The process of 'turning on the expression of genes' due to...

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.11

ICAR AIEEA PG 2024 - Plant Sciences

MCQ (Single Correct) +4 −1

Unlike Mendel's experiments, Bateson and Punnett's experiment with sweet peas demonstrated that, in the $F_2$ generation, genes for flower color and pollen length:

मेंडल के प्रयोगों के विपरीत, मीठी मटर (sweet pea) के साथ बेटसन और पुनेट के प्रयोग ने प्रदर्शित किया कि $F_2$ पीढ़ी में पुष्प के रंग और परागकण की लंबाई के जीन:

Assort independently स्वतंत्र रूप से अपव्यूहित होते हैं Assort randomly यादृच्छिक रूप से अपव्यूहित होते हैं Do not assort independently स्वतंत्र रूप से अपव्यूहित नहीं होते हैं Showed chromosomal non-disjunction गुणसूत्रीय अवियोजन प्रदर्शित करते हैं

Bateson and Punnett's Linkage Experiment:

In 1905, William Bateson and Reginald Punnett conducted dihybrid crosses in sweet pea (Lathyrus odoratus) studying two traits: flower colour (Purple $P$ vs. Red $p$) and pollen shape (Long $L$ vs. Round $l$).
In the $F_2$ generation, instead of the expected Mendelian independent assortment ratio of $9:3:3:1$, the observed phenotypic counts were 1528 (Purple Long) : 106 (Purple Round) : 117 (Red Long) : 381 (Red Round), simplifying to approximately $12:1:1:3$ (showing marked excess of parental types).
The ratio $7:1:1:7$ represents the theoretical gametic coupling ratio ($7PL : 1Pl : 1pL : 7pl$) fitted to explain this coupling phase.
This experiment provided the first evidence of genetic Linkage (Coupling and Repulsion), proving that the two genes reside on the same chromosome and therefore do not assort independently.

Correct Answer: Option 3 (Do not assort independently).

विस्तृत व्याख्या:

Bateson and Punnett's Linkage Experiment (बेटसन और पुनेट का सहलग्नता प्रयोग):

In 1905, William Bateson and Reginald Punnett conducted dihybrid crosses in sweet pea (Lathyrus odoratus) studying two traits: flower colour (Purple $P$ vs. Red $p$) and pollen shape (Long $L$ vs. Round $l$).
In the $F_2$ generation, instead of the expected Mendelian independent assortment ratio of $9:3:3:1$, the observed phenotypic counts were 1528 (Purple Long) : 106 (Purple Round) : 117 (Red Long) : 381 (Red Round), simplifying to approximately $12:1:1:3$ (showing marked excess of parental types).
The ratio $7:1:1:7$ represents the theoretical gametic coupling ratio ($7PL : 1Pl : 1pL : 7pl$) fitted to explain this coupling phase.
This experiment provided the first evidence of genetic Linkage (Coupling and Repulsion), proving that the two genes reside on the same chromosome and therefore do not assort independently.

Correct Answer: Option 3 (Do not assort independently).

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

Q.12

ICAR AIEEA PG 2024 - Plant Sciences

MCQ (Single Correct) +4 −1

________ is a second mutation that compensates for the effect of an original, first mutation.

Choose the most appropriate option from the below-mentioned options to fill in the gap:

________ एक दूसरा उत्परिवर्तन (second mutation) है जो मूल, पहले उत्परिवर्तन के प्रभाव की भरपाई (compensate) करता है। रिक्त स्थान की पूर्ति के लिए

नीचे दिए गए विकल्पों में से सर्वाधिक उपयुक्त विकल्प चुनिए:

Forward mutation अग्रगामी उत्परिवर्तन Supplementary mutation पूरक उत्परिवर्तन Suppressor mutation दमनकारी उत्परिवर्तन Compensatory mutation प्रतिपूरक उत्परिवर्तन

Suppressor Mutation:

Suppressor mutation is a secondary genetic alteration that suppresses or alleviates the phenotypic consequences of an earlier (first) mutation, restoring the wild-type or near wild-type phenotype without reversing the original mutation.
Suppressors are categorized into:

Intragenic suppressors: Occur within the same gene as the first mutation (e.g., a compensatory insertion near an earlier deletion that restores reading frame).
Intergenic (extragenic) suppressors: Occur in a different gene (e.g., a mutant tRNA gene whose anticodon recognizes a nonsense stop codon introduced by the primary mutation).
- Forward mutation: Mutation from wild type to mutant form.
Reverse/back mutation: Direct reversion of the mutant allele back to the wild-type sequence.

Correct Answer: Option 3 (Suppressor mutation).

विस्तृत व्याख्या:

Suppressor Mutation (सप्रेसर/दमनकारी उत्परिवर्तन):

Suppressor mutation is a secondary genetic alteration that suppresses or alleviates the phenotypic consequences of an earlier (first) mutation, restoring the wild-type or near wild-type phenotype without reversing the original mutation.
Suppressors are categorized into:

Intragenic suppressors: Occur within the same gene as the first mutation (e.g., a compensatory insertion near an earlier deletion that restores reading frame).
Intergenic (extragenic) suppressors: Occur in a different gene (e.g., a mutant tRNA gene whose anticodon recognizes a nonsense stop codon introduced by the primary mutation).
- Forward mutation: Mutation from wild type to mutant form.
Reverse/back mutation: Direct reversion of the mutant allele back to the wild-type sequence.

Correct Answer: Option 3 (Suppressor mutation).

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

Q.13

ICAR AIEEA PG 2024 - Plant Sciences

MCQ (Single Correct) +4 −1

In the case of Lac operon, the presence of glucose in the cell growing media will lead to

लैक ऑपेरॉन (Lac operon) के संदर्भ में, कोशिका संवर्धन माध्यम में ग्लूकोज (glucose) की उपस्थिति के कारण क्या होगा?

Increased induction बढ़ा हुआ प्रेरण Catabolite repression अपचयी दमन Slow induction धीमा प्रेरण Zero effect induction शून्य प्रभाव प्रेरण

Q.14

ICAR AIEEA PG 2024 - Plant Sciences

MCQ (Single Correct) +4 −1

The process of 'turning on the expression of genes' due to environmental conditions is called

पर्यावरणीय परिस्थितियों के कारण 'जीन की अभिव्यक्ति को सक्रिय करने' (turning on gene expression) की प्रक्रिया क्या कहलाती है?

Constitutive expression संविधिक/नित्य अभिव्यक्ति Induction प्रेरण Repression दमन Enzymatic catabolism एंजाइमी अपचय

Q.15

ICAR AIEEA PG 2024 - Plant Sciences

MCQ (Single Correct) +4 −1

Which one of the following statements about the mode of reproduction is NOT correct?

प्रजनन की विधियों (modes of reproduction) के बारे में

निम्नलिखित में से कौन सा कथन सही नहीं है?

Self-fertilization, where pollen from a plant will fertilize ovules of the same plant स्व-निषेचन, जहाँ एक पौधे का परागकण उसी पौधे के बीजांड को निषेचित करता है Cross-pollination, where pollen from one plant can only fertilize a different plant पर-परागण, जहाँ एक पौधे का परागकण केवल किसी दूसरे पौधे को निषेचित कर सकता है Asexual propagation, where the new plant is genetically identical to its parent अलैंगिक प्रवर्धन, जहाँ नया पौधा अपने जनक के आनुवंशिक रूप से समान होता है Apomixis, where seeds are produced asexually and the new plant is quite improved and different from its parents एपोमिक्सिस, जहाँ बीज अलैंगिक रूप से बनते हैं और नया पौधा अपने जनकों से काफी उन्नत और भिन्न होता है