Biotechnological Applications in Agriculture Questions in English

(A) $RNA$ interference $(RNAi)$ is a method of cellular defense in all eukaryotic organisms. This method involves silencing of a specific $mRNA$ due to a complementary $dsRNA$ molecule that binds to and prevents translation of the $mRNA$ (silencing).
$1$. The $mRNA$ produced by a gene is called the sense strand because it contains the codons for translation.
$2$. $A$ complementary $RNA$ strand,which cannot be translated into a functional protein,is called antisense $RNA$.
$3$. When antisense $RNA$ is introduced,it base-pairs with the target $mRNA$ to form a double-stranded $RNA$ $(dsRNA)$ molecule.
$4$. This $dsRNA$ cannot be translated by the ribosome,effectively blocking the expression of the specific gene. This is the basis of antisense technology.

(B) The $Cry\ I$ endotoxins produced by the bacterium $Bacillus\ thuringiensis$ $(Bt)$ are specific insecticidal proteins.
These proteins are encoded by $cry$ genes.
Specifically,$Cry\ I$ proteins (such as $Cry\ IAc$ and $Cry\ IIAb$) are highly effective against lepidopterans,which include tobacco budworms and armyworms,commonly referred to as bollworms.
Therefore,the correct option is $B$.

(B) The correct answer is $B$. Golden rice is a genetically modified (transgenic) variety of rice $(Oryza sativa)$ engineered to produce $\beta$-carotene, which is a precursor of Vitamin $A$. Vitamin $A$ deficiency is a major cause of night blindness and other vision-related problems in developing countries. By consuming this rice, individuals can obtain the necessary Vitamin $A$ to prevent such deficiencies.

(C) The primary objective of developing herbicide-resistant $GM$ crops is to allow for the selective application of herbicides to control weeds without harming the crop itself. By engineering crops to be resistant to specific herbicides (like glyphosate,bromoxynil,or glufosinate),farmers can manage weed populations more effectively. This technology is designed to reduce the overall accumulation of toxic herbicide residues in food products,thereby enhancing health safety for consumers. Therefore,the correct option is $C$.

(B) The correct answer is $B$. Golden rice is a transgenic variety of rice ($Oryza$ $sativa$) which is genetically engineered to produce $\beta$-carotene,a precursor of vitamin $A$.
When consumed,the human body converts $\beta$-carotene into vitamin $A$.
Therefore,the cultivation and consumption of golden rice are intended to help in the alleviation of vitamin $A$ deficiency in populations that rely heavily on rice as a staple food.

(A) $Bt$ cotton is a genetically modified crop that expresses the $cry$ gene derived from the bacterium $Bacillus$ $thuringiensis$.
This gene produces a crystal protein (Cry protein) that acts as an insecticidal toxin.
When the caterpillar (larva) of certain butterflies,such as the bollworm,ingests the plant tissue,the alkaline $pH$ of the insect's gut solubilizes the crystal protein.
This activated toxin binds to the surface of midgut epithelial cells,creating pores that cause cell swelling and lysis,eventually leading to the death of the caterpillar.

(B) The full form of $GEAC$ is Genetic Engineering Approval Committee.
This committee is established by the Indian government to make decisions regarding the validity of genetically modified research and the safety of introducing genetically modified organisms for public services.

(C) The corn borer is a major pest of maize crops.
Genetic engineering has been used to develop insect-resistant plants by introducing specific genes from the bacterium $Bacillus$ $thuringiensis$ $(Bt)$.
The gene $Cry$ $IAb$ is specifically responsible for controlling the corn borer.
Therefore,the correct option is $C$.

(C) Genetically modified organisms (GMOs) are created to improve agricultural productivity and food quality.
$1$. Crops are engineered to be more tolerant to abiotic stresses such as cold,drought,salt,and heat ($A$ is correct).
$2$. They are designed to reduce reliance on chemical pesticides by incorporating pest-resistant genes (e.g.,$Bt$ cotton) ($B$ is correct).
$3$. GMOs are often developed to enhance,not reduce,the nutritional value of food (e.g.,Golden Rice,which is enriched with Vitamin $A$) ($C$ is incorrect).
$4$. They are engineered to increase the efficiency of mineral usage by plants,preventing early exhaustion of soil fertility ($D$ is correct).
Therefore,the incorrect statement is that GMOs have reduced nutritional value.

(A) $Bacillus \text{ } thuringiensis$ $(Bt)$ bacteria produce insecticidal proteins known as $Cry$ proteins or $Bt$ toxins.
These proteins exist as inactive protoxins in the bacteria but are converted into active toxins in the alkaline gut of the target insects.
These toxins are highly specific and effectively kill certain insect groups, including lepidopterans (tobacco budworm, armyworm), coleopterans (beetles), and dipterans (flies, mosquitoes).

(B) In $1997$, an American company called RiceTec Inc. was granted a patent by the $US$ Patent and Trademark Office on 'Basmati' rice lines and grains. This was a controversial case of biopiracy, as Basmati rice has been grown in India for centuries. The patent was later challenged and partially revoked.

(D) The correct answer is $Meloidogyne \text{ } incognitia$.
$Meloidogyne \text{ } incognitia$ is a species of root-knot nematode that infects the roots of tobacco plants, causing a significant reduction in yield.
$Periplaneta \text{ } americana$ is the scientific name for the American cockroach (an insect).
$Bacillus \text{ } thuringiensis$ is a soil-dwelling bacterium used as a biological pesticide.
Cotton bollworm is a common name for the larvae of certain moths (insects) that damage cotton crops.

(A) $Bt$ cotton is a transgenic plant.
It is produced by introducing the $cry$ genes from the bacterium $Bacillus$ $thuringiensis$ into the cotton plant genome.
These genes encode for insecticidal proteins that provide resistance against specific pests like bollworms,making it a genetically modified organism $(GMO)$.

(D) $Bacillus$ $thuringiensis$ $(Bt)$ produces insecticidal crystal proteins known as $Cry$ proteins.
These proteins exist in an inactive protoxin form within the bacterium.
When ingested by an insect,the alkaline $pH$ of the insect's gut solubilizes the crystals,converting the protoxin into an active toxin.
This active toxin binds to the surface of midgut epithelial cells and creates pores,causing cell swelling and lysis,eventually leading to the death of the insect.

(B) The toxin produced by the bacterium $Bacillus$ $thuringiensis$ $(Bt)$ is encoded by the $cry$ gene.
In scientific nomenclature,the gene name is written in lowercase italics (e.g.,$cry$),while the protein product is written with the first letter capitalized (e.g.,$Cry$ protein).
Since the question asks for the name of the gene,the correct answer is $cry$.

$(A)$ Golden rice is a genetically modified (transgenic) variety of rice $(Oryza sativa)$.
It is engineered to produce beta-carotene, which is a precursor of Vitamin $A$ (retinol).
This modification was developed to address Vitamin $A$ deficiency in developing countries where rice is a staple food.
Therefore, it is rich in Vitamin $A$.

(D) Genetically Modified Organism $(GMO)$ technology has revolutionized agriculture by allowing scientists to introduce specific traits into crops.
$1$. It helps in making crops more tolerant to abiotic stresses such as cold,drought,salt,and heat.
$2$. It helps to reduce post-harvest losses by delaying the ripening process and increasing shelf life.
$3$. It enhances the nutritional value of food,for example,'Golden Rice' is enriched with Vitamin $A$.
Therefore,all the given options are correct applications of $GMO$ technology.

(C) According to the $NCERT$ textbook,Western nations have attempted to patent several Indian biological resources for commercial exploitation.
$1.$ $Basmati$ rice: An American company received a patent for 'Basmati' rice lines and varieties,which was later challenged.
$2.$ $Neem$: Patents were granted for the fungicidal properties of $Neem$ ($Azadirachta$ $indica$).
$3.$ $Turmeric$: Patents were granted for the wound-healing properties of $Turmeric$ ($Curcuma$ $longa$).
While $Tulsi$ is a significant medicinal plant in India,the $NCERT$ text specifically highlights $Basmati$ rice,$Neem$,and $Turmeric$ in the context of biopiracy and patent controversies.
Therefore,the correct option is $I, II$ and $III$.

(A) is true: Crops genetically modified to express $cry$ genes (e.g.,$Bt$ cotton) produce insecticidal proteins that provide resistance against specific groups of insects,such as lepidopterans,coleopterans,and dipterans.
$R$ is true: The bacterium $Bacillus$ $thuringiensis$ $(Bt)$ produces crystal $(Cry)$ proteins during its growth phase. These proteins exist as inactive protoxins in the bacteria but are converted into active toxins in the alkaline gut environment of susceptible insect larvae,leading to their death.

(B) The genes $cry IAb$ and $cry IIAb$ are derived from the bacterium $Bacillus thuringiensis$ $(Bt)$.
These genes encode for crystal proteins (toxins) that are toxic to specific insect pests.
Specifically,$cry IAb$ is used to control the corn borer,while $cry IIAb$ is used to control cotton bollworms.
Therefore,the correct sequence is corn borer and cotton bollworms respectively.

(D) Golden rice is a genetically modified (transgenic) variety of rice $(Oryza \text{ } sativa)$.
It is engineered to produce beta-carotene, which is a precursor of vitamin-$A$, in the edible parts of the rice grain.
This modification was developed to address vitamin-$A$ deficiency in populations that rely on rice as a staple food, which can otherwise lead to blindness and other health issues.
Therefore, the improved trait in Golden rice is a high vitamin-$A$ content.

(B) $Bacillus$ $thuringiensis$ $(Bt)$ produces a specific protein known as the $Cry$ protein during a particular phase of its growth.
This protein exists in an inactive,non-toxic protoxin form within the bacterial crystal.
When an insect ingests this crystal,the alkaline $pH$ of the insect's gut solubilizes the crystals and converts the inactive protoxin into an active,toxic insecticidal protein.
This active toxin binds to the surface of midgut epithelial cells and creates pores,causing cell swelling and lysis,eventually leading to the death of the insect.

(A) The nematode $Meloidogyne \ incognitia$ infects the roots of tobacco plants and causes a significant reduction in yield.
To prevent this infection,$RNA$ interference $(RNAi)$ technology is used.
$RNAi$ is a method of cellular defense in all eukaryotic organisms,which involves silencing a specific $mRNA$ due to a complementary $dsRNA$ molecule that binds to and prevents translation of the $mRNA$ (silencing).

(A) $Bt$ toxin is produced by the bacterium $Bacillus$ $thuringiensis$.
Specific $Bt$ toxin genes (e.g.,$cryIAc$ and $cryIIAb$) have been incorporated into crop plants to provide resistance against specific insect pests.
$I.$ Tobacco budworm and armyworm are Lepidopterans,which are susceptible to $Bt$ toxins.
$II.$ Beetles are Coleopterans,which are also susceptible to specific $Bt$ toxins.
$III.$ Flies and mosquitoes are Dipterans. While $Bt$ toxins are used for mosquito control in water bodies,they are not typically the primary targets for $Bt$ transgenic crops in the context of agricultural resistance mentioned in standard textbooks.
Therefore,$Bt$ crops are primarily engineered for resistance against Lepidopterans and Coleopterans.
Thus,the correct option is $I$ and $II$ only.

(D) Golden rice is a genetically modified (transgenic) variety of rice ($Oryza$ $sativa$).
It has been engineered to produce high levels of $\beta$-carotene,which is a precursor to vitamin $A$.
This modification was introduced to address vitamin $A$ deficiency in populations that rely heavily on rice as a staple food source.
Therefore,the correct trait is high vitamin $A$ content.

(D) The primary objective of developing herbicide-resistant $GM$ crops is to allow farmers to spray broad-spectrum herbicides on their fields to kill weeds without harming the crop itself. By doing so,the crop remains unaffected while the weeds are eliminated. However,a major concern is the accumulation of these herbicide residues in the food products,which poses health risks. Therefore,the goal is to minimize the need for excessive herbicide application or to manage the residues effectively to ensure food safety.

(D) The bacterium $Bacillus$ $thuringiensis$ $(Bt)$ produces protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein. The $Bt$ toxin protein exists as inactive protoxins but once an insect ingests the inactive toxin,it is converted into an active form of toxin due to the alkaline $pH$ of the gut which solubilizes the crystals. The activated toxin binds to the surface of midgut epithelial cells and creates pores that cause cell swelling and lysis and eventually cause death of the insect. Specific $Bt$ toxin genes were isolated from $Bacillus$ $thuringiensis$ and incorporated into several crop plants such as cotton. The toxins coded by a gene like $cryIAc$ and $cryIIAb$ control the cotton bollworms. Therefore,$Cry-1$ endotoxins are effective against bollworms.

(A) $1$. $Bt$ toxin is produced by the bacterium $Bacillus$ $thuringiensis$ as an inactive protoxin.
$2$. When an insect ingests this inactive protoxin,the alkaline $pH$ of the insect's gut solubilizes the crystals and converts the protoxin into its active form.
$3$. The active toxin then binds to the surface of midgut epithelial cells,creating pores that cause cell swelling and lysis,eventually leading to the death of the insect.
$4$. Therefore,statement $A$ is correct.

(B) $Bacillus$ $thuringiensis$ (often abbreviated as $Bt$) is a soil-dwelling bacterium that produces specific insecticidal crystal proteins (Cry proteins).
These proteins are toxic to certain insect larvae,such as those of lepidopterans,coleopterans,and dipterans.
Because of this property,$Bt$ is extensively used in modern biotechnology and agriculture as a biological control agent (bio-insecticide) to protect crops from pests without relying on harmful chemical pesticides.

(C) The $Ti$ plasmid (Tumor-inducing 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 $DNA$,known as $T-DNA$,into the genome of host plants,causing the formation of tumors (crown galls).
In biotechnology,scientists have modified this $Ti$ plasmid to act as a vector for delivering genes of interest into plants to create transgenic plants,without causing the disease.

(C) $Agrobacterium$ $tumefaciens$ is a soil-borne bacterium that naturally infects a wide range of dicot plants.
It contains a $Ti$ (Tumor inducing) plasmid, which can be modified to act as a vector for delivering foreign $DNA$ into the host plant cells.
Because of this natural ability to transfer its genetic material into the plant genome, it is widely used in genetic engineering to create transgenic crop plants.

(D) The introduction of genetically engineered $(GE)$ crops raises several ethical and safety concerns. One of the primary concerns is the potential for horizontal gene transfer,which could lead to the development of new viral strains or the accidental introduction of allergens and toxic substances into the food chain. Additionally,there are concerns regarding the long-term impact on biodiversity and the potential for creating 'superweeds' through gene flow. Therefore,option $D$ is the most scientifically significant reason among the choices provided.

(D) Golden rice is a genetically modified variety of rice $(Oryza sativa)$ engineered to produce beta-carotene, which is a precursor of vitamin $A$.
Vitamin $A$ deficiency is a major cause of childhood blindness in developing countries.
By consuming Golden rice, individuals can obtain the necessary vitamin $A$ to prevent night blindness and other related vision disorders.

(A) Genetically modified $(GM)$ plants are plants whose $DNA$ has been modified using genetic engineering techniques.
This process involves the introduction of foreign $DNA$ (transgene) into the plant cells.
Once the foreign $DNA$ is successfully integrated into the plant genome,the transformed cells are cultured and regenerated into whole plants using tissue culture techniques.
Therefore,genetically modified plants are those developed from cells into which foreign $DNA$ has been introduced.

(B) The transgenic variety of rice,commonly known as 'Golden Rice',was genetically engineered to produce beta-carotene,which is a precursor of Vitamin-$A$. This modification was introduced to address Vitamin-$A$ deficiency in populations that rely heavily on rice as a staple food. Therefore,it is characterized by its high content of Vitamin-$A$ compared to conventional rice varieties.

(C) $Bt$ cotton is a genetically modified organism $(GMO)$ developed by introducing the $cry$ genes from the bacterium $Bacillus$ $thuringiensis$ into the cotton plant.
These genes encode for toxic crystalline proteins (Cry proteins) that are insecticidal.
When specific pests,such as bollworms,ingest these proteins,they are activated in the alkaline gut of the insect,leading to the formation of pores in the gut lining,which eventually kills the pest.
Therefore,$Bt$ cotton is characterized by its high yield and its inherent ability to produce these toxic proteins to provide resistance against specific insect pests.

(A) The genetically modified $(GM)$ brinjal,known as $Bt$ brinjal,was developed in India to provide resistance against pests,specifically the fruit and shoot borer ($Leucinodes$ $orbonalis$).
This was achieved by introducing the $cry1Ac$ gene from the bacterium $Bacillus$ $thuringiensis$ into the brinjal genome.
The $cry1Ac$ gene produces a protein that is toxic to the larvae of the fruit and shoot borer,thereby protecting the crop without the need for heavy pesticide application.

(A) $RNA$ interference $(RNAi)$ is a method of cellular defense used by all eukaryotic organisms to silence specific genes.
In agriculture,this technique is specifically used to develop resistance against nematodes.
For example,the nematode $Meloidogyne$ $incognita$ infects the roots of tobacco plants,causing a significant reduction in yield.
By introducing nematode-specific genes into the host plant using $Agrobacterium$ vectors,double-stranded $RNA$ $(dsRNA)$ is produced.
This $dsRNA$ initiates $RNAi$,which silences the essential genes of the nematode,thereby preventing the parasite from surviving in the transgenic host.

(C) Night blindness is caused by a deficiency of Vitamin-$A$.
Golden Rice is a genetically modified variety of rice that has been engineered to produce beta-carotene,which is a precursor to Vitamin-$A$.
When consumed,the body converts this beta-carotene into Vitamin-$A$,thereby helping to prevent night blindness and other Vitamin-$A$ deficiency-related disorders.

(C) In India,$Bt$ cotton is the only genetically modified crop that has been approved for commercial cultivation by the Genetic Engineering Appraisal Committee $(GEAC)$.
$Bt$ cotton is engineered to express the $cry$ genes derived from the bacterium $Bacillus$ $thuringiensis$,which provides resistance against bollworms.
While research and trials for other $Bt$ crops like $Bt$ brinjal have been conducted,they have not been approved for commercial cultivation by farmers in India.

(A) Golden rice is a genetically modified variety of rice $(Oryza sativa)$ engineered to produce beta-carotene, which is a precursor of Vitamin-$A$.
This modification was introduced to address Vitamin-$A$ deficiency in populations that rely on rice as a staple food.
The genes inserted into the rice genome are typically derived from the daffodil plant $(Narcissus pseudonarcissus)$ and the bacterium $Erwinia uredovora$.

(A) In $1997$, an American company named RiceTec Inc. was granted a patent by the $US$ Patent and Trademark Office for 'Basmati' rice lines and grains. This was highly controversial because Basmati rice has been grown in India and Pakistan for centuries and is a traditional variety. This act is considered an example of biopiracy, where multinational companies exploit biological resources and traditional knowledge of developing countries without proper authorization or compensation.

(D) The Indian government has established the Genetic Engineering Appraisal Committee $(GEAC)$ under the Ministry of Environment,Forest and Climate Change.
This organization is responsible for making decisions regarding the validity of research involving genetically modified organisms $(GMOs)$ and the safety of introducing them for public use.
While the Research Committee on Genetic Manipulation $(RCGM)$ monitors the safety of research activities,the final approval for commercial release and public use is granted by the $GEAC$.

(A) Golden rice is a genetically modified variety of rice $(Oryza \text{ } sativa)$ that has been engineered to produce beta-carotene, which is a precursor of Vitamin $A$.
This modification was achieved by introducing genes from the daffodil plant $(Narcissus \text{ } pseudonarcissus)$ and the bacterium $Erwinia \text{ } uredovora$ into the rice genome.
Therefore, it is enriched with Vitamin $A$ and contains genes derived from the daffodil plant.

(C) $Bacillus$ $thuringiensis$ $(Bt)$ produces insecticidal protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein. The protein exists as an inactive protoxin but becomes an active toxin when ingested by the insect. The activation of the toxin is triggered by the alkaline $pH$ of the insect's gut, which solubilizes the crystals. Once activated, the toxin binds to the surface of midgut epithelial cells and creates pores that cause cell swelling and lysis, eventually leading to the death of the insect.

(C) Hirudin is a polypeptide that acts as a potent thrombin inhibitor,preventing blood clotting. It is naturally found in the saliva of medicinal leeches ($Hirudo$ $medicinalis$). Through genetic engineering,the gene encoding hirudin has been introduced into transgenic $Brassica$ $napus$ (rapeseed) plants,allowing for the large-scale production of this protein for medical use.

(D) $Bt$ cotton refers to the cultivation of genetically modified cotton plants.
The prefix $Bt$ stands for the bacterium $Bacillus$ $thuringiensis$.
This bacterium naturally produces a specific protein that acts as an endotoxin,which is toxic to certain insect pests such as lepidopterans,coleopterans,and dipterans.
By inserting the gene responsible for this endotoxin into the cotton plant,the plant becomes resistant to these pests,reducing the need for chemical insecticides.

(D) Golden rice is a genetically modified variety of rice engineered to produce beta-carotene,which is a precursor of vitamin $A$. This modification helps in addressing vitamin $A$ deficiency in populations that rely heavily on rice as a staple food.