Q6
(a) Classify carbohydrates by giving suitable examples. Also, mention characteristics of each category. (20 marks) (b) Explain the structure of haemoglobin and its role in carbon dioxide transport. (15 marks) (c) Describe various techniques of in vitro fertilization. (15 marks)
हिंदी में प्रश्न पढ़ें
(a) उपयुक्त उदाहरण दे कर कार्बोहाइड्रेट्स का वर्गीकरण कीजिए। प्रत्येक श्रेणी की विशेषताओं का भी उल्लेख कीजिए। (20 अंक) (b) हीमोग्लोबिन की संरचना एवं कार्बनडाइऑक्साइड परिवहन में इसकी भूमिका की व्याख्या कीजिए। (15 अंक) (c) पात्रे (इन विट्रो) निषेचन की विभिन्न तकनीकों का वर्णन कीजिए। (15 अंक)
Directive word: Describe
This question asks you to describe. 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
The directive 'describe' demands systematic, detailed exposition with appropriate examples. Allocate approximately 40% of time/words to part (a) given its 20 marks, 30% each to parts (b) and (c). Structure: brief introduction on biochemical and reproductive significance; body with clearly demarcated sections for each sub-part using sub-headings; conclusion highlighting integrative biomedical relevance. For part (a), use tabular format for classification; for (b), include a well-labelled diagram; for (c), mention Indian regulatory context (ICMR guidelines) and success rates.
Key points expected
- Part (a): Classification of carbohydrates into monosaccharides (glucose, fructose), disaccharides (sucrose, lactose, maltose), oligosaccharides, and polysaccharides (starch, glycogen, cellulose, chitin) with structural characteristics and biological significance
- Part (a): Distinction between reducing and non-reducing sugars; aldose vs ketose classification; homopolysaccharides vs heteropolysaccharides with Indian examples (starch from rice/wheat, guar gum)
- Part (b): Quaternary structure of haemoglobin (2α2β chains, 4 haem groups, 574 amino acids); cooperative binding and Bohr effect; role in CO₂ transport as carbamino-haemoglobin (20-25%) and Haldane effect
- Part (c): Conventional IVF, Intracytoplasmic Sperm Injection (ICSI), Gamete Intrafallopian Transfer (GIFT), Zygote Intrafallopian Transfer (ZIFT), and Frozen Embryo Transfer (FET) with indications
- Part (c): Indian context: ICMR guidelines, ART Regulation Bill 2021; success rates and ethical considerations; mention of major Indian fertility centres and their contributions
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 25% | 12.5 | Accurately describes glycosidic linkages (α1-4, β1-4, α1-6) for part (a); correctly explains haemoglobin's 2,3-BPG binding pocket and CO₂ transport mechanisms (chloride shift, carbamino formation) for part (b); precisely distinguishes IVF techniques by gamete/zygote handling and implantation site for part (c) | Basic classification correct but errors in linkage types or haemoglobin subunit composition; confuses GIFT with ZIFT or omits ICSI mechanism; minor errors in CO₂ transport percentages | Fundamental errors such as calling haemoglobin a monomer, confusing starch and cellulose linkages, or describing IVF as in vivo fertilization; significant factual inaccuracies across sub-parts |
| Diagram / labelling | 20% | 10 | Clear, self-explanatory diagram of haemoglobin quaternary structure showing α and β chains, haem prosthetic group with Fe²⁺, proximal and distal histidines; OR schematic of IVF-ET procedure with labelled stages; appropriate use of Haworth projections for carbohydrate structures | Diagram present but incomplete labelling (missing haem group details or omitting cleavage stages in IVF); poorly proportioned or unclear structural representations | No diagram despite structural question; or irrelevant diagrams; messy, unlabelled sketches that do not aid explanation; failure to represent three-dimensional aspects where essential |
| Examples & nomenclature | 20% | 10 | Specific Indian examples: lactose from dairy (largest producer), cellulose from jute/cotton, chitin from crustacean fisheries; correct IUPAC-style nomenclature (e.g., β-D-glucopyranose); mentions specific IVF indications (male factor infertility for ICSI, tubal blockage for IVF) | Generic examples without Indian context; some nomenclature errors (confusing furanose/pyranose); limited range of examples across carbohydrate categories | Incorrect examples (calling sucrose reducing, citing glucose as disaccharide); no mention of Indian relevance; fabricated or inappropriate examples for IVF techniques |
| Process explanation | 20% | 10 | Stepwise explanation of CO₂ loading in tissues vs unloading in lungs with pO₂/pCO₂ gradients; detailed IVF protocol including ovarian stimulation (GnRH analogues), oocyte retrieval, fertilization, embryo culture, and transfer; explains carbohydrate digestion/absorption relevance | Sequential but incomplete explanation; misses critical steps like embryo grading or hCG trigger; superficial treatment of cooperative binding mechanism | Disorganized, non-sequential description; confuses tissue and lung conditions for CO₂ transport; fundamentally misunderstands IVF as simple mixing of gametes in vitro without culture/transfer steps |
| Evolutionary / applied context | 15% | 7.5 | Evolutionary significance: fetal haemoglobin (HbF, γ chains) affinity differences; primate carbohydrate digestion (salivary amylase gene duplication); applied aspects: India's burden of β-thalassemia and preimplantation genetic testing (PGT); ethical-legal framework of ART in India | Brief mention of medical relevance without evolutionary depth; generic statement on IVF helping infertile couples without Indian regulatory context | No applied or evolutionary context; irrelevant digressions; failure to connect basic biology to human welfare or conservation (e.g., IVF in endangered species like Indian rhino) |
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