BCS Written Botany cheat sheet

Three basic tissue systems (epidermal, ground, vascular) derive from protoderm, ground meristem, and procambium respectively.

Xylem tracheary elements: tracheids are imperforate and tapered; vessel elements have perforation plates and are wider and shorter.

Monocot stem: scattered vascular bundles, no secondary growth from a vascular cambium; dicot stem: bundles in a ring with interfascicular cambium.

Root anatomy: Casparian strip of suberin in endodermal anticlinal walls forces apoplastic flow into the symplast.

Stomatal guard cells: kidney-shaped in dicots, dumbbell-shaped in grasses; subsidiary cells define stomatal complex types.

Phyllotaxy is set by the golden angle (~137.5 degrees); alternate, opposite, and whorled arrangements are diagnostic.

Placentation types: marginal, parietal, axile, free-central, basal, and superficial - a key family-level character.

Inflorescence types: racemose (indefinite, acropetal) versus cymose (definite, basipetal); umbel, capitulum, catkin are special forms.

Aestivation (valvate, imbricate, twisted, vexillary) and placentation are commonly tested floral formula characters.

ICN rules: valid publication requires effective publication, a Latin diagnosis or description (since 2012 an English one also allowed), and designation of a type.

Priority starts at Linnaeus, Species Plantarum 1753; later homonyms are illegitimate; superfluous names are illegitimate.

Type categories: holotype, isotype, paratype, syntype, lectotype, neotype, epitype - lectotypification is needed when no holotype exists.

Bentham & Hooker used a natural system; Cronquist, Takhtajan, and Thorne are classical; APG IV (2016) is the current angiosperm classification.

APG IV recognises 64 orders and about 416 families; monocots and eudicots are the major clades; magnoliids are basal.

Species concepts: biological (reproductive isolation), morphological, phylogenetic, and evolutionary; cryptic species complicate delimitation.

Cladistics uses synapomorphies to define monophyletic groups; paraphyly and polyphyly are rejected as taxonomic groupings.

Molecular markers used in systematics: ITS and matK/rbcL for barcoding; trnL-F and ndhF for phylogeny.

Herbarium specimens and the type method anchor nomenclature; the ICN recognises ranks from kingdom to forma.

Photosynthesis: light reactions in thylakoids (PSII, cytochrome b6f, PSI), Calvin cycle in stroma; net equation 6CO2 + 12H2O -> C6H12O6 + 6O2 + 6H2O.

C3, C4, and CAM differ in initial CO2 fixation: RuBisCO (C3), PEP carboxylase (C4, CAM); C4 uses Kranz anatomy and has low photorespiration.

Water potential psi = psi_s + psi_p + psi_g; water moves from higher to lower psi; transpiration pull drives xylem flow.

Stomatal opening: blue light activates H+-ATPase, K+ influx, malate synthesis, and guard-cell turgor rise.

Mineral nutrition: macroelements N, P, K, Ca, Mg, S; microelements Fe, Mn, Zn, Cu, B, Mo, Cl, Ni; deficiency symptoms are diagnostic.

Phytohormones: auxin (apical dominance, rooting), gibberellin (stem elongation, seed germination), cytokinin (cell division), ABA (stress, stomatal closure), ethylene (ripening, abscission).

Photoperiodism: short-day plants flower when night exceeds critical length; phytochrome Pr/Pfr ratio measures dark period.

Respiration: glycolysis, TCA cycle, and oxidative phosphorylation; alternative oxidase and cyanide-resistant respiration occur in plants.

Seed dormancy and germination involve stratification, scarification, and gibberellin-ABA balance.

Plant cell-specific structures: cell wall (cellulose, hemicellulose, pectin, lignin), chloroplast, vacuole, plasmodesmata, and middle lamella.

Cell cycle: G1, S, G2, M; plant cytokinesis uses a phragmoplast and cell plate, not a cleavage furrow.

Mitosis stages: prophase, metaphase, anaphase, telophase; meiosis I (reductional) and II (equational); crossing-over in pachytene.

Mendelian ratios: 3:1 monohybrid F2, 9:3:3:1 dihybrid; testcross reveals genotype; independent assortment requires unlinked loci.

Gene interactions: complementary (9:7), epistasis (12:3:1 or 9:3:4), duplicate genes (15:1), and inhibitory (13:3) ratios.

Linkage and mapping: recombination frequency in cM; three-point testcross determines gene order and interference.

Ploidy: autopolyploidy (same genome) vs allopolyploidy (combined genomes); triploids are sterile due to pairing failure.

Cytoplasmic inheritance (chloroplast, mitochondrion) is maternal; cytoplasmic male sterility is used in hybrid seed production.

Chromosomal aberrations: deletion, duplication, inversion, translocation; aneuploidy (trisomy, monosomy) vs euploidy.

Central dogma: DNA replication (semiconservative), transcription (RNA polymerase I, II, III), translation on 80S ribosomes in plants.

DNA structure: antiparallel double helix, A-T and G-C base pairing, 10 bp per turn; Chargaff's rules apply.

Photosynthetic pigments: chlorophyll a (P680, P700), chlorophyll b, carotenoids as accessory pigments and photoprotectants.

Enzyme kinetics: Michaelis-Menten v = Vmax[S]/(Km+[S]); Km is substrate affinity; Lineweaver-Burk gives linear plot.

Secondary metabolites: alkaloids, terpenoids, phenolics (flavonoids, lignin), and cyanogenic glycosides; roles in defence.

Nitrogen assimilation: nitrate reductase converts NO3- to NO2-, nitrite reductase to NH4+, then GS-GOGAT pathway.

PCR steps: denaturation (~94 C), annealing (~50-60 C), extension (~72 C); Taq polymerase; primers define specificity.

Recombinant DNA: restriction enzymes (EcoRI, HindIII), ligase, vectors (pBR322, Ti plasmid), selectable markers.

CRISPR-Cas9 uses guide RNA and Cas9 nuclease to create double-strand breaks for targeted editing in plants.

Bacterial cell: peptidoglycan wall (Gram-positive thick, Gram-negative thin plus outer membrane), 70S ribosomes, no nucleus.

Bacterial growth curve: lag, log (exponential), stationary, and death phases; generation time varies with species and conditions.

Nitrogen fixation: Rhizobium in root nodules, Frankia in actinorhizal plants, Azotobacter free-living, cyanobacteria (Anabaena, Nostoc).

Nitrogenase is oxygen-sensitive; leghemoglobin protects the nodule bacteroids; nod and nif genes control symbiosis.

Soil bacteria: Bacillus, Pseudomonas, Agrobacterium (crown gall via Ti plasmid), Streptomyces (antibiotics).

Viruses: TMV is a classic plant virus; composed of nucleic acid (RNA or DNA) plus protein coat; obligate intracellular parasites.

Bacteriophage lytic vs lysogenic cycles; phage lambda is a classic temperate phage.

Microbial control: pasteurisation, autoclaving (121 C, 15 psi, 15 min), UV, and antibiotics; Koch's postulates establish causation.

Biofertilisers: Rhizobium, Azospirillum, Azolla-Anabaena, mycorrhizal fungi, and phosphate-solubilising bacteria.

Fungal cell wall contains chitin; fungal nutrition is absorptive heterotrophy; mycelium may be septate or coenocytic.

Fungal classes: Oomycetes (cellulose walls, no chitin), Zygomycetes, Ascomycetes (ascospores in asci), Basidiomycetes (basidiospores on basidia).

Lichens are symbiotic associations of fungus (mycobiont) and alga or cyanobacterium (photobiont); sensitive bioindicators.

Disease triangle: susceptible host, virulent pathogen, and favourable environment; disease develops only when all three coincide.

Koch's postulates: isolate pathogen from diseased host, culture, inoculate healthy host, re-isolate same pathogen.

Major diseases: late blight of potato (Phytophthora infestans), rusts (Puccinia), smuts (Ustilago), powdery mildew (Erysiphe), bacterial blight of rice (Xanthomonas oryzae).

Host defence: preformed barriers, hypersensitive response, systemic acquired resistance, and R-gene/avr-gene recognition.

Control methods: cultural, biological (Trichoderma, Bacillus subtilis), chemical fungicides, and resistant varieties.

Mycorrhizae: ectomycorrhiza (Basidiomycetes, sheath) vs endomycorrhiza/AM (Glomeromycota, arbuscules).

Algal pigments define groups: Chlorophyceae (chlorophyll a, b), Phaeophyceae (fucoxanthin), Rhodophyceae (phycoerythrin, phycocyanin).

Algal reproduction: vegetative, asexual (zoospores, aplanospores), and sexual (isogamy, anisogamy, oogamy); alternation of generations varies.

Bryophytes: gametophyte dominant, sporophyte dependent; water required for sperm; liverworts, hornworts, mosses.

Pteridophytes: sporophyte dominant, independent gametophyte (prothallus); homosporous vs heterosporous; sori and sporangia.

Gymnosperms: naked seeds, no ovary; Cycas, Pinus, Ginkgo, Ephedra, Gnetum; archegonia present; wind pollination.

Pinus life cycle: monoecious; male and female cones; pollen tube delivers non-motile sperm; seeds in cones.

Heterospory and seed habit are key evolutionary advances; Selaginella and Isoetes are heterosporous pteridophytes.

Cyanobacteria (blue-green algae) fix nitrogen in heterocysts; Anabaena-Azolla symbiosis is used in rice fields.

Fossil links: Rhynia and Cooksonia are early vascular plants; Psilophyton is an early pteridophyte-like form.

Ecosystem components: producers, consumers, decomposers; energy flow is unidirectional; 10% law of trophic transfer.

Ecological pyramids: numbers, biomass, energy; inverted pyramids occur in some aquatic and parasitic systems.

Biogeochemical cycles: carbon, nitrogen, phosphorus (sedimentary, no atmospheric phase), and water cycles.

Population growth: exponential dN/dt = rN; logistic dN/dt = rN(K-N)/K; carrying capacity K.

Species interactions: competition, predation, parasitism, mutualism, commensalism, amensalism.

Ecological succession: primary vs secondary; hydrarch and xerarch; climax community concept.

Biodiversity hotspots in South Asia include the Western Ghats and the Eastern Himalayas; IUCN Red List categories range from Least Concern to Extinct.

In-situ conservation: national parks, sanctuaries, biosphere reserves; ex-situ: seed banks, botanical gardens, cryopreservation.

Pollution indicators: lichens for SO2, diatoms for water quality; BOD and COD measure organic load.

Cereals: rice (Oryza sativa), wheat (Triticum aestivum), maize (Zea mays); pulses: chickpea, pigeon pea, lentil, mung.

Fibre crops: cotton (Gossypium), jute (Corchorus), sunn hemp (Crotalaria); oilseeds: mustard, groundnut, soybean, coconut.

Beverages: tea (Camellia sinensis), coffee (Coffea arabica), cocoa (Theobroma cacao).

Medicinal plants: Rauwolfia serpentina (reserpine), Cinchona (quinine), Papaver somniferum (morphine), Digitalis (digoxin).

Tissue culture: callus induction, somatic embryogenesis, micropropagation, meristem culture for virus-free plants, anther culture for haploids.

Protoplast fusion and somatic hybridisation (e.g., pomato) overcome sexual incompatibility.

Transgenic crops: Bt cotton (cry1Ac), Golden Rice (beta-carotene), herbicide-resistant soybean; biosafety and biosafety regulations apply.

Biofuels: Jatropha curcas, sugarcane ethanol, algal biodiesel; bioplastics from starch and PHA.

Plant secondary products in industry: rubber (Hevea brasiliensis), tannins, gums, resins, dyes, and essential oils.

Experimental design: randomisation, replication, and local control reduce bias; completely randomised, randomised block, and split-plot designs.

Analysis of variance (ANOVA) partitions variance; F-test compares treatment means; post-hoc tests (LSD, Tukey) separate means.

Chi-square goodness-of-fit tests observed vs expected ratios (e.g., 3:1, 9:3:3:1); degrees of freedom = categories - 1.

Correlation coefficient r ranges from -1 to +1; regression fits y = a + bx and predicts values.

Sampling methods: random, stratified, systematic, and quadrat methods for vegetation; minimum quadrat size by species-area curve.

Herbarium and field techniques: collection, pressing, labelling, and deposition; voucher specimens support identification.

Microscopy: bright-field, phase-contrast, fluorescence, and electron microscopy (TEM, SEM); resolution limits differ.

Chromatography (paper, TLC, HPLC) and electrophoresis separate biomolecules; spectrophotometry quantifies absorbance.

Scientific writing: IMRaD structure, citation ethics, plagiarism avoidance, and peer review.

Experimental design: randomisation, replication, and local control reduce bias; completely randomised, randomised block, and split-plot designs.

ANOVA partitions variance; F-test compares treatment means; post-hoc tests (LSD, Tukey) separate means.

Chi-square goodness-of-fit tests observed vs expected ratios (e.g., 3:1, 9:3:3:1); degrees of freedom = categories - 1.

Correlation coefficient r ranges from -1 to +1; regression fits y = a + bx and predicts values.

Sampling methods: random, stratified, systematic, and quadrat methods for vegetation; minimum quadrat size by species-area curve.

Herbarium and field techniques: collection, pressing, labelling, and deposition; voucher specimens support identification.

Microscopy: bright-field, phase-contrast, fluorescence, and electron microscopy (TEM, SEM); resolution limits differ.

Chromatography (paper, TLC, HPLC) and electrophoresis separate biomolecules; spectrophotometry quantifies absorbance.

Scientific writing: IMRaD structure, citation ethics, plagiarism avoidance, and peer review.