Zoology
प्राणीशास्त्र · CEE · MECEE-BL Medical Entrance
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chapters done
- Evolution and Diversity
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The syllabus asks for
- Origin of life: the Oparin–Haldane theory and the Miller–Urey experiment
- Evidences of evolution: morphological, anatomical, palaeontological, embryological and biochemical
- Lamarckism, Darwinism and Neo-Darwinism
- Human evolution from Ramapithecus to modern man
Key points
- Life arose by chemical evolution (Oparin 1924, Haldane 1929) in a reducing atmosphere of CH₄, NH₃, H₂ and water vapour with no free O₂, energised by UV and lightning: monomers → polymers → coacervates/microspheres → protocell → anaerobic heterotroph.
- Miller–Urey (1953) sparked CH₄, NH₃, H₂ (2 : 2 : 1) and steam for a week and obtained amino acids (glycine, alanine) — monomers, not life.
- Homologous organs (same origin, different use) show divergent evolution; analogous organs (different origin, same use) show convergent evolution; vestigial organs and atavism point to ancestors.
- Connecting links — Peripatus, Neopilina, Balanoglossus, lungfish, Archaeopteryx, platypus — and the horse series (Eohippus → Equus, toes 4 → 1) are the classic fossil and living evidence.
- Haeckel's biogenetic law (embryos), Nuttall's precipitin test, cytochrome c and the universal genetic code (biochemistry) complete the evidence.
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The syllabus asks for
- Diagnostic features and classification of animals from Protozoa to Chordata
Key points
- Animals are classified by level of organisation, symmetry, germ layers, coelom and segmentation: cellular → Porifera; tissue, radial, diploblastic → Coelenterata; acoelomate → Platyhelminthes; pseudocoelomate → Aschelminthes; schizocoelous protostomes → Annelida, Arthropoda, Mollusca; enterocoelous deuterostomes → Echinodermata, Hemichord
- Protozoa are grouped by locomotion: pseudopodia (Amoeba, Entamoeba), flagella (Euglena, Trypanosoma, Leishmania), none (Sporozoa: Plasmodium), cilia (Paramecium, Balantidium).
- Porifera: ostia, osculum, canal system, choanocytes, spicules or spongin, gemmules; Calcarea, Hexactinellida (Euplectella), Demospongiae (Euspongia, Spongilla).
- Coelenterata: radial, diploblastic, coelenteron, nematocysts, polyp and medusa, metagenesis in Obelia; Hydrozoa, Scyphozoa, Anthozoa.
- Platyhelminthes (flame cells; Fasciola, Taenia) and Aschelminthes (pseudocoel, complete gut, separate sexes; Ascaris, Wuchereria, Ancylostoma, Enterobius).
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The syllabus asks for
- Epithelial, connective, muscular and nervous tissues: structure, location and function
Key points
- A tissue is a group of similar cells with a common origin and function; the four primary tissues are epithelial, connective, muscular and nervous.
- Epithelium rests on a basement membrane, has almost no matrix, is avascular and arises from all three germ layers; it is named by layers and cell shape — squamous (alveoli, capillaries), cuboidal (kidney tubules, thyroid), columnar (stomach, intestine), ciliated (oviduct), pseudostratified (trachea), stratified squamous (skin, oesophagus)
- Glands are exocrine, endocrine or heterocrine (pancreas), and secrete in merocrine (salivary), apocrine (mammary) or holocrine (sebaceous) fashion.
- Connective tissue has few cells (fibroblasts, macrophages, mast cells, plasma cells, fat cells) in abundant matrix with collagen, elastic and reticular fibres: areolar, adipose, tendon, ligament, cartilage, bone, blood and lymph.
- Cartilage is avascular with chondrin matrix — hyaline (joints, trachea), elastic (pinna, epiglottis), fibrocartilage (intervertebral discs); bone has ossein and hydroxyapatite, osteocytes in lacunae and Haversian systems.
- Study of Selected Animals
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The syllabus asks for
- Plasmodium: habitat, structure, life cycle and types of malaria
- Earthworm (Pheretima): morphology, body systems, physiology and economic importance
- Frog (Rana): morphology, body systems and physiology
Key points
- Plasmodium (Sporozoa) is a digenetic intracellular parasite: asexual schizogony in man (intermediate host) — liver cells, then the 48-hour Golgi cycle in RBCs — and sexual phase in the female Anopheles (definitive host) — gametes, zygote, ookinete, oocyst, sporozoites in the salivary glands.
- The sporozoite infects man and the gametocyte infects the mosquito; the zygote is the only diploid stage; the fever follows the synchronous bursting of RBCs and the release of haemozoin.
- P. vivax (benign tertian, relapses from hypnozoites, commonest in Nepal), P. falciparum (malignant tertian, cerebral malaria), P. malariae (quartan, 72 h) and P. ovale (ovale tertian).
- Pheretima posthuma: about 100–120 segments; prostomium; clitellum 14–16; perichaetine setae; female pore 14, male pores 18, papillae 17 and 19, spermathecal pores 5/6–8/9.
- Earthworm gut: pharynx 4, gizzard 8–9, stomach 9–14 with calciferous glands, caeca and typhlosole from 26; closed circulation with Hb in plasma and four pairs of hearts (7, 9, 12, 13); cutaneous respiration; septal, integumentary and pharyngeal nephridia.
- Human Biology and Physiology
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The syllabus asks for
- The alimentary canal and the digestive glands
- Physiology of digestion and absorption
Key points
- The canal is a 8–9 m tube of four coats (mucosa, submucosa, muscularis, serosa); the enteric plexus runs peristalsis, modified by vagus (up) and sympathetic (down).
- The mouth has 32 permanent teeth, the bolus is made there, and salivary amylase (pH 6.8) starts starch digestion; the three gland pairs are parotid (Stensen's), submandibular (Wharton's) and sublingual (Rivinus).
- The stomach secretes 2–3 L of juice at pH 1.5–2.5: parietal cells give HCl and intrinsic factor, chief cells pepsinogen, rennin and lipase, G cells gastrin. HCl activates pepsinogen, kills bacteria and denatures protein; pepsin works only at pH 1.5–2 and stops at peptones.
- The small intestine (duodenum 25 cm, jejunum 2.5 m, ileum 3.5 m) receives bile and pancreatic juice, and its folds, villi and microvilli raise the absorptive area to about 200 m².
- The liver (1.5 kg, largest gland) makes 0.5–1 L of bile a day at pH 7.6–8.6 with no enzymes; bile salts emulsify fat. The gall bladder stores and concentrates bile and contracts under CCK.
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The syllabus asks for
- Respiratory organs and the mechanism of breathing
- Exchange and transport of gases; regulation of respiration
- Respiratory disorders
Key points
- Air passes nostrils → nasal cavity → pharynx → larynx → trachea → bronchi → bronchioles → alveoli; the conducting part is lined by pseudostratified ciliated columnar epithelium, the alveolus by simple squamous.
- The trachea has 16–20 C-shaped hyaline rings and divides at the carina; the right bronchus is wider, shorter and more vertical, so it takes inhaled objects.
- The right lung has three lobes, the left two; the pleura holds the lung against the chest wall with a negative intrapleural pressure.
- Alveoli number 300–500 million, give 70–80 m² of surface and a 0.5 μm barrier; type II cells make surfactant, without which premature babies get RDS.
- Inspiration is active (diaphragm, phrenic C3–C5, plus external intercostals); quiet expiration is passive.
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The syllabus asks for
- The heart, the heartbeat, the cardiac cycle and cardiac output
- Arterial and venous systems; blood pressure
- Blood and blood groups
- Cardiovascular disorders
Key points
- The heart (250–300 g) lies in the mediastinum inside the pericardium; its wall is epicardium, myocardium (thickest in the left ventricle) and endocardium.
- Four chambers and four valves: tricuspid and bicuspid (mitral) AV valves with chordae tendineae, and the pulmonary and aortic semilunar valves; all open and close passively.
- Double circulation: right ventricle → lungs → left atrium (pulmonary); left ventricle → body → right atrium (systemic). The coronary arteries arise from the ascending aorta.
- The SA node (70–80 min⁻¹) is the pacemaker because it depolarises fastest; the impulse passes SA → AV → bundle of His → Purkinje, with a 0.1 s delay at the AV node.
- The cardiac cycle lasts 0.8 s: atrial systole 0.1 s, ventricular systole 0.3 s, diastole 0.5 s; S1 is AV valve closure, S2 semilunar closure.
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The syllabus asks for
- Excretory organs and the structure of the nephron
- Formation of urine and its regulation
- Renal disorders
Key points
- The excretory organs are the kidneys, ureters, bladder and urethra; the skin, lungs and liver are accessory routes, and the liver makes urea while the kidney excretes it.
- Each kidney has about one million nephrons, in a cortex (corpuscles, convoluted tubules) and a medulla (pyramids, loops, collecting ducts) that drains through the pelvis into the ureter.
- Ultrafiltration at the glomerulus passes water and small solutes but holds back cells and protein by pore size and negative charge; net pressure ≈ 10 mmHg, GFR ≈ 125 mL min⁻¹ (180 L day⁻¹).
- Reabsorption recovers about 99 % of the filtrate: glucose and amino acids by active transport in the PCT (threshold 180 mg/dL, Tm 375 mg min⁻¹), water by osmosis.
- The counter-current multiplier works because the descending limb is permeable to water and the ascending limb is not but pumps salt; the medulla is graded 300 → 1200 mOsm L⁻¹, and the vasa recta preserve the gradient.
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The syllabus asks for
- Central, peripheral and autonomic nervous systems
- The nerve impulse and the synapse
- The eye and the ear
Key points
- The CNS integrates information; the PNS connects it with receptors and effectors through cranial and spinal nerves.
- Cerebral cortex supports conscious perception and voluntary action, while the hypothalamus, cerebellum and medulla have sharply testable special roles.
- Spinal reflexes use dorsal sensory entry and ventral motor exit and can act before conscious perception.
- Sympathetic and parasympathetic divisions differ in origin, fibre length, transmitter and typical visceral effects.
- An action potential is an all-or-none, self-propagating reversal of membrane potential driven first by Na⁺ entry and then by K⁺ exit.
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The syllabus asks for
- Endocrine glands and their hormones
- Hormonal disorders
Key points
- Hormones are blood-borne messengers whose effects depend on receptors, chemical class, transport and feedback regulation.
- The hypothalamus controls the anterior pituitary through portal blood and supplies the posterior pituitary with ADH and oxytocin.
- Pituitary tropic hormones organise thyroid, adrenal-cortical and gonadal activity; GH and prolactin act more directly on non-endocrine tissues.
- Thyroid hormones set metabolic rate and are essential to development; PTH and calcitonin act in opposite directions on blood calcium.
- The adrenal cortex preserves salt, water and glucose during stress, whereas the medulla supplies a rapid catecholamine emergency response.
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The syllabus asks for
- Male and female reproductive organs
- Gametogenesis
- The ovarian and menstrual cycles
Key points
- The testes produce sperm in seminiferous tubules under FSH, testosterone and Sertoli-cell support; Leydig cells supply testosterone.
- Sperm mature and are stored in the epididymis, then travel through the vas deferens and urethra in semen produced mainly by accessory glands.
- The ovaries produce oocytes and steroid hormones; uterine tubes capture the oocyte and normally host fertilisation in the ampulla.
- Spermatogenesis is continuous and quantitatively equal, whereas oogenesis begins before birth, is interrupted twice and conserves cytoplasm in one ovum.
- Fertilisation restores diploidy, blocks polyspermy and initiates cleavage; the blastocyst implants in a progesterone-prepared endometrium.
- Applied Zoology
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The syllabus asks for
- Typhoid, tuberculosis, HIV/AIDS, cholera, influenza, hepatitis and candidiasis
- Innate and acquired immunity; antigens and antibodies
- Vaccines: live attenuated, inactivated and toxoid
Key points
- The named diseases separate cleanly by agent class, route and mechanism: water-borne typhoid/cholera, airborne TB/influenza, blood/sexual HIV and HBV/HCV, and opportunistic candidiasis.
- TB's mycolic-acid wall explains acid-fast staining and macrophage survival; cholera toxin explains massive fluid loss without requiring bacteraemia.
- HIV disables adaptive immunity at its CD4 coordinator and converts normal microbiota or ordinarily controlled organisms into opportunistic threats.
- Influenza's segmented genome permits reassortment shifts as well as drift.
- Hepatitis viruses A–E share a target organ but differ in genome, route, chronicity and vaccine strategy.
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The syllabus asks for
- Tissue and organ transplantation, in-vitro fertilization, amniocentesis and transgenic animals
- Applied microbiology: dairy and beverage microbes, sewage and drinking-water treatment, bio-control agents
Key points
- Transplant compatibility is an immunological problem centred on HLA recognition; immunosuppression prevents rejection at the cost of infection risk.
- IVF moves fertilisation to the laboratory, while ICSI additionally bypasses failures of sperm number, movement or oocyte penetration.
- Amniocentesis provides fetal cells for definitive chromosome/DNA diagnosis, but as an invasive test it follows careful counselling and screening.
- Transgenic animals produce disease models and valuable proteins, yet require welfare, containment and biosafety oversight.
- Dairy and beverage industries are controlled fermentations whose acids, gases and ethanol explain product texture, preservation and flavour.
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The syllabus asks for
- Animal behaviour: reflex actions, taxes and migration
- Air, water and soil pollution; pesticides
- Aquatic, terrestrial and volant adaptations
- Conservation biology: biodiversity, protected areas, hotspots, Ramsar sites, IUCN categories and endangered species of Nepal
Key points
- Reflexes, taxes and kineses differ by pathway, body involvement and whether movement is directed.
- Migration trades travel costs for seasonal access to food and breeding habitat and relies on multiple navigational cues.
- Air pollution separates into particles/toxic gases, smog, acid deposition, ozone depletion and greenhouse warming.
- Water and soil pollutants may be biodegradable, nutrient-like or persistent; persistence plus fat solubility creates biomagnification.
- Aquatic and terrestrial animals solve opposite mechanical/osmotic problems, while flight imposes the strictest combined demands for lift, power and low mass.
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The paper
3 hours, 200 single-best-answer MCQs with four options, 200 marks, 0.25 deducted per wrong answer, merit list from the 50th percentile
| Section | Questions | Marks each | Total |
|---|---|---|---|
| Zoology | 40 | 1 | 40 |
| Botany | 40 | 1 | 40 |
| Chemistry | 50 | 1 | 50 |
| Physics | 50 | 1 | 50 |
| Mental Agility Test | 20 | 1 | 20 |
Where the questions are
Questions each part carries in the paper, out of 40. Area totals follow the official syllabus; where single chapters are shown, the split between them is the NEBians estimate.
- Human Biology and Physiology15 Qs
- Evolution and Diversity11 Qs
- Applied Zoology8 Qs
- Study of Selected Animals6 Qs