All 8 questions from UPSC Civil Services Mains Botany 2023 Paper II (400 marks total). Every stem reproduced in full, with directive-word analysis, marks, word limits, and answer-approach pointers.
8Questions
400Total marks
2023Year
Paper IIPaper
Topics covered
Cell biology and genetics fundamentals (1)Chromosomes, inheritance and gene transfer (1)Breeding, cell transport and evolution (1)Cell organelles, alleles and molecular techniques (1)Plant physiology and ecology fundamentals (1)Plant movements, respiration and biodiversity (1)Enzymology, nitrogen metabolism and conservation (1)Fatty acid metabolism, ecosystem energetics and pollution (1)
A
Q1
50M150wCompulsorywrite short notesCell biology and genetics fundamentals
Write short notes on the following in about 150 words each : 10×5=50
(a) Cell-cell adhesion mechanism 10
(b) Structure and functions of cytoskeleton 10
(c) Characteristics of triplet codon 10
(d) Crossing over and its significance 10
(e) Correlation, its types and significance 10
हिंदी में पढ़ें
निम्नलिखित में से प्रत्येक पर लगभग 150 शब्दों में संक्षिप्त टिप्पणियाँ लिखिए : 10×5=50
(a) कोशिका-कोशिका आसंजन क्रियाविधि 10
(b) कोशिकापंजर की संरचना एवं कार्य 10
(c) त्रिक कोडोन के अभिलक्षण 10
(d) विनिमय (क्रॉसिंग ओवर) एवं इसका महत्व 10
(e) सहसंबंध, इसके प्रकार एवं महत्व 10
Answer approach & key points
Framework: Botany Paper 2: Define > Structure/Process > Labelled Diagram > Significance. (a) write short notes: define > 3-4 key features > one example > one-line significance | (b) write short notes: define > 3-4 key features > one example > one-line significance | (c) write short notes: define > 3-4 key features > one example > one-line significance | (d) write short notes: define > 3-4 key features > one example > one-line significance | (e) write short notes: define > 3-4 key features > one example > one-line significance Full marks: Precise definitions, specific examples, labelled diagrams, and clear significance for each part.
Cadherins: Ca2+-dependent, homophilic, adherens junctions and desmosomes
Selectins and immunoglobulin superfamily
Integrins and matrix adhesion
Tight and gap junctions; plant middle lamella
Microfilaments: actin, about 7 nm
Intermediate filaments: about 10 nm, tensile strength
Microtubules: tubulin, about 25 nm, spindle, cilia, transport
Functions: shape, motility, transport, division
Triplet, 64 codons, 61 sense and 3 stop
Degenerate with wobble
Non-overlapping, commaless, unambiguous
Start codon AUG and near universality
Exchange between non-sister chromatids at pachytene
Chiasmata at diplotene
Significance: variation, segregation, mapping, evolution and breeding
50MdifferentiateChromosomes, inheritance and gene transfer
(a) Differentiate between polytene chromosomes and normal chromosomes. 15
(b) Describe polygenic inheritance by giving suitable examples. 15
(c) Describe the problems associated with gene transfer in plants. Write a note on the status of transgenic research in India. 15+5=20
हिंदी में पढ़ें
(a) बहुपट्टीय गुणसूत्र एवं सामान्य गुणसूत्र में विभेद कीजिए । 15
(b) उपयुक्त उदाहरणों को देते हुए अनेकजीनी वंशागति का वर्णन कीजिए । 15
(c) पादपों में जीन स्थानांतरण (जीन ट्रांसफर) से जुड़ी समस्याओं का वर्णन कीजिए । भारत में पारजीनी अनुसंधान की स्थिति पर एक टिप्पणी लिखिए । 15+5=20
Answer approach & key points
Framework: null. (a) compare: paired headings or table > key differences > significance > conclusion | (b) describe: define > structure or process in order > labelled diagram > significance | (c(i)) describe: define > structure or process in order > labelled diagram > significance | (c(ii)) write short notes: define > 3-4 key features > one example > one-line significance Full marks: Comprehensive, accurate, with labelled diagrams and specific examples.
Origin: endoreduplication without division versus normal replication
Structure: many chromatids versus one DNA per chromatid
Size, somatic pairing, banding and puffs
Occurrence in dipteran salivary glands; uses in mapping
(a) What are the major requirements for a successful back-crossing programme ? Describe its procedure, advantages and limitations. 5+10=15
(b) Describe the mechanism involved in membrane transport and vesicular transport. 15
(c) Describe the theory of natural selection and its significance. 20
हिंदी में पढ़ें
(a) एक सफल प्रतिप-प्रसंकरण कार्यक्रम की प्रमुख आवश्यकताएँ क्या हैं ? इसकी कार्यविधि, लाभ और सीमाओं का वर्णन कीजिए । 5+10=15
(b) झिल्ली अभिगमन एवं पुटिकामय अभिगमन में शामिल प्रक्रिया का वर्णन कीजिए । 15
(c) प्राकृतिक वरण का सिद्धांत एवं इसके महत्व का वर्णन कीजिए । 20
Answer approach & key points
Framework: null. (a) describe: define > structure or process in order > labelled diagram > significance | (b) describe: define > structure or process in order > labelled diagram > significance | (c) describe: define > structure or process in order > labelled diagram > significance Full marks: Comprehensive, accurate, and well-structured with diagrams and examples.
Requirements: good recurrent parent, donor with trait, heritable trait, enough back-crosses
Procedure: F1 crossed to recurrent parent for six or more generations with selection
Genome recovery 1-(1/2)^(n+1)
Advantages and limitations: linkage drag, single-gene traits
Passive: simple and facilitated diffusion, channels, carriers
50MdescribeCell organelles, alleles and molecular techniques
(a) Describe the structure, kinds, chemical nature, origin and functions of lysosomes. 20
(b) Explain multiple alleles and their characteristics. How are they different from pseudoalleles ? 10+5=15
(c) Describe the procedure, requirements and efficiency level of gene amplification through Polymerase Chain Reaction (PCR). 15
हिंदी में पढ़ें
(a) लाइसोसोम की संरचना, प्रकार, रासायनिक प्रकृति, उत्पत्ति एवं कार्यों का वर्णन कीजिए । 20
(b) बहुविकल्पियों तथा उनके अभिलक्षणों की व्याख्या कीजिए । ये कूटविकल्पियों से किस प्रकार भिन्न हैं ? 10+5=15
(c) पॉलीमेरेज श्रृंखला अभिक्रिया (पी.सी.आर.) के माध्यम से जीन प्रवर्धन की प्रक्रिया, आवश्यकताओं और दक्षता स्तर का वर्णन कीजिए । 15
Answer approach & key points
Framework: UPSC Botany Paper 2. (a) describe: define > structure or process in order > labelled diagram > significance | (b(i)) explain: definition/context > points in order > small example > short close | (b(ii)) compare: paired headings or table > key differences > significance > conclusion | (c) describe: define > structure or process in order > labelled diagram > significance Full marks: Precise definitions, labelled diagrams, and specific examples (e.g., ABO, Taq) for all parts.
Structure: single membrane, acidic pH, size
Kinds: primary, secondary, residual, autophagic
Chemical nature: acid hydrolases, acid phosphatase marker
50M150wCompulsorywrite short notesPlant physiology and ecology fundamentals
Write short notes on the following in about 150 words each : 10×5=50
(a) Biological significance of mineral elements in plants 10
(b) Photo-oxidation of water by photosystem II through oxygen-evolving complex 10
(c) Photoperiodic induction and the perception site of photoperiodic stimulus 10
(d) Role of light as a limiting factor in an ecosystem 10
(e) Forests are an important wealth of the country 10
हिंदी में पढ़ें
निम्नलिखित में से प्रत्येक पर लगभग 150 शब्दों में संक्षिप्त टिप्पणियाँ लिखिए : 10×5=50
(a) पौधों में खनिज तत्त्वों का जैविक महत्व 10
(b) ऑक्सीजन उत्पन्न सम्मिश्र के माध्यम से फोटोसिस्टम II द्वारा जल का प्रकाश-ऑक्सीकरण 10
(c) दीप्तिकालिक प्रेरण तथा दीप्तिकालिक उदीपन का अवगम स्थल 10
(d) पारिस्थितिकी तंत्र में एक सीमाकारी कारक के रूप में प्रकाश की भूमिका 10
(e) वन देश की महत्वपूर्ण संपदा हैं 10
Answer approach & key points
Framework: Botany Paper 2: Define > Structure/Process > Labelled Diagram > Significance. (a) write short notes: define > 3-4 key features > one example > one-line significance | (b) write short notes: define > 3-4 key features > one example > one-line significance | (c) write short notes: define > 3-4 key features > one example > one-line significance | (d) write short notes: define > 3-4 key features > one example > one-line significance | (e) write short notes: define > 3-4 key features > one example > one-line significance Full marks: All parts have labelled diagrams, specific examples, and clear biological mechanisms.
50MexplainPlant movements, respiration and biodiversity
(a) What are nastic movements, their types and mechanism ? Explain. 15
(b) How is the transport of electrons and pumping of protons associated with ATP synthesis in mitochondria ? Explain. 15
(c) Why is the conservation of biodiversity important ? Discuss the various steps adopted for it by our country. 10+10=20
हिंदी में पढ़ें
(a) अनुकूंचन गतियाँ, उनके प्रकार और कार्यविधि क्या हैं ? समझाइए । 15
(b) माइटोकॉन्ड्रिया में इलेक्ट्रॉन अभिगमन और प्रोटॉन की पम्पिंग ए.टी.पी. संश्लेषण से किस प्रकार जुड़ी है ? समझाइए । 15
(c) जैवविविधता संरक्षण क्यों महत्वपूर्ण है ? हमारे देश द्वारा इसके लिए अपनाए गए विभिन्न उपायों की चर्चा कीजिए । 10+10=20
Answer approach & key points
Framework: UPSC Botany Paper 2. (a) explain: definition/context > points in order > small example > short close | (b) explain: definition/context > points in order > small example > short close | (c) discuss: intro > 3-4 dimensions > example > balanced close Full marks: Comprehensive, accurate, and well-structured answers with labelled diagrams and specific examples.
50MexplainEnzymology, nitrogen metabolism and conservation
(a) How can the reaction equilibria and reaction rates be explained by using free energy diagram in a simple enzymatic reaction ? 20
(b) Explain the following : 5+5=10
(i) Nitrate and nitrite reduction in the leaves of higher plants. 5
(ii) Protection of enzyme nitrogenase against oxygen and hydrogen damage. 5
(c) Comment on the following : 10+10=20
(i) Biosphere reserves 10
(ii) Red Data Book 10
हिंदी में पढ़ें
(a) एक साधारण एन्जाइमी अभिक्रिया में मुक्त ऊर्जा आरेख का उपयोग करके अभिक्रिया संतुलन और अभिक्रिया दरों को कैसे समझाया जा सकता है ? 20
(b) निम्नलिखित को समझाइए : 5+5=10
(i) उच्च पादपों की पत्तियों में नाइट्रेट और नाइट्राइट का अपचयन । 5
(ii) ऑक्सीजन और हाइड्रोजन क्षति के विरुद्ध एन्जाइम नाइट्रोजिनेज का संरक्षण । 5
(c) निम्नलिखित पर टिप्पणी कीजिए : 10+10=20
(i) जीवमंडल निचय 10
(ii) संकटग्रस्त जीव पुस्तिका 10
Answer approach & key points
Framework: Botany Paper 2: Define > Structure/Process > Labelled Diagram > Significance. (a) explain: definition/context > points in order > small example > short close | (b(i)) explain: definition/context > points in order > small example > short close | (b(ii)) explain: definition/context > points in order > small example > short close | (c(i)) comment: context > arguments both sides > judgment > close | (c(ii)) comment: context > arguments both sides > judgment > close Full marks: All parts fully addressed with labelled diagrams, exact terminology, and specific examples; no factual errors.
Free energy vs reaction coordinate: S, transition state, P
Equilibrium fixed by delta G0' and K_eq; enzyme does not alter it
Rate fixed by activation energy; enzyme lowers it
ES, ES-double-dagger, EP intermediates and forward/reverse equal effect
50MexplainFatty acid metabolism, ecosystem energetics and pollution
(a) (i) How do the three stages in fatty acid oxidation converge to conserve energy as ATP ? 5
(ii) What is β-oxidation ? Describe various steps in fatty acid oxidation pathway involving saturated fatty acids. 15
(b) Explain the transfer of energy between different trophic levels of an ecosystem. 15
(c) What are the major gaseous pollutants and their sources ? Explain the effects of air pollutants on human health. 15
हिंदी में पढ़ें
(a) (i) ए.टी.पी. (ATP) के रूप में ऊर्जा के संरक्षण के लिए वसा अम्ल ऑक्सीकरण में तीन चरण कैसे अभिसरण करते हैं ? 5
(ii) बीटा-ऑक्सीकरण क्या है ? संतृप्त वसा अम्लों से युक्त वसा अम्ल ऑक्सीकरण मार्ग के विभिन्न चरणों का वर्णन कीजिए । 15
(b) पारिस्थितिकी तंत्र में विभिन्न पोषी स्तरों के मध्य ऊर्जा के स्थानांतरण को समझाइए । 15
(c) प्रमुख गैसीय प्रदूषक एवं उनके स्रोत क्या हैं ? मानव स्वास्थ्य पर वायु प्रदूषकों के प्रभावों की व्याख्या कीजिए । 15
Answer approach & key points
Framework: Botany, Paper 2. (a(i)) explain: definition/context > points in order > small example > short close | (a(ii)) describe: define > structure or process in order > labelled diagram > significance | (b) explain: definition/context > points in order > small example > short close | (c) explain: definition/context > points in order > small example > short close Full marks: Comprehensive, accurate, and well-structured answers with labelled diagrams and specific examples.