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.36

ICAR AIEEA PG 2024 - Plant Sciences

Arranging Order +4 −1

Arrange the following concepts/principles chronologically from the oldest to the latest:

(A) Gene-for-gene hypothesis

(B) Dominance hypothesis

(C) Transforming principles

(D) Concept of heterosis

Choose the correct answer from the options given below:

निम्नलिखित अवधारणाओं/सिद्धांतों को सबसे पुराने से नवीनतम के कालानुक्रमिक क्रम में व्यवस्थित कीजिए:

(A) जीन-के-लिए-जीन परिकल्पना (Gene-for-gene hypothesis)

(B) प्रभाविता परिकल्पना (Dominance hypothesis of heterosis)

(C) रूपांतरणकारी सिद्धांत (Transforming principle)

(D) संकर ओज की अवधारणा (Concept / term Heterosis)

नीचे दिए गए विकल्पों में से सही उत्तर चुनिए:

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

Q.37

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) : In nature, the tetraploid and hexaploid wheat reproduce as diploid ($2n=28$ or $2n = 42$).

Reason (R) : In the presence of the Ph1 allele in chromosome 5B, each chromosome pairs only with its homologue from the same genome and reproduces as diploid.

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) : प्रकृति में, चतुर्गुणित (tetraploid) और षट्गुणित (hexaploid) गेहूँ द्विगुणित ($2n=28$ या $2n = 42$) के रूप में प्रजनन करते हैं।

कारण (R) : गुणसूत्र 5B में Ph1 एलील की उपस्थिति में, प्रत्येक गुणसूत्र केवल उसी जीनोम के अपने समजात (homologue) के साथ युग्मित होता है और द्विगुणित के रूप में प्रजनन करता है।

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

Genetic Control of Diploid-like Pairing in Polyploid Wheat:

Assertion (A) is TRUE: Bread wheat (Triticum aestivum, $2n = 6x = 42$, AABBDD) and durum wheat (Triticum durum, $2n = 4x = 28$, AABB) are allopolyploids containing closely related, homoeologous subgenomes. Despite having multiple related genomes, they strictly form bivalents (21 bivalents in hexaploid, 14 bivalents in tetraploid) during meiotic metaphase I and behave cytogenetically as functional diploids with regular disomic inheritance.
Reason (R) is TRUE and correctly explains (A): This regular bivalent pairing is strictly regulated by the $Ph1$ (Pairing homoeologous 1) locus located on the long arm of chromosome 5B (discovered by Ralph Riley and Ernest Sears). The dominant $Ph1$ gene suppresses pairing between homoeologous (related) chromosomes, restricting synapsis strictly to true homologous pairs within the same genome. When $Ph1$ is deleted or mutated, homoeologous pairing and multivalent formation occur.

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

विस्तृत व्याख्या:

Genetic Control of Diploid-like Pairing in Polyploid Wheat (गेहूँ में द्विगुणित युग्मन का आनुवंशिक नियंत्रण):

Assertion (A) is TRUE: Bread wheat (Triticum aestivum, $2n = 6x = 42$, AABBDD) and durum wheat (Triticum durum, $2n = 4x = 28$, AABB) are allopolyploids containing closely related, homoeologous subgenomes. Despite having multiple related genomes, they strictly form bivalents (21 bivalents in hexaploid, 14 bivalents in tetraploid) during meiotic metaphase I and behave cytogenetically as functional diploids with regular disomic inheritance.
Reason (R) is TRUE and correctly explains (A): This regular bivalent pairing is strictly regulated by the $Ph1$ (Pairing homoeologous 1) locus located on the long arm of chromosome 5B (discovered by Ralph Riley and Ernest Sears). The dominant $Ph1$ gene suppresses pairing between homoeologous (related) chromosomes, restricting synapsis strictly to true homologous pairs within the same genome. When $Ph1$ is deleted or mutated, homoeologous pairing and multivalent formation occur.

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

Q.38

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) : Self-incompatibility, male sterility, and pistillate condition have one effect in common: they prevent self-pollination.

Reason (R) : Self-incompatibility and male sterility are used in hybrid seed production while pistillate condition is used in inbred development.

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

अभिकथन (A) : स्व-अनिषेच्यता (self-incompatibility), नर बाँझपन (male sterility), और स्त्री-केसरी अवस्था (pistillate condition) का एक सामान्य प्रभाव होता है: वे स्व-परागण को रोकते हैं।

कारण (R) : स्व-अनिषेच्यता और नर बाँझपन का उपयोग संकर बीज उत्पादन में किया जाता है जबकि स्त्री-केसरी अवस्था का उपयोग अंतःप्रजात विकास में किया जाता है।

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

Mechanisms Preventing Self-Pollination:

Assertion (A) is TRUE: Self-incompatibility (physiological barrier), male sterility (lack of functional pollen), and pistillate condition (production of only female flowers, as in dioecious plants or gynoecious lines) all physically or genetically enforce cross-pollination by preventing self-fertilization.
Reason (R) is FALSE: Pistillate lines (gynoecious lines) are widely utilized for commercial hybrid seed production—most notably in castor (Ricinus communis - e.g., VP-1, TSP 10R) and cucurbits (cucumber)—where 100% pistillate lines act as female parents without requiring emasculation. Inbred development, conversely, requires consecutive generations of selfing, which pistillate plants cannot achieve on their own without chemical sex reversion (e.g., silver nitrate/GA).

Therefore, (A) is true but (R) is false. Correct Answer: Option 3.

विस्तृत व्याख्या:

Mechanisms Preventing Self-Pollination (स्व-परागण रोकने की प्रणालियाँ):

Assertion (A) is TRUE: Self-incompatibility (physiological barrier), male sterility (lack of functional pollen), and pistillate condition (production of only female flowers, as in dioecious plants or gynoecious lines) all physically or genetically enforce cross-pollination by preventing self-fertilization.
Reason (R) is FALSE: Pistillate lines (gynoecious lines) are widely utilized for commercial hybrid seed production—most notably in castor (Ricinus communis - e.g., VP-1, TSP 10R) and cucurbits (cucumber)—where 100% pistillate lines act as female parents without requiring emasculation. Inbred development, conversely, requires consecutive generations of selfing, which pistillate plants cannot achieve on their own without chemical sex reversion (e.g., silver nitrate/GA).

Therefore, (A) is true but (R) is false. Correct Answer: Option 3.

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

Q.39

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) : Incomplete penetrance and variable expressivity confuse the relationship between the genotype and phenotype.

Reason (R) : Progeny test for more than one generation may be used to study the nature of penetrance and expressivity, and to establish the genotype of a plant beyond reasonable doubt.

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

अभिकथन (A) : अपूर्ण प्रवेश्यता (Incomplete penetrance) और परिवर्तनशील अभिव्यक्तित्व (variable expressivity) जीनोटाइप और फेनोटाइप के बीच के संबंध को भ्रमित/जटिल कर देते हैं।

कारण (R) : प्रवेश्यता और अभिव्यक्तित्व की प्रकृति का अध्ययन करने और किसी पौधे के जीनोटाइप को संदेह से परे स्थापित करने के लिए एक से अधिक पीढ़ियों के संतति परीक्षण (progeny test) का उपयोग किया जा सकता है।

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

Penetrance, Expressivity, and Genotype Elucidation:

Assertion (A) is TRUE: When individuals with the exact same genotype fail to show the trait (incomplete penetrance) or express it with varying degrees of severity (variable expressivity) due to modifier genes and environmental fluctuations, a simple 1-to-1 correspondence between genotype and phenotype breaks down, confounding phenotypic selection.
Reason (R) is TRUE and correctly explains (A): Because individual phenotype cannot reliably reveal the underlying genotype in the presence of incomplete penetrance, multi-generational progeny testing is required to observe segregation patterns across large offspring populations and conclusively verify whether non-expressing or mildly-expressing individuals actually carry the mutant allele.

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

विस्तृत व्याख्या:

Penetrance, Expressivity, and Genotype Elucidation (प्रवेश्यता एवं संतति परीक्षण):

Assertion (A) is TRUE: When individuals with the exact same genotype fail to show the trait (incomplete penetrance) or express it with varying degrees of severity (variable expressivity) due to modifier genes and environmental fluctuations, a simple 1-to-1 correspondence between genotype and phenotype breaks down, confounding phenotypic selection.
Reason (R) is TRUE and correctly explains (A): Because individual phenotype cannot reliably reveal the underlying genotype in the presence of incomplete penetrance, multi-generational progeny testing is required to observe segregation patterns across large offspring populations and conclusively verify whether non-expressing or mildly-expressing individuals actually carry the mutant allele.

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

Q.40

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) : In field experiments, the word 'replication' means doing something again in exactly the same way or repeating the treatments.

Reason (R) : The $F_2$ seeds cannot be replicated in the field experiment as the genotype of each seed in an $F_2$ generation is not the same and hence can't be repeated.

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

अभिकथन (A) : क्षेत्रीय प्रयोगों (field experiments) में, 'पुनरावृत्ति' (replication) शब्द का अर्थ है किसी कार्य को बिल्कुल उसी तरीके से दोबारा करना या उपचारों को दोहराना।

कारण (R) : $F_2$ बीजों को क्षेत्रीय प्रयोग में दोहराया (replicate) नहीं जा सकता क्योंकि $F_2$ पीढ़ी में प्रत्येक बीज का जीनोटाइप समान नहीं होता है और इसलिए इसे दोहराया नहीं जा सकता है।

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

Principles of Replication in Field Experimentation:

Assertion (A) is TRUE: In statistical experimental design (R.A. Fisher), 'replication' means applying each treatment to multiple independent experimental plots under identical conditions to provide an estimate of experimental error and increase precision.
Reason (R) is TRUE: Individual $F_2$ plants from a hybrid cross are segregate for multiple loci; each single $F_2$ seed represents an entirely unique, non-identical recombinant genotype. True clonal/genotypic replication cannot be performed on individual $F_2$ seeds (unlike homozygous inbreds or clonal lines).
However, Reason (R) does not explain the foundational statistical definition of replication given in Assertion (A).

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

विस्तृत व्याख्या:

Principles of Replication in Field Experimentation (क्षेत्रीय प्रयोगों में पुनरावृत्ति सिद्धांत):

Assertion (A) is TRUE: In statistical experimental design (R.A. Fisher), 'replication' means applying each treatment to multiple independent experimental plots under identical conditions to provide an estimate of experimental error and increase precision.
Reason (R) is TRUE: Individual $F_2$ plants from a hybrid cross are segregate for multiple loci; each single $F_2$ seed represents an entirely unique, non-identical recombinant genotype. True clonal/genotypic replication cannot be performed on individual $F_2$ seeds (unlike homozygous inbreds or clonal lines).
However, Reason (R) does not explain the foundational statistical definition of replication given in Assertion (A).

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