All 8 questions from UPSC Civil Services Mains Botany 2024 Paper II (400 marks total). Every stem reproduced in full, with directive-word analysis, marks, word limits, and answer-approach pointers.
8Questions
400Total marks
2024Year
Paper IIPaper
Topics covered
Chromosome structure, inheritance, cell signaling, RNA evolution, breeding probability (1)Plant breeding, gene mapping, apomixis, cell cycle, gene silencing (1)Cell organelles, cytoplasmic inheritance, sex determination, protein synthesis (1)Gene transfer, biosafety, polytene chromosomes, mass selection, organic evolution (1)Plant physiology, secondary active transport, GOGAT, phytohormones, metallophytes, invasive species (1)Photorespiration, phytochrome structure, Himalayan vegetation zonation (1)Leaf senescence, chloroplast ATP synthase, eutrophication, biosphere reserves (1)Allosteric enzymes, gluconeogenesis, environmental management, ecological interactions (1)
A
Q1
50M150wCompulsoryexplainChromosome structure, inheritance, cell signaling, RNA evolution, breeding probability
Write short notes on the following in about 150 words each : 10×5=50
(a) Explain the types of variations found in the structure of chromosomes and discuss their importance and significance. 10
(b) Explain with at least two examples what is incomplete dominance and polygenic inheritance and what happens as a result of these events ? 10
(c) Discuss what are cell receptors and how do they help in cell signalling ? Elaborate the answer with the help of at least one example. 10
(d) Discuss with one example the role of RNA in the origin and evolution of life. 10
(e) Probability and distribution are two important factors which should always be taken into account to establish a successful breeding programme. Explain with a suitable example. 10
हिंदी में पढ़ें
निम्नलिखित में से प्रत्येक पर लगभग 150 शब्दों में संक्षिप्ट टिप्पणियाँ लिखिए : 10×5=50
(a) गुणसूत्रों की संरचना में पाए जाने वाले बदलाव के प्रकार को स्पष्ट कीजिए तथा उनके महत्व एवं उपयोगिता का वर्णन कीजिए । 10
(b) कम से कम दो उदाहरणों सहित स्पष्ट कीजिए, अधूरा प्रभुत्व तथा पॉलीजेनिक वंशागति क्या है तथा इनके परिणाम स्वरूप क्या होता है ? 10
(c) कोशिका ग्राही (रिसेप्टर्स) क्या हैं वर्णन कीजिए तथा वे कोशिका सिग्नलिंग में कैसे सहायता करते हैं ? कम से कम एक उदाहरण सहित उत्तर को विस्तार से लिखिए । 10
(d) कम से कम एक उदाहरण सहित जीव की उत्पत्ति तथा विकास में आर.एन.ए. की भूमिका का वर्णन कीजिए । 10
(e) प्रायिकता तथा वितरण दो महत्वपूर्ण कारक हैं जिन्हें सफल प्रजनन कार्य को स्थापित करने के लिए हमेशा ध्यान में रखना चाहिए । उपयुक्त उदाहरण सहित स्पष्ट कीजिए । 10
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 | (d) discuss: intro > 3-4 dimensions > example > balanced close | (e) explain: definition/context > points in order > small example > short close Full marks: Comprehensive, accurate, with specific examples and clear explanations
Define chromosomal structural variations
List types: deletion, duplication, inversion, translocation
(a) Explain briefly the process and importance of the following : 5+5+5=15
(i) Male sterility and heterosis breeding. 5
(ii) Molecular basis of cell cycle. 5
(iii) Gene silencing. 5
(b) Discuss briefly different methods of gene mapping. How molecular maps are of help in evulating the gene function ? 12+8=20
(c) Explain what is apomixis and how this may be of help in plant breeding ? Elaborate the answer with suitable examples. 15
हिंदी में पढ़ें
(a) निम्नलिखित की प्रक्रिया तथा महत्व को संक्षिप्त में स्पष्ट कीजिए : 5+5+5=15
(i) नरबंध्यता तथा संकर ओज (हेटेरोसिस) प्रजनन । 5
(ii) कोशिका चक्र का आणविक आधार । 5
(iii) जीन साइलेंसिंग । 5
(b) जीन चित्रण की विभिन्न विधियों पर संक्षिप्त में चर्चा कीजिए । आणविक मानचित्र जीन कार्यों के मूल्यांकन में कैसे सहायक होते हैं ? 12+8=20
(c) असंगजनन क्या है तथा यह पादपप्रजनन में कैसे लाभदायक है ? उत्तर को उपयुक्त उदाहरणों सहित विस्तार से लिखिए । 15
Answer approach & key points
Framework: null. (a(i)) explain: definition/context > points in order > small example > short close | (a(ii)) explain: definition/context > points in order > small example > short close | (a(iii)) explain: definition/context > points in order > small example > short close | (b) discuss: intro > 3-4 dimensions > example > balanced close | (c) explain: definition/context > points in order > small example > short close Full marks: Precise definitions, clear mechanisms, specific examples, and strong links to biotech/crops.
50MdescribeCell organelles, cytoplasmic inheritance, sex determination, protein synthesis
(a) Describe along with illustrated diagrams the structure and function of mitochondria and endoplasmic reticulum. 8+7=15
(b)(i) Explain with example how male sterility is related to cytoplasmic inheritance ? 8
(b)(ii) Discuss in brief the molecular basis of sex determination in plants. 7
(c) Explain the process of protein synthesis in plants and write a note on the structure and function of proteins. 20
हिंदी में पढ़ें
(a) माइटोकॉन्ड्रिया तथा एण्डोप्लाज्मिक रेटिकुलम की संरचना तथा कार्यों का सचित्र वर्णन कीजिए । 8+7=15
(b)(i) नरबंधता कोशिकाद्रव्यी वंशागति से कैसे संबंधित है उदाहरण के साथ स्पष्ट कीजिए ? 8
(b)(ii) पादप में लिंग निर्धारण के आणविक आधार का संक्षिप्त में वर्णन कीजिए । 7
(c) पौधों में प्रोटीन संश्लेषण की प्रक्रिया को स्पष्ट कीजिए तथा प्रोटीन की संरचना तथा कार्यों पर टिप्पणी कीजिए । 20
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)) discuss: intro > 3-4 dimensions > example > balanced close | (c) explain: definition/context > points in order > small example > short close Full marks: Comprehensive, accurate, with labelled diagrams and specific examples.
50MdiscussGene transfer, biosafety, polytene chromosomes, mass selection, organic evolution
(a) Discuss briefly the following and comment on their significance : 10+5+5=20
(i) In what way the transfer of genes in plants help in their sustainable development ? Support the answer with an example. 10
(ii) Importance of biosafety aspects of transgenic crops. 5
(iii) Polytene chromosomes. 5
(b) Explain how mass selection will be of help in a successful breeding program. Elaborate the answer with a suitable example. 15
(c) Briefly discuss various theories of organic evolution. Support the answer with a suitable example and evidence. 15
हिंदी में पढ़ें
(a) निम्नलिखित पर संक्षिप्त में वर्णन कीजिए तथा उनके महत्व पर चर्चा कीजिए : 10+5+5=20
(i) पौधों में जीन स्थानांतरण सतत विकास में किस प्रकार मदद करते हैं ? एक उदाहरण द्वारा अपने उत्तर की पुष्टि कीजिए । 10
(ii) ट्रांसजेनिक फसलों के जैव सुरक्षा पहलुओं का महत्व । 5
(iii) पॉलिटीन गुणसूत्र । 5
(b) एक सफल प्रजनन कार्यक्रम में सामूहिक चयन कैसे सहायक होगा स्पष्ट कीजिए । उपयुक्त उदाहरण सहित उत्तर को विस्तृत कीजिए । 15
(c) जैव विकास के विभिन्न सिद्धांतों पर संक्षेप में चर्चा कीजिए । उपयुक्त उदाहरण तथा प्रमाण सहित अपने उत्तर का समर्थन कीजिए । 15
Answer approach & key points
Framework: null. (a(i)) explain: definition/context > points in order > small example > short close | (a(ii)) highlight: name the salient points > one line of substance each > close | (a(iii)) 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: Comprehensive, accurate, and well-structured answers with specific examples and evidence.
Mechanism of gene transfer (e.g., Agrobacterium, biolistics)
Link to sustainable development (e.g., reduced pesticide use)
Specific example of a transgenic crop
Benefit to environment or resource conservation
Definition of biosafety in context of transgenics
Environmental risks (e.g., gene flow to wild relatives)
Health risks (e.g., allergenicity, toxicity)
Regulatory framework or containment measures
Definition of polytene chromosomes
Formation process (endoreduplication)
Location (e.g., salivary glands of Drosophila)
Significance in cytogenetics (e.g., banding patterns)
Definition of mass selection
Process of selecting superior plants from a population
Advantages (e.g., simplicity, low cost)
Suitable example of a crop improved by mass selection
Overview of major theories (e.g., Darwin, Lamarck, Modern Synthesis)
Key points of each theory
Evidence supporting each theory (e.g., fossils, genetics)
50M150wCompulsorywrite short notesPlant physiology, secondary active transport, GOGAT, phytohormones, metallophytes, invasive species
Write short notes on the following in about 150 words each : 10×5=50
(a) Explain what is secondary active transport. Discuss its importance in ion acquisition in plants. 10
(b) Discuss what is GOGAT ? Comment on its catalytic function. 10
(c) Regulation of seed dormancy and germination by phytohormones. 10
(d) Metallophytes and their practical importance. 10
(e) Invasive alien species and their impact on biodiversity. 10
हिंदी में पढ़ें
निम्नलिखित में से प्रत्येक पर लगभग 150 शब्दों में संक्षिप्त टिप्पणियाँ लिखिए : 10×5=50
(a) द्वितीयक सक्रिय परिवहन क्या है, समझाइए । पौधों में इसके द्वारा आयन अर्जन के महत्व पर चर्चा कीजिए । 10
(b) गोगेट (GOGAT) क्या है चर्चा कीजिए । इसकी उत्प्रेरक अभिक्रिया पर टिप्पणी कीजिए । 10
(c) पादप हार्मोन्स का बीज प्रसुप्ति तथा अंकुरण में विनियमन । 10
(d) मेटलोफाइट्स तथा उनकी प्रायोगिक उपयोगिता । 10
(e) आक्रामक विदेशी प्रजातियाँ तथा जैव विविधता पर उनके प्रभाव । 10
Answer approach & key points
Framework: UPSC Botany Paper 2 (PHKM-B-BTN). (a) explain: definition/context > points in order > small example > short close | (b) discuss: intro > 3-4 dimensions > example > balanced close | (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 mechanisms, and labelled diagrams where appropriate.
Define secondary active transport (symport/antiport)
(a) Explain the compartmentation of biochemical reactions in photorespiration. Comment upon the significance of the process. 15+5=20
(b) Describe the structure of phytochrome. Explain its mode of action in flowering plants. 5+10=15
(c) Give a concise account on altitudinal zonation of vegetation with special reference to Himalayan Vegetation. 15
हिंदी में पढ़ें
(a) प्रकाश श्वसन में जैवरासायनिक क्रियाओं के विभागों को समझाइए । प्रक्रिया के महत्व पर टिप्पणी कीजिए । 15+5=20
(b) पादपवर्णक (फाइटोक्रोम) की संरचना का वर्णन कीजिए । फूल वाले पौधों में उनकी प्रक्रिया को स्पष्ट कीजिए । 5+10=15
(c) हिमालय के वनस्पतियों के विशेष संदर्भ के साथ वनस्पति के तुंगीय क्षेत्र वर्गीकरण का संक्षिप्त वर्णन कीजिए । 15
Answer approach & key points
Framework: UPSC Botany Paper 2. (a) explain: definition/context > points in order > small example > short close | (b) describe: define > structure or process in order > labelled diagram > significance | (c) account for: state the phenomenon > the causes in order of weight > conclusion Full marks: Comprehensive, accurate, and well-structured with diagrams and specific examples.
Identify chloroplast, peroxisome, and mitochondria as sites
Detail the C2 cycle (glycolate pathway) steps
Explain the significance as a CO2 salvage mechanism
Mention the energy cost (ATP/NADH) of the process
Describe the chromophore (linear tetrapyrrole) and apoprotein
Explain the Pr (red) and Pfr (far-red) interconversion
Link Pfr to the phytochrome B (phyB) pathway
Explain the role in flowering (long-day vs short-day)
List the major vegetation zones (e.g., subtropical, temperate, alpine)
Provide approximate altitude ranges for each zone
Name characteristic species for each zone
Explain the factors driving zonation (temperature, moisture)
50MdescribeLeaf senescence, chloroplast ATP synthase, eutrophication, biosphere reserves
(a) Define leaf senescence. Describe important physiological and biochemical changes taking place during this process. Comment upon the regulation of senescence by phytohormones. 20
(b) Describe the molecular organization of chloroplast ATP synthase. Explain its mechanism of action. 10+5=15
(c)(i) Discuss the causes, consequences and control of eutrophication. 8
(c)(ii) In present Indian scenario, explain the importance of biosphere reserves in bio-diversity conservation. 7
हिंदी में पढ़ें
(a) पत्ती जीर्णता को परिभाषित कीजिए । इस प्रक्रिया के दौरान होने वाले क्रियात्मक तथा जैवरासायनिक परिवर्तनों का वर्णन कीजिए । पादप हार्मोन द्वारा जीर्णता के विनियमन पर टिप्पणी कीजिए । 20
(b) हरित लवक (क्लोरोप्लास्ट) ATP synthase की आणविक संरचना का वर्णन कीजिए । इसकी कार्यविधि को स्पष्ट कीजिए । 10+5=15
(c)(i) यूट्रोफिकेशन के कारणों, परिणामों तथा नियंत्रण पर चर्चा कीजिए । 8
(c)(ii) वर्तमान भारतीय परिदृश्य में जैव विविधता संरक्षण में संरक्षित जीवमंडल की उपयोगिता को समझाइए । 7
Answer approach & key points
(a) define: precise definition > the distinguishing feature > one example | (b(i)) describe: define > structure or process in order > labelled diagram > significance | (b(ii)) explain: definition/context > points in order > small example > short close | (c(i)) discuss: intro > 3-4 dimensions > example > balanced close | (c(ii)) explain: definition/context > points in order > small example > short close Full marks: Comprehensive, accurate, with diagrams and specific examples.
Precise definition of leaf senescence
Chlorophyll degradation and carotenoid accumulation
Protein hydrolysis and nutrient remobilization
Role of ethylene, ABA, and cytokinins
Structure of the CF1 sector (alpha3 beta3 head, gamma/epsilon stalk, delta)
Structure of the CF0 sector (c-ring, a, b, b-prime subunits)
Location in the thylakoid membrane
Subunit roles in proton channelling and catalysis
Chemiosmotic hypothesis and proton gradient
Proton flow through Fo sector
Rotational catalysis mechanism
ATP synthesis in F1 sector
Causes: nutrient loading (N, P) from agriculture
Consequences: algal blooms, hypoxia, fish kills
Control: wastewater treatment, buffer zones
Balanced discussion of human and natural factors
Definition of biosphere reserves (UNESCO MAB)
Zonation: core, buffer, transition areas
Role in in-situ conservation
Link to Indian context (e.g., Nilgiri, Sundarbans)
(a)(i) What are allosteric enzymes ? Explain in detail on the allosteric enzyme modulation. 8
(a)(ii) Describe the process of gluconeogenesis and its significance. 7
(b) What is environmental management ? Discuss various control measures to minimize environmental pollution. 20
(c) Differentiate between mutualism and commensalism by citing two examples for each of them. 15
हिंदी में पढ़ें
(a)(i) एलोस्टेरिक प्रकिण्व (एंजाइम) क्या हैं ? एलोस्टेरिक प्रकिण्व (एंजाइम) मॉड्यूलेशन को विस्तार पूर्वक समझाइए । 8
(a)(ii) ग्लूकोनियोजेनेसिस की प्रक्रिया तथा इसके महत्व का वर्णन कीजिए । 7
(b) पर्यावरण प्रबंधन क्या है ? पर्यावरण प्रदूषण को न्यूनतम करने में सहायक विधियों का वर्णन कीजिए । 20
(c) प्रत्येक के दो उदाहरण देते हुए सहोपकारिता तथा सहभोजिता में अंतर स्पष्ट कीजिए । 15
Answer approach & key points
Framework: null. (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) discuss: intro > 3-4 dimensions > example > balanced close | (c) compare: paired headings or point-wise contrast > key differences > significance > conclusion Full marks: Precise definitions, labelled diagrams, and specific scientific examples for all parts.
Definition of allosteric enzymes
Distinction between active and allosteric sites
Mechanism of positive/negative modulation
Sigmoidal kinetics vs Michaelis-Menten
Definition of gluconeogenesis and its non-carbohydrate precursors
The bypass enzymes (PEPCK, fructose-1,6-bisphosphatase; in animals also pyruvate carboxylase and glucose-6-phosphatase)
Energy cost (6 high-energy phosphates per glucose: 4 ATP + 2 GTP in animals)
Significance: sucrose from stored fat/protein in germinating seeds (glyoxylate cycle), CAM and senescing leaves; in animals blood glucose and the Cori cycle