Zoology Quick Revision

Animal kingdom, human physiology, reproduction, health & biotech.

Animal kingdom classification

Levels: cellular (Porifera) → tissue (Cnidaria) → organ (Platyhelminthes) → organ system.
Symmetry: asymmetrical (sponge), radial (Cnidaria), bilateral (rest).
Coelom: acoelomate (flatworm), pseudocoelomate (roundworm), coelomate (rest).
Notochord: non-chordates none; chordates present at some stage.
Chordates: Urochordata (Ascidia), Cephalochordata (Branchiostoma), Vertebrata.
Vertebrata: Cyclostomata → Chondrichthyes → Osteichthyes → Amphibia → Reptilia → Aves → Mammalia.

Epithelium: covering (simple, stratified) + glandular.
Connective: loose (areolar, adipose), dense (tendon, ligament), specialised (blood, cartilage, bone).
Muscle: skeletal (striated, voluntary), smooth (visceral), cardiac (striated, involuntary).
Nervous: neuron + neuroglia.
Frog: cold-blooded, 3-chambered heart, pulmocutaneous respiration.

Dentition (human): 2:1:2:3 = 32 teeth (thecodont, diphyodont, heterodont).
Saliva: salivary amylase (ptyalin) — starch → maltose (pH ~6.8).
Stomach: HCl (kills, activates pepsinogen), pepsin (protein), rennin (milk).
Small intestine: bile emulsifies fats; pancreatic trypsin, lipase, amylase; brush border enzymes.
Absorption mainly in jejunum; water in large intestine.
Vitamin deficiencies: A (night blindness), B1 (beriberi), B12 (anaemia), C (scurvy), D (rickets), K (bleeding).

Blood: plasma 55% + formed 45%; RBC (biconcave, no nucleus, 120 d life).
WBC: granulocytes (neutrophil, eosinophil, basophil) + agranulocytes (lymphocyte, monocyte).
Neutrophils most abundant; lymphocytes for immunity.
Platelets ~1.5–4 lakh/mm³; clotting via thrombin/fibrin cascade.
Blood groups: ABO (I^A, I^B, i); Rh factor.
Heart: 4 chambers; SA node = pacemaker; AV node → bundle of His → Purkinje.
Cardiac cycle 0.8 s; CO = SV × HR ≈ 5 L/min.
ECG: P (atrial depol), QRS (ventricular depol), T (repol).
BP normal 120/80; hypertension >140/90.

Nephron = functional unit; ~1 million per kidney.
Parts: Bowman capsule + PCT + Loop of Henle + DCT + collecting duct.
GFR ~125 mL/min; regulated by JGA (renin–angiotensin).
ADH: acts on DCT/CD → water reabsorption.
Aldosterone: Na⁺ reabsorption in DCT.
Urea cycle in liver; uricotelic (birds), ureotelic (mammals), ammonotelic (fish).
Disorders: uremia, nephritis, renal calculi; dialysis.

Skeletal muscle: sarcomere Z–Z; A band (dark, myosin), I band (light, actin), H zone.
Sliding filament theory: actin slides over myosin; ATP + Ca²⁺ required.
Bones: 206 in adult; axial (80) + appendicular (126).
Joints: fibrous, cartilaginous, synovial (ball & socket, hinge, pivot).
Disorders: arthritis, osteoporosis, gout, muscular dystrophy, myasthenia gravis.

Neuron: dendrite → soma → axon → synapse.
Resting potential −70 mV (Na⁺ out, K⁺ in via Na–K pump).
Action potential: Na⁺ influx → depolarisation → K⁺ efflux → repolarisation.
Synapse: chemical (neurotransmitter) or electrical (gap junction).
CNS: brain + spinal cord; PNS: cranial (12) + spinal (31) nerves + autonomic.
Brain: forebrain (cerebrum, thalamus, hypothalamus), midbrain, hindbrain (pons, cerebellum, medulla).
Reflex arc: receptor → afferent → CNS → efferent → effector.

Hypothalamus: releasing/inhibiting factors.
Pituitary: GH, TSH, ACTH, FSH, LH, prolactin (ant); oxytocin, ADH (post).
Thyroid: T3, T4 (BMR); parathyroid: PTH (Ca²⁺ ↑).
Pancreas: insulin (β, ↓ glucose), glucagon (α, ↑ glucose).
Adrenal cortex: aldosterone, cortisol; medulla: adrenaline, noradrenaline.
Testes: testosterone; Ovaries: estrogen, progesterone.
Diabetes mellitus: type 1 (insulin), type 2 (resistance); goitre (iodine deficiency).

Male: testes in scrotum (2°C < body); seminiferous tubules → sperm.
Sperm: head (nucleus + acrosome), middle piece (mitochondria), tail.
Female: ovary → primary follicle → Graafian follicle → ovulation.
Oogenesis begins in fetal life; arrested in prophase-I until puberty.
Menstrual cycle ~28 d: menstrual, follicular, ovulation (~day 14, LH surge), luteal.
Fertilisation in ampulla; cleavage → morula → blastocyst → implantation day 7.
Placenta: hCG maintains corpus luteum early; hPL, estrogen, progesterone later.
Gestation ~40 weeks; parturition triggered by oxytocin.

Contraceptives: barrier (condom, diaphragm), IUD (Cu-T, LNG-20), hormonal (pill), sterilisation (vasectomy, tubectomy).
MTP legal in India up to 24 weeks (recent amendment).
STDs: gonorrhoea, syphilis, chlamydia, trichomoniasis, HIV (curable? HIV/hepatitis no).
ART: IVF (test-tube), ZIFT, GIFT, ICSI.
Amniocentesis banned for sex determination (PC-PNDT Act).

Pathogens: bacteria (typhoid – Salmonella, pneumonia – Streptococcus), virus (common cold, dengue, chikungunya), protozoa (Plasmodium malaria, Entamoeba amoebiasis), helminth (Ascaris, filaria – Wuchereria).
Malaria vector: female Anopheles; dengue: Aedes.
Immunity: innate (physical, physiological, cellular, cytokine barriers) + acquired.
Antibody: Y-shaped, 2H + 2L chains; classes IgG, IgA, IgM, IgE, IgD.
Vaccination: active immunity via antigen; passive via preformed antibodies.
Allergy: IgE-mediated; histamine, serotonin.
AIDS: HIV attacks CD4⁺ T cells; ELISA test; ART treatment.
Cancer: uncontrolled cell division; benign vs malignant (metastasis).
Drugs of abuse: opioids (heroin), cannabinoids, cocaine, tobacco.

Tools: restriction enzymes, vectors, host, DNA ligase.
PCR amplifies DNA (Taq polymerase).
Gel electrophoresis: separates DNA by size (agarose).
Southern (DNA), Northern (RNA), Western (protein) blot.
Applications: recombinant insulin, GM crops, gene therapy (ADA), molecular diagnosis.
Bt cotton: Cry1Ac, Cry2Ab kill bollworm.
RNA interference (RNAi): silences gene; used against nematodes.

Adaptations: kangaroo rat (desert), thick fur (arctic), Bergmann's rule (larger in cold).
Population attributes: density, natality, mortality, sex ratio, age pyramid.
Growth: exponential J-shaped; logistic S-shaped with carrying capacity K.
Interactions: predation, competition, parasitism, commensalism, mutualism.
Fig–wasp, orchid–bee: obligate mutualism.