UPHESC Assistant Professor Zoology 2025 PYQs

Concept: The backbone has three dihedral angles: φ (N–Cα), ψ (Cα–C) and ω (C–N, the peptide bond).

1. The peptide C–N bond has partial double-bond character (resonance), so it is planar and rigid: ω ≈ 180° (trans, usual) or ≈ 0° (cis, mainly before proline).
2. The Ramachandran plot itself plots φ vs ψ, not ω – so B and C describe φ/ψ, not ω.

Short trick: ω = "peptide plane lock": 180° trans / 0° cis.

Concept: Karl von Frisch decoded the honey-bee dance language: round dance (food near) and waggle dance (direction relative to the sun and distance).

1. He shared the 1973 Nobel Prize with Konrad Lorenz (imprinting) and Niko Tinbergen (stimulus–response, sign stimuli).
2. Emil Fischer – chemist (lock-and-key model of enzymes).

Short trick: "Frisch = Fresh flowers" → bees.

Concept: The middle piece contains a spiral sheath of mitochondria (mitochondrial spiral / nebenkern) around the axoneme.

1. Their oxidative enzymes produce ATP that powers dynein arms of the tail flagellum → motility.
2. The haploid nucleus lies in the head; the acrosome carries hydrolytic enzymes for penetrating the egg.

Short trick: Head = DNA + acrosome; Middle = mitochondria (power house); Tail = movement.

Concept: Mesoderm induction (Nieuwkoop, Xenopus) – vegetal cells induce the marginal zone to form mesoderm.

1. TGF-β family signals (Nodal/Xnr, Activin, Vg1; BMP for ventral mesoderm) are the main inducers.
2. FGF signalling is required in parallel to maintain mesodermal genes (e.g. Brachyury); blocking FGF receptors prevents mesoderm formation.
3. Shh and Notch act later (neural tube patterning, somitogenesis).

Short trick: Mesoderm needs "T + F" – TGF-β (Nodal) + FGF.

Concept: Leishmania and Trypanosoma (Kinetoplastida) cause distinct diseases.

1. Oriental sore (cutaneous leishmaniasis) – L. tropica (iii).
2. Espundia (mucocutaneous) – L. braziliensis (i).
3. African sleeping sickness – T. brucei (gambiense/rhodesiense), tsetse fly (ii).
4. Chagas disease – T. cruzi, reduviid bug (iv).

Short trick: Tropica → Oriental (tropics of Orient); Brazil-iensis → Espundia (S. America); Cruzi → Chagas (both S. American).

Concept: Crustaceans (prawn, crab, lobster) are mainly aquatic and respire by gills (branchiae), usually on thoracic appendages in a branchial chamber.

1. Insects, centipedes, millipedes – tracheae.
2. Arachnids (scorpion, spider) – book lungs; Limulus – book gills.
3. Very small crustaceans (copepods) may use the general body surface, but gills are typical.

Short trick: Crust-acean = aquatic → Gills; Insect = Tracheae; Arachnid = Book lungs.

Concept: Classic deficiency diseases.

1. Vitamin A (retinol, part of rhodopsin) – night blindness (II).
2. Vitamin B₁ (thiamine) – beriberi (I).
3. Vitamin D (calciferol) – rickets in children (IV).
4. Vitamin C (ascorbic acid, collagen hydroxylation) – scurvy (III).

Short trick: A-Andhapan (night blindness), B-Beriberi, C-sCurvy, D-Dwarfed bones (rickets).

Concept: In autoimmune disease the immune system attacks self antigens.

1. Psoriasis – T-cell mediated skin disease; rheumatoid arthritis – attack on synovial joints; Addison's disease – autoimmune destruction of adrenal cortex (commonest cause).
2. Alzheimer's disease is a neurodegenerative disorder (β-amyloid plaques, tau tangles), not classed as autoimmune.

Short trick: Alzheimer = amyloid + memory loss (degeneration), not self-attack.

Concept: Second messengers are small intracellular molecules produced in response to a first messenger (hormone) binding a receptor.

1. cAMP (Sutherland), cGMP, Ca²⁺, IP₃ and DAG (from PIP₂ by phospholipase C) are second messengers.
2. NADH is a reduced coenzyme that carries electrons to the electron transport chain – a metabolic cofactor, not a signalling messenger.

Short trick: Messengers: "cAMP, cGMP, Ca, IP₃, DAG" – NADH belongs to respiration.

Concept: Innate (instinctive) behaviour is genetically programmed, performed correctly the first time without learning or practice.

1. A spider that hatches in isolation spins a species-typical web perfectly – no learning involved, so D is wrong.
2. Its stereotyped sequences are of the fixed-action-pattern kind, but FAP is a sub-type of innate behaviour; the general category is innate behaviour.
3. "Releaser" is the stimulus that triggers a behaviour, not the behaviour itself.

Short trick: Born knowing it = innate (web-spinning, nest building, suckling).

Concept: A neurogenic heart beats in response to impulses from a nerve ganglion (cardiac ganglion) on the heart.

1. Neurogenic hearts: many arthropods (crustaceans such as Limulus, crabs; insects) and some annelids.
2. Vertebrates (birds, mammals, reptiles) and molluscs have myogenic hearts – the beat starts in modified muscle (SA node); nerves only modify the rate.

Short trick: Vertebrate = Myogenic (SA node); Arthropod = Neurogenic (ganglion).

Concept: Carl Woese (1977) used small-subunit ribosomal RNA (16S in prokaryotes, 18S in eukaryotes) to build the universal tree and discovered the three domains.

1. rRNA is present in all cellular life, has the same function everywhere, and contains both highly conserved and variable regions – ideal for comparing distant and close relatives.
2. mRNA and tRNA are too variable/short; DNA is used too, but the classic molecular chronometer is rRNA.

Short trick: Woese + 16S rRNA = three domains (Bacteria, Archaea, Eukarya).

Concept: Both rho-independent and rho-dependent terminators contain a GC-rich inverted repeat (palindrome) whose transcript folds into a stem-loop (hairpin) that pauses RNA polymerase.

1. A sequence can form a hairpin only if it equals its own reverse complement.
2. 5′-GGTACC-3′ → reverse complement 5′-GGTACC-3′: a perfect GC-rich palindrome (the other strand reads 3′-CCATGG-5′).
3. CGTATG, CGAATG and GACTAC are not self-complementary.

Short trick: Read the bottom strand right-to-left – if it matches the top strand, it is a palindrome → hairpin.

Concept: The 5′ cap is a 7-methylguanosine joined by an unusual 5′–5′ triphosphate bridge.

1. RNA triphosphatase removes the terminal γ-phosphate.
2. Guanylyl transferase (capping enzyme) adds GMP from GTP – this is the step that attaches the cap.
3. Guanine-7-methyltransferase then methylates it (m⁷G); methylation only modifies the cap already added.
4. Poly(A) polymerase acts at the 3′ end.

Short trick: Cap = G added by Guanylyl transferase, then Methylated.

Concept: The synaptonemal complex (SC) is the protein ladder holding homologues together during synapsis.

1. Leptotene – lateral (axial) elements form along each chromosome.
2. Zygotene – SC begins to form, synapsis starts (zipping up).
3. Pachytene – SC is complete along the entire length of bivalents; crossing over occurs.
4. Diplotene – SC dissolves, chiasmata become visible.

Short trick: Pachy = thick – fully zipped, SC complete, crossing over.

Concept: Among terrestrial forests, productivity is highest where light, temperature and water are high all year.

1. Tropical rain forest NPP ≈ 2000–2200 g m^–2 yr^–1 (Whittaker) – highest; its gross productivity is also the highest.
2. Tropical seasonal (deciduous) forest ≈ 1600; temperate evergreen ≈ 1300; temperate deciduous ≈ 1200.

Short trick: Warm + wet + all-year growing season = tropical rain forest on top (whether gross or net).

Concept: Molecular data place humans in the African great-ape clade: chimpanzee/bonobo closest (~98.8 % DNA), then gorilla, then orangutan.

1. Chimpanzee is not offered; among the options the gorilla (split ~8–10 Ma) is closest.
2. Orangutan (Asian great ape, ~14 Ma), gibbon (lesser ape) and langur (Old World monkey) are progressively more distant.

Short trick: Distance order: Chimp < Gorilla < Orangutan < Gibbon < Monkeys.

Concept: Each mitochondrial compartment has marker enzymes.

1. Inner membrane – respiratory chain complexes I–IV, coenzyme Q, cytochrome c (on its outer face), ATP synthase, succinate dehydrogenase.
2. Outer membrane – monoamine oxidase (marker); hexokinase binds porin on the outer surface.
3. Intermembrane space – adenylate kinase (marker).
4. Matrix – Krebs-cycle enzymes.

Short trick: MAO = Outer; AK = in-Between; ETC = Inner; Krebs = matrix.

Concept: Each cell-cycle transition is driven by a specific cyclin–CDK pair.

1. Cyclin D–CDK4/6 acts in early-mid G1 (growth-factor dependent), starting Rb phosphorylation.
2. Cyclin E–CDK2 completes Rb hyperphosphorylation, releases E2F and triggers the G1→S transition (initiates DNA replication).
3. Cyclin A–CDK2 – progression through S; Cyclin B–CDK1 (MPF) – G2→M.

Short trick: D → E → A → B along G1 → S → G2 → M; "E = Entry into S".

Concept: Glycation is the non-enzymatic (Maillard) reaction of a reducing sugar with amino groups of proteins, lipids or nucleic acids.

1. It forms a Schiff base → Amadori product → advanced glycation end-products (AGEs), e.g. HbA1c; important in diabetic complications.
2. Glycosylation is the enzyme-controlled addition of sugars (in ER/Golgi by glycosyltransferases).
3. Glycolysis = glucose breakdown; ligation = joining of DNA ends by ligase.

Short trick: Glyc-ation = accidental; Glyco-sylation = enzyme-controlled.