CUET UG Biology Booster Test 2-Pest Resistance Technology -

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CUET UG Biology Booster Test 2-Pest Resistance Technology

⏱️ 30 Minutes

❓ 20 Questions

📌 Answers are locked once submitted — results and explanations appear at the end.

CUET UG Biology Booster Test 2-Pest Resistance Technology

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QUESTION 1 OF 20

Which of the following is NOT an advantage of utilising Bacillus thuringiensis in agricultural crop management?

Answer Review

1 Which of the following is NOT an advantage of utilising Bacillus thuringiensis in agricultural crop management?

A It reduces the reliance on chemical pesticides.

B It acts as a bio-pesticide when expressed in plants.

C It increases the reliance on traditional agrochemical applications.

D It is target-specific, largely affecting certain insect groups.

💡 Short Explanation

Bt technology is designed to decrease chemical use. Increased reliance on agrochemicals is a failure, not an advantage. It contradicts the primary purpose of transgenic crops.

✅ Correct Answer Explanation

The objective of using Bt crops is to replace chemical sprays with bio-pesticides. Statement C claims it increases chemical reliance, which is the exact opposite of the technological intent. All other options (A, B, D) are well-documented advantages of Bt technology.

❓ Why Other Options Are Incorrect

Option A → Reducing chemical pesticide reliance is a major environmental benefit.
Option B → Bt genes expressed in plants function as integrated bio-pesticides.
Option D → Target specificity minimizes harm to non-target/beneficial insects.

🎯 Strategy

Used: Elimination

Application: Identifying the option that describes a negative outcome rather than an advantage.

Final Logic: Bt = Less chemicals, not more.

🧠 Memory Trick

"Bt = Fewer Chemicals."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Cotton –

2 If a scientist wants to create a pest-resistant tomato plant, why would they choose to clone and express the Bt toxin gene rather than applying conventional chemical pesticides?

A The Bt gene prevents the plant from absorbing heavy metals from the soil.

B The Bt gene allows the plant to produce its own insecticide, providing continuous protection without chemical sprays.

C The Bt gene increases the post-harvest shelf life of the tomato.

D The Bt gene improves the nutritional value by adding Vitamin A.

💡 Short Explanation

Bt crops are genetically programmed to kill target pests. It provides "in-built" protection. Options A, C, and D describe different functions (heavy metal, shelf-life, or nutrition), not pest resistance.

✅ Correct Answer Explanation

Cloning the Bt toxin gene into a plant enables the plant to produce its own insecticidal protein, which provides constant, internal protection against target pests, thereby eliminating the need for periodic chemical applications.

❓ Why Other Options Are Incorrect

Option A → Bt genes are for pest control, not heavy metal management.
Option C → Delayed ripening is for shelf-life, not insect resistance.
Option D → Nutritional improvement is the goal of Golden Rice, not Bt technology.

🎯 Strategy

Used: Contextual/Tonal Matching

Application: Matching the specific function (pest resistance) to the Bt gene's primary purpose.

Final Logic: Bt = Insecticide production.

🧠 Memory Trick

"Self-made Insecticide."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Cotton –

3 A farmer notices that tobacco budworms are devastating his crops. Knowing the specificity of Bt toxins, he should look for a transgenic plant strain designed to target which specific order of insects?

A Dipterans

B Coleopterans

C Lepidopterans

D Nematodes

💡 Short Explanation

Tobacco budworms belong to the Order Lepidoptera. Bt toxins are order-specific. Therefore, he needs a strain effective against Lepidopterans.

✅ Correct Answer Explanation

Bt toxin proteins are highly specific. Tobacco budworms (and armyworms) are biologically classified as Lepidopterans. To control them, the crop must express a Bt toxin gene that specifically targets the Lepidopteran order.

❓ Why Other Options Are Incorrect

Option A → Dipterans (flies/mosquitoes) are not the target group for budworms.
Option B → Coleopterans (beetles) have a different target toxin profile.
Option D → Nematodes are not insects and require different management.

🎯 Strategy

Used: Substitution

Application: Identifying the correct biological order for the mentioned pest.

Final Logic: Budworm = Lepidopteran.

🧠 Memory Trick

"Lepidopteran = Budworm."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Toxin Specificity –

4 Match the specific agricultural pests to their broader biological classifications as outlined in pest-resistance technologies:

Column I	Column II
1. Armyworm	i. Coleopteran
2. Beetle	ii. Nematode
3. Mosquito	iii. Lepidopteran
4. Meloidogyne	iv. Dipteran

A 1-iii, 2-i, 3-iv, 4-ii

B 1-i, 2-iii, 3-ii, 4-iv

C 1-iii, 2-iv, 3-i, 4-ii

D 1-ii, 2-i, 3-iv, 4-iii

💡 Short Explanation

Armyworm (1) = Lepidopteran (iii). Beetle (2) = Coleopteran (i). Mosquito (3) = Dipteran (iv). Meloidegyne (4) = Nematode (ii).

✅ Correct Answer Explanation

Correct matching follows standard entomological classification: Armyworms are moths/butterflies (Lepidopter A), Beetles are Coleoptera, Mosquitoes are Diptera, and Meloidegyne is a parasitic Nematode.

❓ Why Other Options Are Incorrect

Options B, C, D → Misalign the order and class labels, leading to taxonomic errors.

🎯 Strategy

Used: Option Grouping

Application: Sorting pests into their specific orders as required for biotech application.

Final Logic: Taxonomic precision.

🧠 Memory Trick

"A-L, B-C, M-D, N-N."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Pest Specificity –

5 Why is the timing of protein crystal formation (during a particular phase of growth) significant for the survival of Bacillus thuringiensis?

A The crystals are only active during this specific phase, allowing the bacteria to reproduce first.

B The crystals are formed as inactive protoxins, ensuring they do not harm the bacteria during their critical growth period.

C The crystals immediately break down the bacterial cell wall once growth is complete.

D The crystals require light for formation, which only occurs during this phase.

💡 Short Explanation

Crystals are toxic if active. Production as inactive protoxins prevents self-harm. This ensures the bacteria survive while creating the insecticide.

✅ Correct Answer Explanation

Bacillus thuringiensis must survive to proliferate. By synthesizing the toxin in an inactive "protoxin" form during a specific growth phase, the bacterium avoids autotoxicity (killing itself) while successfully packaging the insecticidal protein.

❓ Why Other Options Are Incorrect

Option A → The crystals are inert until ingested; it's not about the bacterium's reproduction cycle.
Option C → This would be suicidal for the bacteria.
Option D → Light is not a factor in this process.

🎯 Strategy

Used: Elimination

Application: Eliminating options that would cause the bacteria to die.

Final Logic: Bacteria survival depends on protoxin .

🧠 Memory Trick

"Inactive = Safe."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Toxin Mechanism –

6 Which of the following is NOT an accurate statement regarding the toxic insecticidal protein found in the crystals?

A It solubilises in an alkaline environment.

B It requires ingestion by an insect to become active.

C It binds specifically to the surface of hindgut epithelial cells.

D It creates pores leading to cell swelling and lysis.

💡 Short Explanation

The text specifies binding to midgut epithelial cells, not hindgut. Therefore, C is the inaccurate statement.

✅ Correct Answer Explanation

Bt toxins specifically target receptors on the surface of the midgut epithelial cells. The hindgut is not the site of action for this toxin. All other statements (A, B, D) accurately describe the toxin's chemical and physiological path.

❓ Why Other Options Are Incorrect

Option A → Alkaline conditions do indeed solubilise the crystals.
Option B → Ingestion is the required step for activation.
Option D → Pores causing lysis is the standard mechanism of action.

🎯 Strategy

Used: Substitution

Application: Correcting the specific anatomy mentioned (midgut vs hindgut).

Final Logic: Binding occurs in the midgut.

🧠 Memory Trick

"Bt = Midgut target."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Toxin Mechanism –

📄 Passage

"Actually, the Bt toxin protein exist as inactive protoxins but once an insect ingest the inactive toxin, it is converted into an active form of toxin due to the alkaline pH of the gut which solubilise the crystals. The activated toxin binds to the surface of midgut epithelial cells..."

Based on the passage, the primary reason the Bacillus is immune to its own toxin is because:

A It lacks a midgut epithelium.

B The toxin exists strictly as an inactive protoxin within the bacteria.

C The bacteria continuously secrete alkaline neutralizing agents.

D The toxin is immediately expelled upon creation.

💡 Short Explanation

The protoxin state is non-toxic. Immunity is not about lacking an epithelium or neutralizing agents; it is about the state of the toxin.

✅ Correct Answer Explanation

The Bacillus produces the toxin in an inactive form (protoxin) that does not interact with cellular machinery. It only gains toxicity after being solubilized in the alkaline gut of the target insect, keeping the host bacterium safe.

❓ Why Other Options Are Incorrect

Option A → Bacillus lack epithelial cells entirely, so it's not a primary reason for immunity; the protoxin state is the functional barrier.
Option C → No secretion of neutralizing agents is involved.
Option D → No expulsion happens; the crystals remain.

🎯 Strategy

Used: Substitution

Application: Identifying the core mechanism (protoxin) mentioned in the passage.

Final Logic: Protoxin = Immunity.

🧠 Memory Trick

"Inactive = Safe."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Toxin Mechanism –

📄 Passage

According to the passage, the specific biochemical function of the alkaline pH in the insect's gut is to:

A Bind the toxin to the epithelial cells.

B Cause the epithelial cells to swell and lyse.

C Solubilise the protein crystals.

D Initiate RNA interference.

💡 Short Explanation

The passage states: "alkaline pH of the gut which solubilise the crystals." Solubilisation is the first step in activation.

✅ Correct Answer Explanation

Alkalinity is the environmental key that releases the active toxin from the crystalline state by solubilising it, allowing it to interact with gut receptors.

❓ Why Other Options Are Incorrect

Option A → Binding is mediated by receptors, not pH.
Option B → Lysis is the result of pore formation, not pH directly.
Option D → RNAi is a different technique.

🎯 Strategy

Used: Contextual/Tonal Matching

Application: Extracting the exact process (solubilisation) described in the passage.

Final Logic: Alkaline pH = Solubiliser.

🧠 Memory Trick

"Alkaline = Solubiliser."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Toxin Mechanism –

9 Sequence the cellular level actions from the moment an activated Bt toxin encounters the insect's internal anatomy:
1. Create pores.
2. Bind to epithelial surfaces.
3. Death of insect.
4. Cell swelling and lysis (caused by pores).

A 2, 1, 4, 3

B 1, 2, 4, 3

C 2, 4, 1, 3

D 4, 1, 2, 3

💡 Short Explanation

1. Bind to epithelial surfaces. 2. Create pores. 3. Cell swelling and lysis (caused by pores). 4. Death of insect.

✅ Correct Answer Explanation

The toxin binds to receptors on the cell surface (2), causing holes/pores (1) to form in the membrane. This triggers water influx, leading to swelling and lysis (4). The destruction of the gut epithelium results in the insect's death (3).

❓ Why Other Options Are Incorrect

Options B, C, D → Misorder the physiological cause-and-effect chain.

🎯 Strategy

Used: Elimination

Application: Logic follows Bind -> Pore -> Lysis -> Death.

Final Logic: Binding starts the chain.

🧠 Memory Trick

"Bind-Pore-Lysis-Death."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Toxin Mechanism –

10 Consider the physiological impacts of Bt toxin pore formation:
I. It leads directly to the dehydration of the insect.
II. It causes cell swelling and lysis of the midgut epithelium.
III. It eventually causes the death of the insect. Which of the statements is/are correct?

A II only

B I and II only

C II and III only

D I, II, and III

💡 Short Explanation

Statement I is false: The pores cause lysis via osmotic swelling (intake of water), not dehydration. Statement II is true: This is the mechanism of action. Statement III is true: The death is the outcome.

✅ Correct Answer Explanation

Pore formation leads to osmotic water uptake, not dehydration. The subsequent swelling and cell bursting (lysis) destroy the gut, leading to the insect's eventual death. Thus, only II and III are correct.

❓ Why Other Options Are Incorrect

Options A, B, D → These include the incorrect claim about dehydration.

🎯 Strategy

Used: Elimination

Application: Filtering for the incorrect process (dehydration).

Final Logic: Osmotic swelling = Lysis, not dehydration.

🧠 Memory Trick

"Swelling = Water intake."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Toxin Mechanism –

11 Match the elements involved in the genetic engineering of pest-resistant crops to their roles:

Column I	Column II
1. Bacillus thuringiensis	i. Lepidopteran or Coleopteran
2. Isolated Gene	ii. Expresses the toxin
3. Targeted Pest	iii. Source organism
4. Host Plant	iv. Determines specificity (cryIAc)

A 1-iii, 2-iv, 3-i, 4-ii

B 1-iii, 2-ii, 3-i, 4-iv

C 1-iv, 2-iii, 3-ii, 4-i

D 1-ii, 2-iv, 3-i, 4-iii

💡 Short Explanation

Bacillus thuringiensis (1) = Source organism (iii). Isolated Gene (2) = Determines specificity (cryIA C) (iv). Targeted Pest (3) = Lepidopteran or Coleopteran (i). Host Plant (4) = Expresses the toxin (ii).

✅ Correct Answer Explanation

Bacillus thuringiensis is the source bacterium. The specific gene isolated determines the insect specificity (e.g., cryIA C). The target pest (e.g., bollworm) dictates which gene is needed, and the transgenic host plant expresses the protein to act as a bio-pesticide.

❓ Why Other Options Are Incorrect

Options B, C, D → Incorrectly pair the source, gene, pest, or role, leading to mismatched biological functions.

🎯 Strategy

Used: Option Grouping

Application: Aligning the biological components with their respective roles in transgenic plant production.

Final Logic: Proper matching of source, gene, pest, and host roles.

🧠 Memory Trick

"B-S, G-S, P-T, H-E." (Bacteria-Source, Gene-Specificity, Pest-Target, Host-Expression).

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Gene Isolation –

12 When incorporating Bt toxin genes into host plants, why must farmers select specific plant varieties containing specific cry genes rather than a universal Bt crop?

A Because all cry genes require different fertilizers to function.

B Because most Bt toxins are highly insect-group specific, depending on the targeted pest of that specific crop.

C Because some plants naturally repel Agrobacterium vectors.

D Because universal Bt crops degrade the soil's mineral usage efficiency.

💡 Short Explanation

Bt toxins are order-specific. A toxin effective against beetles (ColeopterA) won't work on moths (LepidopterA). Specificity is the fundamental principle of Bt technology.

✅ Correct Answer Explanation

The effectiveness of Bt toxin is strictly tied to the interaction between the toxin protein and the specific receptors in the target insect's gut. Since different insects have different gut receptors, a specific cry gene must be selected for the specific pest being managed.

❓ Why Other Options Are Incorrect

Option A → Fertilizers are not related to Bt gene function.
Option C → The vector choice (Agrobacterium) is distinct from the insect-group specificity.
Option D → Bt crops do not inherently decrease mineral usage efficiency.

🎯 Strategy

Used: Substitution

Application: Identifying the principle of "Target-Specificity."

Final Logic: Specific Gene = Specific Pest.

🧠 Memory Trick

"Bt = Specific Lock & Key."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Toxin Specificity –

13 Trace the intended path of the cryIAc encoded protein from its genetic blueprint to its target:
1. Plant expresses the protein.
2. Isolate gene from B. thuringiensis.
3. Bollworm ingests the tissue.
4. Incorporate gene into cotton genome.

A 2, 4, 1, 3

B 2, 1, 4, 3

C 4, 2, 1, 3

D 1, 2, 4, 3

💡 Short Explanation

1. Isolate gene from B. thuringiensis. 1. Incorporate gene into cotton genome. 1. Plant expresses the protein. 1. Bollworm ingests the tissue.

✅ Correct Answer Explanation

The sequence begins with isolating the gene (2) from the bacterium, followed by genetic transformation to insert it into the host plant (4). The plant then expresses the insecticidal protein (1), and finally, the pest ingests the tissue (3) to be controlled.

❓ Why Other Options Are Incorrect

Options B, C, D → Misorder the sequence of gene transfer, protein expression, and ingestion.

🎯 Strategy

Used: Elimination

Application: Ordering the biotechnological pipeline from source to field application.

Final Logic: Isolation -> Insertion -> Expression -> Ingestion.

🧠 Memory Trick

"Isolate-Insert-Express-Ingest."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Bt Cotton –

14 Which of the following is NOT correctly paired regarding the cry genes and their primary insect targets?

A cryIAc - Cotton bollworms

B cryIIAb - Cotton bollworms

C cryIAb - Corn borer

D cryIAb - Tobacco budworms

💡 Short Explanation

Tobacco budworms are targeted by cryIAc/IIAb, not cryIAb. cryIAb is associated with corn borer.

✅ Correct Answer Explanation

According to the NCERT reference table, cryIAb is specifically used for the corn borer. Tobacco budworms and cotton bollworms are controlled by cryIAc and cryIIAb. Therefore, pairing D is incorrect.

❓ Why Other Options Are Incorrect

Option A, B, C → These are correct mappings based on the NCERT table.

🎯 Strategy

Used: Option Grouping

Application: Identifying the incorrect mapping of gene-to-pest.

Final Logic: Check the specific gene code against the pest name.

🧠 Memory Trick

"Corn = IAb."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: Cry Genes Table –

15 If a crop field is heavily infested with Meloidegyne incognitia, which innovative biotechnological discussed in the text would be most appropriate to deploy?

A Introduction of cryIAb genes into the crop

B Application of traditional agro-chemical pesticides

C Adoption of a based on RNA interference (RNAi)

D Micro-propagation of the existing infected plants

💡 Short Explanation

Meloidegyne incognitia is a nematode. Bt genes (like cryIA B) target insects, not nematodes. RNAi is the specific biotech method for nematode control.

✅ Correct Answer Explanation

Meloidegyne incognitia is a root-knot nematode. Since it is not an insect, Bt toxins are ineffective. RNAi, a process of gene silencing, is specifically employed to create resistance against this nematode by interfering with its vital mRNA.

❓ Why Other Options Are Incorrect

Option A → Bt genes only work on target insects.
Option B → The question asks for an innovative biotech , not traditional chemicals.
Option D → Micro-propagation does not solve the infestation.

🎯 Strategy

Used: Substitution

Application: Matching the pest type (nematode) with the correct technological solution (RNAi).

Final Logic: Nematode = RNAi.

🧠 Memory Trick

"Nematode = RNAi."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: RNAi/Nematodes –

16 Regarding the infection of tobacco roots by nematodes, which of the following statements is NOT a consequence or characteristic of this specific pest-host interaction?
Options:

A A) The infection leads to a great reduction in agricultural yield.

B B) The infection targets the root system of the tobacco plant.

C C) The pest involved is a parasitic nematode.

D D) The infection is effectively countered by alkaline solubilisation of crystals in the nematode's gut.

💡 Short Explanation

Alkaline solubilisation describes Bt toxin action (insects), not RNAi (nematode).

Nematodes are controlled by RNAi, not crystalline toxins.

✅ Correct Answer Explanation

Statement D describes the Bacillus thuringiensis toxin mechanism, which applies to insects, not nematodes. Nematodes like Meloidegyne are managed via RNAi, not crystalline toxin ingestion.

❓ Why Other Options Are Incorrect

Option A, B, C → These are all true characteristics of the Meloidegyne infection on tobacco roots.

🎯 Strategy

Strategy Used: Elimination

Application: Identifying the statement that confuses two different technologies (Bt vs RNAi).

Final Logic: Nematode control is not via toxin crystals.

🧠 Memory Trick

"Nematode = Silence (RNAi), not Toxin."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: RNAi Mechanism – –201

17 Consider the cellular defense mechanism of RNAi:
I. It occurs in all eukaryotic organisms.
II. It can be naturally initiated by infections from viruses with RNA genomes.
III. It can be naturally initiated by mobile genetic elements (transposons). Which of the statements are correct?

A I and II only

B II and III only

C I and III only

D I, II, and III

💡 Short Explanation

RNAi is a universal eukaryotic defense (I). Viral RNA triggers RNAi (II). Transposons are also known to trigger RNAi pathways (III).

✅ Correct Answer Explanation

RNA interference is a fundamental eukaryotic process. It serves to protect the genome from exogenous RNA (like viruses) and endogenous genetic hazards (like mobile genetic elements or transposons), making all three statements correct.

❓ Why Other Options Are Incorrect

Options A, B, C → These are incomplete as all three statements align with NCERT facts.

🎯 Strategy

Used: Contextual/Tonal Matching

Application: Confirming the universal nature and trigger points of RNAi as defined in the text.

Final Logic: RNAi protects against both "outside" (viruses) and "inside" (transposons) threats.

🧠 Memory Trick

"RNAi = Global Eukaryotic Guard."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: RNAi –

18 In the process of RNA interference, how does the complementary dsRNA molecule effectively neutralize the threat?

A By digesting the target organism's cell wall

B By binding to and preventing the translation of specific mRNA

C By altering the pH of the cellular cytoplasm

D By creating pores in the midgut epithelial cells

💡 Short Explanation

RNAi silences gene expression. The dsRNA binds to the mRNA, preventing protein synthesis. This is the definition of "silencing."

✅ Correct Answer Explanation

The complementary dsRNA molecule created through RNAi binds to the target mRNA of the parasite, preventing the parasite from producing the proteins it needs to infect or colonize the host plant. This "silencing" effectively neutralizes the threat.

❓ Why Other Options Are Incorrect

Option A, C, D → These are not the mechanism of RNAi; D describes the Bt toxin mechanism.

🎯 Strategy

Used: Substitution

Application: Explaining the term "silencing" as mRNA translation prevention.

Final Logic: dsRNA prevents translation.

🧠 Memory Trick

"Silencing = mRNA Block."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: RNAi Mechanism –

19 What specific role do Agrobacterium vectors play in developing nematode-resistant plants?

A They act as the complementary RNA to silence the nematode mRNA.

B They are used to introduce nematode-specific genes into the host plant.

C They directly attack and kill the nematode in the soil.

D They produce the toxic protein crystals that paralyze the nematode.

💡 Short Explanation

Agrobacterium is a tool for transformation. It introduces the DNA construct (for sense/anti-sense RN A) into the plant. It does not attack the nematode directly.

✅ Correct Answer Explanation

Agrobacterium tumefaciens is a natural genetic engineer used to transfer specific nematode-derived DNA sequences into the plant genome. The plant then uses this DNA to produce the dsRNA required for silencing the nematode's genes.

❓ Why Other Options Are Incorrect

Option A → The plant's genetic machinery does the work; the vector just delivers the DNA.
Option C → The vector is a plant pathogen/delivery tool, not a nematode predator.
Option D → Protein crystals are part of the Bt technology, not RNAi.

🎯 Strategy

Used: Elimination

Application: Identifying the vector's function as a delivery mechanism.

Final Logic: Agrobacterium = DNA delivery tool.

🧠 Memory Trick

"Agro = DNA Deliverer."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: RNAi Methodology –

20 For RNAi to successfully protect a transgenic plant from a parasite, the introduced DNA must be arranged to produce both sense and anti-sense RNA. Why is this dual production necessary?

A trigger.

B They are complementary to each other and form the required double-stranded RNA (dsRN

C The sense RNA kills the nematode, while the anti-sense RNA heals the root.

D It ensures the plant can still conduct photosynthesis while defending itself.

💡 Short Explanation

dsRNA (double-stranded RNA) is needed for silencing. Sense + Anti-sense = Complementary strands. Complementary strands form the "trigger" (dsRNA).

✅ Correct Answer Explanation

The RNAi mechanism relies specifically on double-stranded RNA. By designing the transgene to produce both sense and anti-sense RNA, the plant creates these complementary molecules that naturally hybridize to form the dsRNA trigger, which then initiates the silencing of he parasite's mRNA.

❓ Why Other Options Are Incorrect

Option A, C, D → These are incorrect; they represent misconceptions about the mechanism of interference.

🎯 Strategy

Used: Substitution

Application: Defining the necessity of "double-stranded" structure for the RNAi trigger.

Final Logic: Complementary strands = dsRNA.

🧠 Memory Trick

"Sense + Anti-sense = dsRNA (The Trigger)."

📚 Class XII – Biology – Chapter: Biotechnology and its Applications – Topic: RNAi Mechanism –

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