Given below are two statements, one is labelled as Assertion (A)...

All Subjects General Agriculture, Crop Production & Soils Cell Biology, Genetics, Physiology, Biochemistry & Plant Protection Genetics, Plant Pathology, Seed Science & Agricultural Microbiology Food & Industrial Microbiology, Rural Development

Q.61

ICAR AIEEA PG 2024 - Plant Sciences

Assertion & Reason +4 −1

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

Assertion (A) : Phytoplasma do not have cell wall and motility.

Reason (R) : Phytoplasma colonize phloem.

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) : फाइटोप्लाज्मा (Phytoplasma) में कोशिका भित्ति और गतिशीलता (motility) नहीं होती है।

कारण (R) : फाइटोप्लाज्मा फ्लोएम (phloem) को उपनिवेशित (colonize) करते 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

Biology and Ultrastructure of Phytoplasmas:

Assertion (A) is TRUE: Phytoplasmas (formerly known as Mycoplasma-like organisms or MLOs) belong to the class Mollicutes. They are bounded solely by a triple-layered unit lipoprotein membrane, completely lack a peptidoglycan cell wall, and lack flagella or motility structures (pleomorphic non-motile prokaryotes).
Reason (R) is TRUE: Within host plants, phytoplasmas are strictly restricted to the nutrient-rich sieve tube elements of the phloem tissue, from which they are acquired and transmitted by phloem-feeding insect vectors (leafhoppers and planthoppers).
However, inhabiting the phloem is not the evolutionary or mechanistic reason why phytoplasmas lack a cell wall (their wall-less state evolved through reductive genome evolution from ancestral Firmicutes).

Therefore, both (A) and (R) are true, but (R) is NOT the correct explanation of (A). Correct Answer: Option 2.

विस्तृत व्याख्या:

Biology and Ultrastructure of Phytoplasmas (फाइटोप्लाज्मा की संरचना एवं वास):

Assertion (A) is TRUE: Phytoplasmas (formerly known as Mycoplasma-like organisms or MLOs) belong to the class Mollicutes. They are bounded solely by a triple-layered unit lipoprotein membrane, completely lack a peptidoglycan cell wall, and lack flagella or motility structures (pleomorphic non-motile prokaryotes).
Reason (R) is TRUE: Within host plants, phytoplasmas are strictly restricted to the nutrient-rich sieve tube elements of the phloem tissue, from which they are acquired and transmitted by phloem-feeding insect vectors (leafhoppers and planthoppers).
However, inhabiting the phloem is not the evolutionary or mechanistic reason why phytoplasmas lack a cell wall (their wall-less state evolved through reductive genome evolution from ancestral Firmicutes).

Therefore, both (A) and (R) are true, but (R) is NOT the correct explanation of (A). Correct Answer: Option 2.

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

Q.62

ICAR AIEEA PG 2024 - Plant Sciences

Statement Based +4 −1

Given below are two statements

Statement (I) : Bacteria need pre-existing openings or wounds on plants to initiate infection.

Statement (II) : Bacteria do not produce specialized infective structures.

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

नीचे दो कथन दिए गए हैं

कथन (I) : जीवाणुओं (Bacteria) को संक्रमण शुरू करने के लिए पौधों पर पहले से मौजूद प्राकृतिक छिद्रों या घावों की आवश्यकता होती है।

कथन (II) : जीवाणु विशेष संक्रामक संरचनाओं (specialized infective structures) का निर्माण नहीं करते हैं।

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

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

Bacterial Ingress and Mode of Infection:

Statement (I) is CORRECT: Plant pathogenic bacteria lack the mechanical force to breach the intact plant cuticle directly. They can only enter host plant tissues through natural openings (such as stomata, hydathodes, lenticels, nectaries) or through mechanical wounds (caused by cultivation, hail, pruning, or insect feeding).
Statement (II) is CORRECT: Unlike phytopathogenic fungi that differentiate specialized morphological infection structures (such as appressoria, penetration pegs, and haustoria), bacteria enter passively as individual cells suspended in water films without producing specialized morphological penetration structures.

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

विस्तृत व्याख्या:

Bacterial Ingress and Mode of Infection (जीवाणु संक्रमण की विधि):

Statement (I) is CORRECT: Plant pathogenic bacteria lack the mechanical force to breach the intact plant cuticle directly. They can only enter host plant tissues through natural openings (such as stomata, hydathodes, lenticels, nectaries) or through mechanical wounds (caused by cultivation, hail, pruning, or insect feeding).
Statement (II) is CORRECT: Unlike phytopathogenic fungi that differentiate specialized morphological infection structures (such as appressoria, penetration pegs, and haustoria), bacteria enter passively as individual cells suspended in water films without producing specialized morphological penetration structures.

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

Q.63

ICAR AIEEA PG 2024 - Plant Sciences

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।

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

Q.64

ICAR AIEEA PG 2024 - Plant Sciences

Statement Based +4 −1

Given below are two statements

Statement (I) : Vertical resistance is exploited in agriculture by pathologists and breeders for crop improvement.

Statement (II) : Vertical resistance is mostly monogenic in nature.

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

नीचे दो कथन दिए गए हैं

कथन (I) : फसल सुधार के लिए रोगविज्ञानियों और प्रजनकों द्वारा कृषि में ऊर्ध्वाधर प्रतिरोध (Vertical resistance) का उपयोग किया जाता है।

कथन (II) : ऊर्ध्वाधर प्रतिरोध प्रकृति में अधिकांशतः एकलजीनी (monogenic) होता है।

Both Statement (I) and Statement (II) are true कथन (I) और कथन (II) दोनों सत्य हैं Both Statement (I) and Statement (II) are false कथन (I) और कथन (II) दोनों असत्य हैं Statement (I) is true but Statement (II) is false कथन (I) सत्य है लेकिन कथन (II) असत्य है Statement (I) is false but Statement (II) is true कथन (I) असत्य है लेकिन कथन (II) सत्य है

Q.65

ICAR AIEEA PG 2024 - Plant Sciences

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