Zoology 2023 Paper II 50 marks 150 words Compulsory Explain

Q1

Write your answer in about 150 words for each of the following: (a) Write about different ways by which biodiversity is being threatened. (10 marks) (b) How is hn RNA (primary transcript) modified into functional m-RNA in eukaryotes? Explain. (10 marks) (c) "Continental drift has resulted in discontinuous distribution of alligators and lungfishes". Justify. (10 marks) (d) Write principle and application of RFLP. (10 marks) (e) Describe receptor-mediated endocytosis (RME) along with its advantage. (10 marks)

हिंदी में प्रश्न पढ़ें

निम्नलिखित प्रत्येक के लिए लगभग 150 शब्दों में उत्तर लिखिए: (a) उन विभिन्न तरीकों के बारे में लिखिए जिनसे जैव-विविधता को खतरा हो रहा है। (10 अंक) (b) सूकेंद्रिकियों (यूकेरियोट्स) में किस प्रकार से एच एन आर.एन.ए. (प्रारंभिक अनुलेख) कार्यात्मक एम-आर.एन.ए. में परिवर्तित होता है? व्याख्या कीजिए। (10 अंक) (c) "ऐलिगेटर्स एवं फुफुस मीनों का असंतत वितरण महाद्वीपीय विस्थापन के परिणामस्वरूप हुआ है"। उचित सिद्ध कीजिए। (10 अंक) (d) आर.एफ.एल.पी. के सिद्धांत एवं इसके प्रयोग के बारे में लिखिए। (10 अंक) (e) ग्राही-माध्यित अंतःकोशिकता (रिसेप्टर-मीडिएटेड एंडोसाइटोसिस) का वर्णन इसके लाभ सहित कीजिए। (10 अंक)

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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.

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How this answer will be evaluated

Approach

This multi-part question requires explaining five distinct zoological concepts in approximately 150 words each. Allocate roughly equal time (~6 minutes) and word count per sub-part since all carry equal marks. Structure each part with a concise definition, followed by mechanistic/process details, and end with specific examples or applications. For (a), prioritize H-I-P-P-O framework; for (b), emphasize 5' cap, poly-A tail, and splicing; for (c), link Gondwanaland fragmentation to vicariance; for (d), mention restriction enzymes and Southern blot; for (e), detail clathrin-coated pits and LDL receptor example.

Key points expected

  • (a) Biodiversity threats: Habitat destruction (deforestation, wetland drainage), Invasive species (Lantana camara, Parthenium), Pollution (eutrophication, biomagnification), Population overgrowth, Overexploitation (fishing, poaching); mention IUCN Red List categories
  • (b) hnRNA processing: 5' methyl guanosine cap addition, 3' polyadenylation (poly-A tail), spliceosome-mediated intron removal (GU-AG rule), alternative splicing significance; mention snRNPs and spliceosome assembly
  • (c) Continental drift & disjunct distribution: Gondwanaland breakup (~180-30 MYA), alligatorid distribution (Alligator mississippiensis vs. Alligator sinensis), lungfish relicts (Protopterus, Lepidosiren, Neoceratodus), vicariance biogeography vs. dispersal
  • (d) RFLP principle: Restriction endonuclease digestion of DNA, fragment length polymorphism due to point mutations/deletions in restriction sites, Southern blot hybridization with labeled probes; applications: DNA fingerprinting (Ale Jeffreys), paternity testing, genetic mapping, forensic science (Nirbhaya case), disease diagnosis (sickle cell, Huntington's)
  • (e) RME mechanism: Ligand-receptor specificity (LDL, transferrin, insulin), clathrin-coated pit formation, coated vesicle budding via dynamin, uncoating and fusion with early endosome, receptor recycling; advantages: specificity, concentration against gradient, protection from lysosomal degradation, cellular cholesterol homeostasis

Evaluation rubric

DimensionWeightMax marksExcellentAveragePoor
Concept correctness20%10Scientifically accurate across all five parts: correctly identifies HIPPO categories for (a), distinguishes 5' cap from poly-A tail with correct chemistry for (b), accurately dates Gondwanaland fragmentation for (c), correctly describes restriction site polymorphism for (d), and precisely defines coated vesicle dynamics for (e)Generally correct but with minor errors: confuses intron/exon terminology in (b), vague on continental drift timing in (c), or oversimplifies RFLP mechanism in (d)Major conceptual errors: states prokaryotic processing for (b), confuses alligators with crocodiles in (c), describes RAPD instead of RFLP in (d), or equates RME with phagocytosis in (e)
Diagram / labelling20%10Includes at least 2-3 well-drawn diagrams: spliceosome assembly or RNA processing schematic for (b), Gondwanaland reconstruction map for (c), RFLP gel/autoradiograph pattern for (d), or coated pit/vesicle cycle for (e); all with proper labels and neat presentationOne relevant diagram with basic labeling, or attempts diagrams with incomplete labels; may describe diagrammatically without actual drawingNo diagrams despite clear visual potential in (b), (c), (d), (e); or completely unrecognizable sketches without labels
Examples & nomenclature20%10Precise scientific nomenclature: cites specific Indian examples like Western Ghats amphibian loss for (a), names snRNPs (U1, U2, U4/U5/U6) for (b), distinguishes Alligatoridae from Crocodylidae with species names for (c), mentions specific restriction enzymes (EcoRI, HindIII) for (d), and details LDL receptor/apolipoprotein B-100 for (e)Generic examples without specificity: mentions 'habitat loss' without Indian instance, 'lungfish' without genus names, 'restriction enzymes' without examples; some terminology gapsNo valid examples or incorrect nomenclature: invents non-existent species, confuses RFLP with PCR, or describes pinocytosis instead of RME
Process explanation20%10Clear stepwise mechanistic descriptions: sequential processing order (capping before splicing) for (b), chronological continental breakup sequence for (c), DNA extraction→digestion→electrophoresis→blotting→hybridization workflow for (d), and ligand binding→clustering→vesicle formation→uncoating→sorting for (e)Lists steps without logical flow or temporal sequence; mentions processes but not their causal relationships or regulatory significanceDescriptive only with no process logic; random fact accumulation without connecting mechanisms; confuses order of events
Evolutionary / applied context20%10Strong contextual integration: links biodiversity loss to ecosystem services and Sustainable Development Goals for (a), explains evolutionary significance of introns and exon shuffling for (b), connects vicariance to phylogenetic biogeography and refugia theory for (c), discusses replacement by STR/SNP analysis in forensics for (d), and relates RME defects to familial hypercholesterolemia for (e)Brief mention of applications without depth: notes 'forensic use' for RFLP or 'cholesterol uptake' for RME without disease connection; superficial evolutionary mentionNo applied or evolutionary context; treats all topics as isolated facts without broader biological significance; misses medical/forensic/conservation relevance entirely

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