PLANT–PATHOGEN RECOGNITION & DEFENSE (Part–B Type MCQs)
CSIR-NET Life Science (Unit 6: Plant Physiology → Plant–Pathogen Interaction, Defense Mechanisms).
30 Part-B type MCQs that are conceptual + memory-based, exactly as CSIR asks.
Each question will help you understand recognition, elicitors, PRRs, effectors, toxins, hormones, and defense signaling (JA/systemin) deeply.
🌿 PLANT–PATHOGEN RECOGNITION & DEFENSE (Part–B Type MCQs)
1.
Plants recognize insect attack mainly through:
a) Mechanical wounding only
b) Compounds present in insect saliva
c) Change in leaf temperature
d) Oxygen depletion
Ans: b) Compounds present in insect saliva
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2.
The compounds in insect saliva that trigger defense responses are known as:
a) Hormones
b) Elicitors
c) Effectors
d) Isoenzymes
Ans: b) Elicitors
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3.
Elicitors derived from insect saliva are collectively termed as:
a) DAMPs
b) PAMPs
c) HAMPs
d) PRRs
Ans: c) HAMPs (Herbivore-Associated Molecular Patterns)
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4.
Which of the following is an example of a bacterial MAMP?
a) Chitin
b) Flagellin
c) Cellulose
d) Glycoprotein
Ans: b) Flagellin
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5.
Chitin acts as a conserved MAMP for which class of microorganisms?
a) Bacteria
b) Virus
c) Fungi
d) Protozoa
Ans: c) Fungi
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6.
Plants detect MAMPs and PAMPs using:
a) Transcription factors
b) Pattern recognition receptors (PRRs)
c) Ribosomes
d) Vacuoles
Ans: b) PRRs
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7.
Which of the following PRRs contains an intracellular kinase domain?
a) RLP
b) RLK
c) Both
d) None
Ans: b) RLK (Receptor-like kinase)
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8.
RLPs differ from RLKs because they:
a) Lack extracellular domain
b) Lack kinase domain
c) Lack transmembrane domain
d) Lack receptor function
Ans: b) Lack kinase domain
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9.
LysM and LRR domains are part of:
a) Receptor extracellular regions
b) Cytoplasmic enzymes
c) DNA-binding proteins
d) Chloroplast proteins
Ans: a) Receptor extracellular regions
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10.
Plant molecules released upon damage that signal danger are called:
a) DAMPs
b) MAPKs
c) JA conjugates
d) Phytoalexins
Ans: a) DAMPs (Damage-Associated Molecular Patterns)
---
11.
The first elicitors identified in insect saliva were:
a) Protein–lipid complexes
b) Fatty acid–amino acid conjugates
c) Simple sugars
d) Terpenoids
Ans: b) Fatty acid–amino acid conjugates
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12.
These fatty acid–amino acid conjugates are synthesized using plant-derived:
a) Linolenic acid and linoleic acid
b) Malic acid and citric acid
c) Acetic acid and lactic acid
d) Stearic acid and oleic acid
Ans: a) Linolenic acid and linoleic acid
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13.
Which molecule in tomato acts as a DAMP during wound signaling?
a) Jasmonic acid
b) Prosystemin
c) Salicylic acid
d) Ethylene
Ans: b) Prosystemin
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14.
Prosystemin is proteolytically processed to form:
a) Systemin
b) Phytoalexin
c) JA
d) ABA
Ans: a) Systemin
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15.
Systemin triggers which major signaling pathway?
a) SA pathway
b) JA pathway
c) Ethylene pathway
d) Auxin pathway
Ans: b) JA pathway (Jasmonic Acid pathway)
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16.
Which enzyme is activated by systemin receptor phosphorylation?
a) Phospholipase A2
b) ATP synthase
c) Nitric oxide synthase
d) Cellulase
Ans: a) Phospholipase A2
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17.
The enzyme phospholipase A2 initiates the biosynthesis of:
a) Jasmonic acid
b) Salicylic acid
c) Abscisic acid
d) Cytokinin
Ans: a) Jasmonic acid
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18.
Jasmonic acid induces expression of genes encoding:
a) Protease inhibitors
b) Kinases
c) Cellulose synthase
d) Transporters
Ans: a) Protease inhibitors
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19.
Effectors secreted by pathogens help them by:
a) Activating plant defense
b) Helping colonization and nutrient gain
c) Promoting drought tolerance
d) Increasing photosynthesis
Ans: b) Helping colonization and nutrient gain
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20.
Effectors are categorized into:
a) Enzymes, toxins, and growth regulators
b) Carbohydrates, lipids, and proteins
c) RNAs, DNAs, and hormones
d) None of these
Ans: a) Enzymes, toxins, and growth regulators
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21.
Which enzyme helps a pathogen degrade the plant cuticle?
a) Amylase
b) Cutinase
c) Kinase
d) Protease
Ans: b) Cutinase
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22.
Which toxin from Cochliobolus carbonum targets histone deacetylases?
a) FC toxin
b) HC toxin
c) GA toxin
d) SA toxin
Ans: b) HC toxin
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23.
The fungus Fusicoccum amygdali produces:
a) Fusicoccin
b) Cytokinin
c) Gibberellin
d) Auxin
Ans: a) Fusicoccin
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24.
Fusicoccin mainly affects:
a) Guard cells causing permanent stomatal opening
b) Chlorophyll biosynthesis
c) Nodule formation
d) Root elongation
Ans: a) Guard cells causing permanent stomatal opening
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25.
Fusicoccin activates the plant:
a) H⁺-ATPase
b) Na⁺-K⁺ pump
c) Ca²⁺ channels
d) Pyruvate kinase
Ans: a) H⁺-ATPase
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26.
Overactivation of plasma membrane H⁺-ATPase causes:
a) Hyperpolarization and cell death
b) Depolarization
c) Increased sugar synthesis
d) Chloroplast rupture
Ans: a) Hyperpolarization and cell death
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27.
The pathogen Gibberella fujikuroi produces:
a) Abscisic acid
b) Gibberellic acid (GA₃)
c) Cytokinin
d) Ethylene
Ans: b) Gibberellic acid (GA₃)
---
28.
The disease caused by Gibberella fujikuroi in rice is called:
a) Wilt disease
b) Smut
c) Foolish seedling disease
d) Rice blast
Ans: c) Foolish seedling disease
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29.
MAP kinase cascade is involved in:
a) Signal transduction during systemin–JA pathway
b) Water transport
c) Sugar metabolism
d) Photosynthesis regulation
Ans: a) Signal transduction during systemin–JA pathway
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30.
JA and its conjugates are transported through:
a) Xylem
b) Phloem sieve elements
c) Apoplast only
d) Symplast only
Ans: b) Phloem sieve elements
✅ Summary Insight:
If you practice these 30 MCQs regularly (2–3 times/week), you’ll master.
— जब कोई एक पूरे topic को “question bank + concept clarity” से master करता है, तो exam में memory और logic दोनों काम करते हैं।
नीचे दिए गए 30 Advanced MCQs (Medium → High difficulty level) पूरे topic “How Plants Identify Pathogens” पर आधारित हैं।
इनमें शामिल हैं:
Conceptual + Mechanistic Qs
Multi-statement Qs
Experimental / Research-based Qs
CSIR-NET Part C pattern (4 options में analytical सोच की जरूरत)
👉 Answers सबसे नीचे दिए गए हैं ताकि तुम पहले खुद कोशिश कर सको।
🌿 CSIR-NET Life Science: Plant–Pathogen Interaction (Part C Level MCQs)
Q1.
Which of the following molecular classes can function as elicitors in plant–insect interactions?
A. Fatty acid–amino acid conjugates
B. Glycosidic linkages of cellulose
C. Chitin oligomers
D. Both A and C
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Q2.
The plant’s ability to differentiate between mechanical injury and pathogen/insect attack mainly depends on:
A. Jasmonic acid synthesis
B. Recognition of elicitors
C. Increased turgor pressure
D. Lignin deposition
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Q3.
Identify the correct match:
1. HAMPs → Insect saliva
2. PAMPs → Microbial molecules
3. DAMPs → Plant-derived danger signals
A. 1 and 2 only
B. 1 and 3 only
C. 1, 2, and 3
D. 2 and 3 only
---
Q4.
In the systemin signaling pathway of tomato, the initial peptide released upon wounding is:
A. Jasmonic acid
B. Systemin
C. Prosystemin
D. Phospholipase A2
---
Q5.
Which of the following statements about PRRs is true?
A. PRRs are cytosolic receptors without a transmembrane domain
B. RLKs and RLPs act as PRRs localized on the plasma membrane
C. PRRs are exclusively present in the nucleus
D. PRRs only detect insect-derived elicitors
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Q6.
The key structural difference between RLKs and RLPs is:
A. RLPs lack the intracellular kinase domain
B. RLKs lack the extracellular domain
C. Both contain LysM domains
D. RLKs lack transmembrane regions
---
Q7.
The systemic nature of defense activation upon insect herbivory involves transport of:
A. Salicylic acid
B. Jasmonic acid (JA) or its conjugates
C. Abscisic acid
D. Ethylene
---
Q8.
Which step in the tomato defense pathway directly precedes the synthesis of JA?
A. Activation of MAP kinase
B. Activation of phospholipase A2 (PLA2)
C. Cleavage of systemin
D. Expression of proteinase inhibitors
---
Q9.
Which statement correctly describes the function of HC-toxin?
A. Inhibits histone deacetylases in maize
B. Inhibits H+-ATPase in guard cells
C. Promotes stomatal closure
D. Inhibits cellulose biosynthesis
---
Q10.
The fungus Fusicoccum amygdali induces wilting by:
A. Blocking water uptake
B. Activating plasma membrane H+-ATPase
C. Inhibiting guard cell K+ uptake
D. Inducing ethylene biosynthesis
---
Q11.
Which hormone-like fungal metabolite causes "foolish seedling disease" in rice?
A. Cytokinin
B. Gibberellin (GA₃)
C. Auxin
D. Abscisic acid
---
Q12.
Identify the correct sequence of signaling in the systemin pathway:
1. PLA2 activation
2. JA synthesis
3. Proteinase inhibitor gene activation
4. Systemin binding to receptor
A. 4 → 1 → 2 → 3
B. 1 → 4 → 3 → 2
C. 4 → 2 → 1 → 3
D. 1 → 3 → 2 → 4
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Q13.
DAMPs in plants are generated mainly due to:
A. Viral RNA replication
B. Breakdown of plant cell components during damage
C. External light stress
D. Nutrient deficiency
---
Q14.
Which of the following correctly lists MAMPs of bacteria and fungi?
A. Peptidoglycan (Bacteria), Chitin (Fungi)
B. Lipopolysaccharide (Fungi), Cellulose (Bacteria)
C. Flagellin (Fungi), Glycoprotein (Bacteria)
D. Xylan (Bacteria), Pectin (Fungi)
---
Q15.
Which of the following is not considered a pathogen effector molecule?
A. Pectinase
B. Cutinase
C. Auxin
D. Rubisco
---
Q16.
Fusicoccin acts through formation of a complex between H+-ATPase and:
A. 14-3-3 proteins
B. Calmodulin
C. Actin filaments
D. MAP kinases
---
Q17.
Histone deacetylase inhibition by HC-toxin leads to:
A. Reduced gene expression
B. Enhanced gene expression
C. Degradation of DNA
D. Blocked RNA splicing
---
Q18.
The function of PRRs is most similar to which mammalian immune system component?
A. Antibodies
B. Toll-like receptors
C. Cytokines
D. Complement proteins
---
Q19.
Systemin peptide is perceived in which plant tissue type?
A. Xylem parenchyma
B. Phloem parenchyma
C. Mesophyll cells
D. Guard cells
---
Q20.
Which of the following is a fungal effector that mimics a plant hormone?
A. Fusicoccin
B. HC-toxin
C. Chitinase
D. Peptidoglycan
---
Q21.
A mutant tomato plant lacking the receptor for systemin would show:
A. Reduced proteinase inhibitor production after wounding
B. Increased JA production
C. Overactivation of H+-ATPase
D. Constitutive lignin synthesis
---
Q22.
MAP kinase cascade in the systemin pathway acts:
A. Upstream of PLA2
B. Downstream of PLA2
C. Parallel to PLA2
D. Independently of JA
---
Q23.
The main evolutionary advantage of having PRRs recognizing MAMPs is:
A. Recognition of highly variable microbial proteins
B. Recognition of conserved microbial structures
C. Detection of unique plant-specific peptides
D. Specific binding to insect saliva only
---
Q24.
Which of the following would NOT likely function as a PAMP?
A. Flagellin fragment
B. Peptidoglycan
C. LPS (lipopolysaccharide)
D. Jasmonic acid
---
Q25.
A researcher treated wounded tomato leaves with purified systemin. Which of the following responses would confirm its activity?
A. Immediate callose deposition
B. Increased expression of proteinase inhibitor genes
C. Stomatal opening
D. Reduced photosynthesis
---
Q26.
During a pathogen attack, secondary metabolite accumulation (phytoalexins) is part of which defense type?
A. Constitutive defense
B. Induced defense
C. Passive defense
D. Mechanical barrier defense
---
Q27.
In the interaction between Gibberella fujikuroi and rice, the pathogen benefits because:
A. It gains entry via closed stomata
B. It diverts plant energy toward abnormal elongation
C. It decreases host auxin levels
D. It inhibits H+-ATPase
---
Q28.
Which of the following statements about fusicoccin is incorrect?
A. It activates plasma membrane H+-ATPase
B. It binds with 14-3-3 proteins
C. It causes stomatal opening
D. It is produced by Cochliobolus carbonum
---
Q29.
Which of the following best describes a pattern-triggered immunity (PTI) response?
A. Recognition of conserved microbial patterns by PRRs
B. Recognition of effector proteins by intracellular receptors
C. Overproduction of gibberellin
D. Infection by necrotrophic fungi
---
Q30.
The first elicitors identified in insect saliva were:
A. Chitin oligomers
B. Fatty acid–amino acid conjugates
C. Flavonoids
D. Pectinases
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✅ Answer Key
1. D
2. B
3. C
4. B
5. B
6. A
7. B
8. B
9. A
10. B
11. B
12. A
13. B
14. A
15. D
16. A
17. B
18. B
19. B
20. A
21. A
22. B
23. B
24. D
25. B
26. B
27. B
28. D
29. A
30. B
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