Q7
(a) Give an account of hormonal regulation of menstruation in human females. (20 marks) (b) Explain the source(s) and functions of the following: (5×3=15 marks) (i) Vitamin B₁ (ii) Vitamin B₂ (iii) Vitamin B₁₂ (c) Write in detail three phases of oogenesis in human females. (15 marks)
हिंदी में प्रश्न पढ़ें
(a) मानव महिलाओं में माहवारी के हार्मोनल नियमन का विवरण दीजिए। (20 अंक) (b) निम्नलिखित के स्रोतों एवं कार्यों की व्याख्या कीजिए: (5×3=15 अंक) (i) विटामिन बी₁ (ii) विटामिन बी₂ (iii) विटामिन बी₁₂ (c) मानव महिलाओं में अंडजनन के तीन चरणों को विस्तार से लिखिए। (15 अंक)
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
The directive 'explain' demands clear causal reasoning and mechanistic detail across all parts. Allocate approximately 40% of time/words to part (a) hormonal regulation (20 marks), 30% to part (b) B vitamins (15 marks), and 30% to part (c) oogenesis (15 marks). Structure with brief introductions for each part, detailed body covering mechanisms, and conclude with integrated significance of reproductive physiology and nutrition.
Key points expected
- Part (a): Hypothalamic-pituitary-ovarian axis with GnRH, FSH, LH, estrogen and progesterone feedback loops; follicular and luteal phase hormonal profiles; menstrual phase endometrial changes
- Part (b)(i): Thiamine sources (whole grains, legumes, yeast) and functions (TPP cofactor, decarboxylation in energy metabolism, nerve conduction)
- Part (b)(ii): Riboflavin sources (milk, eggs, green vegetables) and functions (FAD/FMN cofactors, electron transport chain, antioxidant via glutathione reductase)
- Part (b)(iii): Cobalamin sources (animal products, liver, dairy; absent in plant sources—relevant for Indian vegetarian populations) and functions (methylmalonyl-CoA mutase, methionine synthase, myelin synthesis, pernicious anemia risk)
- Part (c): Three phases—multiplication (oogonia, mitosis), growth (primary oocyte, meiosis I arrest at diplotene/dictyate), maturation (secondary oocyte formation, meiosis II arrest at metaphase II until fertilization); include polar body formation and hormonal triggers
Evaluation rubric
| Dimension | Weight | Max marks | Excellent | Average | Poor |
|---|---|---|---|---|---|
| Concept correctness | 25% | 12.5 | Accurately describes positive and negative feedback mechanisms in (a); correctly identifies coenzyme forms and metabolic pathways for all three B vitamins in (b); precisely distinguishes meiotic arrest points and hormonal regulation in (c); no confusion between oogenesis and spermatogenesis | Basic hormonal sequence correct but feedback mechanisms vague; vitamin functions listed without coenzyme linkage; oogenesis phases named but arrest points confused or missing | Major errors like attributing progesterone rise to follicular phase; confusing water-soluble/fat-soluble vitamin properties; stating meiosis completes before ovulation |
| Diagram / labelling | 15% | 7.5 | Clear, self-drawn hormonal fluctuation graph for (a) showing FSH, LH, estrogen, progesterone across cycle days with ovulation marked; schematic of oogenesis stages in (c) with ploidy changes indicated; proper axes and labels | One relevant diagram present but poorly scaled or missing labels; or diagrams described textually without visual representation | No diagrams despite clear need; or irrelevant diagrams copied from memory without adaptation to question |
| Examples & nomenclature | 20% | 10 | Uses correct biochemical nomenclature (TPP, FAD, FMN, methylcobalamin, adenosylcobalamin); cites Indian dietary sources (bajra, jowar for B1; dairy for B2; limited B12 in vegetarian diets linking to Indian public health); names specific enzymes (pyruvate dehydrogenase, succinate dehydrogenase) | Generic source lists without Indian context; enzyme names missing or incorrect; vitamin forms confused | Wrong vitamin-letter associations (B12 as folate); no source differentiation; invented enzyme names |
| Process explanation | 25% | 12.5 | Stepwise causal chains: for (a) how estrogen surge triggers LH surge via positive feedback; for (b) how B vitamin deficiencies cascade to specific clinical outcomes (beriberi, ariboflavinosis, megaloblastic anemia); for (c) temporal sequence from fetal oogenesis through menarche to menopause with hormonal triggers at each transition | Lists processes sequentially but lacks causal connectors; describes 'what' without 'how' or 'why' | Random fact listing without process logic; confuses cause and effect in feedback systems |
| Evolutionary / applied context | 15% | 7.5 | Briefly notes evolutionary significance of meiotic arrest (quality control, maternal resource investment); connects B12 deficiency to Indian vegetarian population health and fortification programs; mentions assisted reproductive technology implications of hormonal understanding; notes declining oocyte pool with maternal age | Generic statement about importance of vitamins or reproduction without specific application | No applied or evolutionary context; purely descriptive answer without broader significance |
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