In humans traits are much easier to identify than traits. Choose...

Q.1

ICAR AIEEA PG 2024 - Plant Sciences (Q.6)

MCQ (Single Correct) +4 −1

If an individual does not show trait even though they have the appropriate genotype, the trait is said to exhibit

यदि कोई व्यक्ति उपयुक्त जीनोटाइप (genotype) होने के बावजूद लक्षण (trait) प्रदर्शित नहीं करता है, तो इस लक्षण को क्या कहा जाता है?

Variable expressivity परिवर्तनशील अभिव्यक्तित्व Incomplete penetrance अपूर्ण प्रभाविता/प्रवेश्यता Partial dominance आंशिक प्रभाविता Co-dominance सह-प्रभाविता

Penetrance vs. Expressivity:

Penetrance: The proportion of individuals carrying a particular genotype who actually manifest the corresponding phenotype. When individuals possessing the genotype fail to express the phenotype, the trait exhibits Incomplete Penetrance.
Expressivity: The degree or intensity with which a genotype is expressed phenotypically among individuals showing the trait (e.g., polydactyly having varied numbers of extra digits).
Co-dominance: Both alleles are expressed equally in the heterozygote (e.g., AB blood group).
Partial dominance: Heterozygote has an intermediate phenotype (e.g., pink flowers in Mirabilis jalapa).

Correct Answer: Option 2 (Incomplete penetrance).

विस्तृत व्याख्या:

Penetrance vs. Expressivity (प्रवेश्यता बनाम अभिव्यक्तित्व):

Penetrance (प्रवेश्यता): The proportion of individuals carrying a particular genotype who actually manifest the corresponding phenotype. When individuals possessing the genotype fail to express the phenotype, the trait exhibits Incomplete Penetrance (अपूर्ण प्रवेश्यता).
Expressivity (अभिव्यक्तित्व): The degree or intensity with which a genotype is expressed phenotypically among individuals showing the trait (e.g., polydactyly having varied numbers of extra digits).
Co-dominance (सह-प्रभाविता): Both alleles are expressed equally in the heterozygote (e.g., AB blood group).
Partial dominance (आंशिक प्रभाविता / Incomplete dominance): Heterozygote has an intermediate phenotype (e.g., pink flowers in Mirabilis jalapa).

Correct Answer: Option 2 (Incomplete penetrance).

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Q.2

ICAR AIEEA PG 2024 - Plant Sciences (Q.7)

MCQ (Single Correct) +4 −1

In humans ________ traits are much easier to identify than ________ traits. Choose the correct pair of words from the options given below for filling in the blanks:

मानव में ________ लक्षण, ________ लक्षणों की तुलना में पहचानने में बहुत आसान होते हैं। रिक्त स्थानों की पूर्ति के लिए

नीचे दिए गए विकल्पों में से सही शब्द-युग्म चुनिए:

Recessive autosomal traits; X-linked traits अप्रभावी ऑटोसोमल लक्षण; X-सहलग्न लक्षण X-linked traits; Dominant autosomal traits X-सहलग्न लक्षण; प्रभावी ऑटोसोमल लक्षण X-linked traits; Recessive autosomal traits X-सहलग्न लक्षण; अप्रभावी ऑटोसोमल लक्षण Dominant autosomal traits; X-linked traits प्रभावी ऑटोसोमल लक्षण; X-सहलग्न लक्षण

Inheritance and Pedigree Analysis in Humans:

X-linked traits: In human males ($XY$), who are hemizygous for the X chromosome, any allele on the X chromosome (whether dominant or recessive) is immediately expressed in the phenotype because there is no homologous counterpart on the Y chromosome. Furthermore, X-linked traits display characteristic criss-cross inheritance (father to daughter to grandson), making them readily distinguishable and much easier to identify.
Recessive autosomal traits: These require two copies of the mutant allele (homozygosity) to be expressed phenotypically, often skip multiple generations silently via unaffected heterozygous carriers, and are much harder to track and identify without extensive pedigree and consanguinity data.

Therefore, X-linked traits are much easier to identify than recessive autosomal traits. Correct Answer: Option 3 (X-linked traits; Recessive autosomal traits).

विस्तृत व्याख्या:

Inheritance and Pedigree Analysis in Humans (मानव में वंशागति):

X-linked traits (X-सहलग्न लक्षण): In human males ($XY$), who are hemizygous for the X chromosome, any allele on the X chromosome (whether dominant or recessive) is immediately expressed in the phenotype because there is no homologous counterpart on the Y chromosome. Furthermore, X-linked traits display characteristic criss-cross inheritance (father to daughter to grandson), making them readily distinguishable and much easier to identify.
Recessive autosomal traits (अप्रभावी ऑटोसोमल लक्षण): These require two copies of the mutant allele (homozygosity) to be expressed phenotypically, often skip multiple generations silently via unaffected heterozygous carriers, and are much harder to track and identify without extensive pedigree and consanguinity data.

Therefore, X-linked traits are much easier to identify than recessive autosomal traits. Correct Answer: Option 3 (X-linked traits; Recessive autosomal traits).

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Q.3

ICAR AIEEA PG 2024 - Plant Sciences (Q.28)

Match the Following +4 −1

Match List-I with List-II:

Choose the correct answer from the options given below:

सूची-I को सूची-II के साथ सुमेलित कीजिए:

नीचे दिए गए विकल्पों में से सही उत्तर चुनिए:

List - I		List - II
A	Streptococcus pneumoniae Streptococcus pneumoniae	I	One gene-one enzyme एक जीन-एक एंजाइम सिद्धांत
B	Neurospora crassa Neurospora crassa	II	RNA is the genetic material आरएनए आनुवंशिक पदार्थ है
C	T4 Bacteriophage (rII locus) T4 बैक्टीरियोफेज	III	DNA is the genetic material डीएनए आनुवंशिक पदार्थ है
D	TMV (Tobacco Mosaic Virus) टीएमवी (टोबैको मोज़ेक वायरस)	IV	Fine structure of gene जीन की सूक्ष्म संरचना

(A) - (III), (B) - (I), (C) - (IV), (D) - (II) (A) - (III), (B) - (I), (C) - (IV), (D) - (II) (A) - (III), (B) - (I), (C) - (II), (D) - (IV) (A) - (III), (B) - (I), (C) - (II), (D) - (IV) (A) - (II), (B) - (IV), (C) - (I), (D) - (III) (A) - (II), (B) - (IV), (C) - (I), (D) - (III) (A) - (II), (B) - (I), (C) - (IV), (D) - (III) (A) - (II), (B) - (I), (C) - (IV), (D) - (III)

Microorganisms in Milestone Genetic Discoveries:

Streptococcus pneumoniae: Used by Oswald Avery, Colin MacLeod, and Maclyn McCarty (1944) following Frederick Griffith's (1928) work to prove decisively that DNA is the transforming principle / genetic material $\rightarrow$ (III).
Neurospora crassa (red bread mold): Used by George Beadle and Edward Tatum (1941) to propose the famous One gene-one enzyme hypothesis via biochemical nutritional auxotrophs $\rightarrow$ (I).
T4 Bacteriophage (rII locus): Used by Seymour Benzer (1955–1961) to elucidate the Fine structure of the gene (cistron, recon, muton) $\rightarrow$ (IV).
TMV (Tobacco Mosaic Virus): Used by Heinz Fraenkel-Conrat and Beatrice Singer (1957, Biochim. Biophys. Acta) in viral reconstitution experiments to prove that RNA is the genetic material in RNA viruses $\rightarrow$ (II).

Matching sequence: (A) - (III), (B) - (I), (C) - (IV), (D) - (II).
Correct Answer: Option 1.

विस्तृत व्याख्या:

Microorganisms in Milestone Genetic Discoveries (ऐतिहासिक आनुवंशिक खोजें):

Streptococcus pneumoniae: Used by Oswald Avery, Colin MacLeod, and Maclyn McCarty (1944) following Frederick Griffith's (1928) work to prove decisively that DNA is the transforming principle / genetic material $\rightarrow$ (III).
Neurospora crassa (red bread mold): Used by George Beadle and Edward Tatum (1941) to propose the famous One gene-one enzyme hypothesis via biochemical nutritional auxotrophs $\rightarrow$ (I).
T4 Bacteriophage (rII locus): Used by Seymour Benzer (1955–1961) to elucidate the Fine structure of the gene (cistron, recon, muton) $\rightarrow$ (IV).
TMV (Tobacco Mosaic Virus): Used by Heinz Fraenkel-Conrat and Beatrice Singer (1957, Biochim. Biophys. Acta) in viral reconstitution experiments to prove that RNA is the genetic material in RNA viruses $\rightarrow$ (II).

Matching sequence: (A) - (III), (B) - (I), (C) - (IV), (D) - (II).
Correct Answer: Option 1.

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Q.4

ICAR AIEEA PG 2024 - Plant Sciences (Q.36)

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.5

ICAR AIEEA PG 2024 - Plant Sciences (Q.39)

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:

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

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:

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

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.

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