Biotechnological Applications in Agriculture Questions in English

(D) $Bt$ stands for $Bacillus$ $thuringiensis$.
Genetic engineering has been used to incorporate the $cry$ genes from this bacterium into crops like cotton.
These $cry$ genes produce insecticidal proteins that specifically target and kill lepidopteran pests,such as $Bollworms$.
Therefore,$Bt$ crops are engineered to be resistant to $Bollworms$.

(B) The $Cry$ genes are derived from the bacterium $Bacillus$ $thuringiensis$ $(Bt)$.
When these genes are introduced into cotton plants,they express themselves by producing specific insecticidal proteins (Cry proteins).
These proteins are toxic to certain insect pests (like bollworms),thereby protecting the plant.
Therefore,the introduction of the $Cry$ gene results in the production of a new protein within the cotton plant,which is the primary mechanism of $Bt$ cotton.

(C) The $Bt$ toxin protein exists as an inactive protoxin in the bacterium $Bacillus$ $thuringiensis$.
When an insect ingests the inactive toxin,it reaches the midgut of the insect.
Due to the alkaline $pH$ of the insect's gut,the inactive protoxin is converted into an active toxin.
This active toxin binds to the surface of the midgut epithelial cells and creates pores.
These pores cause cell swelling and lysis (bursting),which eventually leads to the death of the insect.

(D) $RNAi$ stands for $RNA$ interference.
It is a biological process in which $RNA$ molecules inhibit gene expression or translation,by neutralizing targeted $mRNA$ molecules.
This mechanism is widely used in biotechnology for gene silencing.

(D) The process of $RNA$ 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). The source of this complementary $dsRNA$ could be:
$1$. Infection by viruses having $RNA$ genomes.
$2$. Mobile genetic elements (transposons) that replicate via an $RNA$ intermediate.

(C) The nematode $Meloidogyne \text{ } incognita$ infects the roots of tobacco plants and causes a significant reduction in yield.
To prevent this infection, a strategy based on the process of $RNA$ interference $(RNAi)$ was developed.
$RNAi$ takes place in all eukaryotic organisms as a method of cellular defense.
This method involves silencing of a specific $mRNA$ due to a complementary $dsRNA$ molecule that binds to and prevents translation of the $mRNA$ (silencing).

(B) $GEAC$ stands for Genetic Engineering Approval Committee. This is an Indian government body established under the Environment Protection Act,$1986$. Its primary function is to regulate the use,manufacture,storage,import,and export of hazardous microorganisms or genetically engineered organisms and cells in India.

(D) The Indian Government has established the $GEAC$ (Genetic Engineering Appraisal Committee) to handle matters related to genetically modified organisms $(GMOs)$.
Its primary functions include:
$1$. Making decisions regarding the validity of research involving genetically modified organisms.
$2$. Assessing the safety of introducing genetically modified organisms for public services.
Therefore,the correct option is $D$.

(B) The statement '$37$ identified varieties of Basmati rice are grown in India' is incorrect. In reality,there are $27$ documented varieties of Basmati rice grown in India. The other statements are correct: India has a massive diversity of rice (about $2$ lakh varieties),which is among the highest in the world,and Basmati rice has a long historical and cultural significance,as evidenced by its mention in ancient literature and poetry.

(A) 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 patent allowed the company to sell a 'new' variety of Basmati,which was essentially derived from Indian farmer's varieties.
This act was considered an act of biopiracy as Basmati rice has been grown in India for centuries.

(B) Statement $I$ is true: $Bt$ toxins are indeed insect-group specific and are encoded by specific $cry$ genes, such as $cry$ $IAc$.
Statement $II$ is false: While $Bt$ toxin exists as an inactive protoxin in $B. \text{ thuringiensis}$, its conversion into an active toxin in the insect gut is triggered by the alkaline $pH$ of the gut, not the acidic $pH$. The alkaline $pH$ solubilizes the crystals, allowing the protoxin to be activated by gut proteases.
Therefore, Statement $I$ is true and Statement $II$ is false.

(A) $RNA$ interference $(\text{RNAi})$ is a biological process in which $\text{RNA}$ molecules inhibit gene expression or translation,by neutralizing targeted $\text{mRNA}$ molecules.
This process is initiated by the presence of double-stranded $\text{RNA}$ $(\text{dsRNA})$.
These $\text{dsRNA}$ molecules are cleaved into small interfering $\text{RNA}$ $(\text{siRNA})$ by an enzyme called Dicer.
These $\text{siRNA}$ molecules then bind to a complementary sequence on the target $\text{mRNA}$,leading to its degradation or preventing its translation,thereby silencing the specific gene.

(A) The bacterium $Bacillus$ $thuringiensis$ produces a protein known as $Bt$ toxin.
This protein is produced in an inactive form called protoxin within the bacterium,which is why it does not kill the host bacterium itself.
When an insect ingests this inactive protoxin,it is converted into its active form due to the alkaline $pH$ of the insect's gut.
Therefore,both Assertion $(A)$ and Reason $(R)$ are correct,and $(R)$ is the correct explanation of $(A)$.

(A) Genetic modification of crops (Genetically Modified Crops or $GM$ crops) involves the alteration of the plant's genome to introduce desirable traits.
$1$. It enhances the nutritional value of food,for example,Golden Rice is enriched with Vitamin $A$.
$2$. It helps to reduce post-harvest losses,not increase them.
$3$. It increases the efficiency of mineral usage by plants,which prevents early exhaustion of soil fertility.
$4$. It makes crops more tolerant to abiotic stresses such as cold,drought,salt,and heat.
Therefore,option $A$ is the correct statement.

(D) $Bt$ cotton is a genetically modified organism $(GMO)$ created by introducing the $cry$ genes from the bacterium $Bacillus$ $thuringiensis$ into the cotton plant.
These genes produce insecticidal proteins that are toxic to specific groups of insects,particularly lepidopterans (like tobacco budworm and armyworm),coleopterans (beetles),and dipterans (flies and mosquitoes).
Therefore,$Bt$ cotton is not resistant to all insects,but rather provides resistance against specific target pests,primarily bollworms.
Thus,the correct feature is that the plant is resistant to certain insects.

(A) The transgenic tobacco plant was developed using $\text{RNA}$ interference $(\text{RNAi})$ technology to provide resistance against the nematode $\text{Meloidogyne incognita}$.
$\text{RNAi}$ is a cellular defense mechanism in eukaryotes where specific double-stranded $\text{RNA}$ $(\text{dsRNA})$ molecules inhibit gene expression by causing the degradation of complementary messenger $\text{RNA}$ $(\text{mRNA})$.
In this process,$\text{Agrobacterium}$ vectors are used to introduce nematode-specific genes into the host plant. These genes produce both sense and antisense $\text{RNA}$ in the host cells,which form $\text{dsRNA}$.
When the nematode infects the transgenic plant,this $\text{dsRNA}$ initiates the $\text{RNAi}$ pathway,silencing essential genes in the nematode and preventing it from surviving or reproducing within the plant.

(C) Option $C$ is correct.
$1$. The anticoagulant hirudin is a protein that prevents blood clotting. It is produced by the medicinal leech ($Hirudo$ $medicinalis$).
$2$. Scientists have successfully transferred the gene responsible for hirudin production into $Brassica$ $napus$ (rapeseed) plants.
$3$. The hirudin protein accumulates in the seeds of these transgenic plants, from which it can be extracted and purified for medical use.
$4$. Option $A$ is incorrect because $Bt$ stands for the bacterium $Bacillus$ $thuringiensis$, not just a general term for biotechnology.
$5$. Option $B$ is incorrect because somatic hybridization involves the fusion of isolated protoplasts, not complete plant cells (which have cell walls).
$6$. Option $D$ is incorrect because $Flavr$ $Savr$ tomato was engineered to have reduced ethylene production to delay ripening and increase shelf life, not enhanced production.

(D) $Meloidogyne$ $incognita$ is a parasitic nematode that infects the roots of tobacco plants.
This infection leads to the formation of root galls,which significantly reduces the yield of the tobacco crop.
In biotechnology,this organism is famously used as a target for $RNA$ interference $(RNAi)$ technology to develop pest-resistant tobacco plants.

(A) Bacillus thuringiensis $(Bt)$ produces insecticidal crystal proteins (Cry proteins) during a particular phase of their growth.
These proteins exist as inactive protoxins in the bacterium.
When an insect ingests the inactive toxin,it is converted into an active form 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,eventually leading to the death of the insect.
Therefore,option $A$ is correct.

(D) $Bacillus$ $thuringiensis$ $(Bt)$ produces insecticidal proteins (Cry proteins) that are toxic to specific insect orders.
These include:
$1$. Lepidopterans: Tobacco budworm,Army worm.
$2$. Coleopterans: Beetles.
$3$. Dipterans: Flies,Mosquitoes.
Since the $Bt$ toxin is effective against all the listed insects,the correct option is $d$.

(C) Transgenic plants are genetically modified organisms (GMOs) that contain and express a transgene,which is a gene introduced from another organism using recombinant $\text{DNA}$ technology.
$1$. The process involves isolating the desired gene from a donor organism.
$2$. This gene is then inserted into a vector (like a plasmid) and introduced into the host plant cell.
$3$. Once the foreign $\text{DNA}$ is successfully integrated into the plant genome,the transformed cell is cultured in an artificial medium to regenerate a whole plant through tissue culture techniques.
$4$. Therefore,option $C$ correctly describes the generation of transgenic plants.

(D) Golden rice is a genetically modified crop developed through biotechnology.
It is engineered to produce $\beta-carotene$, which is a precursor of $Vitamin A$.
This modification is specifically designed to address $Vitamin A$ deficiency in populations that rely heavily on rice as a staple food.
Therefore, the primary purpose of Golden rice is to enhance the nutritional value of the crop.

(A) Statement-$A$ is true: As per the $NCERT$ textbook,there are about $30$ recombinant therapeutics that have been approved for human use the world over. Currently,$12$ of these are being marketed in India.
Statement-$B$ is false: There are $27$ documented varieties of Basmati rice grown in India,but the statement is often contrasted with the fact that there are over $200,000$ varieties of rice in India alone. However,the specific claim regarding $27$ varieties of Basmati is factually correct according to the $NCERT$ textbook (Chapter: Biotechnology and its Applications). Therefore,both statements are true.

(C) Statement-$I$ is incorrect because in the cloning vector $\text{pBR}-322$,the restriction site for $\text{BamHI}$ is located within the $\text{Tetracycline}$ resistance gene $(tet^R)$,not the $\text{Ampicillin}$ resistance gene $(amp^R)$.
Statement-$II$ is correct because $\text{RNA}$ interference $(\text{RNAi})$ is a method of cellular defense used in all eukaryotic organisms. This method was used to develop nematode-resistant tobacco plants by introducing nematode-specific genes via an $\text{Agrobacterium}$ vector,which produces double-stranded $\text{RNA}$ in the host plant,silencing the essential genes of the nematode.

(C) Artemisinin is a potent drug used for the treatment of malaria. It is derived from the plant $Artemisia \text{ } annua$ (sweet wormwood). Scientists have used transgenic techniques to increase the production of artemisinin in these plants to meet global demand. Therefore, it is classified as an antimalarial drug.

(C) The $cry$ genes are derived from the soil bacterium $Bacillus \text{ } thuringiensis$.
These genes encode for crystal proteins (Cry proteins) which are toxic to specific insect pests.
When these genes are introduced into crop plants, the plants produce these proteins, which act as a natural pesticide, thereby providing the plant with insecticidal properties.

(C) The bacterium $Bacillus$ $thuringiensis$ $(Bt)$ produces protein crystals during a particular phase of their growth. These crystals contain a toxic insecticidal protein called $Cry$ protein. When the larvae of certain insects,such as the tobacco budworm or armyworm (which feed on plants like $Brassica$),ingest these spores,the alkaline $pH$ of the gut solubilizes the crystals,releasing the active toxin. This 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 larva.

(B) The bacterium $Bacillus$ $thuringiensis$ (often abbreviated as $Bt$) produces insecticidal proteins known as $Cry$ proteins. These proteins are toxic to certain insect larvae,including the cotton bollworm. By incorporating the genes encoding these proteins into the cotton plant,the plant becomes resistant to the bollworm,creating what is known as $Bt$ cotton.

(B) The $Clarias$ $gariepinus$ (African catfish) was introduced illegally for aquaculture purposes in India. This species has become a major threat to the indigenous catfish species in our rivers because it is highly invasive, aggressive, and competes for food and habitat, leading to the decline of native populations.

(C) $RNAi$ ($RNA$ interference) is a method of cellular defense in all eukaryotic organisms. In this process,a specific $mRNA$ is prevented from translation due to the formation of a complementary $dsRNA$ (double-stranded $RNA$) molecule. This $dsRNA$ binds to the $mRNA$ and silences it,thereby preventing the expression of the specific gene.

(D) The genes $Cry I Ac$ and $Cry II Ab$ are responsible for encoding proteins that control cotton bollworms.
These genes are introduced into cotton plants to create transgenic $Bt$ cotton.
The proteins produced by these genes are toxic to specific insect pests,particularly lepidopterans like cotton bollworms.
Therefore,the correct combination is $Cry I Ac$ and $Cry II Ab$.

(C) $Meloidegyne incognitia$ is a nematode that infects the roots of tobacco plants,causing a significant reduction in crop yield. To combat this,$RNA$ interference $(RNAi)$ technology is used to create pest-resistant tobacco plants by silencing specific genes of the nematode.

(D) $RNA$ interference $(RNAi)$ is a biological process in which $RNA$ molecules inhibit gene expression or translation,by neutralizing targeted $mRNA$ molecules. This method involves the silencing of a specific $mRNA$ due to a complementary $dsRNA$ molecule. The $dsRNA$ is processed into small interfering $RNA$ $(siRNA)$ which binds to the target $mRNA$ and prevents its translation.

(A) Transgenic plants are genetically modified organisms designed to improve agricultural productivity and sustainability. One of their primary goals is to reduce the reliance on chemical pesticides by incorporating genes that provide resistance to pests (e.g.,$Bt$ cotton). Therefore,increasing dependency on chemical pesticides is not a goal or a characteristic of transgenic plants. Options $B$,$C$,and $D$ are all recognized benefits of transgenic technology.

(B) The full form of $G.E.A.C.$ is Genetic Engineering Approval Committee.
This committee is responsible for making decisions regarding the validity of research involving genetically modified organisms $(GMOs)$ and the safety of introducing genetically modified organisms for public services.

(D) $BT$ cotton is a genetically modified or transgenic crop that expresses the $cry$ gene from the bacterium $Bacillus$ $thuringiensis$.
This gene produces an insecticidal protein that provides resistance against specific lepidopteran,coleopteran,and dipteran pests.
Therefore,it is a transgenic plant and is insect-resistant.
However,it is not resistant to all insecticides; it is specifically engineered to target certain pests,and its resistance is limited to those specific insect groups.
Thus,the statement that it is resistant to all insecticides is incorrect.

(A) Golden rice is a genetically modified crop developed to combat vitamin deficiency. It is engineered to produce high levels of beta-carotene,which is a precursor to $Vitamin \ A$. When consumed,the human body converts this beta-carotene into $Vitamin \ A$. Therefore,the correct option is $A$.

(B) The $Bt$ toxin produced by the bacterium $Bacillus \text{ } thuringiensis$ exists in an inactive protoxin form within the bacterial cell.
It only becomes active when it is ingested by an insect, where the alkaline $pH$ of the insect's gut solubilizes the crystals and converts the protoxin into its active toxic form.
Therefore, the bacteria remain unharmed because the toxin is not in its active state while inside the bacterial cell.

(C) $Bt$ toxin is produced by the bacterium $Bacillus$ $thuringiensis$ as an inactive protoxin. When an insect ingests the $Bt$ cotton,the inactive protoxin enters the insect's midgut. The alkaline pH of the insect's midgut solubilizes the crystals and converts the inactive protoxin into its active form,which then binds to the surface of midgut epithelial cells and creates pores,causing cell swelling and lysis,eventually leading to the death of the insect.

(D) $RNA$ Interference $(RNAi)$ is a biological process in which $RNA$ molecules inhibit gene expression or translation,by neutralizing targeted $mRNA$ molecules. This method is used in biotechnology to develop pest-resistant plants,such as tobacco plants resistant to the nematode $Meloidegyne$ $incognitia$. By introducing $RNAi$ constructs,the plant produces double-stranded $RNA$ that silences specific genes essential for the pest's survival,thereby protecting the plant.

(A) The correct answer is $A$. The nematode $Meloidogyne \, incognitia$ infects the roots of tobacco plants and causes a significant reduction in yield. Biotechnology, specifically $RNA$ interference $(RNAi)$, is used to develop pest-resistant tobacco plants by silencing specific genes of this nematode.

(A) The proteins encoded by the genes $CryIAc$ and $CryIAb$ are used to control cotton bollworms and corn borers,respectively.
These genes are derived from the bacterium $Bacillus$ $thuringiensis$ $(Bt)$.
$CryIAc$ is specifically effective against cotton bollworms,while $CryIAb$ is effective against corn borers.
Therefore,the correct sequence is Cotton bollworm and Corn borer.

(D) The corn borer is controlled by the protein encoded by the gene $cry I Ab$.
This gene is derived from the bacterium $Bacillus thuringiensis$.
When the corn borer ingests the plant tissue containing this protein,the toxin is activated in the alkaline gut of the insect,leading to its death.
Therefore,the correct option is $D$.

(B) cotton bollworms.
$Bt$ cotton is a genetically modified organism that produces insecticidal proteins.
The specific genes $cryIAc$ and $cryIIAb$ are introduced into the cotton plant to provide resistance against cotton bollworms.
These genes encode for crystal proteins that,when ingested by the larvae of the bollworm,cause pore formation in the midgut,leading to the death of the insect.

(C) The correct answer is $C$.
Gene silencing is a biological process in which the expression of a specific gene is suppressed or turned off.
This can be achieved using $RNA$ interference $(RNAi)$,which involves short interfering $RNA$ molecules that bind to complementary $mRNA$ and trigger its degradation.
Similarly,antisense $RNA$ technology involves introducing an $RNA$ molecule that is complementary to the target $mRNA$,thereby preventing its translation into protein.
Therefore,both $RNAi$ and antisense $RNA$ are effective methods for gene silencing.

(D) $RNA$ interference $(RNAi)$ is a method of cellular defense in eukaryotes.
In this process,a double-stranded $RNA$ $(dsRNA)$ molecule is introduced,which is complementary to the target $mRNA$.
This $dsRNA$ binds to the specific $mRNA$ and silences it by preventing its translation into protein.
Therefore,the correct answer is $D$.

(D) is the correct answer.
Genetically modified $(GM)$ crops are plants whose $DNA$ has been modified through genetic engineering to introduce a new trait that does not occur naturally in the species.
Advantages of $GM$ crops include:
$1$. Improved nutritional quality of crops (e.g.,Golden Rice).
$2$. Reduced reliance on chemical pesticides and insecticides during farming.
$3$. Increased efficiency of mineral usage by plants,which prevents early exhaustion of soil fertility.
$4$. Enhanced tolerance to abiotic stresses like cold,drought,salt,and heat.
Increasing post-harvest losses is a disadvantage,not an advantage,of any agricultural practice.

(B) $RNA$ interference $(RNAi)$ is a method of cellular defense in all eukaryotic organisms. In this technique,double-stranded $RNA$ $(dsRNA)$ is used to silence specific messenger $RNA$ $(mRNA)$ of the pest. When a nematode infects the transgenic tobacco plant,the $dsRNA$ produced by the plant triggers the $RNAi$ mechanism,which prevents the translation of the pest's essential genes,thereby protecting the plant.

$(A)$ $Statement I$ is incorrect because $RNA$ interference $(RNAi)$ is a method of cellular defence that occurs only in eukaryotic organisms, not in prokaryotes.
$Statement II$ is correct because $RNAi$ involves the silencing of specific $mRNA$ due to a complementary $dsRNA$ molecule, which prevents the translation of the $mRNA$ into protein. Thus, it is a pre-translational process.

(B) - preventing the process of translation of mRNA.
$RNA$ interference $(RNAi)$ is a biological process in which $RNA$ molecules inhibit gene expression or translation by neutralizing targeted mRNA molecules.
In the case of $Meloidogyne \ incognita$ infecting tobacco plants,$dsRNA$ is introduced into the host cells.
This $dsRNA$ initiates the $RNAi$ pathway,which leads to the degradation of the specific mRNA of the nematode,thereby preventing its translation into essential proteins required for the parasite's survival.