30 MCQs — Biotic stress & plant defenses (CSIR-NET Part B & C style

Biotic stress & plant responses टॉपिक से CSIR-NET (Part B) स्टाइल के 30 MCQs बनाए हैं। हर प्रश्न memory-/concept-based है ताकि बार-बार करने पर आपका कॉन्सेप्ट crystal clear हो जाए। सभी प्रश्नों के सही उत्तर और संक्षिप्त (1-2 लाइन) explanations मैंने अंत में एक साथ दिए हैं — पहले खुद attempt करिए, फिर answer-key से मिलाइए।

30 MCQs — Biotic stress & plant defenses (CSIR-NET Part B style)

Q1. Constitutive plant defenses are best described as:

A. Induced only after attack

B. Always present and pre-formed

C. Always proteinaceous

D. Only produced in roots

Q2. Which of the following is an example of a constitutive chemical defense?

A. Phytoalexins

B. Proteinase inhibitors induced after herbivory

C. Tannins present in young leaves by default

D. Jasmonic acid surge after wounding

Q3. The Optimal Defense Hypothesis predicts:

A. Older tissues have higher constitutive defenses than younger ones

B. Defense compounds are randomly distributed in plant

C. Younger, valuable tissues will have higher levels of defense compounds

D. Inducible defenses are always absent in young leaves

Q4. A major disadvantage of maintaining high constitutive defenses is:

A. They promote faster growth

B. High metabolic cost reducing allocation to growth/reproduction

C. They are ineffective against all herbivores

D. They always trigger systemic acquired resistance

Q5. Which insect feeding guild typically activates the jasmonic acid (JA) signaling pathway?

A. Phloem feeders (aphids)

B. Chewing insects (caterpillars)

C. Biotrophic pathogens

D. Root-nodule symbionts

Q6. Phloem feeders such as aphids more closely elicit plant responses similar to:

A. Chewing herbivores

B. Necrotrophic pathogens

C. Biotrophic pathogens (salicylic acid-type responses)

D. Drought stress responses

Q7. Proteinase inhibitors in plants act by:

A. Blocking insect feeding behavior via taste only

B. Inhibiting herbivore digestive proteases like trypsin and chymotrypsin

C. Lysing insect midgut cells directly

D. Stimulating insect growth

Q8. Which statement about insect adaptation to proteinase inhibitors is TRUE?

A. Insects cannot adapt to proteinase inhibitors

B. Some insects express inhibitor-resistant digestive proteases

C. Insects use proteinase inhibitors for their own digestion

D. Proteinase inhibitors only affect microbial pathogens

Q9. GLR (glutamate receptor-like) genes in Arabidopsis are required for:

A. Localized cell death only

B. Long-distance electrical signaling after herbivory

C. Constitutive synthesis of tannins

D. Direct synthesis of jasmonic acid

Q10. A glr3.3/glr3.6 double mutant shows:

A. Enhanced long-distance electrical signals

B. Loss of electrical wave propagation and reduced distal jasmonate responses

C. Constitutive jasmonate production in all leaves

D. No change in herbivore response

Q11. Herbivore-induced plant volatiles (HIPVs) function to:

A. Attract natural enemies (parasitoids/predators) of the herbivore

B. Increase leaf palatability to herbivores

C. Decrease systemic signaling within the plant

D. Replace constitutive defenses

Q12. Volicitin, an elicitor in caterpillar saliva, primarily induces:

A. Protease inhibitors only

B. Volatile terpenoid emission that attracts parasitoids

C. Cuticle thickening within seconds

D. Systemic acquired resistance via salicylic acid only

Q13. Which classes of secondary metabolites commonly make up HIPV blends?

A. Terpenoids, alkaloids, phenylpropanoids

B. Only polysaccharides

C. Only proteins and peptides

D. Nucleic acids

Q14. Green-leaf volatiles released after wounding are derived from:

A. Carotenoid pathway

B. Lipid peroxidation (lipoxygenase pathway) — C6 aldehydes/alcohols

C. Shikimate pathway only

D. Nitrogen fixation

Q15. Inducible defenses are advantageous because:

A. They are cost-free to the plant

B. They are produced only when needed, saving resources

C. They always work faster than constitutive defenses

D. They prevent any future attack permanently

Q16. Which signaling molecule/pathway is most commonly associated with defense against sap-sucking insects and many biotrophic pathogens?

A. Jasmonic acid (JA)

B. Salicylic acid (SA)

C. Abscisic acid (ABA) only

D. Ethylene only

Q17. Systemic induced resistance in an uninjured leaf after localized herbivore attack is mediated primarily by:

A. Local electrical signals alone without hormones

B. Long-distance signaling involving JA/other signals and electrical waves

C. Only diffusion of proteinase inhibitors through phloem

D. Direct movement of herbivores

Q18. Proteinase inhibitor transgenic plants typically show:

A. Increased susceptibility to herbivores

B. Reduced herbivore growth rates and damage

C. No measurable change in herbivore performance

D. Immediate plant cell death

Q19. Which of the following is a non-chemical constitutive defense?

A. Cuticle and wax layer

B. Phytoalexin induced after attack

C. JA surge after wounding

D. Volatile emission only after herbivory

Q20. According to the Optimal Defense Hypothesis, inducible responses are:

A. Uniform across leaves of all ages

B. Stronger or more responsive in tissues of higher fitness value (e.g., younger leaves)

C. Absent in reproductive tissues

D. Random and unrelated to tissue value

Q21. Which class of herbivore would most likely be a vector for plant viruses?

A. Chewing caterpillars

B. Phloem feeders (aphids, whiteflies)

C. Soil nematodes

D. Leaf miners

Q22. Which volatile compound often serves as a mobile signal and can also prime neighboring plants?

A. Methyl salicylate (MeSA)

B. Gibberellin

C. Glucose

D. ATP

Q23. Which of the following statements about constitutive vs inducible defenses is CORRECT?

A. Constitutive defenses are always cheaper energetically than inducible defenses

B. Inducible defenses never involve secondary metabolites

C. Constitutive defenses may drive herbivore adaptation, reducing their effectiveness over time

D. Inducible defenses are fixed traits and cannot be primed

Q24. HIPVs emitted belowground (from roots) may:

A. Attract insect-parasitizing nematodes that attack the herbivore

B. Only repel soil microbes indiscriminately

C. Increase soil pH instantly

D. Prevent root water uptake

Q25. Which of the following is a common mechanism by which necrotrophic pathogens attack plants?

A. Releasing haustoria to feed on living cells only

B. Secreting cell-wall degrading enzymes and toxins that kill cells and then feed on dead tissue

C. Fixing atmospheric nitrogen to supply plant

D. Forming mutualistic mycorrhizae

Q26. Hemibiotrophic pathogens are characterized by:

A. Being strictly biotrophic throughout life cycle

B. Being strictly necrotrophic throughout life cycle

C. Starting with a biotrophic phase then switching to necrotrophy

D. Only infecting roots

Q27. Which of the following is NOT an ecological function of herbivore-induced volatiles?

A. Attract predators/parasitoids of herbivores

B. Repel ovipositing female insects

C. Directly fix carbon for the plant

D. Prime neighboring plants for defense

Q28. A plant investing heavily in constitutive chemical defenses is likely to show which trade-off?

A. Increased allocation to reproduction at no cost

B. Reduced growth or seed yield due to resource allocation to defense

C. Immunity to all herbivores with no evolutionary consequences

D. Instant increase in photosynthetic efficiency

Q29. Which of the following best describes proteinase inhibitors’ mode of action in herbivores?

A. They act as neurotoxins and immediately paralyze insects

B. They bind to digestive proteases and reduce protein digestion efficiency

C. They strengthen insect midgut peritrophic matrix to enhance digestion

D. They chelate iron in insect hemolymph

Q30. Which plant response illustrates long-distance electrical signaling following wounding?

A. Local accumulation of tannins only at wound site

B. Rapid electrical wave propagation through vascular system leading to distal JA induction

C. Immediate constitutive wax deposition on all leaves

D. Permanent stomatal closure in roots

Answer Key — options + short explanations

1. B — Constitutive defenses are pre-formed, always present (cuticle, lignin, tannins).

2. C — Tannins (phenolics) are classical constitutive chemical defenses present by default in tissues.

3. C — Optimal Defense predicts higher defense in younger/more valuable tissues.

4. B — Constitutive defenses have metabolic costs, reducing resources for growth/reproduction.

5. B — Chewing damage strongly induces jasmonic acid (JA) signaling.

6. C — Phloem feeders elicit SA-like pathogen responses (often vector viruses).

7. B — Proteinase inhibitors block herbivore digestive proteases (trypsin/chymotrypsin).

8. B — Some herbivores evolve inhibitor-resistant proteases to overcome inhibitors.

9. B — GLR genes mediate long-distance electrical signaling after herbivore wounding.

10. B — glr3.3/glr3.6 double mutants lose the electrical wave and distal JA responses.

11. A — HIPVs commonly attract predators/parasitoids of the attacker (indirect defense).

12. B — Volicitin in insect saliva induces terpenoid volatiles that attract parasitoids.

13. A — HIPVs typically include terpenoids, alkaloids, phenylpropanoids (and green-leaf volatiles).

14. B — Green-leaf volatiles are C6 compounds from lipid (LOX) pathway after damage.

15. B — Inducible defenses are produced on demand, conserving resources until needed.

16. B — Salicylic acid (SA) is associated with phloem feeders and many biotrophs.

17. B — Systemic responses involve long-distance electrical/hormonal signaling (e.g., JA).

18. B — Transgenic PI accumulation commonly reduces herbivore growth/damage.

19. A — Physical barriers like cuticle/waxes are non-chemical constitutive defenses.

20. B — Inducible responses are often stronger in tissues of higher fitness value (young leaves).

21. B — Phloem feeders (aphids/whiteflies) commonly vector plant viruses.

22. A — Methyl salicylate is a volatile that serves as a mobile signal and primes neighbors.

23. C — Constitutive defenses can select for adapted herbivores, reducing effectiveness.

24. A — Belowground HIPVs can attract nematode predators/parasitoids of root herbivores.

25. B — Necrotrophs secrete CWDEs and toxins to kill tissue, then feed on dead matter.

26. C — Hemibiotrophs begin biotrophic, then switch to necrotrophy (two-phase strategy).

27. C — Fixing carbon is not a function of HIPVs; HIPVs mediate ecological interactions.

28. B — Heavy investment in constitutive defense often reduces growth/seed yield (trade-off).

29. B — PIs bind digestive proteases, lowering protein digestion efficiency in herbivores.

30. B — Wounding triggers rapid electrical waves (via GLRs) that induce distal JA and defenses.

बहुत बढ़िया ✅ अब हम इसी Biotic stress & plant defenses टॉपिक से एक Mock Test (30 Questions, CSIR NET – Part B pattern) बनाएँगे।

👉 नियम:

• हर प्रश्न के 4 विकल्प होंगे।
• पहले आप खुद solve करें (answers note करें)।
• अंत में मैं आपको पूरा Answer Key + Short Explanation दूँगा।

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📘 Mock Test — Biotic Stress & Plant Defenses (30 Q, Part B)

Q1. Which of the following is NOT a constitutive defense?
A. Cuticle
B. Lignin
C. Phytoalexins
D. Waxes

Q2. Optimal Defense Hypothesis predicts:
A. All tissues have equal defense levels
B. Old leaves have maximum secondary metabolites
C. Young valuable tissues are more defended
D. Defense allocation is random

Q3. Which of the following is an inducible defense?
A. Preformed tannins
B. Cuticle wax
C. Jasmonic acid-induced proteinase inhibitors
D. Lignified cell wall

Q4. Constitutive defenses are costly because:
A. They increase photosynthesis
B. They reduce allocation to growth/reproduction
C. They never deter herbivores
D. They are unstable compounds

Q5. Which pathway is primarily activated by aphid feeding?
A. Jasmonic acid
B. Abscisic acid
C. Salicylic acid
D. Gibberellin

Q6. Jasmonic acid is mainly induced by:
A. Chewing insects
B. Phloem feeders
C. Viral infection
D. Symbiotic bacteria

Q7. The function of proteinase inhibitors is to:
A. Block DNA replication in herbivores
B. Inhibit digestive proteases in insect gut
C. Strengthen insect cuticle
D. Kill microbial pathogens

Q8. Which mutant loses long-distance wound signaling?
A. coi1
B. glr3.3/glr3.6
C. aba2
D. sid2

Q9. HIPVs can attract:
A. Herbivore predators
B. Pollinators only
C. Symbiotic fungi
D. Rhizobia

Q10. Volicitin, present in insect saliva, induces:
A. Cuticle thickening
B. Terpenoid volatile emission
C. Salicylic acid surge only
D. Chloroplast division

Q11. Green-leaf volatiles are:
A. Phenolics
B. Lipid-derived C6 aldehydes/alcohols
C. Polysaccharides
D. Sterols

Q12. Which is a disadvantage of constitutive defenses?
A. Energy cost and herbivore adaptation
B. Lack of immediate response
C. Absence of chemical compounds
D. No ecological role

Q13. Which class of insect causes most tissue destruction?
A. Phloem feeders
B. Chewing insects
C. Cell-content feeders
D. Gall-formers

Q14. Salicylic acid pathway is usually linked with:
A. Necrotroph attack
B. Biotroph attack
C. Abiotic stress
D. Seed germination

Q15. Which of the following is NOT a secondary metabolite used in defense?
A. Alkaloids
B. Terpenoids
C. Phenylpropanoids
D. Glucose

Q16. Systemic acquired resistance (SAR) is most associated with:
A. Jasmonic acid
B. Salicylic acid
C. Cytokinin
D. Ethylene

Q17. In HIPVs, methyl salicylate functions as:
A. Volatile signal to prime neighboring plants
B. Constitutive structural barrier
C. Direct digestive inhibitor
D. Carbohydrate reserve

Q18. A hemibiotrophic pathogen:
A. Lives biotrophically only
B. Lives necrotrophically only
C. Shifts from biotrophy to necrotrophy
D. Infects only roots

Q19. Which physical barrier is constitutive?
A. Proteinase inhibitors
B. Cuticle
C. JA signaling
D. SA signaling

Q20. Electrical wave propagation in wounded plants requires:
A. GLR ion channels
B. ABA transport
C. Callose deposition
D. Stomatal closure

Q21. Belowground HIPVs can attract:
A. Herbivorous insects
B. Symbiotic bacteria
C. Insect-parasitizing nematodes
D. Pathogenic fungi

Q22. Which is the BEST example of an inducible chemical defense?
A. Phytoalexins
B. Tannins in oak leaves
C. Wax deposition on epidermis
D. Cellulose in walls

Q23. Which insect group resembles pathogen attack in plant response?
A. Caterpillars
B. Grasshoppers
C. Aphids
D. Beetles

Q24. A transgenic plant with higher proteinase inhibitors will show:
A. Increased herbivore survival
B. Reduced herbivore growth rate
C. No effect
D. Increased virus replication

Q25. Which signaling pathway is usually activated by necrotrophic fungi?
A. Salicylic acid
B. Jasmonic acid + Ethylene
C. Cytokinin
D. Auxin

Q26. HIPVs may serve to:
A. Repel ovipositing insects
B. Attract herbivores
C. Enhance seed germination
D. Increase transpiration

Q27. Constitutive defense compounds in milkweed can be tolerated by:
A. Aphids
B. Monarch caterpillars
C. Beetles
D. Viruses

Q28. Which one is NOT an ecological role of HIPVs?
A. Attract parasitoids
B. Prime neighboring plants
C. Repel female insects
D. Fix atmospheric nitrogen

Q29. Which defense is most costly but provides constant protection?
A. Inducible
B. Constitutive
C. Electrical signaling
D. Hormonal priming

Q30. Young leaves show stronger inducible defenses because:
A. They are metabolically inactive
B. They have lower fitness value
C. They contribute more to plant fitness
D. They are less responsive to herbivory

✅ Answer Key – Biotic Stress & Plant Defenses (30 Qs)

Q1. C. Phytoalexins

➡ Phytoalexins inducible होते हैं (infection के बाद बनते हैं), बाकी सब constitutive barrier हैं।

Q2. C. Young valuable tissues are more defended

➡ Optimal Defense Hypothesis कहता है high-fitness tissues (young leaves, reproductive organs) को ज्यादा defense मिलता है।

Q3. C. Jasmonic acid-induced proteinase inhibitors

➡ Inducible = signal मिलने पर activate होते हैं।

Q4. B. They reduce allocation to growth/reproduction

➡ Constitutive defense = high metabolic cost।

Q5. C. Salicylic acid

➡ Aphids (phloem feeders) → SA pathway activate करते हैं।

Q6. A. Chewing insects

➡ Jasmonic acid (JA) = chewing herbivores + necrotrophs।

Q7. B. Inhibit digestive proteases in insect gut

➡ Proteinase inhibitors insect gut में proteolysis रोक देते हैं।

Q8. B. glr3.3/glr3.6

➡ GLR ion channels long-distance wound signaling के लिए जरूरी हैं।

Q9. A. Herbivore predators

➡ HIPVs (herbivore-induced plant volatiles) natural enemies को attract करते हैं।

Q10. B. Terpenoid volatile emission

➡ Volicitin (insect saliva elicitor) = volatile emission induce करता है।

Q11. B. Lipid-derived C6 aldehydes/alcohols

➡ GLVs = fatty acid derived volatiles।

Q12. A. Energy cost and herbivore adaptation

➡ Constitutive defenses का नुकसान → costly और herbivores adapt हो जाते हैं।

Q13. B. Chewing insects

➡ Caterpillars, grasshoppers = maximum tissue loss।

Q14. B. Biotroph attack

➡ SA defense = biotrophic pathogens (fungi, bacteria)।

Q15. D. Glucose

➡ Glucose = primary metabolite; बाकी सब secondary defense metabolites।

Q16. B. Salicylic acid

➡ SAR = systemic acquired resistance → SA dependent।

Q17. A. Volatile signal to prime neighboring plants

➡ Methyl salicylate airborne signal है।

Q18. C. Shifts from biotrophy to necrotrophy

➡ Hemibiotroph early stage में biotrophic → बाद में necrotrophic हो जाता है।

Q19. B. Cuticle

➡ Cuticle = constitutive physical barrier।

Q20. A. GLR ion channels

➡ Electrical signaling = GLR glutamate receptor-like channels।

Q21. C. Insect-parasitizing nematodes

➡ Roots से emitted HIPVs nematodes attract करते हैं।

Q22. A. Phytoalexins

➡ Classic inducible chemical defense = phytoalexins।

Q23. C. Aphids

➡ Aphids (phloem feeders) plant response mimic pathogen → SA pathway activate।

Q24. B. Reduced herbivore growth rate

➡ Proteinase inhibitors digestion slow कर देते हैं।

Q25. B. Jasmonic acid + Ethylene

➡ Necrotrophs (Botrytis, Alternaria) = JA + ET defense।

Q26. A. Repel ovipositing insects

➡ HIPVs = repel, attract parasitoids, prime plants।

Q27. B. Monarch caterpillars

➡ Monarchs milkweed cardenolides tolerate करते हैं।

Q28. D. Fix atmospheric nitrogen

➡ HIPVs का nitrogen fixation से कोई संबंध नहीं।

Q29. B. Constitutive

➡ Costly लेकिन हमेशा protection देता है।

Q30. C. They contribute more to plant fitness

➡ Young leaves = high photosynthetic future → ज्यादा protected।

✅ Final Answer Pattern:

1-C, 2-C, 3-C, 4-B, 5-C, 6-A, 7-B, 8-B, 9-A, 10-B,

11-B, 12-A, 13-B, 14-B, 15-D, 16-B, 17-A, 18-C, 19-B, 20-A,

21-C, 22-A, 23-C, 24-B, 25-B, 26-A, 27-B, 28-D, 29-B, 30-C.

CSIR-NET Life Sciences – Part C level (data + logic + experimental setup) mock test, ये questions Part B से ज़्यादा analytical होंगे।

🌱 Mock Test – Biotic Stress & Plant Defenses (30 Qs, Part C style)

Q1. A transgenic Arabidopsis plant is engineered to overproduce jasmonic acid (JA) constitutively. What phenotype is MOST likely?

A. Faster growth, lower defense

B. Stunted growth, high resistance to chewing insects

C. Normal growth, but sensitive to drought

D. Increased susceptibility to necrotrophs

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Q2. In an experiment, tobacco plants were treated with aphid saliva extract. Researchers measured signaling hormones. Which spike is expected?

A. Strong SA increase, low JA

B. Strong JA increase, low SA

C. Strong ABA increase

D. Strong GA increase

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Q3. You infect a mutant Arabidopsis line defective in NPR1. What will you observe in pathogen resistance?

A. Loss of JA-induced defenses

B. Loss of systemic acquired resistance (SAR)

C. Hyper-resistance to biotrophs

D. Stronger ethylene responses

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Q4. An experiment shows that maize roots under attack by rootworm larvae emit volatiles that attract nematodes. This is an example of:

A. Direct defense

B. Indirect defense

C. Constitutive barrier

D. Structural modification

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Q5. Which combination is correct?

A. Necrotroph → SA

B. Biotroph → JA

C. Aphid → SA

D. Chewing insect → SA

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Q6. In a defense trade-off experiment, plants were given JA treatment. Which of the following changes in secondary metabolism is most expected?

A. High alkaloids, low lignin

B. High proteinase inhibitors, reduced growth

C. High sugars, reduced phenolics

D. High starch, reduced alkaloids

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Q7. Phytoalexins differ from phytoanticipins because:

A. Phytoalexins = constitutive; Phytoanticipins = inducible

B. Phytoalexins = inducible; Phytoanticipins = constitutive

C. Both are inducible

D. Both are constitutive

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Q8. Researchers block the GLR3.3 and GLR3.6 channels in Arabidopsis. Wound signaling is impaired. What response will fail?

A. Systemic JA induction

B. Root callose deposition

C. Guard cell closure

D. SAR activation

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Q9. HIPVs act in “tritrophic interactions.” Which of the following BEST illustrates this?

A. Plant → insect predator → herbivore suppression

B. Plant → herbivore → virus spread

C. Plant → rhizobia → nitrogen fixation

D. Plant → stomatal closure → pathogen resistance

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Q10. The cost–benefit model of defense predicts:

A. Plants with low resources will always invest in maximum constitutive defenses

B. Defense investment depends on tissue value and probability of attack

C. All leaves have equal secondary metabolite investment

D. Defense cost is negligible compared to growth

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Q11. If a plant mutant lacks JAZ repressor proteins, what phenotype do you expect?

A. No JA signaling at all

B. Constitutive JA signaling and stunted growth

C. SA pathway hyperactivation

D. Loss of SAR

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Q12. A fungal pathogen triggers SA accumulation in wild-type Arabidopsis but not in sid2 mutants. What is the role of SID2?

A. Converts JA into SA

B. Involved in SA biosynthesis

C. Represses SAR

D. Induces ABA accumulation

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Q13. A biotrophic pathogen infects rice. Which hormonal response is expected?

A. JA + ET signaling

B. SA signaling

C. ABA signaling

D. GA signaling

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Q14. Which herbivore damage is most likely to trigger green-leaf volatile (GLV) release?

A. Aphid stylet feeding

B. Caterpillar chewing

C. Fungal necrosis

D. Root-knot nematodes

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Q15. Experiment: Plants were treated with methyl jasmonate. Within 12 hours, insect herbivore growth rates decreased. Which mechanism is MOST likely?

A. Increased cuticle deposition

B. Induction of proteinase inhibitors

C. Increased SA accumulation

D. Decreased ABA transport

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Q16. Which of the following defenses is pre-formed (constitutive) rather than inducible?

A. Wax cuticle

B. Phytoalexins

C. Pathogenesis-related proteins

D. Proteinase inhibitors

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Q17. Transgenic cotton with Bt toxin represents which defense type?

A. Structural constitutive

B. Chemical constitutive (engineered)

C. Inducible signaling

D. Ecological indirect defense

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Q18. If HIPVs fail to attract parasitoids but still repel herbivores, what type of defense is functioning?

A. Indirect only

B. Direct only

C. Both indirect + direct

D. Structural only

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Q19. Plants under combined drought + pathogen stress often show:

A. Synergistic defense activation

B. Antagonism between ABA and SA pathways

C. Hyperactivation of JA

D. Stomatal opening to facilitate defense

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Q20. In an experiment, jasmonic acid signaling mutants showed normal response to aphids but defective resistance to caterpillars. What does this indicate?

A. Aphids trigger JA

B. Caterpillars trigger SA

C. Aphids trigger SA, caterpillars trigger JA

D. Both use ABA

✅ Answer Key + Explanations (Part C set)

Q1. B – Stunted growth, high resistance (JA constitutive = costly growth-defense tradeoff).

Q2. A – Aphids = SA spike.

Q3. B – NPR1 = master regulator of SAR.

Q4. B – Indirect defense (attracting enemies of herbivores).

Q5. C – Aphid → SA.

Q6. B – JA → proteinase inhibitors, costly growth.

Q7. B – Phytoalexins inducible; phytoanticipins constitutive.

Q8. A – GLR mutants fail in systemic wound JA signaling.

Q9. A – Classic tritrophic (plant–parasitoid–herbivore).

Q10. B – Defense depends on tissue value + attack probability.

Q11. B – No JAZ = JA signaling always ON.

Q12. B – SID2 = SA biosynthesis enzyme.

Q13. B – Biotrophs trigger SA.

Q14. B – Chewing → GLVs.

Q15. B – Proteinase inhibitors reduce insect digestion.

Q16. A – Wax cuticle = pre-formed barrier.

Q17. B – Bt toxin = constitutive engineered chemical defense.

Q18. B – If only repel, it’s direct defense.

Q19. B – ABA–SA antagonism under combined stress.

Q20. C – Aphids trigger SA; caterpillars trigger JA.