmers to spray herbicides on the field to kill weeds without harming the crop plants. This eliminates the need for manual weeding (labor-intensive process) and ensures that the crop grows without competition for nutrients,light,and water. Therefore,the most accurate description of the primary objective is to eliminate weeds without the need for manual labor.

(B) $Bacillus$ $thuringiensis$ $(Bt)$ is a soil bacterium that produces insecticidal proteins (Cry proteins).
These proteins are encoded by $cry$ genes.
When these genes are introduced into plants through genetic engineering,they produce the toxin within the plant tissues,making the plants resistant to specific insect pests.
Therefore,$Bt$ strains are primarily used to develop bio-insecticidal plants (e.g.,$Bt$ cotton,$Bt$ corn).

(A) Vitamin $A$ deficiency is a major cause of blindness in developing countries.
Golden Rice is a genetically modified variety of rice $(Oryza sativa)$ that has been engineered to produce beta-carotene, which is a precursor of Vitamin $A$.
When consumed, the human body converts beta-carotene into Vitamin $A$, thereby helping to prevent blindness caused by its deficiency.
Therefore, the correct option is $A$.

(A) The most significant application of biotechnology in agriculture is the development of genetically modified crops that are resistant to pests. By introducing genes like $cryIAc$ from $Bacillus$ $thuringiensis$ $(Bt)$,plants can produce their own insecticidal proteins,which significantly reduces the reliance on chemical pesticides and increases crop yield.

(D) $Bt$ stands for $Bacillus$ $thuringiensis$.
$Bt$ cotton is a genetically modified pest-resistant plant cotton variety.
It is created by introducing the $cry$ gene from the bacterium $Bacillus$ $thuringiensis$ into the cotton genome.
This gene produces an insecticidal protein (endotoxin) that kills specific pests like bollworms, thereby protecting the crop.

(A) The use of transgenic plants as biological factories for the production of special chemicals, such as pharmaceuticals, proteins, or industrial compounds, is known as $Molecular \text{ farming}$ or $Molecular \text{ pharming}$. This process leverages genetic engineering to turn plants into efficient production systems for high-value products.

(A) $RNA$ interference $(RNAi)$ is a cellular mechanism used to silence specific genes. In biotechnology,this process is utilized to create pest-resistant plants. Specifically,it has been successfully used to protect tobacco plants from infestation by the nematode $Meloidogyne$ $incognita$. By introducing nematode-specific genes into the host plant,the plant produces double-stranded $RNA$ $(dsRNA)$ that triggers the $RNAi$ pathway in the nematode upon ingestion,leading to the silencing of essential genes and the death of the parasite.

(A) $Bacillus$ $thuringiensis$ $(Bt)$ is a soil bacterium that produces insecticidal crystal proteins. Scientists have incorporated the genes responsible for these proteins into various crops,such as $Bt$ cotton,$Bt$ corn,etc. These genetically modified crops act as biopesticides because they produce their own toxins to kill specific insect pests,thereby reducing the need for chemical pesticides.

(C) Transgenic brinjal,also known as $Bt$ brinjal,was developed in India by incorporating the $cry1Ac$ gene from the bacterium $Bacillus$ $thuringiensis$. The primary objective of creating this transgenic crop was to provide resistance against the fruit and shoot borer,which is a major pest of brinjal. Therefore,it is a pest-resistant crop.

(D) The $Bt$ toxin is produced by the bacterium $Bacillus$ $thuringiensis$.
Since the toxin is insect-group specific,the selection of the $Bt$ gene depends on the target insect pest that needs to be controlled.
Furthermore,the gene must be expressed effectively within the specific host plant or crop being modified.
Therefore,the choice of the $Bt$ gene is determined by both the target insect and the host plant/crop.

$(A)$ Golden rice is a genetically engineered variety of rice $(Oryza sativa)$ that has been modified to produce beta-carotene, which is a precursor of vitamin $A$.
This modification was specifically designed to address vitamin $A$ deficiency in populations that rely heavily on rice as a staple food, particularly in developing countries.
Therefore, consuming golden rice helps in alleviating vitamin $A$ deficiency.

(A) Golden rice is a genetically modified (transgenic) variety of rice $(Oryza sativa)$.
It is engineered to produce high levels of beta-carotene, which is a precursor to Vitamin $A$.
This modification was specifically designed to address Vitamin $A$ deficiency in populations that rely heavily on rice as a staple food.
Therefore, the correct option is $A$.

(C) Statement $C$ is correct. The anticoagulant hirudin is produced from the seeds of transgenic $Brassica \, napus$.
Statement $A$ is incorrect because "Bt" stands for the bacterium $Bacillus \, thuringiensis$, not just biotechnology.
Statement $B$ is incorrect because somatic hybridization involves the fusion of protoplasts, not complete cells.
Statement $D$ is incorrect because the 'Flavr Savr' tomato was engineered to delay ripening by inhibiting the production of polygalacturonase, not by increasing ethylene.

(B) $Agrobacterium \text{ } tumefaciens$ is a soil bacterium that naturally transfers a portion of its $DNA$, known as $T-DNA$, into the plant genome, causing crown gall disease. Because of this natural ability to transfer genes into plants, it is widely used as a vector in genetic engineering to introduce foreign genes into plant cells.

(B) The $Bt$ toxin produced by the bacterium $Bacillus \text{ } thuringiensis$ exists as an inactive protoxin in the bacteria.
When an insect ingests the inactive protoxin, it enters the insect's gut.
The alkaline $pH$ of the insect's gut solubilizes the crystals, converting the inactive protoxin into an active toxin.
This active toxin binds to the surface of midgut epithelial cells and creates pores, causing cell swelling and lysis, which eventually leads to the death of the insect.

(A) Golden rice is a genetically modified variety of rice $(Oryza \text{ } sativa)$ engineered to produce beta-carotene, which is a precursor of Vitamin $A$. Consumption of golden rice helps in overcoming Vitamin $A$ deficiency, thereby preventing conditions like night blindness. $Bt$-brinjal is modified for pest resistance, Flavr Savr tomato for delayed ripening, and Canola is often modified for herbicide tolerance or oil quality, but they do not address Vitamin $A$ deficiency.