Evolution and Population Genetics
Core concepts
Understand the mechanisms of evolution: mutation, migration (gene flow), genetic drift, and natural selection. Know Hardy-Weinberg equilibrium (p² + 2pq + q² = 1) and its five assumptions: no mutation, no migration, no selection, infinite population size, and random mating. Be fluent with selection types (directional, stabilizing, disruptive), sexual selection, kin selection, and the levels of selection. Understand speciation (allopatric, sympatric, parapatric), reproductive isolating mechanisms (prezygotic and postzygotic), adaptive radiation, convergent and divergent evolution, and molecular evolution (neutral theory, molecular clock). Know evidence for evolution: fossil record, homology, biogeography, and molecular data.
Common traps
Hardy-Weinberg describes a non-evolving population; deviations indicate evolution. Genetic drift is strongest in small populations. Do not confuse allele frequency with genotype frequency. Speciation requires reproductive isolation, not merely geographic separation. Natural selection acts on phenotypes, not directly on genotypes.
Worked example
Rule of thumb: if q² (homozygous recessive frequency) is given, take the square root to get q, then p = 1 − q and 2pq gives the heterozygote frequency. For example, if 16% of a population is affected, q² = 0.16, q = 0.4, p = 0.6, and carriers (2pq) are 48%.
Fisheries, Aquaculture and Wildlife Management
Core concepts
In fisheries, understand stock assessment, maximum sustainable yield (MSY), recruitment, growth overfishing, and the logistic yield curve. Know gear types (gillnet, trawl, longline), bycatch issues, and management tools (quotas, closed seasons, marine protected areas). In aquaculture, know culture systems (pond, cage, raceway, recirculating), species selection, feed conversion ratio, breeding, and disease management. Understand induced breeding, hatchery operations, and water quality parameters (dissolved oxygen, pH, ammonia, temperature). In wildlife management, know carrying capacity, habitat management, census methods, and human-wildlife conflict mitigation. Understand the difference between extensive and intensive systems.
Common traps
MSY occurs at roughly half the carrying capacity but ignores ecological and economic realities. Overfishing can be growth overfishing or recruitment overfishing - distinguish them. Do not confuse feed conversion ratio (lower is better) with growth rate. In aquaculture, high stocking density raises ammonia and lowers dissolved oxygen. Wildlife census methods (direct counts, dung counts, camera traps) suit different species.
Worked example
Rule of thumb: FCR = feed offered ÷ live weight gain. If 200 kg of feed produces 100 kg of fish, FCR = 2.0. Lower FCR means more efficient feed use. For MSY under a logistic model, the maximum sustainable yield equals rK/4, achieved at N = K/2.
Parasitology, Immunology and Public Health
Core concepts
Know the major parasite groups (protozoa, helminths - trematodes, cestodes, nematodes - and arthropod vectors) and their life cycles, hosts (definitive, intermediate, reservoir), and transmission routes. Study malaria (Plasmodium, Anopheles vector), leishmaniasis (sandfly), trypanosomiasis (tsetse), schistosomiasis (snail intermediate host), and intestinal helminths. In immunology, understand innate versus adaptive immunity, antibody classes (IgG, IgM, IgA, IgE, IgD), T-cell subsets, antigen presentation, complement, and hypersensitivity types I–IV. Know vaccine types and herd immunity. In public health, know epidemiological measures (incidence, prevalence), disease surveillance, vector control, and sanitation.
Common traps
Incidence counts new cases; prevalence counts all existing cases. IgM is the first antibody produced; IgG dominates the secondary response. Hypersensitivity type I is IgE-mediated (anaphylaxis), type IV is delayed and T-cell mediated (tuberculin reaction). The snail in schistosomiasis is an intermediate host, not a vector. Do not confuse a reservoir host with a vector.
Worked example
Rule of thumb: classify a parasite by its definitive host - the host where the adult or sexual stage occurs. In malaria, the definitive host is the mosquito (sexual reproduction), while humans are intermediate. This often surprises candidates, so always ask where sexual reproduction happens.
Applied Zoology
Core concepts
Apply zoological knowledge to economic and practical settings: sericulture (Bombyx mori, mulberry, rearing stages), apiculture (Apis species, hive products, pollination), lac culture (Kerria lacca), poultry and livestock production, and pest management (biological control, integrated pest management, economic thresholds). Understand insect pests of crops and stored products, and vectors of disease. Know beneficial insects (predators, parasitoids, pollinators) and the principles of IPM: monitoring, thresholds, cultural, biological, and chemical controls in that order of preference. Be familiar with animal breeding for productivity, and with the role of animals in soil fertility and waste recycling (vermicomposting).
Common traps
IPM does not mean zero pesticides; it means judicious use after other methods. Biological control uses natural enemies, not broad-spectrum chemicals. Do not confuse the lac insect with the silkworm. Economic threshold differs from economic injury level. Pollination services are an economic product of apiculture, not a by-product to ignore.
Worked example
Rule of thumb: when a pest population is below the economic threshold, no chemical action is warranted. If a question describes a pest at low density with abundant natural enemies, the correct intervention is monitoring and conservation of predators, not spraying.
Biotechnology and Research Methods
Core concepts
Know core molecular techniques: DNA extraction, PCR (denaturation, annealing, extension; primers, Taq polymerase, thermal cycling), gel electrophoresis, restriction enzymes, ligation, cloning vectors, transformation, and selection markers. Understand sequencing (Sanger and next-generation), Southern, Northern, and Western blotting (DNA, RNA, protein respectively), ELISA, and chromatography. In reproductive biotechnology, know artificial insemination, embryo transfer, cryopreservation, and cloning. Understand transgenic animals and their applications. For research methods, know hypothesis formulation, controls (positive, negative), replication, randomization, blinding, sampling, and basic statistics (mean, standard deviation, t-test, chi-square, ANOVA). Understand ethical and biosafety considerations.
Common traps
Do not mix up blotting types: Southern is DNA, Northern is RNA, Western is protein. PCR needs a thermostable polymerase and primers flanking the target. A high annealing temperature increases specificity but may reduce yield. Correlation is not causation. A significant result does not imply a large effect - report effect size. Controls must differ from the treatment in only the variable tested.
Worked example
Rule of thumb: for a chi-square goodness-of-fit test, compare observed to expected counts, compute Σ(O − E)²/E, and compare with the critical value at the appropriate degrees of freedom (categories minus one). If the calculated value exceeds the critical value, reject the null hypothesis at that significance level.