All 8 questions from UPSC Civil Services Mains Botany 2025 Paper II (400 marks total). Every stem reproduced in full, with directive-word analysis, marks, word limits, and answer-approach pointers.
8Questions
400Total marks
2025Year
Paper IIPaper
Topics covered
Cell biology and genetics fundamentals (1)DNA sequencing and chromosome genetics (1)Sex determination and plant hybridization (1)Evolution, chloroplast structure and mutations (1)Plant physiology, ecology and conservation (1)Transgenic crops, nitrogen fixation and forest ecology (1)Gene transfer, carbon fixation and climate change (1)Biodiversity conservation and plant hormones (1)
A
Q1
50M150wCompulsorywrite short notesCell biology and genetics fundamentals
Write short notes on the following in about 150 words each:
(a) Nuclear pore complex (10 marks)
(b) Epistasis (10 marks)
(c) Synaptonemal complex (10 marks)
(d) Amphidiploidy (10 marks)
(e) Lysosome (10 marks)
हिंदी में पढ़ें
निम्नलिखित में से प्रत्येक पर लगभग 150 शब्दों में संक्षिप्त टिप्पणी लिखिए :
(a) केन्द्रक छिद्र सम्मिश्र (10 अंक)
(b) प्रभलता (अर्थतरण) (10 अंक)
(c) युग्मसूत्री सम्मिश्र (10 अंक)
(d) उभयद्विगुणितता (10 अंक)
(e) लाइसोसोम (10 अंक)
Answer approach & key points
Framework: Botany Paper 2: Define > Structure/Process > 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, accurate diagrams, specific examples, clear mechanisms.
Definition of NPC (massive assembly perforating the nuclear envelope; octagonal symmetry, ~30 nucleoporins)
FG-nucleoporins lining the central channel
Bidirectional transport: passive (<40 kDa) vs karyopherin-mediated; Ran-GTP/GDP gradient
Compartmentalisation and gene-expression regulation (no diagram required — question asks only for a short note)
Definition of epistasis
Explanation of gene interaction
Specific example with species name (e.g., *Cucurbita pepo* 12:3:1, sweet pea 9:7)
50MelaborateDNA sequencing and chromosome genetics
(a) What are the different methods of DNA sequencing? Elaborate the shotgun sequencing method. (20 marks)
(b) Describe the phenomenon of linkage by giving suitable examples. Why is the linkage an exception to Mendel's second law? (15 marks)
(c) Explain the structure and behaviour of B chromosomes in plants. (15 marks)
हिंदी में पढ़ें
(a) डी० एन० ए० अनुक्रमण के विभिन्न तरीके क्या हैं? शॉटगन अनुक्रमण तरीके को विस्तृत कीजिए। (20 अंक)
(b) उपयुक्त उदाहरणों की सहायता से सहलग्नता की क्रिया का वर्णन कीजिए। सहलग्नता मेंडल के दूसरे नियम का एक अपवाद क्यों है? (15 अंक)
(c) पौधों में B गुणसूत्रों की संरचना तथा गतिविधि को समझाइए। (15 अंक)
Answer approach & key points
Framework: UPSC Botany Paper 2. (a) describe: define > structure or process in order > labelled diagram > significance | (b) describe: define > structure or process in order > labelled diagram > significance | (c) explain: definition/context > points in order > small example > short close Full marks: Precise definitions, named species, clear diagrams, and logical flow.
List Sanger, Maxam-Gilbert, and Next-Gen methods
Define shotgun sequencing as random fragmentation
Explain assembly of overlapping reads (contigs)
Mention of paired-end reads, scaffolding and BAC/fosmid libraries for large genomes
Define linkage as co-inheritance of alleles
Cite *Lathyrus odoratus* (Bateson and Punnett) or *Drosophila* (Morgan) example
Explain physical proximity on same chromosome
Contrast with Mendel's Law of Independent Assortment
50MelucidateSex determination and plant hybridization
(a) Elucidate the molecular basis of sex determination in plants. Explain the role of homomorphic and heteromorphic sex chromosomes. (20 marks)
(b) Describe the structure of nucleosome and its role in DNA packaging. (15 marks)
(c) Explain in detail the various methods of plant hybridization. (15 marks)
हिंदी में पढ़ें
(a) पादपों में लिंग निर्धारण के आण्विक आधार को स्पष्ट कीजिए। समरूपी एवं विषमरूपी लिंग गुणसूत्रों की भूमिका को समझाइए। (20 अंक)
(b) न्यूक्लियोसोम की संरचना तथा डी० एन० ए० पैकेजिंग में इसकी भूमिका का वर्णन कीजिए। (15 अंक)
(c) पादप संकरण के विभिन्न तरीकों को विस्तारपूर्वक समझाइए। (15 अंक)
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) describe: define > structure or process in order > labelled diagram > significance | (c) explain: definition/context > points in order > small example > short close Full marks: Precise molecular/structural details, labelled diagrams, specific species examples, and clear significance.
50MdiscussEvolution, chloroplast structure and mutations
(a) What is organic evolution? Discuss in detail the indirect evidences of organic evolution with suitable examples. (20 marks)
(b) Describe the structure of chloroplast with labelled diagram and write about its functions. (15 marks)
(c) Discuss in detail the role of mutations in plant breeding and crop improvement. (15 marks)
हिंदी में पढ़ें
(a) जैविक विकास क्या है? जैविक विकास के अप्रत्यक्ष प्रमाणों पर उपयुक्त उदाहरणों द्वारा विस्तारपूर्वक चर्चा कीजिए। (20 अंक)
(b) हरितलवक (क्लोरोप्लास्ट) की संरचना का नामांकित आरेख द्वारा वर्णन कीजिए तथा इसके कार्यों के बारे में लिखिए। (15 अंक)
(c) पादप प्रजनन तथा फसल सुधार में उत्परिवर्तनों की भूमिका पर विस्तारपूर्वक चर्चा कीजिए। (15 अंक)
Answer approach & key points
(a) discuss: intro > 3-4 dimensions > example > balanced close | (b) describe: define > structure or process in order > labelled diagram > significance | (c) discuss: intro > 3-4 dimensions > example > balanced close Full marks: Comprehensive coverage of all points with specific examples, clear diagrams, and accurate terminology.
Definition of organic evolution (descent with modification)
Fossil evidence with specific examples (e.g., *Horse*, *Whale*)
50M150wCompulsorywrite short notesPlant physiology, ecology and conservation
Write short notes on the following in about 150 words each:
(a) Tests of significance (10 marks)
(b) Kranz anatomy and its significance (10 marks)
(c) Vernalization (10 marks)
(d) The IUCN Red List categories (10 marks)
(e) Endemism (10 marks)
हिंदी में पढ़ें
निम्नलिखित में से प्रत्येक पर लगभग 150 शब्दों में संक्षिप्त टिप्पणी लिखिए :
(a) सार्थकता परीक्षण (10 अंक)
(b) क्रांज ऐनाटॉमी और इसका महत्व (10 अंक)
(c) वसंतीकरण (10 अंक)
(d) आई० यू० सी० एन० लाल सूची श्रेणियाँ (10 अंक)
(e) विशेषक्षेत्रिता (स्थानिकता) (10 अंक)
Answer approach & key points
Framework: Botany Paper 2: Define > Structure/Process > 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: Clear definitions, specific examples, and accurate explanations of mechanisms and significance.
Definition of null hypothesis (H0) and alternative hypothesis (H1)
Explanation of p-value and level of significance (α)
Distinction between Type I and Type II errors
Mention of specific tests (e.g., t-test, chi-square, ANOVA)
Description of concentric arrangement of mesophyll and bundle sheath cells
Identification of C4 plants (e.g., *Zea mays*, *Sorghum bicolor*)
Explanation of spatial separation of initial CO2 fixation and Calvin cycle
Significance in reducing photorespiration and increasing efficiency
50MdiscussTransgenic crops, nitrogen fixation and forest ecology
(a) What are transgenic crops? Discuss the prospects and risks involved in their cultivation. (20 marks)
(b) What is biological nitrogen fixation? Explain the mechanism of symbiotic nitrogen fixation with examples. (15 marks)
(c) Describe the different forest types in India. Discuss in detail the crucial ecosystem services provided by these forests. (15 marks)
हिंदी में पढ़ें
(a) ट्रांसजेनिक फसलें क्या हैं? उनकी खेती में शामिल संभावनाओं तथा जोखिमों पर चर्चा कीजिए। (20 अंक)
(b) जैविक नाइट्रोजन स्थिरीकरण क्या है? सहजीवी नाइट्रोजन स्थिरीकरण की प्रक्रिया को उदाहरण सहित समझाइए। (15 अंक)
(c) भारत में विभिन्न वन प्रकारों का वर्णन कीजिए। इन वनों द्वारा प्रदान की गई महत्वपूर्ण पारितंत्र सेवाओं की विस्तारपूर्वक विवेचना कीजिए। (15 अंक)
Answer approach & key points
Framework: UPSC Botany Paper 2. (a) discuss: intro > 3-4 dimensions > example > balanced close | (b) explain: definition/context > points in order > small example > short close | (c) describe: define > structure or process in order > labelled diagram > significance Full marks: Comprehensive coverage of all sub-parts with specific examples, binomials, and balanced analysis.
Precise definition of transgenic crops (GMOs)
Prospects: pest resistance (e.g., Bt cotton), herbicide tolerance
Risks: gene flow to wild relatives, biodiversity loss
50MexplainGene transfer, carbon fixation and climate change
(a) What are the different gene transfer methods in plants? Give a brief account of direct gene transfer methods. (20 marks)
(b) What are the different carbon fixation pathways in plants? Discuss in detail the CAM pathway and its role in stomatal activity. (15 marks)
(c) What are the causes and consequences of global warming and climate change? Explain the approaches to deal with global warming. (15 marks)
हिंदी में पढ़ें
(a) पादपों के जीन स्थानांतरण की विभिन्न विधियाँ क्या हैं? प्रत्यक्ष जीन स्थानांतरण विधियों का संक्षिप्त विवरण दीजिए। (20 अंक)
(b) पादपों में कार्बन स्थिरीकरण के विभिन्न मार्ग (पाथवे) क्या हैं? कैम पाथवे तथा रंध्रीय गतिविधि में इसकी भूमिका पर विस्तारपूर्वक चर्चा कीजिए। (15 अंक)
(c) वैश्विक उष्मीकरण तथा जलवायु परिवर्तन के कारण तथा परिणाम क्या हैं? वैश्विक उष्मीकरण से निपटने के उपायों को समझाइए। (15 अंक)
Answer approach & key points
Framework: UPSC Botany Paper 2. (a) describe: define > structure or process in order > labelled diagram > significance | (b) discuss: intro > 3-4 dimensions > example > balanced close | (c) analyse: intro > causes > effects > stakeholders/linkages > way forward Full marks: Comprehensive, accurate, with labelled diagrams and specific examples.
List indirect (Agrobacterium/Ti T-DNA; virus vectors) and direct methods
Biolistics (gene gun) mechanism and limitations
Electroporation and PEG-mediated transformation
Microinjection and silicon carbide whiskers (no diagram required — question asks only for an account)
50MexplainBiodiversity conservation and plant hormones
(a) Define biodiversity. Explain the various ex situ and in situ methods of conserving biodiversity. (20 marks)
(b) What are phytohormones? Briefly discuss the role of auxin in plant growth and development. Explain its mechanism of action. (15 marks)
(c) Describe the various types of tropic movements in plants. Discuss their mechanism. (15 marks)
हिंदी में पढ़ें
(a) जैव विविधता की परिभाषा दीजिए। जैव विविधता संरक्षण के विभिन्न बाह्य-स्थाने (एक्स सिटु) तथा स्व-स्थाने (इन सिटु) तरीकों की व्याख्या कीजिए। (20 अंक)
(b) पादप हार्मोन क्या हैं? पौधों की वृद्धि एवं विकास में ऑक्सिन की भूमिका की संक्षेप में विवेचना कीजिए। इसकी क्रियाविधि को समझाइए। (15 अंक)
(c) पौधों में विभिन्न प्रकार की अनुवर्ती गतियों (ट्रॉपिक मूवमेंट) का वर्णन कीजिए। उनकी क्रियाविधि पर विवेचना कीजिए। (15 अंक)
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) describe: define > structure or process in order > labelled diagram > significance Full marks: Comprehensive coverage of all sub-parts with precise mechanisms, specific examples, and clear distinction between concepts.
Precise definition of biodiversity (genetic, species, ecosystem)
In situ methods: National Parks, Sanctuaries, Biosphere Reserves
Ex situ methods: Botanical gardens, Seed banks, Tissue culture
Comparison or distinction between in situ and ex situ
Definition of phytohormones (plant growth regulators)
Role of auxin: Apical dominance, phototropism, cell elongation