BCS Written Zoology cheat sheet

Fluid mosaic model: membrane is a phospholipid bilayer with embedded integral proteins, peripheral proteins, cholesterol, and glycoproteins; lateral diffusion of lipids and proteins is rapid.

Mitochondrial oxidative phosphorylation: electron transport chain (Complexes I-IV) pumps H+ to intermembrane space; ATP synthase (Complex V) uses proton-motive force; ~30-32 ATP per glucose in eukaryotes.

Cell cycle checkpoints: G1/S (restriction point, p53/Rb control), G2/M (cyclin B-CDK1), and spindle assembly checkpoint (MAD/BUB proteins) ensure fidelity.

Apoptosis is caspase-dependent and energy-requiring; necrosis is passive and inflammatory. Intrinsic pathway uses cytochrome c release and apoptosome; extrinsic uses death receptors (Fas/FasL).

Osmosis: water moves from low to high solute concentration; tonicity terms (hypertonic, hypotonic, isotonic) describe the external solution relative to the cell.

Cytoskeleton: microtubules (tubulin, 25 nm, spindle and transport), microfilaments (actin, 7 nm, motility and cytokinesis), intermediate filaments (keratin, 10 nm, mechanical strength).

Enzyme kinetics: Michaelis-Menten v = Vmax[S]/(Km+[S]); Km equals substrate concentration at half Vmax; Lineweaver-Burk plot is 1/v vs 1/[S] with y-intercept 1/Vmax.

Mendelian ratios: monohybrid F2 phenotype 3:1, genotype 1:2:1; dihybrid F2 phenotype 9:3:3:1 with independent assortment.

Central dogma: DNA replication is semiconservative; transcription uses RNA polymerase; translation uses ribosomes, mRNA, tRNA, and aminoacyl-tRNA synthetases.

Hardy-Weinberg equilibrium: p + q = 1 and p^2 + 2pq + q^2 = 1; violations indicate selection, drift, mutation, migration, or nonrandom mating.

Lac operon: glucose absence and lactose presence induce expression; CAP-cAMP is positive regulator, lac repressor is negative regulator.

DNA mutation types: silent, missense, nonsense, frameshift (insertion/deletion not multiple of three); transition vs transversion; UV causes thymine dimers.

PCR cycle: denaturation (~95 C), annealing (~50-65 C), extension (~72 C); Taq polymerase is thermostable; exponential amplification 2^n.

Restriction enzymes cut palindromic sequences; sticky ends allow ligation; gel electrophoresis separates DNA by size with smaller fragments moving faster.

Porifera: cellular level of organization, choanocytes drive water flow, spicules of calcium carbonate or silica; no true tissues.

Cnidaria: diploblastic with ectoderm and endoderm separated by mesoglea; nematocysts; polyp and medusa forms; radial symmetry.

Platyhelminthes: acoelomate, triploblastic, dorsoventrally flattened; flame cells for osmoregulation; many are parasitic (Trematoda, Cestoda).

Annelida: true coelom, metameric segmentation, closed circulatory system; earthworms have setae and clitellum; Hirudinea lack setae.

Arthropoda: chitinous exoskeleton, jointed appendages, open circulatory system with hemocoel; largest phylum; insects have Malpighian tubules.

Echinodermata: pentaradial symmetry in adults, bilateral larvae, water vascular system with tube feet; exclusively marine; ossicles of calcite.

Chordate hallmarks: notochord, dorsal hollow nerve cord, pharyngeal slits, post-anal tail, thyroid gland; Vertebrata replace notochord with vertebral column.

Binomial nomenclature (Linnaeus): genus capitalized, species lowercase, italicized or underlined; ICZN governs animals, ICBN plants.

Taxonomic hierarchy: Domain, Kingdom, Phylum, Class, Order, Family, Genus, Species; species is the basic unit.

Biological species concept: groups of interbreeding natural populations reproductively isolated from others; fails for asexuals and fossils.

Monophyletic group includes ancestor and all descendants; paraphyletic excludes some descendants; polyphyletic excludes the common ancestor.

Cladistics uses shared derived characters (synapomorphies) to build cladograms; parsimony minimizes evolutionary changes.

Homology indicates common ancestry; analogy (convergent evolution) does not; homoplasy confounds phylogenetic reconstruction.

Type specimens: holotype is the single reference specimen; paratype, syntype, and neotype serve different nomenclatural roles.

Resting membrane potential is about -70 mV in neurons; depolarization opens voltage-gated Na+ channels; repolarization follows K+ efflux; refractory periods prevent backward conduction.

Nephron: filtration at glomerulus, reabsorption in proximal tubule (glucose, amino acids), countercurrent multiplication in loop of Henle; ADH increases collecting duct water permeability.

Respiratory gas transport: hemoglobin carries O2; Bohr effect shifts curve right with low pH, high CO2, high temperature; CO2 mostly transported as bicarbonate via carbonic anhydrase.

Cardiac cycle: SA node is pacemaker; P wave atrial depolarization, QRS ventricular depolarization, T wave ventricular repolarization; cardiac output = heart rate x stroke volume.

Hormone signaling: peptide hormones act via surface receptors and second messengers (cAMP); steroid and thyroid hormones enter cells and act on nuclear receptors.

Hypothalamic-pituitary axis: releasing hormones (GnRH, TRH, CRH) stimulate anterior pituitary; negative feedback from target gland hormones.

Insulin lowers blood glucose by promoting uptake and glycogen synthesis; glucagon and cortisol raise it; thyroid hormones regulate basal metabolic rate.

Fertilization: acrosomal reaction, cortical reaction (block to polyspermy), and completion of meiosis II in the oocyte; zygote is diploid.

Cleavage patterns: holoblastic in microlecithal eggs (frogs, mammals); meroblastic in telolecithal eggs (birds, reptiles) and centrolecithal eggs (insects).

Gastrulation forms ectoderm, mesoderm, endoderm; the blastopore lip (Spemann organizer) induces dorsal axis in amphibians.

Neurulation: notochord induces overlying ectoderm to form neural plate, neural folds, and neural tube; failure causes spina bifida or anencephaly.

Germ layers give rise: ectoderm to epidermis and nervous system; mesoderm to muscle, bone, blood, and kidneys; endoderm to gut and respiratory lining.

Embryonic induction and competence: organizer secretes signals (e.g., BMP antagonists) that direct neighboring tissue fate.

Extraembryonic membranes in amniotes: amnion (fluid), chorion (gas exchange), allantois (waste and vessels), yolk sac (nutrient).

Population growth: exponential dN/dt = rN; logistic dN/dt = rN(K-N)/K, where K is carrying capacity; maximum growth at K/2.

Species interactions: mutualism (+,+), commensalism (+,0), parasitism (+,−), predation (+,−), competition (−,−); competitive exclusion principle.

Energy flow: 10% rule between trophic levels; pyramids of numbers, biomass, and energy; decomposers recycle nutrients.

Biogeochemical cycles: carbon (photosynthesis, respiration, combustion), nitrogen (fixation, nitrification, denitrification), phosphorus (no gaseous phase).

Ecological succession: primary begins on bare substrate with pioneer species; secondary follows disturbance with soil intact; climax community is stable end stage.

Limiting factors: Liebig's law of the minimum; Shelford's law of tolerance; density-dependent vs density-independent regulation.

Biomes: tropical rainforest, savanna, desert, temperate forest, grassland, taiga, tundra; determined by temperature and precipitation.

Biodiversity levels: genetic, species, and ecosystem diversity; hotspots combine high endemism with high habitat loss.

IUCN Red List categories: Extinct, Extinct in the Wild, Critically Endangered, Endangered, Vulnerable, Near Threatened, Least Concern, Data Deficient.

In-situ conservation (national parks, biosphere reserves, sanctuaries) maintains species in habitat; ex-situ uses zoos, seed banks, and cryopreservation.

Threats: habitat fragmentation, invasive species, overexploitation, pollution, climate change; HIPPO acronym summarizes them.

Minimum viable population and effective population size (Ne) determine genetic drift and inbreeding risk; small populations lose heterozygosity.

Keystone species exert disproportionate influence; flagship species attract conservation funding; indicator species signal ecosystem health.

Protected area categories follow IUCN I-VI; corridors reduce isolation and maintain gene flow between fragments.

Darwin-Wallace theory: descent with modification and natural selection acting on heritable variation; evidence from fossils, biogeography, and comparative anatomy.

Modern synthesis combines Mendelian genetics with Darwinian selection; mutation, recombination, and gene flow generate variation.

Hardy-Weinberg assumptions: large population, random mating, no mutation, no migration, no selection; deviations indicate evolutionary forces.

Selection types: directional shifts mean; stabilizing favors intermediate; disruptive favors extremes; sexual selection acts on mating success.

Genetic drift reduces variation randomly; founder effect and bottleneck are drift phenomena; effective population size is smaller than census size.

Speciation: allopatric (geographic isolation), sympatric (polyploidy, host shifts); prezygotic and postzygotic isolating mechanisms.

Molecular evolution: neutral theory (Kimura) and molecular clock; synonymous substitutions accumulate largely neutrally.

Maximum sustainable yield (MSY) occurs near half carrying capacity; overfishing reduces stock below MSY and can cause collapse.

Fish stock assessment uses catch per unit effort (CPUE), age structure, and recruitment data; gear selectivity affects estimates.

Aquaculture systems: extensive (ponds), semi-intensive, intensive (raceways, cages); water quality parameters include dissolved oxygen, ammonia, pH, temperature.

Induced breeding in carps uses pituitary extract or synthetic hormones (HCG, GnRH analogs); hypophysation is standard practice.

Fish culture practices: polyculture, integrated fish farming, monosex culture, and biofloc; tilapia and carp dominate freshwater aquaculture.

Wildlife management tools: carrying capacity, habitat improvement, hunting quotas, translocation, and population census (mark-recapture).

Mark-recapture estimate: N = (M x C)/R, where M is marked, C is total second sample, R is recaptured marked individuals.

Plasmodium life cycle: sporozoites from Anopheles enter liver, become merozoites, infect RBCs, cause cyclical fever; gametocytes taken up by mosquito.

Entamoeba histolytica causes amoebic dysentery via cysts in contaminated water; trophozoite is invasive form.

Ascaris lumbricoides: fecal-oral transmission, larvae migrate through lungs, adults in small intestine; eggs in stool diagnosis.

Immunity types: innate (barriers, phagocytes, complement) and adaptive (B cells humoral, T cells cell-mediated); primary vs secondary response.

Antibody structure: Y-shaped immunoglobulin with two heavy and two light chains, variable regions for antigen binding; IgG, IgM, IgA, IgE, IgD classes.

Vaccines: live attenuated, inactivated, toxoid, subunit, and mRNA; herd immunity requires adequate coverage threshold.

Epidemiology measures: incidence (new cases), prevalence (all cases), case fatality rate; vector control and sanitation reduce transmission.

Sericulture: Bombyx mori lifecycle (egg, larva, pupa, adult); mulberry feeding; silk from salivary glands of larvae.

Apiculture: Apis mellifera and A. cerana colonies; queen, drones, workers; honey and beeswax production; pollination services.

Recombinant DNA: restriction digestion, ligation into vector, transformation, selection, and expression; insulin and vaccines produced this way.

Biotechnology tools: PCR, gel electrophoresis, Southern/Northern/Western blotting, ELISA, DNA sequencing, and CRISPR-Cas9 gene editing.

Experimental design: control group, randomization, replication, blinding; null hypothesis and p-value threshold (often 0.05).

Statistical tests: t-test compares two means; ANOVA compares three or more; chi-square tests goodness of fit or association.

Scientific reporting: IMRaD structure (Introduction, Methods, Results, Discussion); cite sources; ethical approval for animal research.