AP Intermediate Botany (BIEAP) flashcards

32 cards. Read the term and the definition here. The deck at the top of this page is optional.

Binomial nomenclature

System of naming species with two Latinized words: capitalized genus and lowercase species, both italicized, followed by author abbreviation. Devised by Linnaeus.

Heterospory

Production of two kinds of spores, microspores and megaspores, by the same plant. Occurs in Selaginella and Salvinia, a precursor to seed habit.

Double fertilization

Fusion of one male gamete with the egg to form a zygote, and a second with two polar nuclei to form triploid endosperm. Unique to angiosperms.

Lichen symbiosis

Mutualistic association between a fungus (mycobiont) providing shelter and minerals, and an alga or cyanobacterium (phycobiont) providing food by photosynthesis.

Placentation

Arrangement of ovules on the placenta within the ovary: marginal, axile, parietal, free-central, or basal. A key taxonomic character in flowering plants.

Pneumatophores

Negatively geotropic, spongy aerial roots of mangrove plants such as Rhizophora. They bear lenticels and help in gaseous exchange in waterlogged soil.

Vascular bundle

Strand of xylem and phloem with or without cambium. Conjoint bundles occur in dicots; radial bundles occur in roots.

Stomatal apparatus

Pore bounded by two guard cells, often with subsidiary cells. Guard cell turgor changes regulate gas exchange and transpiration.

Fluid mosaic model

Description of the plasma membrane as a phospholipid bilayer with embedded proteins moving laterally. Proposed by Singer and Nicolson in 1972.

Endosymbiotic theory

Mitochondria and chloroplasts arose from engulfed prokaryotes, evidenced by their own circular DNA, 70S ribosomes, and double membranes.

Enzyme inhibition

Competitive inhibitors bind the active site and are overcome by more substrate; non-competitive inhibitors bind elsewhere and reduce activity regardless of substrate.

Meiosis crossing over

Exchange of segments between non-sister chromatids of homologous chromosomes during pachytene of prophase I, producing genetic recombination.

Water potential

Sum of solute potential and pressure potential, measured in megapascals. Pure water at atmospheric pressure has a water potential of zero.

Cohesion-tension theory

Explains ascent of sap: transpiration creates tension in xylem, and cohesion between water molecules maintains a continuous column from roots to leaves.

Calvin cycle

Light-independent fixation of CO2 by RuBisCO into 3-phosphoglycerate, then reduction to triose phosphate and regeneration of ribulose bisphosphate. Occurs in stroma.

Photorespiration

RuBisCO binds oxygen instead of CO2, wasting carbon and energy. Suppressed in C4 plants by spatial separation and in CAM plants by temporal separation.

Oxidative phosphorylation

ATP synthesis driven by a proton gradient across the inner mitochondrial membrane, generated by electron transport and coupled through ATP synthase.

Embryo sac

Female gametophyte of angiosperms, typically eight-nucleate and seven-celled: egg, two synergids, three antipodals, and a central cell with two polar nuclei.

Apomixis

Production of viable seeds without fertilization or meiosis, giving offspring genetically identical to the parent. Found in some grasses and Citrus.

Parthenocarpy

Development of fruit without fertilization, yielding seedless fruits. Can be induced by applying auxin or gibberellin to flowers.

Apical dominance

Inhibition of lateral bud growth by auxin produced in the shoot apex. Removing the apex releases buds and promotes branching.

Test cross

Cross of an individual of unknown genotype with a homozygous recessive parent. The offspring ratio reveals whether the unknown was homozygous or heterozygous.

Incomplete dominance

Heterozygote shows an intermediate phenotype, so the F2 ratio is 1:2:1 instead of 3:1. Seen in Snapdragon flower color.

Linkage

Tendency of genes located close together on the same chromosome to be inherited together, reducing the frequency of recombinant offspring.

Non-disjunction

Failure of homologous chromosomes or sister chromatids to separate during meiosis, producing gametes with extra or missing chromosomes, as in Down syndrome.

Semi-conservative replication

Each daughter DNA molecule retains one parental strand and one newly synthesized strand. Demonstrated by Meselson and Stahl using nitrogen isotopes.

Lac operon

Inducible operon of E. coli with regulator, promoter, operator, and structural genes z, y, a. Lactose inactivates the repressor, allowing transcription.

Restriction endonuclease

Enzyme that cleaves DNA at specific palindromic recognition sequences, producing sticky or blunt ends. Used to create recombinant DNA.

Polymerase chain reaction

In vitro amplification of DNA through repeated cycles of denaturation, primer annealing, and extension by Taq polymerase, doubling DNA each cycle.

Logistic growth

Population growth that slows as density approaches carrying capacity K, producing a sigmoid curve. Described by dN/dt = rN(K−N)/K.

Ecological succession

Predictable sequence of community replacement over time, from pioneer species to climax community. Primary starts on bare substrate; secondary follows disturbance.

Micropropagation

In vitro clonal propagation of plants from small explants through tissue culture. The auxin-to-cytokinin ratio determines root or shoot formation.