Q1
Answer the following questions in about 150 words each: (a) How many types of gametophytes are found in Lycopodium ? Why is it difficult to collect such prothalli in nature ? 5+5=10 (b) How does heterocyst differ from vegetative cell ? Mention the factors controlling its formation and add a note on functions of heterocysts. 5+5=10 (c) Explain how the numerical expression of data is utilized in plant systematics. 10 (d) "Mycoplasma causes serious diseases in humans, animals and plants." Substantiate the statement with suitable examples. 10 (e) How does the infection of a pathogen affect the host plant physiology ? 10
हिंदी में प्रश्न पढ़ें
निम्नलिखित प्रत्येक प्रश्न का उत्तर लगभग 150 शब्दों में दीजिए : (a) लाइकोपोडियम में कितने प्रकार के युग्मकोद्भिद पाए जाते हैं ? ऐसे प्रोथेलाई को प्रकृति में संग्रह करना दुष्कर क्यों है ? 5+5=10 (b) हेटेरोसिस्ट कायिक कोशिका से कैसे भिन्न है ? इसके निर्माण को नियंत्रित करने वाले कारकों का उल्लेख कीजिए और हेटेरोसिस्ट के कार्यों पर टिप्पणी लिखिए । 5+5=10 (c) पादप वर्गिकी में संख्यात्मक अभिव्यक्त आँकड़े कैसे प्रयुक्त होते हैं, समझाइए । 10 (d) "माइकोप्लाज्मा मनुष्यों, जंतुओं एवं पादपों में गंभीर रोग पैदा करते हैं।" इस कथन को उचित उदाहरणों से सिद्ध कीजिए । 10 (e) रोगजनक का संक्रमण परपोषी पादप की कार्यिकी (फिजियोलॉजी) को कैसे प्रभावित करता है ? 10
Directive word: Explain
This question asks you to explain. The directive word signals the depth of analysis expected, the structure of your answer, and the weight of evidence you must bring.
See our UPSC directive words guide for a full breakdown of how to respond to each command word.
How this answer will be evaluated
Approach
This multi-part question requires explaining diverse botanical concepts across five sub-parts. Allocate approximately 30 words (20%) to each of parts (a), (b), (d), and (e) at 10 marks each, and 30 words (20%) to part (c). Structure each sub-part as: direct answer → brief elaboration → specific example where applicable. Prioritize precision over breadth given the 150-word limit per sub-part.
Key points expected
- Part (a): Two types of gametophytes in Lycopodium (independent subterranean mycorrhizal type and green photosynthetic type); difficulty in collection due to subterranean habit, slow growth, and mycorrhizal dependence
- Part (b): Heterocyst structural differences (thick wall, polar nodules, absence of photosystem II); formation controlled by nitrogen limitation, oxygen levels, and hetR gene expression; nitrogen fixation and hormogonia production functions
- Part (c): Numerical taxonomy/phenetics using cluster analysis, principal component analysis, and computer-assisted classification; operational taxonomic units (OTUs) and character weighting in Angiosperm Phylogeny Group (APG) systems
- Part (d): Mycoplasma diseases—human (atypical pneumonia), animal (contagious bovine pleuropneumonia), plant (aster yellows, little leaf of brinjal, witches' broom of potato)
- Part (e): Pathogen-induced physiological changes including altered photosynthesis, respiration rate increase, translocation disruption, hormone imbalance (IAA, ethylene), and stomatal dysfunction leading to wilting
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 20% | 10 | Accurately identifies two gametophyte types in Lycopodium; correctly describes heterocyst ultrastructure and genetic regulation; precisely defines numerical taxonomy methods; accurately classifies mycoplasma diseases by host; correctly explains pathophysiological mechanisms | Identifies gametophyte types with minor errors; describes heterocyst features generally without genetic detail; mentions numerical methods superficially; lists mycoplasma diseases with some confusion; explains physiological effects broadly | Confuses gametophyte types or numbers; misidentifies heterocyst characteristics; conflates numerical taxonomy with cladistics; misattributes diseases to wrong pathogens; describes symptoms rather than physiological mechanisms |
| Diagram / labelling | 15% | 7.5 | Includes labeled diagram of heterocyst structure showing pore channel, polar nodules, and thick laminated layer; or sketches Lycopodium gametophyte morphology with mycorrhizal associations; diagrams are neat, proportional, and properly annotated | Provides basic diagram of heterocyst or gametophyte with partial labeling; diagram conveys general structure but lacks specific features like pore plugs or fungal hyphae | No diagram provided; or diagram is unlabeled, disproportionate, or anatomically incorrect; confuses heterocyst with akinete or vegetative cell structure |
| Examples & nomenclature | 20% | 10 | Cites specific examples: L. cernuum and L. clavatum for gametophytes; Anabaena and Nostoc for heterocysts; Indian examples like little leaf of brinjal (Solanum melongena) and sandal spike disease; uses correct scientific names and disease terminology | Provides some correct examples but misses Indian context; uses common names without scientific nomenclature; examples are relevant but not specific to the question's demands | Examples are incorrect or irrelevant; confuses mycoplasma with virus or bacteria examples; uses outdated terminology (PPLO instead of mycoplasma); no Indian examples cited |
| Process explanation | 25% | 12.5 | Clearly explains mycorrhizal dependency for subterranean gametophyte nutrition; details hetR/hetN gene cascade in heterocyst differentiation; describes algorithmic steps in numerical taxonomy (character coding, similarity matrices, clustering); explains toxin-mediated or enzyme-mediated pathogenesis | Describes processes in general terms without mechanistic detail; mentions gene regulation or statistical methods without explaining how they function; explains disease progression descriptively | No process explanation provided; describes static structures only; confuses cause and effect in pathogenesis; misrepresents genetic or statistical methodologies |
| Application / ecology | 20% | 10 | Connects subterranean gametophyte ecology to forest floor microhabitats and conservation challenges; links heterocyst biology to rice field cyanobacterial biofertilizer applications; discusses numerical taxonomy in APG IV classification revisions; addresses mycoplasma disease management in Indian agriculture; explains systemic acquired resistance in host physiology | Mentions ecological or applied relevance superficially; notes biofertilizer use without elaboration; acknowledges disease impact without management context | No applied or ecological context provided; misses agricultural significance entirely; fails to connect basic biology to practical outcomes or conservation concerns |
Practice this exact question
Write your answer, then get a detailed evaluation from our AI trained on UPSC's answer-writing standards. Free first evaluation — no signup needed to start.
Evaluate my answer →More from Botany 2025 Paper I
- Q1 Answer the following questions in about 150 words each: (a) How many types of gametophytes are found in Lycopodium ? Why is it difficult to…
- Q2 (a) Enumerate the types of fruiting bodies of Ascomycota and Basidiomycota. Write the various steps of ascus formation in Ascomycetous memb…
- Q3 (a) Discuss how progressive sterilization of sporogenous tissue occurs in bryophytes, with suitable diagrams and examples. 20 (b) Describe…
- Q4 (a) Describe the causal organisms, disease cycle and control measures of Early Blight of Potato and Blast of Rice. 10+10=20 (b) What are eu…
- Q5 Answer the following questions in about 150 words each: (a) Give an account of post-fertilization changes leading to formation of seeds in…
- Q6 (a) What are the diagnostic characters of the families – Cucurbitaceae and Poaceae ? Write the botanical names and economic importance of a…
- Q7 (a) Write the botanical name, family, morphology of useful parts and uses of the following plants: (i) Safflower (ii) Fennel (iii) Chicory…
- Q8 (a) What is micropropagation and how does it differ from traditional plant propagation methods ? Give an account of the applications of mic…