Male sterile cytoplasm in crop plants usually arises from- (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

ICAR AIEEA PG 2024 - Plant Sciences

MCQ (Single Correct)

Which of the following groups of seeds represents the orthodox class of seeds?

निम्नलिखित में से बीजों का कौन सा समूह रूढ़िवादी (orthodox) वर्ग के बीजों का प्रतिनिधित्व करता है?

Coconut and Mango नारियल और आम Rubber and Cocoa रबर और कोको Rice and Wheat धान और गेहूँ Coffee and Oilpalm कॉफी और ऑयलपाम

Seed Storage Behavior:

Orthodox Seeds:
- Can tolerate drying to very low moisture content (less than 5%) and survive freezing temperatures (down to $-20^\circ\text{C}$ or liquid nitrogen).
Their longevity increases with decreasing seed moisture and storage temperature.
Examples: Rice, Wheat, Chickpea, Maize, Mustard, Tomato, and most agricultural field crops.

Recalcitrant Seeds:
- Seeds that lose viability when dried below a relatively high critical moisture content (typically 12–30%) and cannot tolerate freezing temperatures.
Examples: Mango, Coconut, Rubber, Cocoa, Jackfruit, Citrus.

Intermediate Seeds: Coffee, Oilpalm, Papaya.

Therefore, Rice and Wheat represent orthodox seeds. Correct Answer: Option 3 (Rice and Wheat).

विस्तृत व्याख्या:

Seed Storage Behavior (बीज भंडारण व्यवहार - Roberts, 1973):

Orthodox Seeds (ऑर्थोडॉक्स/रूढ़िवादी बीज):
- Can tolerate drying to very low moisture content (less than 5%) and survive freezing temperatures (down to $-20^\circ\text{C}$ or liquid nitrogen).
Their longevity increases with decreasing seed moisture and storage temperature.
Examples: Rice (धान), Wheat (गेहूँ), Chickpea, Maize, Mustard, Tomato, and most agricultural field crops.

Recalcitrant Seeds (रिकैलसिट्रेंट/अहठी बीज):
- Seeds that lose viability when dried below a relatively high critical moisture content (typically 12–30%) and cannot tolerate freezing temperatures.
Examples: Mango (आम), Coconut (नारियल), Rubber (रबर), Cocoa (कोको), Jackfruit, Citrus.

Intermediate Seeds: Coffee, Oilpalm, Papaya.

Therefore, Rice and Wheat represent orthodox seeds. Correct Answer: Option 3 (Rice and Wheat).

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

ICAR AIEEA PG 2024 - Plant Sciences

MCQ (Single Correct)

Select the correct statements about origin of the tetraploid and hexaploid wheat:

(A) The tetraploid species Triticum turgidum is an allopolyploid.

(B) The hexaploid species Triticum aestivum is an allopolyploid.

(C) Triticum turgidum arose from a combination of Triticum monococcum and Triticum timopheevii genomes.

(D) Triticum aestivum arose from a combination of Triticum turgidum and Aegilops tauschii genomes.

Choose the correct answer from the options given below:

चतुर्गुणित (tetraploid) और षट्गुणित (hexaploid) गेहूँ की उत्पत्ति के बारे में सही कथनों का चयन कीजिए:

(A) चतुर्गुणित प्रजाति Triticum turgidum एक एलोपॉलीप्लॉयड (allopolyploid) है।

(B) षट्गुणित प्रजाति Triticum aestivum एक एलोपॉलीप्लॉयड है।

(C) Triticum turgidum की उत्पत्ति Triticum monococcum और Triticum timopheevii जीनोम के संयोजन से हुई।

(D) Triticum aestivum की उत्पत्ति Triticum turgidum और Aegilops tauschii जीनोम के संयोजन से हुई।

नीचे दिए गए विकल्पों में से सही उत्तर चुनिए:

(A), (B) and (C) only केवल (A), (B) और (C) (A), (B) and (D) only केवल (A), (B) और (D) (A), (C) and (D) only केवल (A), (C) और (D) (B), (C) and (D) only केवल (B), (C) और (D)

Evolution of Wheat:

Statement (A) is CORRECT: Tetraploid wheat (Triticum turgidum ssp. durum, $2n = 4x = 28$, genome AABB) is an allopolyploid formed by natural hybridization between T. urartu (AA donor) and an ancestor related to Aegilops speltoides (BB donor).
Statement (B) is CORRECT: Bread wheat (Triticum aestivum, $2n = 6x = 42$, genome AABBDD) is an allohexaploid.
Statement (C) is INCORRECT: T. turgidum (AABB) did NOT arise from T. timopheevii (AAGG); they are distinct tetraploid lineages.
Statement (D) is CORRECT: Hexaploid bread wheat (T. aestivum, AABBDD) arose from spontaneous hybridization between cultivated tetraploid wheat (T. turgidum, AABB) and the wild goat grass Aegilops tauschii (Ae. squarrosa, DD donor), followed by spontaneous chromosome doubling.

Thus, statements (A), (B), and (D) are correct. Correct Answer: Option 2 ((A), (B) and (D) only).

विस्तृत व्याख्या:

Evolution of Wheat (गेहूँ की उत्पत्ति एवं उद्विकास):

Statement (A) is CORRECT: Tetraploid wheat (Triticum turgidum ssp. durum, $2n = 4x = 28$, genome AABB) is an allopolyploid formed by natural hybridization between T. urartu (AA donor) and an ancestor related to Aegilops speltoides (BB donor).
Statement (B) is CORRECT: Bread wheat (Triticum aestivum, $2n = 6x = 42$, genome AABBDD) is an allohexaploid.
Statement (C) is INCORRECT: T. turgidum (AABB) did NOT arise from T. timopheevii (AAGG); they are distinct tetraploid lineages.
Statement (D) is CORRECT: Hexaploid bread wheat (T. aestivum, AABBDD) arose from spontaneous hybridization between cultivated tetraploid wheat (T. turgidum, AABB) and the wild goat grass Aegilops tauschii (Ae. squarrosa, DD donor), followed by spontaneous chromosome doubling.

Thus, statements (A), (B), and (D) are correct. Correct Answer: Option 2 ((A), (B) and (D) only).

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

ICAR AIEEA PG 2024 - Plant Sciences

MCQ (Single Correct)

The physiological characteristics of wheat plants that adapt different wheat cultivars to different climates include

(A) Fertilizer requirement

(B) Vernalization requirement

(C) Winter hardiness (cold tolerance)

(D) Photoperiod response

Choose the correct answer from the options given below:

गेहूँ के पौधों की वे कार्यिकीय विशेषताएं (physiological characteristics) जो विभिन्न गेहूँ किस्मों को विभिन्न जलवायु के अनुकूल बनाती हैं, उनमें शामिल हैं:

(A) उर्वरक आवश्यकता (Fertilizer requirement)

(B) वसंतीकरण आवश्यकता (Vernalization requirement)

(C) शीत सहिष्णुता (Winter hardiness / cold tolerance)

(D) दीप्तिकाल प्रतिक्रिया (Photoperiod response)

नीचे दिए गए विकल्पों में से सही उत्तर चुनिए:

Climatic Adaptation in Wheat:

Physiological traits governing wide climatic adaptation in wheat cultivars worldwide are controlled by major gene systems:

Vernalization requirement ($Vrn$ genes): Cold temperature requirement to switch from vegetative to reproductive phase (distinguishes winter wheat from spring wheat).
Winter hardiness / freezing tolerance: Ability of winter wheat crowns to survive extreme sub-zero soil and air temperatures.
Photoperiod response ($Ppd$ genes): Day-length sensitivity governing heading date and flowering time across different latitudes.
- In contrast, Fertilizer requirement is an agronomic/nutritional management factor, not an intrinsic physiological climatic adaptation trait.

Therefore, (B), (C), and (D) are the physiological adaptation traits. Correct Answer: Option 4 ((B), (C) and (D) only).

विस्तृत व्याख्या:

Climatic Adaptation in Wheat (गेहूँ में जलवायु अनुकूलन कार्यिकी):

Physiological traits governing wide climatic adaptation in wheat cultivars worldwide are controlled by major gene systems:

Vernalization requirement ($Vrn$ genes): Cold temperature requirement to switch from vegetative to reproductive phase (distinguishes winter wheat from spring wheat).
Winter hardiness / freezing tolerance: Ability of winter wheat crowns to survive extreme sub-zero soil and air temperatures.
Photoperiod response ($Ppd$ genes): Day-length sensitivity governing heading date and flowering time across different latitudes.
- In contrast, Fertilizer requirement is an agronomic/nutritional management factor, not an intrinsic physiological climatic adaptation trait.

Therefore, (B), (C), and (D) are the physiological adaptation traits. Correct Answer: Option 4 ((B), (C) and (D) only).

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

ICAR AIEEA PG 2024 - Plant Sciences

MCQ (Single Correct)

Male sterile cytoplasm in crop plants usually arises from-

(A) Inter-specific hybridization

(B) Self-incompatibility

(C) Spontaneous mutation

(D) Induced mutation through Ethidium Bromide

Choose the correct answer from the options given below:

फसली पौधों में नर बाँझ कोशिकाद्रव्य (Male sterile cytoplasm / CMS) आमतौर पर किससे उत्पन्न होता है?

(A) अंतर-विशिष्ट संकरण (Inter-specific hybridization)

(B) स्व-अनिषेच्यता (Self-incompatibility)

(C) स्वतःस्फूर्त उत्परिवर्तन (Spontaneous mutation)

(D) एथिडियम ब्रोमाइड द्वारा प्रेरित उत्परिवर्तन (Induced mutation through Ethidium Bromide)

नीचे दिए गए विकल्पों में से सही उत्तर चुनिए:

Origins of Cytoplasmic Male Sterility:

CMS is controlled by mitochondrial genes (mtDNA) causing failure of viable pollen production.
CMS originates via three primary pathways:

Inter-specific / wide hybridization (A): Combining nuclear genome of one species with foreign cytoplasm of a related wild species (alloplasmic male sterility, e.g., Tift 23A pearl millet, WA cytoplasm in rice from wild rice Oryza rufipogon).
Spontaneous mutation (C): Spontaneous mutations or rearrangements in the mitochondrial genome (e.g., Texas cytoplasm in maize, CMS-S, CMS-C).
Induced mutation using mitochondrial mutagens (D): Chemical mutagens like Ethidium bromide and streptomycin specifically target and mutagenize extranuclear/mitochondrial DNA to induce CMS.
- Self-incompatibility (B) is a genetic pre-fertilization barrier preventing self-pollen fertilization, governed by nuclear $S$-alleles, and has no causal relation to CMS cytoplasm.

Thus, (A), (C), and (D) are correct. Correct Answer: Option 3 ((A), (C) and (D) only).

विस्तृत व्याख्या:

Origins of Cytoplasmic Male Sterility (CMS की उत्पत्ति):

CMS is controlled by mitochondrial genes (mtDNA) causing failure of viable pollen production.
CMS originates via three primary pathways:

Inter-specific / wide hybridization (A): Combining nuclear genome of one species with foreign cytoplasm of a related wild species (alloplasmic male sterility, e.g., Tift 23A pearl millet, WA cytoplasm in rice from wild rice Oryza rufipogon).
Spontaneous mutation (C): Spontaneous mutations or rearrangements in the mitochondrial genome (e.g., Texas cytoplasm in maize, CMS-S, CMS-C).
Induced mutation using mitochondrial mutagens (D): Chemical mutagens like Ethidium bromide and streptomycin specifically target and mutagenize extranuclear/mitochondrial DNA to induce CMS.
- Self-incompatibility (B) is a genetic pre-fertilization barrier preventing self-pollen fertilization, governed by nuclear $S$-alleles, and has no causal relation to CMS cytoplasm.

Thus, (A), (C), and (D) are correct. Correct Answer: Option 3 ((A), (C) and (D) only).

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

ICAR AIEEA PG 2024 - Plant Sciences

MCQ (Single Correct)

Which of the following statements is NOT correct?
(A) Seeds of synthetic varieties need to be replaced every year.
(B) Hybrid crops need intensive care and more inputs.
(C) Open pollinated progeny test is used in Maize and Pearlmillet.
(D) Composite varieties exploit both GCA and SCA.
Choose the correct answer from the options given below:

निम्नलिखित में से कौन से कथन सही नहीं हैं?
(A) संश्लिष्ट किस्मों (synthetic varieties) के बीजों को प्रत्येक वर्ष बदलने की आवश्यकता होती है।
(B) संकर फसलों (hybrid crops) को गहन देखभाल और अधिक आदानों (inputs) की आवश्यकता होती है।
(C) मक्का और बाजरा में ओपन पॉलिनेटेड संतति परीक्षण (Open pollinated progeny test) का उपयोग किया जाता है।
(D) संकुल किस्में (composite varieties) GCA और SCA दोनों का विदोहन करती हैं।
नीचे दिए गए विकल्पों में से सही उत्तर चुनिए:

Analysis of Statements:

is INCORRECT: Unlike $F_1$ hybrids, farmers do not need to replace seeds of synthetic varieties every year; the open-pollinated synthetic population maintains heterozygosity and can be grown for 3–4 seasons without significant yield decline.
is CORRECT: Hybrid crops require optimal agronomic conditions, higher fertilization, irrigation, and careful management to realize their full heterotic yield potential.
is INCORRECT: In maize and pearl millet breeding, evaluating parental lines for general combining ability is done via topcross or polycross tests, not open-pollinated progeny tests (which are used mainly in perennial tree crops/forestry).
is INCORRECT: Composite varieties are developed by mixing open-pollinated genotypes evaluated for General Combining Ability (GCA), primarily exploiting additive gene action and GCA rather than Specific Combining Ability (SCA).

Therefore, statements (A), (C), and (D) are NOT correct. Correct Answer: Option 3 ((A), (C) and (D) only).

विस्तृत व्याख्या:

Analysis of Statements (कथनों का विश्लेषण):

is INCORRECT: Unlike $F_1$ hybrids, farmers do not need to replace seeds of synthetic varieties every year; the open-pollinated synthetic population maintains heterozygosity and can be grown for 3–4 seasons without significant yield decline.
is CORRECT: Hybrid crops require optimal agronomic conditions, higher fertilization, irrigation, and careful management to realize their full heterotic yield potential.
is INCORRECT: In maize and pearl millet breeding, evaluating parental lines for general combining ability is done via topcross or polycross tests, not open-pollinated progeny tests (which are used mainly in perennial tree crops/forestry).
is INCORRECT: Composite varieties are developed by mixing open-pollinated genotypes evaluated for General Combining Ability (GCA), primarily exploiting additive gene action and GCA rather than Specific Combining Ability (SCA).

Therefore, statements (A), (C), and (D) are NOT correct. Correct Answer: Option 3 ((A), (C) and (D) only).

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