UPHESC Assistant Professor Zoology 2025 PYQs

Concept: Lungfishes (Dipnoi) share several primitive features with elasmobranchs but are bony fishes with an operculum.

1. Shared with cartilaginous fishes: spiral valve in intestine, a conus arteriosus, absence of nephrostomes in the adult kidney.
2. Gills covered by an operculum is an osteichthyan feature; sharks/rays have naked gill slits.

Short trick: "Shark = 5–7 open slits, no lid"; operculum = bony-fish lid.

Concept: Erwin Chargaff (1950) found that in double-stranded DNA A = T and G = C, so purines = pyrimidines (A+G = T+C).

1. This later supported Watson–Crick base pairing.
2. Van't Hoff plot (thermodynamics), Coulomb's law (electrostatics) and Le Chatelier's principle (equilibrium) are unrelated.

Short trick: "Chargaff = Charge-equal pairs: A=T, G≡C".

Concept: Hydrophobicity comes from long non-polar hydrocarbon (alkyl) chains of fatty acids.

1. C–H bonds are non-polar, cannot form H-bonds with water.
2. Hydroxyl, carbonyl and phosphate groups are polar/charged – they make the hydrophilic "head" of amphipathic lipids.

Short trick: Tail = alkyl = water-hating; head = phosphate/OH = water-loving.

Concept: The glycocalyx ("sugar coat") is the carbohydrate-rich layer on the outer surface of the plasma membrane.

1. It is formed by oligosaccharide chains of glycoproteins and glycolipids plus proteoglycans.
2. Glycans, glycoproteins and proteoglycans are its components, not the name of the zone.
3. Functions: cell recognition, adhesion, protection (e.g. intestinal microvilli).

Short trick: Glyco = sugar, calyx = cup/coat → sugar coat.

Concept: Cenozoic epochs, oldest to youngest: Palaeocene → Eocene → Oligocene → Miocene → Pliocene → Pleistocene → Holocene.

1. Palaeocene (I) 66–56 Ma, Eocene (II) 56–34 Ma, Oligocene (IV) 34–23 Ma.
2. Pleistocene (III) 2.6 Ma–11,700 yr is the youngest of the four.
3. Order = I, II, IV, III.

Short trick: "Put Eggs On My Plate Please Honey" – Palaeo, Eo, Oligo, Mio, Plio, Pleisto, Holo.

Concept: The obturator foramen is the large opening in each hip bone (os innominatum), bounded by the pubis and ischium.

1. It lies just below the acetabulum; the obturator nerve and vessels pass through it.
2. Heart has foramen ovale (foetal); vertebrae have the vertebral foramen; the pectoral girdle has no obturator foramen.

Short trick: Obturator = "between pubis and ischium" → pelvis.

Concept: Match each term to its function/association.

1. Mons pubis – fatty pad over the pubic symphysis, part of the vulva → female external genitalia (iii).
2. Glomerulus – ultrafiltration, first step of urine formation (i).
3. Ferroptosis – iron-dependent, lipid-peroxidation cell death; iron links it to haemoglobin/haem (iv).
4. Protein hormones cannot enter cells; they act through second messengers such as cAMP (ii).

Short trick: Ferr- = iron → haemoglobin; protein hormone → stays outside → needs a messenger.

Concept: Hominin sequence (oldest → youngest): Australopithecus → Homo habilis → Homo erectus → Homo sapiens.

1. Australopithecus (II) ~4–2 Ma, bipedal ape-man.
2. Homo habilis (III) ~2.4–1.4 Ma, "handy man", first stone tools.
3. Homo erectus (IV) ~1.9 Ma–110 ka, used fire.
4. Homo sapiens (I) ~300 ka to present. Order: II, III, IV, I.

Short trick: "A-H-E-S": Ape-man → Handy → Erect → Sapiens (wise).

Concept: Kin selection (W. D. Hamilton, 1964) explains altruism by inclusive fitness: helping relatives spreads shared genes.

1. Hamilton's rule: altruism is favoured when $rB>C$ (r = coefficient of relatedness, B = benefit to recipient, C = cost to altruist).
2. Example: sterile worker bees (r = 0.75 with sisters in haplodiploidy).
3. Reciprocal benefit is "reciprocal altruism" (Trivers), a different mechanism.

Short trick: "Kin = Genes in common" → $rB>C$.

Concept: Know the molecular target of common drugs/toxins.

1. Cyclosporin-A binds cyclophilin and inhibits calcineurin, a protein phosphatase (the "phosphate inhibitor" of the list) → a–III.
2. Rapamycin (with FKBP12) inhibits the kinase mTOR → b–II.
3. A rise in cAMP activates PKA, which acts by phosphorylation → c–IV.
4. Ouabain blocks the Na⁺/K⁺ pump that moves K⁺ into the cell → d–I.

Short trick: CsA → Calcineurin (phosphatase); Rapa → mTOR (kinase); Ouabain → Na/K pump.

Concept: In humans the Y chromosome (SRY gene) determines maleness regardless of the number of X chromosomes.

1. XXY (47 chromosomes) = Klinefelter syndrome: phenotypic male, tall, small testes, sterile, sometimes gynaecomastia.
2. Super female is XXX; this differs from Drosophila, where the X:A ratio decides sex.

Short trick: "Y = guy" – any Y makes a male in humans.

Concept: Though worded as a sequence, this is a disease–pathogen matching.

1. Jaundice (Weil's disease, leptospirosis) – spirochaete Leptospira (I–b).
2. Kala-azar (visceral leishmaniasis) – Leishmania donovani, spread by sandfly (II–a).
3. Bacillary dysentery – Shigella (III–c).
4. Whooping cough – Bordetella pertussis (IV–d).

Short trick: Kala-azar ↔ Leishmania is the anchor; only option A has II–a with I–b.

Concept: Ribophorins I and II are transmembrane glycoproteins of the RER membrane that help bind the large (60S) ribosomal subunit; they are part of the oligosaccharyl-transferase complex.

1. Glycophorins – sialoglycoproteins of the RBC membrane.
2. Lipophorins – lipid-carrying proteins of insect haemolymph.
3. Transferrin – iron-transport protein of plasma.

Short trick: Ribo-phorin = "ribosome carrier" on RER.

Concept: Optimal foraging theory (MacArthur & Pianka, 1966) says natural selection favours foraging that maximises net energy gain per unit time, i.e. benefit minus cost.

1. Animals choose prey, patch and time spent so that search/handling energy cost is minimised relative to intake (e.g. Charnov's marginal value theorem).
2. B, C, D describe need, capacity or instinct – not optimisation.

Short trick: "Optimal" = best profit: max energy in, min energy out.

Concept: Palaeozoic periods: Cambrian → Ordovician → Silurian → Devonian → Carboniferous → Permian; then Mesozoic; Pliocene is a late Cenozoic epoch.

1. Cambrian (I) 541–485 Ma.
2. Carboniferous (III) 359–299 Ma.
3. Permian (II) 299–252 Ma.
4. Pliocene (IV) 5.3–2.6 Ma. Order: I, III, II, IV.

Short trick: "Camels Often Sit Down Carefully, Perhaps" – Cam, Ord, Sil, Dev, Carb, Perm.

Concept: A sugar is reducing if it has a free anomeric (aldehyde/ketone) carbon.

1. Sucrose: glucose α1→β2 fructose – both anomeric carbons are bonded → non-reducing.
2. Raffinose (galactose–glucose–fructose) contains the sucrose linkage → non-reducing.
3. Glucose and maltose have a free anomeric carbon → reducing, so A, B and D are wrong.

Short trick: "Sucrose family" (sucrose, raffinose, stachyose) and trehalose are non-reducing.

Concept: Sterols (e.g. cholesterol) are essential in eukaryotes: they regulate membrane fluidity and are precursors of steroid hormones, bile acids and vitamin D.

1. A is true.
2. R is also true: cholesterol/oxysterols act as signalling molecules in development – cholesterol is covalently attached to Hedgehog and sterols activate Smoothened, acting as a second messenger in Hedgehog signalling.
3. This signalling role is one of the reasons sterols are physiologically essential, so R explains A.

Short trick: Cholesterol = membrane + hormones + Hedgehog signal → "essential".

Concept: Glucose binds non-enzymatically to haemoglobin (glycation); the % of HbA1c reflects the average blood glucose of the previous 2–3 months (RBC life ~120 days).

1. Used to diagnose and monitor diabetes mellitus: normal <5.7 %, prediabetes 5.7–6.4 %, diabetes ≥6.5 %.
2. Anaemia/thalassaemia actually make HbA1c unreliable; it is not a heart-attack marker (troponin is).

Short trick: A1c = "Average glucose over 3 months".

Concept: Logistic (Verhulst–Pearl) growth: $\frac{dN}{dt}=rN\left(\frac{K-N}{K}\right)$ – a sigmoid (S-shaped) curve.

1. At low N growth is nearly exponential; as N approaches carrying capacity K, the growth rate falls to zero and the population stabilises.
2. Constant per-capita growth rate gives exponential (J-shaped), not logistic, growth.

Short trick: J = exponential (no limit); S = logistic (stops at K).

Concept: Natural selection is adaptive and cumulative; the bottleneck effect is a form of random genetic drift.

1. A is true – selection acting over many generations accumulates differences that lead to speciation (Darwin).
2. R is true – a drastic fall in population size (bottleneck, e.g. cheetah, northern elephant seal) cuts genetic variation and can decide the species' future survival.
3. But drift is random and different from selection, so R does not explain A.

Short trick: Selection = non-random; bottleneck = chance → both true, no cause–effect.