BCS Written Botany flashcards
BCS Written Botany · Build recall with a focused review session.
32 cards. Read the term and the definition here. The deck at the top of this page is optional.
- Casparian strip
- A band of suberin and lignin in the anticlinal walls of root endodermal cells that blocks apoplastic water movement and forces solutes through the selectively permeable symplast.
- Kranz anatomy
- A leaf arrangement in C4 plants with bundle-sheath cells surrounded by mesophyll cells, enabling spatial separation of initial CO2 fixation and Calvin cycle reactions.
- Holotype
- The single specimen designated by the author as the name-bearing type of a new species; it anchors the application of the scientific name permanently.
- APG IV
- The 2016 Angiosperm Phylogeny Group classification based largely on molecular data, recognising about 64 orders and 416 families within major clades.
- Phragmoplast
- A plant-specific microtubule array that forms between daughter nuclei during telophase and guides vesicles to build the cell plate.
- Epistasis
- Interaction where one gene masks or modifies the phenotypic expression of another locus, producing modified ratios such as 12:3:1 or 9:3:4.
- Km
- The Michaelis constant, the substrate concentration at which an enzyme reaches half its maximum velocity; a low Km indicates high substrate affinity.
- Ti plasmid
- A tumour-inducing plasmid of Agrobacterium tumefaciens used as a natural vector for transferring foreign genes into plant cells.
- Leghemoglobin
- An oxygen-binding protein in legume root nodules that buffers oxygen to protect the oxygen-sensitive nitrogenase enzyme while still supplying respiration needs.
- Disease triangle
- A model stating that disease requires a susceptible host, a virulent pathogen, and a favourable environment to interact simultaneously.
- Koch's postulates
- Criteria for proving pathogenicity: isolate from diseased host, culture it, inoculate a healthy host to cause disease, then re-isolate the same organism.
- Mycorrhiza
- A mutualistic association between a fungus and plant roots; ectomycorrhiza forms a sheath, while arbuscular mycorrhiza penetrates root cells with arbuscules.
- Prothallus
- The small, free-living, independent gametophyte of most pteridophytes, bearing antheridia and archegonia on its underside.
- Heterospory
- Production of two kinds of spores, microspores and megaspores, by the same sporophyte; a key step in the evolution of the seed habit.
- 10 percent law
- Lindeman's rule that only about ten percent of energy at one trophic level is transferred to the next, the rest being lost as heat.
- Carrying capacity
- The maximum population size that an environment can sustain indefinitely, symbolised K in the logistic growth equation.
- Bt cotton
- A transgenic crop carrying a cry gene from Bacillus thuringiensis that produces a protein toxic to specific insect larvae.
- Somatic embryogenesis
- The development of embryos from somatic cells in tissue culture, without fertilisation, producing plants identical to the parent.
- Randomised block design
- An experimental layout in which treatments are randomly assigned within blocks that group similar units, reducing environmental variation among replicates.
- Chi-square test
- A goodness-of-fit statistic comparing observed and expected frequencies; degrees of freedom equal the number of categories minus one.
- Placentation
- The arrangement of ovules within the ovary, classified as marginal, parietal, axile, free-central, basal, or superficial.
- Aestivation
- The arrangement of sepals or petals in a floral bud, such as valvate, imbricate, twisted, or vexillary.
- Synapomorphy
- A shared derived character state that defines a monophyletic group in cladistic analysis.
- Photoperiodism
- The response of plants to the relative lengths of day and night, controlling flowering, tuberisation, and dormancy.
- Phytochrome
- A photoreversible pigment converting between Pr and Pfr forms, measuring the dark period and regulating flowering and germination.
- Autopolyploidy
- A condition in which an organism has more than two sets of chromosomes from the same species, often causing pairing problems and reduced fertility.
- Central dogma
- The flow of genetic information from DNA to RNA to protein, involving replication, transcription, and translation.
- Nitrate reductase
- The enzyme that catalyses the reduction of nitrate to nitrite, the first step in nitrogen assimilation in plants.
- Rhizobium
- A soil bacterium that forms root nodules on legumes, fixing atmospheric nitrogen into ammonia in a mutualistic symbiosis.
- Lichens
- Symbiotic associations of a fungus and an alga or cyanobacterium, sensitive to air pollution and used as bioindicators.
- Alternation of generations
- The life cycle in which a haploid gametophyte and a diploid sporophyte alternate, differing in dominance among plant groups.
- Biosphere reserve
- A protected area with core, buffer, and transition zones, conserving biodiversity while allowing sustainable use and research.