General Agriculture & Statistics Practice Questions (Q26-30) - Plant Sciences

ICAR PG Plant Sciences 29 Jun 2024Shift 1

Arranging Order +4 −1

Arrange the following events in the correct order:

(A) Restoration of Effector Triggered Susceptibility by Pathogen

(B) Effector triggered susceptibility by Pathogen

(C) Effector triggered immunity by Plant

(D) PAMP triggered immunity by Plant

Choose the correct answer from the options given below:

निम्नलिखित घटनाओं को सही क्रम में व्यवस्थित कीजिए:

(A) रोगजनक द्वारा इफेक्टर ट्रिगर्ड ससेप्टिबिलिटी की पुनर्स्थापना (Restoration of Effector Triggered Susceptibility by Pathogen)

(B) रोगजनक द्वारा इफेक्टर ट्रिगर्ड ससेप्टिबिलिटी (Effector triggered susceptibility by Pathogen / ETS)

(C) पौधे द्वारा इफेक्टर ट्रिगर्ड इम्युनिटी (Effector triggered immunity by Plant / ETI)

(D) पौधे द्वारा पीएएमपी ट्रिगर्ड इम्युनिटी (PAMP triggered immunity by Plant / PTI)

नीचे दिए गए विकल्पों में से सही उत्तर चुनिए:

(D), (B), (C), (A) (D), (B), (C), (A) (A), (B), (C), (D) (A), (B), (C), (D) (B), (A), (D), (C) (B), (A), (D), (C) (C), (B), (D), (A) (C), (B), (D), (A)

Zig-Zag Model of Plant Immune System:

The co-evolutionary arms race between plants and pathogens is described in four evolutionary phases:

Phase 1 (D) - PAMP-Triggered Immunity (PTI): Plant pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs/MAMPs like flagellin or chitin), activating basal defense (PTI).
Phase 2 (B) - Effector-Triggered Susceptibility (ETS): Successful pathogens inject specialized virulence effectors into host cells to suppress PTI, resulting in disease (ETS).
Phase 3 (C) - Effector-Triggered Immunity (ETI): Plants evolve nucleotide-binding leucine-rich repeat (NBS-LRR) resistance proteins ($R$ genes) that directly or indirectly recognize specific pathogen effectors (now called avirulence / Avr factors), triggering an accelerated, robust hypersensitive defense response (ETI).
Phase 4 (A) - Restoration of ETS: Natural selection drives the pathogen to shed or alter recognized effectors or acquire novel effectors that suppress ETI, restoring effector-triggered susceptibility.

Therefore, the correct chronological sequence is (D) $\rightarrow$ (B) $\rightarrow$ (C) $\rightarrow$ (A). Correct Answer: Option 1.

विस्तृत व्याख्या:

Zig-Zag Model of Plant Immune System (पादप प्रतिरक्षा प्रणाली का जिग-जैग मॉडल - Jones & Dangl, 2006):

The co-evolutionary arms race between plants and pathogens is described in four evolutionary phases:

Phase 1 (D) - PAMP-Triggered Immunity (PTI): Plant pattern recognition receptors (PRRs) recognize pathogen-associated molecular patterns (PAMPs/MAMPs like flagellin or chitin), activating basal defense (PTI).
Phase 2 (B) - Effector-Triggered Susceptibility (ETS): Successful pathogens inject specialized virulence effectors into host cells to suppress PTI, resulting in disease (ETS).
Phase 3 (C) - Effector-Triggered Immunity (ETI): Plants evolve nucleotide-binding leucine-rich repeat (NBS-LRR) resistance proteins ($R$ genes) that directly or indirectly recognize specific pathogen effectors (now called avirulence / Avr factors), triggering an accelerated, robust hypersensitive defense response (ETI).
Phase 4 (A) - Restoration of ETS: Natural selection drives the pathogen to shed or alter recognized effectors or acquire novel effectors that suppress ETI, restoring effector-triggered susceptibility.

Therefore, the correct chronological sequence is (D) $\rightarrow$ (B) $\rightarrow$ (C) $\rightarrow$ (A). Correct Answer: Option 1.

Explanation not matching this question? क्या व्याख्या इस प्रश्न से मेल नहीं खा रही? Report

ICAR PG Plant Sciences 29 Jun 2024Shift 1

Assertion & Reason +4 −1

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R):

Assertion (A) : The secondary spread of the pathogen propagules that are identical in virulence is mostly responsible for epidemics.

Reason (R) : Secondary propagules are mostly asexually produced.

In light of the above statements, choose the correct answer from the options given below:

नीचे दो कथन दिए गए हैं, एक को अभिकथन (A) और दूसरे को कारण (R) के रूप में लेबल किया गया है:

अभिकथन (A) : रोगजनक प्रवर्ध्यों (propagules) का द्वितीयक प्रसार, जो उग्रता (virulence) में समरूप होते हैं, मुख्य रूप से महामारी (epidemics) के लिए उत्तरदायी होता है।

कारण (R) : द्वितीयक प्रवर्ध्य (secondary propagules) अधिकांशतः अलैंगिक रूप से उत्पन्न होते हैं।

उपरोक्त कथनों के आलोक में, नीचे दिए गए विकल्पों में से सही उत्तर चुनिए:

Both (A) and (R) are true and (R) is the correct explanation of (A) (A) और (R) दोनों सत्य हैं और (R), (A) की सही व्याख्या है Both (A) and (R) are true but (R) is NOT the correct explanation of (A) (A) और (R) दोनों सत्य हैं लेकिन (R), (A) की सही व्याख्या नहीं है (A) is true but (R) is false (A) सत्य है लेकिन (R) असत्य है (A) is false but (R) is true (A) असत्य है लेकिन (R) सत्य है

Epidemiology of Polycyclic Plant Diseases:

Assertion (A) is TRUE: In polycyclic plant diseases (e.g., late blight of potato, powdery mildews, rusts), explosive compound-interest epidemics are driven by multiple repeated cycles of secondary infection occurring within a single growing season.
Reason (R) is TRUE and correctly explains (A): Secondary propagules (e.g., conidia, sporangia, urediniospores) are produced asexually through mitosis. Because they are clonal products, they are genetically identical in virulence to the parent strain, allowing millions of equally virulent spores to rapidly colonize neighboring plants without meiotic gene segregation or loss of fitness.

Therefore, both (A) and (R) are true and (R) is the correct explanation of (A). Correct Answer: Option 1.

विस्तृत व्याख्या:

Epidemiology of Polycyclic Plant Diseases (पादप महामारी विज्ञान एवं द्वितीयक प्रसार):

Assertion (A) is TRUE: In polycyclic plant diseases (e.g., late blight of potato, powdery mildews, rusts), explosive compound-interest epidemics are driven by multiple repeated cycles of secondary infection occurring within a single growing season.
Reason (R) is TRUE and correctly explains (A): Secondary propagules (e.g., conidia, sporangia, urediniospores) are produced asexually through mitosis. Because they are clonal products, they are genetically identical in virulence to the parent strain, allowing millions of equally virulent spores to rapidly colonize neighboring plants without meiotic gene segregation or loss of fitness.

Therefore, both (A) and (R) are true and (R) is the correct explanation of (A). Correct Answer: Option 1.

Explanation not matching this question? क्या व्याख्या इस प्रश्न से मेल नहीं खा रही? Report

ICAR PG Plant Sciences 29 Jun 2024Shift 1

Assertion & Reason +4 −1

Given below are two statements, one is labelled as Assertion (A) and other one labelled as Reason (R):

Assertion (A) : Biotrophs can be easily cultured in artificial medium.

Reason (R) : Biotrophs lost their independent growth due to co-evolution with the host.

In light of the above statements, choose the most appropriate answer from the options given below:

अभिकथन (A) : अविकल्पी परजीवियों (Biotrophs) को कृत्रिम माध्यम (artificial medium) में आसानी से संवर्धित किया जा सकता है।

कारण (R) : बायोट्रोफ्स ने पोषक (host) के साथ सह-विकास (co-evolution) के कारण अपनी स्वतंत्र वृद्धि क्षमता खो दी है।

उपरोक्त कथनों के आलोक में, नीचे दिए गए विकल्पों में से सबसे उपयुक्त उत्तर चुनिए:

Both (A) and (R) are correct and (R) is the correct explanation of (A) (A) और (R) दोनों सही हैं और (R), (A) की सही व्याख्या है Both (A) and (R) are correct but (R) is NOT the correct explanation of (A) (A) और (R) दोनों सही हैं लेकिन (R), (A) की सही व्याख्या नहीं है (A) is correct but (R) is not correct (A) सही है लेकिन (R) सही नहीं है (A) is not correct but (R) is correct (A) सही नहीं है लेकिन (R) सही है

Nature of Obligate Biotrophs:

Assertion (A) is INCORRECT (False): Obligate biotrophic pathogens (such as rust fungi Puccinia, powdery mildews Erysiphe, downy mildews Peronospora, and viruses) cannot be cultured on standard synthetic nutrient agar media because they strictly depend on metabolic signals and living host plant cytoplasm to survive and reproduce.
Reason (R) is CORRECT (True): Over millions of years of co-evolution and genome reduction with their plant hosts, biotrophic organisms have lost critical metabolic biosynthetic genes (such as nitrate and sulfate assimilation pathways and inorganic nitrogen reduction), rendering them entirely reliant on living host cellular metabolism for their nutrition.

Therefore, (A) is not correct but (R) is correct. Correct Answer: Option 4.

विस्तृत व्याख्या:

Nature of Obligate Biotrophs (अविकल्पी परजीवी / बायोट्रोफ्स की प्रकृति):

Assertion (A) is INCORRECT (False): Obligate biotrophic pathogens (such as rust fungi Puccinia, powdery mildews Erysiphe, downy mildews Peronospora, and viruses) cannot be cultured on standard synthetic nutrient agar media because they strictly depend on metabolic signals and living host plant cytoplasm to survive and reproduce.
Reason (R) is CORRECT (True): Over millions of years of co-evolution and genome reduction with their plant hosts, biotrophic organisms have lost critical metabolic biosynthetic genes (such as nitrate and sulfate assimilation pathways and inorganic nitrogen reduction), rendering them entirely reliant on living host cellular metabolism for their nutrition.

Therefore, (A) is not correct but (R) is correct. Correct Answer: Option 4.

Explanation not matching this question? क्या व्याख्या इस प्रश्न से मेल नहीं खा रही? Report

ICAR PG Plant Sciences 29 Jun 2024Shift 1

Statement Based +4 −1

Given below are two statements

Statement (I) : Horizontal gene transfer among the microbes is responsible for the transmission of virulence factors.

Statement (II) : Horizontal gene transfer can happen between microbes and plants also.

In light of the above statements, choose the most appropriate answer from the options given below:

नीचे दो कथन दिए गए हैं

कथन (I) : सूक्ष्मजीवों के बीच क्षैतिज जीन स्थानांतरण (Horizontal gene transfer / HGT) उग्रता कारकों (virulence factors) के संचरण के लिए जिम्मेदार है।

कथन (II) : क्षैतिज जीन स्थानांतरण सूक्ष्मजीवों और पौधों के बीच भी हो सकता है।

Both Statement (I) and Statement (II) are correct कथन (I) और कथन (II) दोनों सही हैं Both Statement (I) and Statement (II) are incorrect कथन (I) और कथन (II) दोनों गलत हैं Statement (I) is correct but Statement (II) is incorrect कथन (I) सही है लेकिन कथन (II) गलत है Statement (I) is incorrect but Statement (II) is correct कथन (I) गलत है लेकिन कथन (II) सही है

Horizontal Gene Transfer in Microbial Virulence and Plants:

Statement (I) is CORRECT: Horizontal Gene Transfer (HGT) via conjugation, transformation, and transduction allows the dissemination of pathogenicity islands (PAIs), plasmids, transposons, and bacteriophages encoding toxins, effectors, type III secretion systems, and antibiotic resistance genes across different bacterial strains and species.
Statement (II) is CORRECT: Cross-kingdom HGT occurs naturally between prokaryotes and plants. The premier example is Agrobacterium tumefaciens, which transfers its transferred-DNA (T-DNA) containing auxin, cytokinin, and opine biosynthesis genes into the plant nuclear genome. Natural transgenic plants (such as Ipomoea batatas / sweet potato) contain ancient Agrobacterium T-DNA integrated into their nuclear genomes.

Therefore, both Statement (I) and Statement (II) are correct. Correct Answer: Option 1.

विस्तृत व्याख्या:

Horizontal Gene Transfer in Microbial Virulence and Plants (क्षैतिज जीन स्थानांतरण):

Statement (I) is CORRECT: Horizontal Gene Transfer (HGT) via conjugation, transformation, and transduction allows the dissemination of pathogenicity islands (PAIs), plasmids, transposons, and bacteriophages encoding toxins, effectors, type III secretion systems, and antibiotic resistance genes across different bacterial strains and species.
Statement (II) is CORRECT: Cross-kingdom HGT occurs naturally between prokaryotes and plants. The premier example is Agrobacterium tumefaciens, which transfers its transferred-DNA (T-DNA) containing auxin, cytokinin, and opine biosynthesis genes into the plant nuclear genome. Natural transgenic plants (such as Ipomoea batatas / sweet potato) contain ancient Agrobacterium T-DNA integrated into their nuclear genomes.

Therefore, both Statement (I) and Statement (II) are correct. Correct Answer: Option 1.

Explanation not matching this question? क्या व्याख्या इस प्रश्न से मेल नहीं खा रही? Report

ICAR PG Plant Sciences 29 Jun 2024Shift 1

Statement Based +4 −1

Given below are two statements

Statement (I) : Viruses can insert their genes into the host genome.

Statement (II) : Viral gene insertion in nature may lead to major phenotypic alteration in the host.

In light of the above statements, choose the most appropriate answer from the options given below:

नीचे दो कथन दिए गए हैं

कथन (I) : विषाणु (Viruses) अपने जीनों को पोषक जीनोम (host genome) में अंतःस्थापित (insert) कर सकते हैं।

कथन (II) : प्रकृति में वायरल जीन अंतःस्थापन से पोषक में प्रमुख फेनोटाइपिक परिवर्तन हो सकते हैं।

Integration of Viral Sequences:

Statement (I) is CORRECT: Retroviruses, pararetroviruses (such as Badnaviruses like Banana streak virus - BSV, and Caulimoviruses), and certain DNA viruses routinely integrate reverse-transcribed viral DNA sequences into the nuclear genome of their host plants (termed Endogenous Viral Elements / EVEs).
Statement (II) is INCORRECT: In nature, the vast majority of integrated endogenous viral sequences undergo epigenetic transcriptional silencing (via DNA methylation and RNA-directed histone modification). They remain dormant and silenced without inducing major visible phenotypic alterations in the healthy host under standard conditions (they only express under specific stress or tissue culture shock triggering episomal release).

Therefore, Statement (I) is correct but Statement (II) is incorrect. Correct Answer: Option 3.

विस्तृत व्याख्या:

Integration of Viral Sequences (पोषक जीनोम में विषाणु जीन का अंतःस्थापन):

Statement (I) is CORRECT: Retroviruses, pararetroviruses (such as Badnaviruses like Banana streak virus - BSV, and Caulimoviruses), and certain DNA viruses routinely integrate reverse-transcribed viral DNA sequences into the nuclear genome of their host plants (termed Endogenous Viral Elements / EVEs).
Statement (II) is INCORRECT: In nature, the vast majority of integrated endogenous viral sequences undergo epigenetic transcriptional silencing (via DNA methylation and RNA-directed histone modification). They remain dormant and silenced without inducing major visible phenotypic alterations in the healthy host under standard conditions (they only express under specific stress or tissue culture shock triggering episomal release).

Therefore, Statement (I) is correct but Statement (II) is incorrect. Correct Answer: Option 3.

Explanation not matching this question? क्या व्याख्या इस प्रश्न से मेल नहीं खा रही? Report