Zoology - Intermediate Second Year Study Notes (Andhra Pradesh Board)

UNIT IA: DIGESTION AND ABSORPTION

• Digestive System Overview: Consists of the alimentary canal and associated glands (salivary, liver, pancreas). Humans are omnivores ($Dental Formula: \frac{2, 1, 2, 3}{2, 1, 2, 3} \times 2 = 32$).

• Alimentary Canal:

  • Mouth/Buccal Cavity: Palate separates nasal and oral chambers. Teeth are thecodont (embedded in sockets), diphyodont (two sets: milk and permanent), and heterodont (incisors, canines, premolars, molars).

  • Tooth Structure: Crown, neck, and root. Dentine is secreted by odontoblasts (mesodermal); enamel—the hardest body substance—is secreted by ameloblasts (ectodermal).

  • Tongue: Muscular organ with papillae (fungiform, filiform, circumvallate, foliate).

  • Pharynx: Common passage for food and air; larynx opening guarded by epiglottis.

  • Stomach: J-shaped, with cardiac, fundic, and pyloric regions.

  • Small Intestine: Longest part; includes duodenum (proximal, U-shaped), jejunum (middle coiled), and ileum (highly coiled). Mucosa contains villi and microvilli (brush border) to increase absorption area.

  • Large Intestine: Caecum (has vermiform appendix), colon (ascending, transverse, descending, sigmoid), and rectum.

• Digestive Glands:

  • Salivary Glands: Parotid, submaxillary, and sublingual ($pH 6.8$; contain ptyalin/salivary amylase).

  • Gastric Glands: Chief cells (pepsinogen, prorennin), Oxyntic/parietal cells ($HCl$ and Castle’s Intrinsic Factor for $B_{12}$ absorption).

  • Liver: Largest gland ($1.2 - 1.5 kg$). Unit is hepatic lobule with Glisson's capsule. Secretes bile (bile salts and pigments—bilirubin/biliverdin). Functions: Glycogenesis, deamination, detoxification (via Kupffer cells), and thermoregulation.

  • Pancreas: Mixed gland. Exocrine acini secrete alkaline juice ($pH 8.4$; trypsinogen, lipase, etc.). Endocrine islets secrete insulin and glucagon.

• Physiology of Digestion:

  • Buccal Cavity: $30\%$ starch hydrolysis by ptyalin.

  • Stomach: Churning turns food into chyme. $HCl$ ($pH 1.8$) activates pepsinogen to pepsin for protein breakdown. Rennin curdles milk in infants.

  • Small Intestine: Chyme mixed with bile (emulsifies fats), pancreatic juice, and intestinal juice (succus entericus, $pH 7.5 - 8.0$). Enzymes like trypsin, chymotrypsin, and carboxypeptidase break proteins into amino acids. Lipases break fats into fatty acids/glycerol. Disaccharidases (maltase, lactase, sucrase) break sugars into monosaccharides.

• Absorption and Assimilation:

  • Glucose and galactose: Secondary active transport with $Na^{+}$.

  • Fructose: Facilitated diffusion.

  • Fats: Re-formed into micelles, then protein-coated chylomicrons for transport through lacteals (lymph capillaries).

  • Energy conversion: $\text{Carbohydrates/Proteins} = 4.0 \text{ kcal/g}$; $\text{Fats} = 9.0 \text{ kcal/g}$.

• Disorders: Kwashiorkor (protein deficiency), Marasmus (protein and calorie deficiency), Jaundice (liver/bile pigments), Indigestion, Vomiting (controlled by medulla), Diarrhoea, and Constipation.

UNIT IB: BREATHING AND EXCHANGE OF GASES

• Respiratory System Structure:

  • Nasal Chambers: Vestibular (hair), respiratory (turbinals/temperature control), and olfactory (smell detection).

  • Larynx: Voice box; contains thyroid, cricoid, epiglottis (unpaired), and arytenoid (paired) cartilages. Adam's apple is laryngeal prominence.

  • Trachea: Windpipe with C-shaped hyaline cartilage rings.

  • Lungs: Covered by double-layered pleura. Pathway: Trachea $\to$ primary bronchi $\to$ secondary $\to$ tertiary $\to$ bronchioles $\to$ terminal bronchioles (conducting part) $\to$ respiratory bronchioles $\to$ alveolar ducts $\to$ alveoli (exchange part).

• Mechanism of Breathing:

  • Inspiration: Active process. Diaphragm and external intercostal muscles contract $\to$ thoracic volume increases $\to$ intra-pulmonary pressure decreases $\to$ air enters.

  • Expiration: Passive process. Muscles relax $\to$ volume decreases $\to$ pressure increases $\to$ air leaves. Forced expiration uses internal intercostals and abdominal muscles.

• Gas Transport:

  • Oxygen: $97\%$ by RBC (haemoglobin), $3\%$ in plasma. Sigmoid dissociation curve; Bohr effect: High $pCO_{2}$ and low $pH$ decrease affinity.

  • Carbon Dioxide: $70\%$ as bicarbonate, $20 - 25\%$ as carbamino-haemoglobin, $7\%$ dissolved in plasma. Carbonic anhydrase enzyme facilitates: $CO<em>{2} + H</em>{2}O \rightleftharpoons H<em>{2}CO</em>{3} \rightleftharpoons HCO_{3}^{-} + H^{+}$.

  • Chloride Shift (Hamburger’s Phenomenon): Exchange of $Cl^{-}$ and $HCO_{3}^{-}$ between RBC and plasma to maintain electrolyte balance.

• Lung Volumes/Capacities:

  • $TV \approx 500 ml$, $IRV \approx 2500 - 3000 ml$, $ERV \approx 1000 - 1100 ml$, $RV \approx 1100 - 1200 ml$.

  • $VC = TV + IRV + ERV$; $TLC = VC + RV$.

• Regulation: Respiratory rhythm centre (medulla), Pneumotaxic centre (pons—moderator), and Chemoreceptors (aortic arch/carotid artery sensitive to $CO_{2}/H^{+}$).

• Disorders: Asthma (inflammation/spasm), Emphysema (damaged alveolar walls—common in smokers), Occupational (Asbestosis, Silicosis).

UNIT IIA: BODY FLUIDS AND CIRCULATION

• Lymphatic System: Open system. Lymph contains water, electrolytes, and lymphocytes; lacks RBCs and large proteins. Functions: return ECF to blood, transport fats via lacteals (chyle), and immunity in lymph nodes.

• Clotting of Blood: Cascade mechanism.

  • Involves 13 factors. Prothrombin activator $\to$ Prothrombin to Thrombin $\to$ Fibrinogen to Fibrin monomers $\to$ Fibrin mesh (clot). $Ca^{++}$ is essential (Factor IV). Clot retraction requires platelets. Serum = Plasma - Clotting factors.

• Human Heart Structure: Mesodermal origin; situated in mediastinum.

  • Pericardium: Double-walled sac with fluid.

  • Chambers: 2 Atria (separated by inter-atrial septum with fossa ovalis) and 2 Ventricles (separated by thick inter-ventricular septum).

  • Valves: Tricuspid (right), Bicuspid/Mitral (left), and Semilunar valves (aortic/pulmonary arches).

  • Nodal Tissue: Sinoatrial node (SAN—Pacemaker, $70 - 80$ beats/min), Atrioventricular node (AVN—Relay point), Bundle of His, and Purkinje fibres.

• Cardiac Cycle ($0.8 sec$): Atrial systole ($0.1 s$), Ventricular systole ($0.3 s$), and Joint diastole ($0.4 s$).

  • Sounds: 'Lub' (closure of AV valves) and 'Dup' (closure of semilunar valves).

  • Cardiac Output: $\text{Stroke Volume } (70 ml) \times \text{ Heart Rate } (72) \approx 5040 ml/min$.

• Blood Vessels:

  • Arteries: Thick-walled, narrow lumen, no valves, carry oxygenated blood (except pulmonary artery).

  • Veins: Thin-walled, wide lumen, have valves, carry deoxygenated blood (except pulmonary vein).

• Double Circulation: Pulmonary circulation (heart $\to$ lungs $\to$ heart) and Systemic circulation (heart $\to$ body $\to$ heart).

• Disorders: Hypertension (> 140/90), CAD (Atherosclerosis—narrowing of coronary arteries), Angina Pectoris (chest pain/ischemia), and Heart failure (congestive).

UNIT IIB: EXCRETORY PRODUCTS AND THEIR ELIMINATION

• Modes of Excretion:

  • Ammonotelism: High toxicity, water-intensive (mostly aquatic life).

  • Ureotelism: Urea produced via Ornithine cycle in liver (mammals, amphibians).

  • Uricotelism: Least toxic, water-conserving (birds, reptiles, insects).

• Human Excretory System: Kidneys (retroperitoneal), Ureters, Urinary bladder, and Urethra.

  • Kidney Internal Anatomy: Outer cortex, inner medulla (renal pyramids, Columns of Bertin). Pelvis leads to ureter.

  • Nephron Structure: Malpighian body (Glomerulus + Bowman’s capsule with podocytes/filtration slits) and Renal tubule (PCT, Henle’s loop, DCT, Collecting duct).

• Urine Formation:

  • Glomerular Filtration: Passive; $NFP = 10 mmHg$ ($60 - [32+18]$). $GFR = 125 ml/min$ ($180 L/day$).

  • Selective Reabsorption: $99\%$ of filtrate reabsorbed. PCT (main site), Henle's loop (concentrates filtrate), DCT/CD (regulated by hormones).

  • Tubular Secretion: $H^{+}, K^{+}, NH_{3}$ added to maintain $pH$.

• Counter Current Mechanism: Involves Henle's loop and vasa recta to maintain medullary osmolarity ($300 \to 1200 mOsml/L$), producing concentrated urine (4x initial filtrate).

• Regulation:

  • ADH (Vasopressin): Released by hypothalamus; increases water reabsorption in CD.

  • RAAS: Fall in pressure $\to$ Renin (from JG cells) $\to$ Angiotensinogen to Angiotensin I/II $\to$ Aldosterone (increases $Na^{+}$ reabsorption).

  • ANP: From heart atria; vasodilator, counters RAAS.

• Disorders: Uremia (excess urea in blood), Renal calculi (stones—oxalates/uric acid), Glomerulonephritis. Artificial kidney (Haemodialysis) uses cellophane tubes.

UNIT IIIA: MUSCULO-SKELETAL SYSTEM

• Muscle Ultra-structure:

  • Sarcolemma (membrane), sarcoplasm (cytoplasm), and sarcoplasmic reticulum (calcium store).

  • Myofibril: Light band (I-band, actin, troponin, tropomyosin) and Dark band (A-band, myosin).

  • Sarcomere: Functional unit between two Z-lines. H-zone is the central portion of the A-band.

  • Regulatory Proteins: Troponin (Tn-T, Tn-I, Tn-C binds $Ca^{2+}$) and Tropomyosin.

  • Motor Proteins: Myosin (meromyosins with HMM globulin head/neck and LMM tail).

• Mechanism of Contraction (Sliding Filament Theory): Nerve impulse $\to$ $Ca^{2+}$ release $\to$ binds to Troponin-C $\to$ shifts Tropomyosin $\to$ Myosin head binds to Actin active site $\to$ ATP hydrolysis $\to$ Power stroke (actin slides over myosin) $\to$ sarcomere shortens ($I$ bands reduce, $A$ bands remain same).

• Muscle Fatigue: Lactic acid accumulation under anaerobic conditions. Cori Cycle: Lactic acid $\to$ Liver $\to$ Glucose.

• Types of Fibres: Red (high myoglobin/mitochondria, aerobic) and White (low myoglobin, anaerobic, fast).

• Skeletal System (206 bones):

  • Axial (80): Skull (22 - Cranium, Face), Hyoid, Ear ossicles (3 pairs: Malleus, Incus, Stapes), Vertebral column (26 units: $C7, T12, L5, S1\text{(fused)}, Co1\text{(fused)}$), Sternum, and Ribs (12 pairs: 7 True, 3 False, 2 Floating).

  • Appendicular (126): Pectoral girdle (Clavicle, Scapula), Pelvic girdle (Coxal bones: Ilium, Ischium, Pubis), Forelimbs (Humerus, Radius, Ulna, Carpals, Metacarpals, Phalanges), Hind limbs (Femur, Tibia, Fibula, Patella, Tarsals, Metatarsals, Phalanges).

• Joints: Fibrous (immovable—sutures), Cartilaginous (slightly movable—pubic symphysis), and Synovial (freely movable—ball and socket, hinge, pivot, gliding, condyloid, saddle).

• Disorders: Myasthenia gravis (autoimmune), Muscular dystrophy (genetic), Tetany (low $Ca^{2+}$), Osteoporosis (low bone mass/oestrogen), Gout (uric acid crystals), Rigor mortis (ATP lack after death).

UNIT IIIB: NEURAL CONTROL AND COORDINATION

• Central Nervous System (CNS):

  • Meninges: Dura mater (outer), Arachnoid (middle), Pia mater (inner).

  • Brain:

    • Forebrain: Olfactory bulbs, Cerebrum (Grey matter cortex, White matter medulla; connected by Corpus Callosum), Diencephalon (Epithalamus, Thalamus, Hypothalamus).

    • Midbrain: Corpora quadrigemina (superior/inferior colliculi).

    • Hindbrain: Cerebellum (Arbor vitae), Pons Varolii (pneumotaxic centre), Medulla Oblongata (vital reflex centres).

  • Spinal Cord: Butterfly-shaped grey matter; central neurocoel. Ends in conus medullaris and filum terminale.

• Peripheral Nervous System (PNS): 12 pairs of Cranial nerves and 31 pairs of Spinal nerves.

• Autonomic Nervous System (ANS):

  • Sympathetic: Thoracolumbar; "Fight or Flight"; norepinephrine; increases heart rate/dilates pupil.

  • Parasympathetic: Craniosacral; "Rest and Digest"; acetylcholine; slows heart rate/constricts pupil.

• Nerve Impulse:

  • Resting Potential: $-70 mV$ (inside negative); maintained by $Na^{+}/K^{+}$ pump ($3 Na^{+}$ out, $2 K^{+}$ in).

  • Action Potential (Depolarization): Stimulus $\to$ $Na^{+}$ influx $\to$ membrane potential becomes $+45 mV$ (spike potential).

  • Repolarization: $K^{+}$ efflux $\to$ potential returns to negative.

  • Saltatory Conduction: Impulse 'jumps' between Nodes of Ranvier in myelinated axons.

• Synapse: Gap junction (electrical) or synaptic cleft (chemical via neurotransmitters like acetylcholine, GABA).

• Sense Organs:

  • Eye: Sclera, Choroid, Retina (Rods for scotopic/periphery vision; Cones for photopic/colour/foveal vision). Macula lutea has fovea centralis (sharpest vision).

  • Ear: Pinna $\to$ Auditory meatus $\to$ Tympanum $\to$ Malleus/Incus/Stapes $\to$ Oval window $\to$ Cochlea (Organ of Corti on basilar membrane). Vestibular apparatus (Semicircular canals, Utricle, Saccule) maintains equilibrium.

• Disorders: Alzheimer’s (dementia), Meningitis, Parkinson’s, and Stroke (CVA).

UNIT IVA: ENDOCRINE SYSTEM AND CHEMICAL COORDINATION

• Hypothalamus: Master control center. Produces releasing/inhibiting hormones (e.g., GHRH, Somatostatin) and neuro-secretions (Oxytocin, ADH).

• Pituitary (Hypophysis):

  • Adenohypophysis: GH (Growth), Prolactin (Milk), TSH (Thyroid), ACTH (Adrenal cortex), FSH/LH (Gonadotropins).

  • Neurohypophysis: Releases Oxytocin (Uterine contraction/milk ejection) and Vasopressin (ADH).

• Thyroid: Secretes Thyroxine ($T<em>{4}$) and Tri-iodothyronine ($T</em>{3}$) for BMR and erythropoiesis; Thyrocalcitonin (TCT) lowers blood $Ca^{2+}$.

• Parathyroid: Secretes Parathormone (PTH); raises blood $Ca^{2+}$ (hypercalcemic) by bone resorption and $Ca^{2+}$ absorption.

• Adrenal Glands:

  • Cortex: Mineralocorticoids (Aldosterone—$Na^{+}$ balance), Glucocorticoids (Cortisol—carb metabolism/stress combat), Sex corticoids (Androgens).

  • Medulla: Catecholamines (Adrenaline/Noradrenaline—Emergency hormones).

• Pancreas: Islets of Langerhans—$\alpha$ cells (Glucagon—raises sugar) and $\beta$ cells (Insulin—lowers sugar).

• Mechanism of Action:

  • Water-soluble: Bind membrane receptors $\to$ secondary messengers (cAMP).

  • Lipid-soluble: Bind intracellular receptors $\to$ gene expression.

• Disorders: Dwarfism/Gigantism/Acromegaly (GH), Simple Goitre (Iodine deficiency), Cretinism/Myxedema (Hypothyroidism), Exophthalmic Goitre (Graves' disease), Diabetes Insipidus (ADH deficiency), Diabetes Mellitus (Insulin deficiency), Addison's Disease (adrenal deficiency), Cushing’s Syndrome (excess cortisol).

UNIT IVB: IMMUNE SYSTEM

• Lines of Defence: 1st (Skin/Mucus), 2nd (Phagocytes/NK cells/Inflammation/Fever), 3rd (Lymphocytes/Antibodies).

• Cells: B-cells (humoral—produce antibodies), T-cells ($T<em>{H}$ helper, $T</em>{C}$ cytotoxic/killer), NK cells (non-specific lysis), Phagocytes (Monocytes, Macrophages, Neutrophils).

• Organs: Primary (Bone marrow, Thymus—maturation); Secondary (Spleen, Lymph nodes, MALT—activation).

• Antibodies (Immunoglobulins): $H<em>{2}L</em>{2}$ structure. Monomeric (IgD, IgE, IgG), dimeric (IgA—colostrum), pentameric (IgM).

• Antigens: Processed by APCs and presented via MHC molecules. MHC-I (on all nucleated cells; to $T<em>{C}$); MHC-II (on APCs; to $T</em>{H}$).

• Types of Immunity:

  • Innate: Inborn, non-specific.

  • Acquired: Specific, memory-based. Active (natural infection/vaccine) or Passive (colostrum/serum).

  • Humoral (HI): B-cells $\to$ Plasma cells $\to$ Antibodies in body fluids.

  • Cell-Mediated (CMI): T-cells $\to$ CTLs $\to$ Perforins/Granzymes kill infected cells.

• HIV/AIDS: Retrovirus (ssRNA + Reverse Transcriptase). Infects $T_{H}$ cells ($CD4^{+}$). Diagnostic: ELISA (Screening), Western Blot (Confirmation).

• Other: Type-I Hypersensitivity (Allergy—IgE mediated), Autoimmune (Myasthenia gravis), Graft rejection.

UNIT VA: HUMAN REPRODUCTIVE SYSTEM

• Male System: Testes (in scrotum, $2 - 2.5^{o}C$ lower temp). Seminiferous tubules (Sertoli cells—nutrition; Leydig cells—testosterone). Pathway: Rete testis $\to$ vasa efferentia $\to$ epididymis $\to$ vas deferens $\to$ ejaculatory duct $\to$ urethra. Glands: Seminal vesicles ($60\%$ volume, fructose), Prostate, Bulbourethral.

• Female System: Ovaries, Fallopian tubes (Infundibulum, Ampulla, Isthmus), Uterus (Endometrium, Myometrium, Perimetrium), Vagina, Vulva. Glands: Mammary (Alveoli $\to$ mammary ducts $\to$ ampulla $\to$ lactiferous ducts).

• Gametogenesis:

  • Spermatogenesis: Spermatogonia $\to$ 1o spermatocyte $\to$ 2 haploid 2o spermatocytes $\to$ 4 spermatids $\to$ 4 spermatozoa (spermiogenesis).

  • Oogenesis: Oogonia $\to$ 1o oocyte $\to$ 1st Polar body + 2o oocyte (at ovulation) $\to$ 2o oocyte arrested in Metaphase II.

• Menstrual Cycle ($28 days$): Menstrual phase ($1 - 5 d$), Follicular phase ($FSH$ stimulates follicles), Ovulatory phase ($LH$ surge on $14th d$ $\to$ ovulation), Luteal phase (Corpus luteum $\to$ progesterone).

• Fertilization: Occurs at ampullary-isthmic junction. Acrosome reaction $\to$ polyspermy block $\to$ completion of meiosis II $\to$ Synkaryon (zygote). Sex determined by sperm ($X$ or $Y$).

• Development: Cleavage $\to$ Morula (16-32 cells) $\to$ Blastocyst (trophoblast + inner cell mass). Implantation on $6th day$. Gastrulation $\to$ Ectoderm, Mesoderm, Endoderm.

• Placenta: Haemochorial, chorioallantoic. Functions: nutrient/oxygen exchange, excretes waste, secretes hCG, oestrogen, progesterone, hPL.

• Preganancy/Birth: Gestation $266 days$. Parturition induced by foetal ejection reflex $\to$ Oxytocin. Colostrum rich in IgA.

UNIT VB: REPRODUCTIVE HEALTH

• Programmes: RCH (Reproductive and Child Healthcare), Janani Suraksha Yojana.

• STDs: Gonorrhoea, Syphilis, HIV, HPV (Cervical cancer), Trichomoniasis, Chlamydiasis. Early detection vital.

• Population Control: Marriageable age 18 (F), 21 (M).

• Contraception:

  • Natural: Periodic abstinence (10-17th day), Withdrawal, Lactational amenorrhea (up to 6 months).

  • Barrier: Condoms (Nirodh), Diaphragms.

  • IUDs: Non-medicated (Lippes loop), Copper-releasing (CuT), Hormone-releasing (Progestasert).

  • Chemical: Oral pills (Saheli—once a week, non-steroidal), Injections (DMPA), Implants.

  • Surgical: Vasectomy (M), Tubectomy (F).

• MTP: Legalised in 1971. Used for medical emergencies or failures.

• Infertility/ART: IVF-ET (Test tube baby), ZIFT (Zygote in tube), GIFT (Gamete in tube), ICSI (Sperm injection), Artificial Insemination, Surrogacy.

• Amniocentesis: Foetal genetic testing; misused for sex determination (female foeticide).

UNIT VI: GENETICS

• Mendel’s Laws:

  • Segregation (Monohybrid ratio $3:1$). Independent Assortment (Dihybrid ratio $9:3:3:1$).

• Multiple Alleles: ABO Blood grouping. Controlled by gene $I$ ($I^{A}, I^{B}, i$). 6 genotypes, 4 phenotypes. I^{A} = I^{B} > i (Codominance). Universal donor: $O^{-}$; Universal recipient: $AB^{+}$.

• Rh Factor: D-antigen. Fisher-Race hypothesis ($C, D, E$ loci). Erythroblastosis Foetalis (Rh incompatible pregnancy): treated with anti-D IgG.

• Polygenic Inheritance: Skin colour (additive effects of 3 genes $A, B, C$).

• Sex Determination:

  • XX-XO (Grasshopper), XX-XY (Human).

  • ZO-ZZ (Moths), ZW-ZZ (Birds).

  • Genic Balance (Drosophila): $X:A$ ratio. $1.0 = F, 0.5 = M, 0.5 - 1.0 = \text{Intersex}$.

  • Haplodiploidy (Honeybees): $\text{Haploid } M (16), \text{ Diploid } F (32)$.

• Sex Linkage: Crisscross inheritance. X-recessive (Haemophilia, Colour blindness, DMD). Y-linked (Hypertrichosis). Incomplete (Pseudoautosomal regions).

• Genetic Disorders:

  • Mendelian: Sickle-cell anaemia (Valine instead of Glutamic acid at 6th position of $\beta$-chain), PKU (phenylalanine accumulation), Thalassemia (alpha/beta globin defects), Alkaptonuria (Black urine).

  • Chromosomal (Aneuploidy): Down syndrome (Trisomy 21), Edwards (Trisomy 18), Patau (Trisomy 13), Klinefelter (47, XXY), Turner (45, X), Cri-du-chat (5p- deletion).

• Human Genome Project: 13-year mega project. $1.4 \text{ million}$ SNPs found. Salient features: $30,000$ genes, $3 \text{ billion}$ bp, only <2\% codes for proteins.

• DNA Fingerprinting: V.N.T.R based. Southern Blotting. Uses: Paternity tests, Forensic investigation, wild life conservation.

UNIT VII: ORGANIC EVOLUTION

• Origin of Life: Chemical Evolution (Oparin-Haldane). Primitive atmosphere: Reducing (no free $O_{2}$). Miller-Urey experiment produced amino acids in simulation.

• Evidences:

  • Palaeontology: Fossils (Archaeopteryx—between reptile and bird).

  • Embryology: Biogenetic Law (Ontogeny repeats Phylogeny).

  • Anatomy: Homologous (Divergent—same origin, e.g., whale flipper/human hand); Analogous (Convergent—same function, e.g., insect/bird wings). Vestigial organs (Appendix, Coccyx).

• Theories:

  • Lamarckism: Use and disuse; acquired characters. Disproved by Weismann (germplasm theory).

  • Darwinism: Natural selection, struggle for existence, survival of the fittest. Proof: Industrial Melanism (Biston betularia).

  • Mutation Theory (De Vries): Sudden saltations.

• Modern Synthetic Theory: Gene mutation, recombination, natural selection, isolation.

• Hardy-Weinberg Equilibrium: $p^{2} + 2pq + q^{2} = 1$. No evolution if allele frequencies are constant.

• Mechanisms: Genetic Drift (Sewall Wright Effect), Founder Effect, Bottleneck Effect. Natural Selection Types: Stabilising, Directional, Disruptive.

• Human Evolution: Dryopithecus $\to$ Ramapithecus $\to$ Australopithecus $\to$ Homo habilis ($650-800 cc$) $\to$ Homo erectus ($900 cc$, Java man) $\to$ Neanderthal ($1400 cc$) $\to$ Homo sapiens.

UNIT VIII: APPLIED BIOLOGY

• Animal Husbandry: Breeding and livestock raising. White Revolution (Dr. Kurian—NDDB/AMUL).

• Breeding: Inbreeding (increases homozygosity; risk of depression) vs Outbreeding (Out-crossing, Cross-breeding—Hisardale sheep, Interspecific hybridisation—Mule).

• MOET: Super ovulation (6-8 eggs) $\to$ nonsurgical recovery $\to$ surrogate mothers.

• Fisheries: Pisciculture (fin fish) and Aquaculture. By-products: Shark liver oil, Fish guano, Isinglass.

• Biotechnology:

  • Humulin: Biosynthetic insulin (A and B chains with disulphide bonds).

  • Vaccines: Attenuated (Yellow fever), Inactivated (Polio Salk), Toxoids (Tetanus).

  • Gene Therapy: Somatic (ex-vivo/in-vivo) or Germ line. First case: ADA deficiency (SCID).

  • Transgenic Animals: Over $95\%$ mice. Use: Disease models, biological products (Transgenic cow Rosie—$\alpha$-lactalbumin rich milk), safety testing.

• Cancer Biology: Neoplasia (Benign vs Malignant/Metastasis). Proto-oncogenes $\to$ Oncogenes. Tumor Suppressor Genes (e.g., $p53$—Guardian Angel). Carcinogens: radiation, tobacco smoke, HPV virus.

• Stem Cells: Totipotent (zygote), Pluripotent (embryonic), Multipotent (adult/HSC). HSCs produce all blood cells.

• Biomedical Technology:

  • Imaging: X-Ray (densities), CT (3D tomogram), MRI (proton resonance/non-ionizing).

  • Tests: ECG (P-wave—atrial contraction; QRS—ventricular contraction; T-wave—repolarisation), EEG (Alpha/Beta/Delta/Theta—brain activity).

  • ELISA: Antigen/Antibody detection. Direct (Sandwich/Competitive) vs Indirect.

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