Biotechnological Applications in Agriculture Questions in English

(C) The first transgenic plant to be successfully developed was tobacco $(Nicotiana \, tabacum)$. In $1983$, researchers introduced antibiotic resistance genes into tobacco plants using the $Ti$ plasmid of $Agrobacterium \, tumefaciens$.

(B) The process of $RNA$ interference $(RNAi)$ is used to protect plants from nematodes like $Meloidogyne$ $incognita$.
In this technique,specific genes from the nematode are introduced into the host plant (e.g.,tobacco) using $Agrobacterium$ vectors.
These genes produce both sense and antisense $RNA$ in the host cells,which form double-stranded $RNA$ $(dsRNA)$.
This $dsRNA$ initiates $RNAi$ and silences the specific mRNA of the nematode,thereby preventing the parasite from surviving in the transgenic host plant.

(A) The correct statement is $(A)$. The term "Bt" in "Bt-cotton" stands for the bacterium $Bacillus$ $thuringiensis$. This bacterium produces insecticidal proteins, and through biotechnology, the genes encoding these proteins are introduced into the cotton plant to make it pest-resistant. Option $(B)$ is incorrect because somatic hybridization involves the fusion of protoplasts, not whole plants. Option $(C)$ is incorrect as it describes the same process as $(B)$. Option $(D)$ is incorrect because the "Flavr Savr" tomato was genetically engineered to delay ripening by inhibiting the production of ethylene, not by producing it.

(D) The transgenic bacterium $Pseudomonas putida$ was genetically engineered by Dr. Ananda Mohan Chakrabarty.
It contains plasmids that allow it to break down hydrocarbons found in crude oil.
This makes it highly effective for bioremediation,specifically in cleaning up oil spills in marine environments.

(A) The $Cry$ proteins are toxic insecticidal proteins produced by the bacterium $Bacillus$ $thuringiensis$ $(Bt)$.
These proteins are encoded by the $cry$ genes.
When the insect ingests the inactive protoxin,it is converted into its active form due to the alkaline $pH$ of the insect gut,which leads to the death of the insect.

(B) $Bacillus$ $thuringiensis$ $(Bt)$ produces insecticidal protein crystals during a particular phase of their growth.
These crystals contain a toxic insecticidal protein.
This protein exists as an inactive protoxin 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.

(A) The $Bt$ toxin genes $cryIAc$ and $cryIIAb$ are specifically incorporated into cotton plants to provide resistance against cotton bollworms.
These genes encode for crystal proteins that are toxic to the larvae of these specific insect pests.
When the bollworm larvae ingest the plant tissues containing these proteins,the toxin is activated in their alkaline gut,leading to their death.
Therefore,these genes are responsible for controlling bollworms.

(C) transgenic plant (or genetically modified plant) is defined as a plant whose $DNA$ has been modified using genetic engineering techniques.
This process involves the introduction of a foreign gene (transgene) into the genome of a plant cell.
Once the foreign $DNA$ is successfully integrated into the host genome,the transformed cell is cultured in a synthetic medium using tissue culture techniques to regenerate a complete,fertile plant that expresses the desired trait.

(C) $RNA$ interference $(RNAi)$ is a cellular mechanism used to silence specific genes. In biotechnology,this technique is employed to protect plants from parasitic infestations. Specifically,the nematode $Meloidogyne$ $incognita$ infects the roots of tobacco plants. 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 plant.

(C) The process of $RNA$ interference $(RNAi)$ is used to prevent the infestation of the nematode $Meloidogyne$ $incognita$ in tobacco plants.
In this method,specific $DNA$ is introduced into the host plant using an $Agrobacterium$ vector.
This $DNA$ produces both sense and antisense $RNA$ in the host cells.
These two $RNA$ strands are complementary to each other and form double-stranded $RNA$ $(dsRNA)$.
This $dsRNA$ initiates $RNAi$ and silences the specific $mRNA$ of the nematode,thereby preventing the translation of essential proteins required for the nematode's survival.

(C) $Agrobacterium tumefaciens$ is a soil bacterium that naturally infects a wide variety of dicot plants.
It contains a large plasmid known as the $Ti$-plasmid (Tumor-inducing plasmid).
In biotechnology,this $Ti$-plasmid is modified into a cloning vector,which is no longer pathogenic but is still capable of delivering genes of interest into the plant genome.
Therefore,it is the most commonly used vector for the transformation of crop plants.

(C) 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 of Vitamin $A$.
Vitamin $A$ deficiency is a major cause of night blindness and other vision-related problems in developing countries.
By consuming Golden rice, populations can increase their Vitamin $A$ intake, thereby helping to alleviate the issue of night blindness.

(D) Transgenic plants,also known as genetically modified $(GM)$ plants,are plants that have been genetically engineered to contain one or more genes from another organism.
This process involves the insertion of foreign $DNA$ (transgene) into the genome of the plant using techniques like Agrobacterium-mediated transformation or biolistics (gene gun).
Therefore,the production of transgenic plants is achieved by introducing foreign genes into the plant's genome.

(B) The $Bt$ cotton plant is a genetically modified crop created by introducing the $cry$ genes from the bacterium $Bacillus$ $thuringiensis$ into the cotton genome.
These $cry$ genes encode for crystal proteins (Cry proteins) that are toxic to specific insect pests,particularly lepidopterans (tobacco budworm,armyworm),coleopterans (beetles),and dipterans (flies,mosquitoes).
Specifically,$Bt$ cotton was engineered to provide resistance against bollworms (which are lepidopteran pests).
Additionally,the primary goal of developing $Bt$ cotton was to increase agricultural productivity by reducing crop loss due to these pests,thus resulting in a high yield.

(D) Genetically Modified Organisms $(GMOs)$ are plants,bacteria,fungi,and animals whose genes have been altered by manipulation. They are used for:
$1$. Creating tailor-made plants to supply alternative resources to industries (in the form of starches,fuels,and pharmaceuticals).
$2$. Increasing the nutritional value of food (e.g.,Golden Rice,which is rich in Vitamin $A$).
$3$. Making crops more tolerant to abiotic stresses (cold,drought,salt,heat).
$4$. Reducing reliance on chemical pesticides (pest-resistant crops).
Therefore,all the given options are correct.

(D) $GM$ brinjal (also known as $Bt$ brinjal) is a genetically modified crop developed in India. It is engineered by inserting a gene from the soil bacterium $Bacillus$ $thuringiensis$ $(Bt)$. This gene produces a protein that is toxic to specific insect pests,particularly the fruit and shoot borer ($Leucinodes$ $orbonalis$). Therefore,it provides resistance against insects.

(D) Carbamates are a class of chemical compounds derived from carbamic acid. They are widely used in agriculture and pest control. Carbamates function as insecticides by inhibiting the enzyme acetylcholinesterase in the nervous system of insects. Some carbamates also exhibit herbicidal and fungicidal properties,making them versatile agricultural chemicals. Therefore,they are used as insecticides,herbicides,and fungicides.

(A) 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 $A$.
This modification was developed to address Vitamin $A$ deficiency in populations that rely on rice as a staple food source.
Therefore,the correct option is $A$.

(C) $2,4-D$ stands for $2,4-dichlorophenoxyacetic$ acid. It is a synthetic auxin used as a selective herbicide to control broad-leaved weeds in crops. $DDT$,$BHC$,and Aldrin are primarily used as insecticides.

(C) $Agrobacterium$ $tumefaciens$ is a soil bacterium that causes crown gall disease in many dicot plants. It is the most extensively studied plant-microbe interaction because of its unique ability to transfer a portion of its $DNA$,known as $T$-$DNA$,into the plant genome. This natural genetic engineering process has been widely utilized in biotechnology for the development of transgenic plants.

(D) $Bacillus$ $thuringiensis$ $(Bt)$ 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 the death of the insect. Specific $Bt$ toxin genes were isolated from $Bacillus$ $thuringiensis$ and incorporated into several crop plants such as cotton. The proteins encoded by the genes $cryIAc$ and $cryIIAb$ control the cotton bollworms.

(A) $Bacillus$ $thuringiensis$ $(Bt)$ is a soil bacterium that produces insecticidal proteins.
Scientists have incorporated specific genes from this bacterium into the cotton plant to provide resistance against insect pests like bollworms.
This genetically modified crop is known as $Bt$-cotton.
Therefore,the correct option is $A$.

(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 encode for crystal $(Cry)$ proteins,which are toxic to specific insect pests like lepidopterans,coleopterans,and dipterans.
When these insects ingest the plant tissue,the alkaline $pH$ of their gut activates the protoxin into its active toxic form,leading to the death of the insect.
Thus,$BT$ cotton acts as a biological insecticide,providing high yield by protecting the crop from pest damage.

(A) The $Bt$ toxin produced by the bacterium $Bacillus$ $thuringiensis$ is initially produced as an inactive protoxin.
When an insect ingests this inactive toxin,it enters the alimentary canal (midgut) of the insect.
Due to the alkaline $pH$ of the insect's gut,the inactive protoxin is converted into its active form.
The active toxin binds to the surface of the midgut epithelial cells and creates pores,causing cell swelling and lysis,which eventually leads to the death of the insect.

(A) $BT$ Cotton is a genetically modified organism $(GMO)$.
It is created by introducing a specific gene from the soil bacterium $Bacillus$ $thuringiensis$ into the cotton plant.
This bacterium produces a protein called the $Cry$ protein,which is toxic to certain insect larvae (like bollworms).
When the insect ingests the plant tissue,the toxin is activated in its gut,leading to the death of the insect.
Therefore,the correct statement is that a gene from a bacterium that produces a toxic substance has been introduced.

(B) The bacterium $Bacillus \text{ } thuringiensis$ $(Bt)$ produces specific insecticidal proteins. The genes responsible for producing these toxic proteins, known as $cry$ genes, are isolated from the bacterium and introduced into the cotton plant genome using genetic engineering techniques. This results in the production of the $Bt$ toxin within the plant tissues, which provides resistance against specific insect pests like bollworms.

(C) The $Bacillus$ $thuringiensis$ $(Bt)$ toxin is introduced into crops using $Genetic$ $engineering$ (also known as Recombinant $DNA$ technology).
Specific genes from the bacterium $Bacillus$ $thuringiensis$ that code for the insecticidal protein (cry proteins) are isolated and inserted into the plant genome.
This allows the plant to produce its own toxin,providing resistance against specific insect pests.
Therefore,the correct method is $Genetic$ $engineering$.

(D) The bacterium $Bacillus$ $thuringiensis$ (often referred to as $Bt$) is widely used in agriculture as a biopesticide.
It produces a specific protein toxin (the $Cry$ protein) that is lethal to certain insect larvae,such as those of lepidopterans,coleopterans,and dipterans.
When these insects ingest the toxin,it gets activated in their alkaline gut,leading to their death.
This makes it an effective and environmentally friendly alternative to chemical pesticides.

(B) The bacterium $Bacillus \text{ } thuringiensis$ $(Bt)$ 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 the death of the insect. This toxin is specific to certain groups of insects, including lepidopterans (tobacco budworm, armyworm), coleopterans (beetles), and dipterans (flies, mosquitoes). Therefore, it is effective against mosquitoes.

(C) The $Bacillus$ $thuringiensis$ $(Bt)$ toxin is introduced into crops using $Genetic$ $engineering$ (recombinant $DNA$ technology).
Specific genes from the bacterium $Bacillus$ $thuringiensis$ that code for the insecticidal crystal protein are isolated and inserted into the plant genome.
This allows the crop to produce its own toxin,providing resistance against specific insect pests.

(B) $Bt$ cotton is a genetically modified pest-resistant plant cotton variety. It is produced by introducing the $cry$ genes from the bacterium $Bacillus$ $thuringiensis$ into the cotton genome. These genes produce insecticidal proteins that protect the plant from bollworms,making it a significant application of biotechnology in agriculture.

(D) Hybrid embryos can be obtained through embryo rescue techniques in various types of hybridization crosses.
These include:
$1$. Intervarietal hybridization: Crossing between different varieties of the same species.
$2$. Interspecific hybridization: Crossing between different species of the same genus.
$3$. Intergeneric hybridization: Crossing between different genera.
Since embryo rescue is a biotechnological tool used to overcome post-fertilization barriers in all these types of crosses to produce viable hybrids,the correct answer is 'All of the above'.

(B) $Meloidogyne \ incognita$ is a nematode that infects the roots of tobacco plants,causing a significant reduction in yield. This infection is prevented using $RNA$ interference $(RNAi)$ technology.

(B) : Golden rice is a transgenic variety of rice ($Oryza$ $sativa$) which contains significant quantities of $\beta$-carotene,which is a provitamin $A$ (an inactive state of vitamin $A$).
$\beta$-carotene serves as a primary precursor for the synthesis of vitamin $A$ in the human body.
The grains of this rice appear yellow due to the presence of $\beta$-carotene,which is why it is commonly referred to as golden rice.

(C) The correct answer is $C$.
Soil bacterium $Bacillus$ $thuringiensis$ produces proteins that kill certain insects like lepidopterans (tobacco budworm,armyworm),coleopterans (beetles),and dipterans (flies,mosquitoes).
$B. thuringiensis$ forms protein crystals containing a toxic insecticidal protein.
This toxin does not kill the bacterium because it exists as an inactive protoxin.
Once an insect ingests the plant tissue,the protoxin is converted into an active form of toxin due to the alkaline $pH$ of the insect's alimentary canal.
The activated toxin binds to the surface of midgut epithelial cells and creates pores,which cause swelling and lysis,eventually leading to the death of the insect.

(B) : Glyphosate is a broad-spectrum herbicide that specifically kills broad-leaved weeds. Since crop plants can also be affected by this herbicide,they are genetically engineered to be resistant to glyphosate. Consequently,when glyphosate is applied to the field,only the weeds are eliminated,while the crop plants remain unharmed.

(D) $Bt$ toxin genes were isolated from $Bacillus$ $thuringiensis$ and incorporated into several crop plants,such as cotton.
The choice of genes depends upon the crop and the targeted pest,as most $Bt$ toxins are insect-group specific.
The toxin is coded by a gene named $cry$. There are numerous such genes.
Two $cry$ genes,$cryIAc$ and $cryIIAb$,have been incorporated into cotton.
The genetically modified crop is called $Bt$ cotton as it contains $Bt$ toxin genes that provide resistance against cotton bollworms.

(B) $RNA$ 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 complementary $dsRNA$ binds to the target $mRNA$,preventing its translation and thereby causing its silencing.
This mechanism serves as a method of cellular defense in all eukaryotic organisms.

(C) The correct answer is $C$.
Golden rice is a genetically modified (transgenic) variety of rice $(Oryza sativa)$ engineered to produce $\beta$-carotene, which is a precursor (provitamin $A$) of vitamin $A$.
When consumed, the human body converts $\beta$-carotene into vitamin $A$.
Regular consumption of golden rice helps in preventing vitamin $A$ deficiency, which is a leading cause of childhood blindness in many developing countries.
The grains of this rice appear yellow due to the presence of $\beta$-carotene, hence the name 'Golden rice'.

(A) : Many nematodes live in plants and animals including human beings. $A$ nematode $Meloidogyne \ incognita$ infests the roots of tobacco plants and causes a great reduction in yield. $A$ novel strategy was adopted to prevent this infection that was based on the process of $RNA$ interference $(RNAi)$.
$RNA$ interference $(RNAi)$ is the phenomenon of inhibiting the activity of a gene by the synthesis of $RNA$ molecules complementary to the $mRNA$. The normal (in vivo synthesized) $mRNA$ of a gene is said to be "sense" because it carries the codons that are "read" during translation.
Normally, the complement to the $mRNA$ "sense" strand will not contain a sequence of codons that can be translated to produce a functional protein; thus, this complementary strand is called "anti-sense $RNA$".
The anti-sense $RNA$ and $mRNA$ molecules will anneal to form duplex $RNA$ molecules (or double-stranded $RNA$), and the duplex $RNA$ molecules cannot be translated. Thus, the presence of anti-sense $RNA$ will block the translation of the $mRNA$ of the affected gene. In fact, recent evidence indicates that these $RNA$ duplexes are often rapidly degraded in vivo.

(A) $RNA$ interference $(RNAi)$ is a method used to develop plants resistant to nematodes.
Many nematodes live in plants and animals, including human beings.
A nematode, $Meloidogyne incognita$, infests the roots of tobacco plants and causes a significant reduction in yield.
A novel strategy was adopted to prevent this infection based on the process of $RNA$ interference $(RNAi)$.
$RNAi$ involves the silencing of a specific $mRNA$ due to a complementary $dsRNA$ molecule that binds to and prevents translation of the $mRNA$.
By introducing nematode-specific genes into the host plant, the plant produces both sense and anti-sense $RNA$ in the host cells.
These two $RNA$ strands form a double-stranded $RNA$ $(dsRNA)$ that initiates $RNAi$ and silences the specific $mRNA$ of the nematode, thereby protecting the plant from infestation.

(A) $Bacillus \text{ } thuringiensis$ $(Bt)$ produces insecticidal proteins that kill specific insect orders such as lepidopterans, coleopterans, and dipterans.
These proteins are produced as inactive protoxins within the bacterial protein crystals.
The toxin remains inactive within the bacterium, so it does not harm the host.
When an insect ingests the crystals, the alkaline $pH$ of the insect's midgut solubilizes the crystals and converts the protoxin into its active form.
The activated toxin then binds to the specific receptors on the surface of the midgut epithelial cells, creating pores that cause cell swelling, lysis, and eventually the death of the insect.

(B) The technique of $RNA$ interference $(RNAi)$ is used to prevent the translation of specific $mRNA$ molecules. This method is used to develop transgenic plants that are resistant to pests. $A$ well-known example is the protection of tobacco plants against the nematode $Meloidogyne$ $incognita$. By introducing nematode-specific genes into the host plant via $Agrobacterium$ vectors,double-stranded $RNA$ $(dsRNA)$ is produced,which triggers $RNAi$ and silences the essential $mRNA$ of the parasite,thereby preventing the nematode from surviving in the transgenic host.

(A) : The genetically modified $(GM)$ $Bt$ brinjal in India has been developed mainly for insect resistance.
Through genetic engineering,$Bt$ toxin genes were isolated from the bacterium $Bacillus$ $thuringiensis$ and incorporated into several crop plants such as cotton and brinjal to provide protection against specific pests.

(D) $Bt$ toxin genes were isolated from $Bacillus$ $thuringiensis$ and incorporated into cotton plants. The genetically modified crop is called $Bt$ cotton.
$Bt$ cotton has the following useful characteristics: pest resistance,herbicide tolerance,high yield,and resistance to bollworm infestation.
Specifically,the $Bt$ toxin protein produced by the plant kills lepidopteran pests like bollworms.

(B) The correct answer is $B$. Transgenic varieties of crops are developed using genetic engineering to introduce desirable traits. In the case of improved transgenic basmati rice,the primary goal is to enhance nutritional value and productivity. Specifically,research has focused on creating varieties that provide a higher yield and are biofortified,such as being enriched with vitamin $A$ (often referred to as Golden Rice technology applied to specific cultivars) to address nutritional deficiencies.

(D) $Bt$ toxin is produced by the soil bacterium $Bacillus$ $thuringiensis$. It is produced as an inactive protoxin within the bacterium,which is why it does not kill the host. When an insect ingests the protoxin,the alkaline $pH$ of the insect's gut solubilizes the crystals and converts the inactive protoxin into an active toxin. This active toxin binds to the surface of the midgut epithelial cells,creating pores that cause cell swelling,lysis,and eventually the death of the insect.

(A) : Transgenic plants are plants that have been genetically modified using recombinant $DNA$ technology.
This process involves the introduction of foreign $DNA$ (a transgene) into the genome of a plant cell.
Once the foreign $DNA$ is integrated,the transformed cell is cultured in an artificial medium to regenerate into a complete,mature plant.
These plants express the traits encoded by the introduced $DNA$,such as pest resistance,herbicide tolerance,or improved nutritional quality.

(A) $Bacillus$ $thuringiensis$ $(Bt)$ is a soil bacterium that produces insecticidal proteins.
These proteins are effective against specific insect groups such as lepidopterans (tobacco budworm,armyworm),coleopterans (beetles),and dipterans (flies,mosquitoes).
$B. thuringiensis$ produces protein crystals containing a toxic insecticidal protein.
This toxin exists as an inactive protoxin within the bacterium,which is why it does not harm the host.
When an insect ingests the crystal,the alkaline $pH$ of the insect's alimentary canal converts the protoxin into an active toxin.
The activated toxin binds to the surface of the midgut epithelial cells,creating pores that cause cell swelling,lysis,and ultimately the death of the insect.
Therefore,it is widely used as a biological insecticide.