All 8 questions from UPSC Civil Services Mains Botany
2021 Paper II (400 marks total). Every stem reproduced in full,
with directive-word analysis, marks, word limits, and answer-approach pointers.
8Questions
400Total marks
2021Year
Paper IIPaper
Topics covered
Cell biology and genetics fundamentals (1)Chromatin structure and genetic linkage (1)Genetic code and transgenic plants (1)Gene transfer and cell signalling (1)Plant biochemistry and ecology (1)Photosynthesis and plant physiology (1)Biodiversity and conservation (1)Seed dormancy and sustainable development (1)
A
Q1
50MCompulsorywrite short notesCell biology and genetics fundamentals
Write short notes on the following : 10×5=50
(a) Cell adhesion molecules 10
(b) Ribosomal RNA processing in nucleolus 10
(c) Genetic consequences of Inversion 10
(d) Gene silencing 10
(e) Use of apomixis in plant breeding 10
हिंदी में पढ़ें
निम्नलिखित पर संक्षिप्त टिप्पणियाँ लिखिए : 10×5=50
(a) कोशिका आसंजन अणु 10
(b) राइबोसोमल आर.एन.ए. का केन्द्रक में प्रसंस्करण 10
(c) प्रतिलोमन के आनुवंशिक परिणाम 10
(d) जीन साइलेंसिंग 10
(e) पादप प्रजनन में असंगजन का उपयोग 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 definition, 3-4 features, example, significance, and labelled diagram.
Definition of cell adhesion molecules
3-4 key features (e.g., Ca2+ dependence, specificity)
One example (e.g., Integrins, Cadherins)
One-line significance (e.g., tissue integrity)
Definition of rRNA processing in nucleolus
3-4 key features (e.g., cleavage, methylation)
One example (e.g., 45S pre-rRNA to 18S, 5.8S, 28S)
50MdescribeChromatin structure and genetic linkage
(a) Describe types and composition of chromatin. How is DNA packaged in a eukaryotic cell ? 10+10=20
(b) Explain coupling and repulsion hypothesis in linkage. Give a brief account of procedure used in preparing a chromosome map with the help of three-point test cross. 5+10=15
(c) What do you understand by standard deviation and coefficient of variation ? Discuss their significance. 10+5=15
हिंदी में पढ़ें
(a) क्रोमेटिन के प्रकारों तथा संयोजन का वर्णन कीजिए । यूकेरियोटिक कोशिका में डी.एन.ए. कैसे पैकेज होता है ? 10+10=20
(b) सहलग्नता में युग्मन और प्रतिकर्षण परिकल्पना की व्याख्या कीजिए । त्री-पॉइंट परीक्षार्थ संकरण की सहायता से गुणसूत्र मानचित्र तैयार करने में प्रयुक्त प्रक्रिया का संक्षिप्त विवरण दीजिए । 5+10=15
(c) मानक विचलन और विचरण गुणांक से आप क्या समझते हैं ? इनके महत्व की चर्चा कीजिए । 10+5=15
Answer approach & key points
Framework: Botany Paper 2: Define > Structure/Process > Labelled Diagram > Significance. (a) describe: define > structure or process in order > labelled diagram > significance | (b) explain: definition/context > points in order > small example > short close | (c) discuss: intro > 3-4 dimensions > example > balanced close Full marks: Complete definitions, accurate diagrams, stepwise processes, specific examples, and clear significance
Distinguish euchromatin and heterochromatin
Identify histone proteins (H1-H4) and nucleosome structure
Describe DNA packaging levels (beads-on-string to 30nm fiber)
(a) Describe properties of genetic code and briefly explain Wobble hypothesis. 15+5=20
(b) What are the characteristic features of Cytoplasmic inheritance ? Describe the role of chloroplast and mitochondrial genes in this inheritance. 7+8=15
(c) Discuss the biosafety concerns of transgenic plants. 15
हिंदी में पढ़ें
(a) आनुवंशिक कूट के गुणों का वर्णन कीजिए तथा वॉबल परिकल्पना की संक्षेप में व्याख्या कीजिए । 15+5=20
(b) कोशिकाद्रव्य वंशानुक्रम की विशेषताएं क्या हैं ? इस वंशानुक्रम में हरितलवक (क्लोरोप्लास्ट) एवं माइटोकॉन्ड्रियल जीनों की भूमिका का वर्णन कीजिए । 7+8=15
(c) पराउपतिमूलक (ट्रांसजेनिक) पौधों की जैव-सुरक्षा चिंताओं की विवेचना कीजिए । 15
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) discuss: intro > 3-4 dimensions > example > balanced close Full marks: Comprehensive, accurate, with specific examples and labelled diagrams where appropriate.
Define genetic code and list 4-5 properties (e.g., degenerate, unambiguous)
Explain Wobble hypothesis (Crick) regarding 3rd base pairing
Mention specific base pairing examples (e.g., G-U, I-A/C/U)
Provide a labelled diagram of tRNA anticodon-mRNA codon interaction
(a) Describe various methods of gene transfer in plants. 20
(b) Give an account of Operon model for regulation of gene activity. 15
(c) Explain the process of cell signalling highlighting the role of various signalling molecules. 15
हिंदी में पढ़ें
(a) पौधों में जीन स्थानांतरण की विभिन्न विधियों का वर्णन कीजिए । 20
(b) जीन गतिविधि के विनियमन के लिए ऑपेरॉन मॉडल का विवरण प्रस्तुत कीजिए । 15
(c) विभिन्न संकेतन अणुओं की भूमिका पर प्रकाश डालते हुए कोशिका संकेतन की प्रक्रिया की व्याख्या कीजिए । 15
Answer approach & key points
Framework: Botany Paper 2: Define > Structure/Process > Labelled Diagram > Significance. (a) describe: define > structure or process in order > labelled diagram > significance | (b) account for: state the phenomenon > the causes in order of weight > conclusion | (c) explain: definition/context > points in order > small example > short close Full marks: Comprehensive coverage of all methods/mechanisms with accurate labelled diagrams, specific examples, and clear logical flow.
50MCompulsorywrite short notesPlant biochemistry and ecology
Write short notes on the following : 10×5=50
(a) Alkaloids and their significance 10
(b) Role of growth substances in agri-horticulture 10
(c) Plant indicators 10
(d) Invasive species and their characteristics 10
(e) IUCN Red List Categories 10
हिंदी में पढ़ें
निम्नलिखित पर संक्षिप्त टिप्पणियाँ लिखिए : 10×5=50
(a) एल्केलॉइड्स और उनके महत्व 10
(b) कृषि-बागवानी में वृद्धि पदार्थों की भूमिका 10
(c) पादप सूचक 10
(d) आक्रामक प्रजातियाँ (स्पीशीज़) और उनकी विशेषताएँ 10
(e) आई.यू.सी.एन. लाल सूची श्रेणियाँ 10
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, specific examples, clear significance, no errors.
Definition: Nitrogenous secondary metabolites
Mention specific alkaloid (e.g., Morphine, Quinine)
(a) Describe C₄ cycle of photosynthesis and differentiate amongst C₃, C₄ and CAM plants. 10+10=20
(b) Define Vernalization. Discuss its mechanism and importance. 5+10=15
(c) What is biological nitrogen fixation ? Describe root nodule formation and role of nitrogenase complex in fixing of nitrogen. 5+5+5=15
हिंदी में पढ़ें
(a) प्रकाश-संश्लेषण के C₄ चक्र का वर्णन कीजिए और C₃, C₄ तथा CAM पौधों के बीच अंतर स्पष्ट कीजिए । 10+10=20
(b) वसंतीकरण की परिभाषा दीजिए । इसकी क्रियाविधि एवं महत्व की विवेचना कीजिए । 5+10=15
(c) जैविक नाइट्रोजन स्थिरीकरण क्या है ? जड़ों पर प्रथिका निर्माण तथा नाइट्रोजन स्थिरीकरण में नाइट्रोजिनेस कॉम्प्लेक्स की भूमिका का वर्णन कीजिए । 5+5+5=15
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) describe: define > structure or process in order > labelled diagram > significance Full marks: Accurate stepwise mechanisms, labelled diagrams, specific species names, and clear differentiation.
Stepwise C4 cycle: PEP carboxylase, mesophyll, bundle sheath
Differentiation: Leaf anatomy (Kranz vs non-Kranz)
Differentiation: CO2 fixation sites and primary products
Differentiation: Stomatal behavior (day/night) for CAM
Precise definition: Chilling requirement for flowering
(a) What is unique of Indian plant biodiversity ? Discuss briefly the threats and various conservation strategies. 5+15=20
(b) What is social forestry ? Explain its types and benefits. 5+10=15
(c) Give a brief account of ecological pyramids. Describe ecological factors and their significance in plants. 5+10=15
हिंदी में पढ़ें
(a) भारतीय पादप जैव-विविधता में अनोखा क्या है ? खतरों एवं विभिन्न संरक्षण रणनीतियों की संक्षेप में चर्चा कीजिए । 5+15=20
(b) सामाजिक वानिकी क्या है ? इसके प्रकारों एवं लाभों की व्याख्या कीजिए । 5+10=15
(c) पारिस्थितिक पिरामिडों का संक्षिप्त लेखा प्रस्तुत कीजिए । पौधों में पारिस्थितिक कारकों एवं उनके महत्व का वर्णन कीजिए । 5+10=15
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, specific, and well-structured answers with named species and legal references.
Mention high endemism and ancient flora (Gymnosperms)
50MdescribeSeed dormancy and sustainable development
(a) What are the different types and causes of seed dormancy ? Describe various methods used to overcome it. Is it an ecological adaptation ? Explain. 10+5+5=20
(b) Describe the concept of sustainable development highlighting its objectives and importance. 15
(c) Describe in detail the endemism highlighting its categories, causes of endemism and conservation priorities. 15
हिंदी में पढ़ें
(a) बीज प्रसुप्तावस्था (प्रसुप्ति) के विभिन्न प्रकार एवं कारण क्या हैं ? इस पर काबू पाने हेतु विभिन्न विधियों का वर्णन कीजिए । क्या यह एक पारिस्थितिक अनुकूलन है ? व्याख्या कीजिए । 10+5+5=20
(b) सतत विकास की अवधारणा का वर्णन इसके उद्देश्यों एवं महत्व पर प्रकाश डालते हुए कीजिए । 15
(c) स्थानिकता का विस्तृत वर्णन, इसकी श्रेणियों, स्थानिकता के कारणों एवं संरक्षण प्राथमिकताओं को बताते हुए कीजिए । 15
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) describe: define > structure or process in order > labelled diagram > significance Full marks: Precise definitions, clear distinction between types/causes, specific examples, and logical flow.
Distinguish exogenous (physical) vs endogenous (physiological) dormancy