Plant Innate Immunity (PTI, ETI, R genes, Guard Hypothesis) – 30 MCQs1.
Plant Innate Immunity (PTI vs ETI, R genes, Guard Hypothesis, MAMP/DAMP, and signaling responses) का core concept बहुत अच्छे से cover है।
अब मैं इसी से CSIR-NET Life Science level के 30 conceptual + analytical MCQs (Part B standard) बना रहा हूँ — जो logical continuation (Set–3) होगा तुम्हारे पिछले topics से।
🌿 Set–3: Plant Innate Immunity (PTI, ETI, R genes, Guard Hypothesis) – 30 MCQs
1.
The perception of MAMPs by plant PRRs leads to which type of defense mechanism?
A. ETI
B. PTI
C. SAR
D. HR
→ Answer: B
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2.
Which of the following is a MAMP in bacteria recognized by plants?
A. Coronatine
B. Flg22
C. AvrPto
D. Jasmonic acid
→ Answer: B
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3.
Flg22-mediated stomatal closure occurs due to inhibition of:
A. Ca²⁺ influx
B. K⁺ uptake
C. H⁺ efflux
D. Cl⁻ uptake
→ Answer: B
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4.
The bacterial toxin coronatine helps pathogens by:
A. Enhancing PRR activation
B. Blocking ROS burst
C. Reversing MAMP-induced stomatal closure
D. Inhibiting R gene signaling
→ Answer: C
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5.
Effectors secreted by pathogens suppress PTI and lead to activation of:
A. DAMP-triggered immunity
B. ETI
C. SAR
D. Hypersensitive response only
→ Answer: B
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6.
R genes mainly code for:
A. Plasma membrane ion channels
B. Intracellular receptors detecting effectors
C. Cell wall–associated kinases
D. Secondary metabolite enzymes
→ Answer: B
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7.
Which is the most abundant class of R gene products in plants?
A. LRR–RLKs
B. NBS–LRRs
C. WRKY transcription factors
D. MAP kinases
→ Answer: B
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8.
The Leucine-rich repeat (LRR) domain in R proteins is primarily involved in:
A. ATP binding
B. Effector recognition
C. Signal transduction
D. ROS production
→ Answer: B
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9.
What is the role of the nucleotide-binding site (NBS) domain in R proteins?
A. Protein degradation
B. Ion transport
C. Activation by ATP/ADP binding
D. Guardee binding
→ Answer: C
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10.
Effector genes that activate ETI were originally termed as:
A. Pathogenic genes
B. Avirulence (Avr) genes
C. PRR genes
D. Guardee genes
→ Answer: B
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11.
Which mechanism do bacteria use to inject Avr proteins into host cells?
A. Type II secretion system
B. Type III secretion system
C. Type IV secretion system
D. Exocytosis
→ Answer: B
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12.
In the Guard Hypothesis, the plant protein that is targeted by the effector is called:
A. Guardee
B. R gene product
C. Decoy
D. Both A and C
→ Answer: D
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13.
According to the Guard Hypothesis, activation of the R gene occurs when:
A. Guardee binds directly to effector
B. Guardee is modified or degraded by effector
C. PRR binds to MAMP
D. None of the above
→ Answer: B
---
14.
Upon R gene activation, which ion flux is commonly observed?
A. Influx of K⁺ and efflux of Ca²⁺
B. Influx of Ca²⁺ and H⁺, efflux of K⁺ and Cl⁻
C. Efflux of H⁺ and Cl⁻ only
D. Influx of Na⁺ only
→ Answer: B
---
15.
The influx of Ca²⁺ during ETI primarily activates:
A. ABA signaling
B. ROS/oxidative burst
C. Photosynthesis
D. Gibberellin response
→ Answer: B
---
16.
Which of the following is not a component of pathogen-stimulated signaling?
A. Nitric oxide
B. MAP kinases
C. Jasmonic acid
D. Ethylene glycol
→ Answer: D
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17.
In plant immunity, DAMPs differ from MAMPs because:
A. DAMPs originate from microbial surfaces
B. DAMPs are host-derived signals released after damage
C. DAMPs act only in ETI
D. DAMPs bind directly to effectors
→ Answer: B
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18.
R gene product activation finally leads to:
A. Cell wall loosening
B. Hypersensitive response (HR)
C. Decrease in ROS
D. Repression of defense genes
→ Answer: B
---
19.
The coiled-coil (CC) and TIR domains in NBS–LRR proteins function mainly in:
A. Effector recognition
B. Signal transduction
C. Transcription regulation
D. PRR activation
→ Answer: B
---
20.
Which of the following R proteins contains a WRKY domain that regulates gene expression in the nucleus?
A. RPM1
B. RPS5
C. RRS1
D. L6
→ Answer: C
---
21.
The hypersensitive response (HR) is characterized by:
A. Cell division near infection site
B. Localized cell death to restrict pathogen spread
C. Decrease in ROS and Ca²⁺
D. None of these
→ Answer: B
---
22.
Which statement best differentiates PTI and ETI?
A. PTI is more specific; ETI is broad
B. PTI is basal defense, ETI is effector-specific and stronger
C. Both rely only on extracellular receptors
D. ETI is slower but weaker than PTI
→ Answer: B
---
23.
ETI often results in activation of:
A. Systemic Acquired Resistance (SAR)
B. RNA interference
C. Phototropism
D. Auxin signaling
→ Answer: A
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24.
Which of the following secondary messengers are shared between PTI and ETI signaling?
A. Ca²⁺ and ROS
B. ATP and ADP
C. NO₂ and SO₄²⁻
D. Glucose and sucrose
→ Answer: A
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25.
The type III secretion system used by bacteria is powered by:
A. SecA-independent pathway
B. SecA-dependent export
C. ABC transporters
D. Diffusion
→ Answer: A
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26.
Which combination correctly represents the plant’s stepwise immune strategy?
A. PRR → PTI → Effector → ETI
B. R gene → ETI → PRR → PTI
C. Effector → PRR → ETI
D. PTI → PRR → Effector
→ Answer: A
---
27.
During PTI activation, which hormone is least involved?
A. Salicylic acid
B. Jasmonic acid
C. Abscisic acid
D. Cytokinin
→ Answer: D
---
28.
NBS–LRR genes belong to which class of immune receptors?
A. Intracellular pattern-recognition receptors
B. Membrane-bound kinases
C. G-protein coupled receptors
D. Transcription factors
→ Answer: A
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29.
In plant evolution, the emergence of effectors by pathogens mainly acted as:
A. Neutral adaptations
B. Virulence factors to overcome PTI
C. Enzymes for metabolism
D. Structural components of flagella
→ Answer: B
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30.
The activation of ETI often leads to localized cell death followed by:
A. Systemic acquired resistance (SAR) via salicylic acid
B. Phytochrome-mediated responses
C. Stomatal reopening
D. PRR degradation
→ Answer: A
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✅ Summary of Key Takeaways
PTI → First line (PRR-mediated, general defense)
ETI → Second line (R gene-mediated, specific defense)
Guard Hypothesis → R gene “guards” a host protein (guardee/decoy) targeted by effectors
Signaling involves Ca²⁺, ROS, NO, MAPK, SA/JA pathways
ETI → HR → SAR activation
🌿 “Hypersensitive Response (HR), Systemic Acquired Resistance (SAR), and Signaling (SA–JA–ET cross-talk)”
ये सारे CSIR-NET Life Science (Part B – Medium to High Level) के हिसाब से conceptual + analytical MCQs हैं।
🌿 Set–4: Hypersensitive Response (HR), Systemic Acquired Resistance (SAR) & Defense Signaling – 30 MCQs
1.
The hypersensitive response (HR) in plants primarily serves to:
A. Increase nutrient supply to pathogens
B. Induce localized cell death at infection sites
C. Promote pathogen colonization
D. Suppress reactive oxygen species
---
2.
Which molecule is most responsible for initiating cell death during HR?
A. Cytokinin
B. Reactive oxygen species (ROS)
C. Abscisic acid
D. Auxin
---
3.
In HR, which signaling molecule plays a synergistic role with ROS to amplify defense gene expression?
A. Nitric oxide (NO)
B. Ethylene
C. Jasmonic acid
D. Calcium
---
4.
Which of the following directly leads to hypersensitive cell death?
A. Inhibition of ATP synthesis
B. Sudden ion flux and oxidative burst
C. Phytochrome activation
D. Cytoplasmic alkalization only
---
5.
The systemic acquired resistance (SAR) is typically induced after:
A. Primary infection causes HR locally
B. PTI activation without cell death
C. ABA signaling
D. Pathogen removal
---
6.
Which molecule is considered the primary signal for SAR activation?
A. Jasmonic acid
B. Salicylic acid
C. Ethylene
D. Abscisic acid
---
7.
Salicylic acid–dependent SAR leads to increased expression of:
A. Pathogenesis-related (PR) proteins
B. Phytochrome genes
C. Auxin transporters
D. Nitrogen assimilation enzymes
---
8.
Which PR protein family functions as β-1,3-glucanases against fungal cell walls?
A. PR-1
B. PR-2
C. PR-3
D. PR-5
---
9.
Which mobile signal translocates from the infected leaf to distant tissues to induce SAR?
A. MeSA (Methyl salicylate)
B. Flg22 peptide
C. Ethylene oxide
D. Hydrogen peroxide
---
10.
During SAR, NPR1 (Nonexpresser of PR genes 1) acts as:
A. A transcriptional activator in the nucleus
B. A plasma membrane receptor
C. A cell wall-bound enzyme
D. A calcium transporter
---
11.
NPR1 becomes active after:
A. Phosphorylation by MAPK
B. Reduction of disulfide bonds leading to monomer formation
C. Glycosylation in Golgi
D. Binding to JA
---
12.
Which transcription factors interact with NPR1 to induce PR gene expression?
A. WRKY
B. TGA
C. MYC
D. HY5
---
13.
Systemic acquired resistance is best described as:
A. Localized response restricted to infected cells
B. Whole-plant immunity against a broad spectrum of pathogens
C. Temporary metabolic inhibition
D. Jasmonic acid–dependent defense
---
14.
Which signaling molecule is antagonistic to salicylic acid in many defense pathways?
A. Ethylene
B. Jasmonic acid
C. Abscisic acid
D. Nitric oxide
---
15.
The jasmonic acid (JA) pathway is more effective against:
A. Biotrophic pathogens
B. Necrotrophic pathogens and insect herbivory
C. Viral pathogens only
D. Fungal spores during dormancy
---
16.
Ethylene often acts synergistically with:
A. Salicylic acid
B. Jasmonic acid
C. ABA
D. Cytokinin
---
17.
In salicylic acid biosynthesis, which enzyme catalyzes conversion of chorismate to isochorismate?
A. PAL (Phenylalanine ammonia-lyase)
B. ICS1 (Isochorismate synthase 1)
C. AOS (Allene oxide synthase)
D. SAM synthetase
---
18.
Which organelle is most closely associated with salicylic acid synthesis via the ICS pathway?
A. Nucleus
B. Chloroplast
C. Peroxisome
D. Mitochondria
---
19.
Which molecule acts as a mobile signal converting to salicylic acid in distal leaves?
A. Methyl salicylate
B. Jasmonic acid
C. ABA
D. MeJA
---
20.
JA biosynthesis mainly occurs in which organelle?
A. Chloroplast and peroxisome
B. Mitochondria
C. Golgi apparatus
D. Nucleus
---
21.
The precursor molecule for jasmonic acid biosynthesis is:
A. α-linolenic acid
B. Phenylalanine
C. Tryptophan
D. Shikimic acid
---
22.
In the JA signaling pathway, which protein acts as a co-receptor with COI1 for jasmonate perception?
A. JAZ
B. MYC2
C. NPR1
D. WRKY70
---
23.
Degradation of JAZ repressors leads to activation of:
A. MYC2 transcription factor
B. NPR1 nuclear import
C. WRKY70
D. SAR suppression
---
24.
WRKY70 transcription factor acts as:
A. Negative regulator of JA pathway
B. Positive regulator of SA pathway
C. Both A and B
D. Unrelated to defense
---
25.
Which plant hormone is primarily involved in drought and abiotic stress but can suppress defense genes?
A. Cytokinin
B. Abscisic acid
C. Gibberellin
D. Ethylene
---
26.
Which term describes defense signaling between infected and uninfected cells via plasmodesmata and volatiles?
A. Systemic acquired resistance
B. Local induced resistance
C. Priming
D. PTI
---
27.
Priming in SAR ensures:
A. Constitutive expression of all PR genes
B. Faster and stronger activation upon secondary infection
C. ROS suppression
D. Decrease in SA biosynthesis
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28.
Ethylene biosynthesis precursor is:
A. Methionine → ACC → Ethylene
B. Phenylalanine → Cinnamic acid → Ethylene
C. Tryptophan → IAA → Ethylene
D. Glutamate → GABA → Ethylene
---
29.
Which statement is true for cross-talk between SA and JA pathways?
A. SA suppresses JA-mediated defense against necrotrophs
B. JA enhances SA biosynthesis
C. Both pathways always act synergistically
D. SA is activated after JA pathway termination
---
30.
Which of the following best represents the correct sequence of plant immune activation?
A. PTI → Effector secretion → ETI → HR → SAR
B. ETI → PTI → HR → SAR
C. SAR → HR → PTI → ETI
D. HR → PTI → ETI → SAR
🌿 Answers (Set–4)
1️⃣ B
2️⃣ B
3️⃣ A
4️⃣ B
5️⃣ A
6️⃣ B
7️⃣ A
8️⃣ B
9️⃣ A
🔟 A
11️⃣ B
12️⃣ B
13️⃣ B
14️⃣ B
15️⃣ B
16️⃣ B
17️⃣ B
18️⃣ B
19️⃣ A
20️⃣ A
21️⃣ A
22️⃣ A
23️⃣ A
24️⃣ C
25️⃣ B
26️⃣ C
27️⃣ B
28️⃣ A
29️⃣ A
30️⃣ A
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