LSU BIO 1202 Exam 3 Review (Chapters 35-38)

Complete vocabulary review for Exam 3 covering Chapters 35-38, including plant anatomy, transport mechanics, soil science, and angiosperm reproduction.

Root system

Belowground organs for anchorage, absorption, transport, and storage.

Shoot system

Stems, leaves, buds, flowers, and fruits.

Node

Attachment point for leaves or branches.

Internode

Stem segment between nodes.

Apical bud

Terminal bud containing a shoot apical meristem.

Axillary bud

Embryonic shoot in the angle between leaf and stem.

Dermal tissue

Protective outer covering; includes epidermis and later periderm.

Ground tissue

Photosynthesis, storage, metabolism, support, short-distance transport.

Vascular tissue

Xylem and phloem long-distance transport system.

Parenchyma

Living thin-walled cells for metabolism, storage, and repair.

Collenchyma

Living cells with unevenly thickened primary walls; flexible support.

Sclerenchyma

Usually dead cells with lignified secondary walls; rigid support.

Tracheid

Tapered lignified xylem cell; water moves through pits.

Vessel element

Wide xylem cell joined end to end through perforation plates.

Sieve-tube element

Living phloem cell with reduced organelles and sieve plates.

Companion cell

Metabolically supports and loads/unloads a sieve-tube element.

Meristem

Region of undifferentiated, continually dividing plant cells.

Primary growth

Increase in length from apical meristems.

Secondary growth

Increase in girth from lateral meristems.

Vascular cambium

Lateral meristem producing secondary xylem inward and phloem outward.

Cork cambium

Lateral meristem producing protective periderm.

Sapwood

Younger conducting secondary xylem.

Heartwood

Older nonconducting secondary xylem.

Periderm

Secondary protective covering.

Bark

All tissues outside vascular cambium.

Morphogenesis

Development of body form and organization.

Differentiation

Specialization caused by different gene-expression patterns.

Determinate growth

Growth that stops after an organ reaches a characteristic form.

Indeterminate growth

Potential for continued growth throughout life.

Apoplast

Continuum of cell walls and extracellular spaces outside plasma membranes.

Symplast

Continuum of cytosol connected by plasmodesmata.

Plasmodesma

Membrane-lined channel connecting adjacent plant-cell cytoplasm.

Water potential

Potential energy of water; determines net movement.

Solute potential

Negative contribution to water potential caused by dissolved solutes.

Pressure potential

Physical pressure contribution to water potential.

Turgid

Firm plant cell with positive turgor pressure.

Flaccid

Plant cell with little or no turgor pressure.

Plasmolyzed

Membrane pulls from cell wall after severe water loss.

Aquaporin

Membrane channel that speeds water movement.

Proton pump

$H^+\text{-ATPase}$ that creates a proton electrochemical gradient.

Cotransport

Movement of one solute down its gradient drives another against its gradient.

Bulk flow

Movement of fluid and dissolved substances together due to a pressure gradient.

Endodermis

Innermost root cortex layer controlling entry to the stele.

Casparian strip

Suberin belt that blocks apoplastic entry across the endodermis.

Transpiration

Loss of water vapor, mainly through stomata.

Cohesion

Attraction between water molecules.

Adhesion

Attraction between water and other surfaces.

Tension

Negative pressure pulling xylem water upward.

Guard cell

Paired epidermal cell controlling a stomatal pore.

Abscisic acid (ABA)

Stress hormone that promotes stomatal closure and seed dormancy.

Xerophyte

Plant adapted to dry conditions.

Source

Organ exporting sugar, often a mature leaf.

Sink

Organ importing sugar for growth or storage.

Translocation

Movement of organic solutes through phloem.

Pressure-flow

Phloem bulk flow created by source loading and sink unloading.

Topsoil

Mineral particles, organic matter, water, air, and organisms in upper soil.

Humus

Partly decomposed organic matter that improves soil structure and retention.

Loam

Productive soil with a balanced mixture of sand, silt, and clay.

Essential element

Required for normal growth/reproduction and not replaceable by another.

Macronutrient

Essential element required in relatively large amounts; includes C, H, O, N, P, K, Ca, Mg, S.

Micronutrient

Essential element required in trace amounts; includes Cl, Fe, Mn, B, Zn, Cu, Ni, Mo.

Limiting nutrient

Nutrient in shortest supply relative to need, restricting growth; nitrogen is common.

Cation exchange

Root $H^+$ displaces mineral cations from negatively charged soil particles.

Nitrogen fixation

Reduction of atmospheric $N_2$ to $NH_3/NH_4^+$.

Ammonification

Conversion of organic nitrogen to $NH_3/NH_4^+$.

Nitrification

Oxidation of $NH_4^+$ to $NO_2^-$ and then $NO_3^-$.

Denitrification

Reduction of $NO_3^-$ to $N_2$ gas.

Rhizobia

Nitrogen-fixing bacteria that can form mutualistic legume nodules.

Nodule

Specialized root organ housing nitrogen-fixing bacteria.

Bacteroid

Nitrogen-fixing form of rhizobium inside a nodule cell.

Nitrogenase

Oxygen-sensitive enzyme complex that reduces $N_2$.

Leghemoglobin

Oxygen-binding nodule protein that protects nitrogenase while supporting respiration.

Mycorrhiza

Mutualistic association of fungus and root.

Ectomycorrhiza

Fungal sheath with hyphae between root cortical cells.

Arbuscular mycorrhiza

Hyphae form branched exchange structures inside cortical cell walls.

Epiphyte

Plant growing on another plant for support without taking nutrients from it.

Parasitic plant

Obtains water, minerals, and/or sugars from a host plant.

Carnivorous plant

Obtains mineral nutrients by digesting animals; still photosynthesizes.

Angiosperm

Flowering plant whose seeds develop within an ovary/fruit.

Sporophyte

Multicellular diploid generation that produces spores by meiosis.

Gametophyte

Multicellular haploid generation that produces gametes by mitosis.

Stamen

Male organ composed of anther and filament.

Carpel

Female organ composed of stigma, style, and ovary.

Microsporocyte

Diploid anther cell that undergoes meiosis to form microspores.

Megasporocyte

Diploid ovule cell that undergoes meiosis to form megaspores.

Pollen grain

Male gametophyte that produces/delivers sperm.

Embryo sac

Female gametophyte within an ovule.

Pollination

Transfer of pollen to a receptive stigma.

Double fertilization

One sperm makes $2n$ zygote; another makes triploid $3n$ endosperm.

Endosperm

Food-storing tissue formed by the second fertilization.

Seed

Mature ovule containing embryo, food supply, and seed coat.

Fruit

Mature ovary, sometimes with accessory tissues, aiding seed protection/dispersal.

Pericarp

Mature ovary wall of a fruit.

Dormancy

Temporary suspension of growth until conditions favor germination.

Staminate

Male flower lacking carpels.

Carpellate

Female flower lacking stamens.

Monoecious

Both flower sexes on one plant.

Dioecious

Flower sexes on separate plants.

Self-incompatibility

Genetic recognition system that rejects self pollen.

Vegetative reproduction

Asexual production of plants from roots, stems, or leaves.