Plant Structure, Growth, Transport, and Development

Comprehensive vocabulary flashcards covering plant tissues, meristems, cell division, transport mechanisms, soil nutrition, angiosperm reproduction, and hormone regulation.

Dermal Tissue

The outer protective covering of a plant (the epidermis) that features a waxy cuticle to prevent water loss.

Vascular Tissue

The tissue system that transports resources and fluid throughout the plant while providing mechanical support.

Ground Tissue

Plant tissue specialized for storage, photosynthesis, structural support, and short-distance transport.

Parenchyma Cells

The least specialized plant cells that carry out the majority of metabolic and photosynthetic functions.

Collenchyma Cells

Living plant cells that provide flexible mechanical support to growing parts of the shoot.

Sclerenchyma Cells

Rigid supporting cells with thick walls heavily reinforced with lignin that are dead at functional maturity.

Meristems

Perpetually embryonic tissues that generate new cells and allow for indeterminate growth in plants.

Apical Meristems

Meristems located at the tips of roots and shoots that drive primary growth to elongate the plant.

Lateral Meristems

Meristems extending along the length of stems and roots (vascular cambium and cork cambium) that drive secondary growth to increase thickness.

Morphogenesis

The developmental process by which a plant establishes its characteristic shape and structural organization, including roots, stems, leaves, and flowers.

Cell Differentiation

The developmental process by which cells become structurally and functionally specialized to perform specific tasks.

Polarity

The condition of possessing structural or biochemical differences at opposite ends of an organism, such as the root and shoot axes.

Asymmetrical Cell Division

A mitotic division in which one daughter cell receives more cytoplasm than the other, establishing cell polarity and directing cell differentiation.

ABC Hypothesis

A genetic model of floral development where three classes of organ identity genes direct the formation of sepals ($A$), petals ($A + B$), stamens ($B + C$), and carpels ($C$).

Phyllotaxy

The arrangement of leaves on a stem, which serves as a species-specific architectural adaptation for capturing light.

Apoplast

The non-living continuum in a plant consisting of everything external to the plasma membranes, including cell walls, intercellular spaces, and tracheids.

Symplast

The continuum of cytoplasm linking living plant cells via intercellular channels called plasmodesmata.

Transmembrane Route

A transport pathway where water and solutes repeatedly exit one cell through its membrane and wall to enter an adjacent cell.

Bulk Flow

The long-distance movement of liquid fluid driven by a gradient of pressure rather than solute concentration.

Water Potential ($\Psi$)

A physical measurement combining solute concentration ($\Psi_S$) and physical pressure ($\Psi_P$) that dictates the direction of spontaneous water movement.

Transpiration

The evaporative loss of water vapor from aerial plant organs, primarily exiting through microscopic leaf stomata.

Guard Cells

A pair of specialized, kidney-shaped epidermal cells flanking a stoma that regulate opening and closing by changing turgor pressure.

Loams

Topsoils containing roughly balanced proportions of sand, silt, and clay, providing the most fertile texture for plant cultivation.

Cation Exchange

The release of mineral cations bound to negatively charged soil particles displaced by protons ($H^+$) released by plant roots.

Humus

Decomposed organic matter within the topsoil that enhances soil structure, retains moisture, and supplies mineral nutrients.

Essential Element

A chemical element indispensable for a plant to grow, survive, and complete its normal life cycle from seed to seed.

Nitrogen Fixation

The biochemical conversion of atmospheric nitrogen ($N_2$) into ammonia ($NH_3$) performed by specialized prokaryotes.

Nitrifying Bacteria

Soil microorganisms that oxidize ammonia ($NH_3$) into nitrite ($NO_2^-$) and subsequently oxidize nitrite into nitrate ($NO_3^-$).

Denitrifying Bacteria

Soil bacteria that convert soil nitrates ($NO_3^-$) back into gaseous nitrogen ($N_2$), which is released back to the atmosphere.

Mycorrhizae

Mutualistic associations between fungal hyphae and plant root systems that significantly expand root surface area for water and mineral uptake.

Epiphyte

A non-parasitic plant that grows anchored upon another plant, gathering moisture and minerals from rainwater and airborne dust.

Carpel

The female floral reproductive unit composed of a sticky stigma, an elongated style, and a basal ovary containing ovules.

Alternation of Generations

A life cycle alternating between a multicellular diploid ($2n$) sporophyte generation and a multicellular haploid ($n$) gametophyte generation.

Double Fertilization

The characteristic angiosperm process in which one sperm fertilizes an egg cell forming a diploid zygote ($2n$), while the second fuses with polar nuclei to yield triploid endosperm ($3n$).

Endosperm

A nutrient-laden triploid ($3n$) nutritive tissue created during angiosperm fertilization that sustains the developing embryo.

Self-Incompatibility

A biochemical recognition mechanism preventing self-fertilization by enabling a flower to reject its own pollen or pollen from close relatives.

Auxin

A plant hormone synthesized primarily at shoot apices that induces cell elongation, governs shoot architecture, and promotes adventitious rooting.

Abscisic Acid (ABA)

A plant hormone critical for maintaining seed dormancy and mediating stomatal closure during drought conditions.

Ethylene

A volatile plant hormone regulating fruit ripening and provoking the triple response (stem thickening, horizontal bending, and slowed elongation).

Statoliths

Dense starch-filled organelles (amyloplasts) within root cap cells that sediment in response to gravity, enabling positive gravitropism.

Hypersensitive Response

A targeted plant immune response triggering localized cell death and antimicrobial barrier formation to isolate invading pathogens.