Q.How has the use of Agrobacterium as vectors helped in controlling Meloidegyne incognitia infestation in tobacco plants? Explain in correct sequence.
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🔒 Start your 14-day free trial to unlock the full solution →Concept understanding — Genetically Modified Organisms
Imagine you have a recipe for a simple sponge cake. Now, suppose you want that cake to also have chocolate chips inside it. You wouldn't throw away the original recipe and start from scratch. Instead, you would take the basic cake batter and deliberately add chocolate chips to it. You have modified the original recipe to give it a new, useful property.
A Genetically Modified Organism (GMO) works on the same principle, but instead of adding chocolate chips to batter, scientists add a specific gene (a tiny instruction manual inside a living cell) from one organism into the DNA of another organism. The result is a living thing — a plant, animal, or microbe — whose genetic material has been artificially altered in a way that does not occur naturally through mating or natural recombination.
The key word here is deliberate. GMOs are not the same as the natural evolution or selective breeding that farmers have done for thousands of years (like breeding wolves into dogs). Selective breeding mixes thousands of genes at once, like shuffling two entire decks of cards. Genetic modification is like taking a single, specific card from one deck and inserting it into a specific spot in another deck.
How does it actually work? (The core idea)
Every living thing — from a bacterium to a mango tree to a human — carries its hereditary information in a molecule called DNA. A gene is a specific segment of that DNA that contains the instructions for making one particular protein. That protein then gives the organism a particular trait, like the colour of a flower or the ability to resist a pest.
In genetic modification, scientists:
- Identify a useful gene from one organism (say, a gene from a soil bacterium that makes a protein toxic to certain insects).
- Isolate that gene and copy it.
- Insert that gene into the DNA of a different organism (say, a cotton plant).
- The cotton plant now reads that new gene and starts producing the insect-killing protein. The cotton plant has been genetically modified to be pest-resistant.
Why does this matter? (The real-world significance)
GMOs are not just a lab curiosity. They are a major part of modern agriculture and medicine. The NCERT textbook highlights two main areas where this technology has had a huge impact:
1. Agriculture: Making crops more useful
The most common GMOs you will encounter are crop plants. The goal is usually to give the plant a new, valuable trait without having to breed it for many generations.
- Pest resistance (Bt crops): A gene from the bacterium Bacillus thuringiensis (Bt) is inserted into crops like cotton and corn. This gene produces a protein that kills specific insect pests (like the cotton bollworm). The plant protects itself, so farmers need to spray fewer chemical pesticides.
- Herbicide tolerance: Some crops are modified to be resistant to a specific weed-killer (herbicide). This allows farmers to spray the herbicide to kill weeds without harming the crop itself.
- Increased nutritional value: A famous example is Golden Rice, which is genetically modified to produce beta-carotene (which the body converts to Vitamin A). This was developed to address Vitamin A deficiency in regions where rice is a staple food.
The NCERT textbook specifically mentions Bt cotton as a major success story in India. It has been widely adopted by farmers because it reduces the need for pesticides and can lead to higher yields. However, it also raises important questions about cost, seed patents, and long-term effects on soil and biodiversity — issues that are debated in economics and environmental studies.
2. Medicine: Producing life-saving drugs
This is where GMOs have had an arguably even more profound impact. Instead of modifying whole plants, scientists often modify microorganisms like bacteria or yeast to act as tiny factories.
- Human Insulin (Humulin): Before GMOs, people with diabetes used insulin from cows or pigs, which could cause allergic reactions. Scientists inserted the human gene for insulin into E. coli bacteria. The bacteria then multiplied and produced large quantities of pure human insulin. This was the first-ever commercial GMO product approved for human use.
- Vaccines and other proteins: Many modern vaccines (like the Hepatitis B vaccine) and other therapeutic proteins are now produced using genetically modified yeast or animal cells. This is safer, cheaper, and more scalable than extracting them from human or animal tissues.
A balanced perspective (What you should know) …
Nematode resistance in tobacco was engineered using RNA interference (RNAi) delivered by an Agrobacterium vector — a landmark example in the NCERT Class 12 Biology chapter on biotechnology and its applications. …
Agrobacterium delivered nematode-specific genes into tobacco to produce dsRNA, which by RNA interference (RNAi) silenced the nematode's own mRNA, so Meloidogyne incognita could not survive in the plant.
Concept. RNA interference (RNAi) is a cellular defence method of silencing a specific mRNA using a complementary double-stranded RNA (dsRNA) molecule. This principle was used to develop nematode-resistant tobacco.
The problem. A nematode, Meloidogyne incognita, infests the roots of tobacco plants and causes a great reduction in yield.
Explanation in correct sequence.
- Nematode-specific genes were identified, and DNA constructs producing both the sense and the antisense RNA of these genes were prepared.
- Using Agrobacterium as a vector, these genes (constructs) were introduced into the tobacco plant (transformation).
- In the transformed (transgenic) plant cells, both the sense and antisense RNA were produced; being complementary, they combined to form a double-stranded RNA (dsRNA).
- This dsRNA initiated RNA interference (RNAi), which silenced the specific (target) mRNA of the nematode. …
Showing the 12 most recent of 17 on this concept.
- AP EAPCET 2026Set ap-2026-05-19-FN1 markMCQQ.Match the following Transgenic plant | Purpose A. Male sterile Brassica plant | I. Herbicide tolerance B. Round up ready soyabean | II. Vector for transgenic plants C. Tomato Flavr Savr | III. For hybrid seed products D. Ti plasmid of Agrobacterium | IV. Bruise resistant (A) A-I, B-II, C-IV, D-III (B) A-II, B-III, C-I, D-IV (C) A-III, B-IV, C-II, D-I (D) A-III, B-I, C-IV, D-II
›Reveal solutionSolution
Match each named transgenic plant/tool to its purpose: male-sterile Brassica→hybrid seed production, Roundup Ready soybean→herbicide tolerance, Flavr Savr tomato→bruise resistance, Ti plasmid→vector — giving A-III, B-I, C-IV, D-II.
Concept and Intuition
Plant biotechnology has produced several landmark transgenic examples, each solving a distinct agricultural problem. Engineered male sterility in Brassica (mustard/cabbage family) prevents self-pollination, making large-scale hybrid seed production practical without labour-intensive manual emasculation. Roundup Ready soybean carries a bacterial gene conferring tolerance to the herbicide glyphosate (Roundup), letting farmers spray the herbicide to kill weeds without harming the crop. The Flavr Savr tomato was engineered (via antisense RNA against the polygalacturonase gene) to soften more slowly, resisting bruising/over-ripening during transport. Separately, the Ti (tumour-inducing) plasmid of Agrobacterium tumefaciens is the natural gene-transfer vector exploited in plant genetic engineering to insert foreign DNA into plant genomes.
Step-by-Step Solution …
- AP EAPCET 2026Set ap-2026-05-19-FN1 markMCQQ.Match the following I | II A. Vitamin A enriched plant | I. lablab B. Protein enriched plant | II. Bitter gourd C. β-carotene enriched plant | III. Carrot D. Vitamin C enriched plant | IV. Rice (A) A-III, B-I, C-IV, D-II (B) A-IV, B-I, C-III, D-II (C) A-II, B-I, C-II, D-III (D) A-I, B-II, C-III, D-IV
›Reveal solutionSolution
Vitamin A→carrot, protein→lablab, β-carotene→(golden) rice, vitamin C→bitter gourd → A-III, B-I, C-IV, D-II.
Concept and Intuition
Biofortification and everyday nutrition both draw on well-known plant-nutrient associations: carrots are a textbook source of vitamin A (via beta-carotene conversion in the body); legumes such as lablab (hyacinth bean, Dolichos lablab) are valued as protein-rich foods, being pulses; genetically enhanced ('Golden') rice is specifically engineered to accumulate beta-carotene, the provitamin-A pigment, addressing vitamin-A-deficiency in rice-staple diets; and bitter gourd (karela) is a vegetable notably rich in vitamin C, often exceeding citrus fruits gram-for-gram.
Step-by-Step Solution
- Vitamin A enriched plant → Carrot = III.
- Protein enriched plant → lablab = I.
- β-carotene enriched plant → Rice (Golden Rice) = IV. …
- AP EAPCET 2026Set ap-2026-05-20-FN1 markMCQQ.Round up ready soyabean has which one of the following feature (A) Rich vitamin-A (B) Herbicide tolerant (C) Male sterility (D) Bacterial blight
›Reveal solutionSolution
Roundup Ready soybean is a genetically modified crop made tolerant to the herbicide glyphosate (Roundup), allowing farmers to spray the herbicide to kill weeds without damaging the soybean crop itself.
Concept and Intuition
One of the earliest and most widely adopted applications of genetic engineering in agriculture is herbicide-tolerant crops. Weeds compete with crop plants for nutrients, light, and water, and are normally controlled by herbicides that unfortunately also kill the crop. By introducing a gene that makes the crop resistant to a specific herbicide, that herbicide can be applied broadly to kill weeds while leaving the crop unharmed.
Step-by-Step Solution
- Roundup is the trade name for the broad-spectrum herbicide glyphosate, which works by inhibiting the EPSPS enzyme in the shikimate pathway — a pathway present in plants and microbes but not animals.
- "Roundup Ready" crops (soybean, and later maize, cotton, canola) were engineered by inserting a gene (originally from an Agrobacterium strain, CP4) that encodes a glyphosate-insensitive version of EPSPS.
- This lets the crop survive normal field doses of glyphosate, so farmers can spray the herbicide over the whole field, killing weeds while the modified soybean plants remain unaffected. …
- AP EAPCET 2026Set ap-2026-05-20-AN1 markMCQQ.Transgenic Brassica napus has following feature (A) Rich in vitamin-C (B) Herbicide tolerant (C) Insect resistance (D) Male sterility
›Reveal solutionSolution
This tests a specific application of genetic engineering to crop improvement: the
barnase–barstar male-sterility/fertility-restorer system, engineered in transgenic
Brassica napus for hybrid seed production.
Concept and Intuition
Producing hybrid seed on a commercial scale requires preventing a chosen female
parent line from self-pollinating, which classically means hand-removing anthers
(emasculation) — slow and expensive at scale. Genetic engineering solved this with
the barnase–barstar system: the barnase gene (a ribonuclease that is lethal to
developing tapetal cells) is engineered into the male parent line under a
tapetum-specific promoter, destroying pollen development and rendering that line
male-sterile; the barstar gene (an inhibitor of barnase) is engineered into the
other (restorer) parent line, so that when the two are crossed, barstar neutralises
barnase in the resulting hybrid and fertility is restored. Brassica napus (canola)
was the crop in which this system was first developed and demonstrated.
Step-by-Step Solution
- Consider each option as a known transgenic-crop trait: vitamin-C enrichment, herbicide tolerance, insect resistance, and male sterility are all real traits engineered into various crops.
- Recall which crop-trait pairing is specifically associated with Brassica napus in genetic-engineering applications: the barnase–barstar male-sterility/ fertility-restoration system for hybrid seed production.
- Vitamin-C enrichment, herbicide tolerance and insect resistance are traits more …
- AP EAPCET 2025Set ap-2025-05-19-AN1 markMCQQ.Choose the correct statement among the following I. Validity of GM research and safety of introduing GMO has to be given by GEAC. II. Molecular farming means utilization of plants as biofactories for obtaining commercially useful products. III. Basmati Rice variety is a transgenic plant with improved nutritional value. IV. "Flaur savr" is suitable for food storage technology. (A) I, II, III (B) II, III, IV (C) I, II, IV (D) I, III, IV
›Reveal solutionSolution
GEAC's regulatory role, the definition of molecular farming, and Flavr Savr's storage benefit are all textbook-correct; only the "Basmati Rice" claim is wrong (that describes Golden Rice), so the correct set is I, II, IV.
Concept and Intuition
Applications of genetic engineering in agriculture and biotechnology governance are commonly tested together: who regulates GMO safety (GEAC), what "molecular farming"/"pharming" means (using plants/animals as production factories for valuable biomolecules), and specific named examples of transgenic crops and their purposes (Flavr Savr for shelf life, Golden Rice for nutrition).
Step-by-Step Solution
- Statement I: GEAC decides the validity of GM research and the safety of introducing GMOs for public/commercial use — this is its defined regulatory role in India — TRUE.
- Statement II: Molecular farming refers to using plants (or animals) as biofactories to produce commercially useful biomolecules (e.g., antibodies, vaccines, pharmaceuticals) — TRUE, standard definition. …
- AP EAPCET 2025Set ap-2025-05-20-FN1 markMCQQ.Study the following lists List - I (Variety) / List - II (Resistance to) A. Transgenic papaya - I. Herbicide B. Bt - cotton - II. Ringspot virus C. Roundup Ready soyabean - III. Phytophthora D. Transgenic Tomato - IV. Insects V. Pseudomonas The correct match is (A) A-II, B-V, C-I, D-IV (B) A-II, B-III, C-IV, D-I (C) A-III, B-I, C-V, D-II (D) A-II, B-IV, C-I, D-V
›Reveal solutionSolution
Matching each transgenic crop to what it was engineered to resist gives papaya–ringspot virus, Bt-cotton–insects, Roundup Ready soybean–herbicide, transgenic tomato–Pseudomonas (bacterial wilt), i.e. A-II, B-IV, C-I, D-V, option (D).
Concept and Intuition
Genetic engineering has produced several well-known transgenic crop varieties, each modified for resistance against a specific biotic or chemical stress — recognising each crop's specific engineered trait is the task here.
Step-by-Step Solution
- A) Transgenic papaya was engineered to resist ringspot virus infection, a major papaya disease → II.
- B) Bt-cotton carries a Bacillus thuringiensis toxin gene that confers resistance to insect pests (bollworms) → IV.
- C) Roundup Ready soybean was engineered to tolerate the herbicide glyphosate (Roundup), allowing broad-spectrum weed control without harming the crop → I. …
- AP EAPCET 2024Set ap-2024-05-16-AN1 markMCQQ.This Nutrient is present more in Golden rice when compare to conventional Rice (A) Vitamin C (B) Iron (C) Calcium (D) Beta Carotene
›Reveal solutionSolution
Golden rice is genetically engineered to accumulate beta-carotene (pro-vitamin A) in its endosperm, unlike conventional rice, the hallmark trait behind its name and purpose.
Concept and Intuition
Vitamin A deficiency is a major public health problem in populations that rely heavily on polished rice, since rice endosperm naturally contains essentially no beta-carotene (the plant does synthesise it in the leaves, but the biosynthetic pathway is switched off in the endosperm). Golden rice was created by introducing genes encoding key enzymes of the beta-carotene biosynthetic pathway (from daffodil, and later a more efficient version from maize, plus a bacterial gene) into rice, restoring beta-carotene production specifically in the edible endosperm. Beta-carotene gives the rice grains their characteristic golden-yellow colour (hence the name) and, once consumed, is converted by the human body into vitamin A, helping address deficiency-related conditions like childhood blindness.
Step-by-Step Solution
- Recall the specific genetic engineering goal behind Golden rice: restoring beta-carotene synthesis in the rice endosperm. …
- AP EAPCET 2024Set ap-2024-05-17-AN1 markMCQQ.Match the following A - lablab, B - Golden Rice, C - Pumpkin, D - Bitter gourd I - β-carotene, II - Enriched protein, III - Vitamin C, IV - Vitamin A (A) A – II B - IV C - III D - I (B) A – IV B - III C - II D - I (C) A – III B - IV C - II D - I (D) A – II B - I C - IV D - III
›Reveal solutionSolution
This is a biofortification/nutrient-content matching question. Golden Rice's signature trait is β-carotene enrichment, which alone fixes the correct combination.
Concept and Intuition
Biofortification means breeding or engineering crops for higher nutrient content. Golden Rice is the textbook example — genetically engineered with genes for β-carotene (provitamin A) biosynthesis. The other three crops in the list are valued as natural dietary sources of specific nutrients (protein, vitamin A, vitamin C).
Step-by-Step Solution
- Golden Rice (B): engineered specifically to accumulate β-carotene → B–I.
- Lablab (A): a legume valued for its high protein content, used to biofortify diets with enriched protein → A–II.
- Pumpkin (C): a natural dietary source rich in carotenoids, commonly cited as a Vitamin A-rich food → C–IV.
- Bitter gourd (D): well known as a Vitamin C-rich vegetable → D–III. …
- AP EAPCET 2024Set ap-2024-05-17-FN1 markMCQQ.Study the table and find correct combination(A) I, III (B) II, IV (C) I, II (D) III, IV
I Brassica napus Male sterile plants Herbicide tolerance II Nematodes RNA Interference Tobacco III Insulin Eli Willey Agrobacterium IV Basmati Transgenic plant Abiotic stress ›Reveal solutionSolution
Male-sterility in Brassica is for hybrid-seed production (not herbicide tolerance), and insulin production uses E. coli (not Agrobacterium) — eliminating I and III leaves II and IV as the correctly matched rows.
Concept and Intuition
Biotechnology application questions like this test whether the "organism/process," "technique," and "purpose/host" are genuinely linked as per known case studies: male-sterility engineering (e.g., barnase-barstar in Brassica) exists to make hybrid seed production efficient by preventing self-pollination — it is unrelated to herbicide tolerance (a different trait, engineered via genes like EPSPS/bar). RNA interference (RNAi) silences specific genes via double-stranded RNA; a textbook case is producing nematode-resistant tobacco by targeting genes essential to the nematode Meloidogyne incognita. Recombinant insulin (Humulin, by Eli Lilly) is manufactured by inserting the human insulin A and B chain genes into E. coli, not via Agrobacterium (which is specifically a plant-transformation vector, irrelevant to bacterial fermentation-based insulin production).
Step-by-Step Solution
- Row I: Brassica napus male-sterile plants are a hybrid-seed-production tool, not a herbicide-tolerance trait — mismatch, false.
- Row II: Nematode resistance via RNAi expressed in tobacco is the standard cited example — true.
- Row III: recombinant insulin (associated with Eli Lilly) is produced in E. coli, not via Agrobacterium-mediated transformation — mismatch, false. …
- AP EAPCET 2023Set ap-2023-05-22-FN1 markMCQQ.The introduction of nematode specific genes into host using agrobacterium vectors causes the following action. I. Formation of dsRNA. II. Production of sense and antisense RNAs in the host cells. III. RNA intermediate not formed. IV. Silencing of specific mRNA of the nematode. (A) II, III, IV (B) I, II, III (C) I, II, IV (D) I, III, IV
›Reveal solutionSolution
This is RNAi-based nematode resistance in transgenic plants: sense and antisense RNA form dsRNA, which silences the nematode's mRNA — so I, II, and IV are correct, and III (claiming no RNA intermediate forms) is false.
Concept and Intuition
RNA interference is a natural cellular defence mechanism against foreign/aberrant double-stranded RNA. Biotechnologists exploit it: a nematode-specific gene is cloned into an Agrobacterium-based vector in a way that the host cell transcribes both the sense (coding-strand) and antisense (template-strand) RNA of that gene. These two complementary RNAs base-pair to form double-stranded RNA (dsRNA) inside the transgenic root cells. When a nematode invades and feeds on these root cells, it takes up the dsRNA, which triggers the RNAi pathway and specifically degrades/silences the nematode's own corresponding mRNA — so the nematode cannot express that gene and cannot survive/reproduce on the transgenic host.
Step-by-Step Solution
- Nematode-specific gene delivered into the plant genome via Agrobacterium (Ti-plasmid-based vector).
- Host cell's own transcription machinery produces both sense and antisense RNA copies of this gene (Statement II — true). …
- AP EAPCET 2023Set ap-2023-05-23-FN1 markMCQQ.The transgenic Flavr Savr tomato carries cloned genes for A. delay in ripening process B. longer shelf life C. added flavors D. vitamin A (A) A & D (B) A & B (C) A, C & D (D) A, B & C
›Reveal solutionSolution
Flavr Savr = delayed ripening + longer shelf life + retained flavour (antisense polygalacturonase). Vitamin A is Golden Rice, not Flavr Savr. So A, B and C only.
Concept and Intuition
Why does a tomato go soft? As it ripens, the enzyme polygalacturonase (PG) digests the pectin that cements the cell walls together. Soft fruit bruises in transit, so growers pick tomatoes green, ship them hard, and gas-ripen them with ethylene at the destination — which is precisely why supermarket tomatoes taste of nothing: they never ripened on the vine, where flavour compounds are made.
The Flavr Savr solution is elegant antisense technology:
- A reverse-oriented (antisense) copy of the PG gene is inserted into the tomato genome.
- It transcribes an antisense mRNA that is complementary to the normal (sense) PG mRNA.
- The two strands hybridise to form double-stranded RNA, which cannot be translated and is degraded — so very little PG enzyme is made.
- Pectin survives; the fruit softens far more slowly.
The consequences chain together: slower softening → the fruit can be left to ripen on the vine and still survive transport → it keeps for longer (longer shelf life) → and, having ripened naturally, it keeps its taste and flavour. That is the whole marketing promise packed into the name Flavr Savr.
Step-by-Step Solution
- A. Delay in ripening process — the direct effect of silencing polygalacturonase. Correct.
- B. Longer shelf life — the immediate commercial consequence of slower softening. Correct. …
- AP EAPCET 2022Set ap-2022-07-11-AN1 markMCQQ.Transgenic Golden Rice obtained from 'Taipei' is a rich source of ______________ prevents blindness (A) Vitamin - K (B) Vitamin - C (C) Vitamin - B (D) Vitamin - A
›Reveal solutionSolution
Golden Rice is genetically engineered to produce beta-carotene, the precursor of Vitamin A, to address Vitamin A deficiency-related blindness.
Concept and Intuition
Vitamin A deficiency is a leading cause of preventable childhood blindness, especially in populations that rely heavily on rice, which naturally lacks beta-carotene in its edible endosperm. Scientists genetically engineered a rice variety (using Oryza sativa cv. Taipei 309 as the transformation host) by introducing genes for the beta-carotene biosynthetic pathway, producing what is popularly called "Golden Rice" due to its yellow-orange colour from the accumulated beta-carotene.
Step-by-Step Solution
- Recall the specific transgenic crop example from biotechnology applications: Golden Rice.
- Golden Rice was engineered specifically to biosynthesize beta-carotene, the metabolic precursor that the human body converts into Vitamin A. …
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