Plant Biology Terms

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archegonium

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female sex organ

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antheridium

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male sex organ

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mitosis

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mechanism for consistency. parent nucleus produces two daughter nuclei. Nuclei is identical to parents

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meiosis

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mechanism for diversity. 4 daughter haploids that are different from parents and its sisters

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nontracheophytes

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non vascular plants. obtain water by:

-growing in dense masses which water can move by capillary action
-possessing leaf-life structures to catch and hold water from splashes or rain.
-being so small that minerals are evenly distributed
-evolved tens of millions of years before tracheophytes

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vascular tissue

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able to have water and food conducting cells

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tracheophytes

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vascular plants. developed vascular system two two specialized tissues for transport: xylem and phloem

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phloem

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used to conduct photosynthesis from source to sinnk

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xylem

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used to conduct water and minerals from soil to aerial parts of plant. also provides support in terrestrial environment

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rhizomes

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anchor leaves and roots to soil by horizontal stem

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homospory

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plants that bear a single type of spore

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heterospory

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plants that bear two distinct types of spores

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megaspore

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develops into larger female gametophyte

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microspore

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develops into smaller male gametophyte

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gymnosperms

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naked seeds like ginkos, confers; don't produce flowers

-secondary growth: stems and roots grow larger in diameter
-great diversity

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angiosperms

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flowers (monocotyledons and dicotyledons...closed seeds)

-sporophyte gen. becomes larger and more independent of gametophyte; gametophytes become smaller and more dependent on sporophyte

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double fertilization

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two male gametes participate in independent fertilization events within megagametophyte. one sperm combines with the egg to produce a diploid zygote (2n); other sperm nucleus combines with two other haplod nuclei of the female gametophyte to form a triploid nucleus that gives rise to endosperm (3n)

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triploid endosperm (angio)

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triploid tissue (3n); nourishes the embryonic sporophyte during early development

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carpel

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ovules and seeds of angiosperms are enclosed by this modified leaf.

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vessel elements (xylem)

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specialized water transportating cells

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fibers (xylem)

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supporting plant body

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companion cells

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found in angio. phloem

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stamens

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microsporangia bearing structures in a flower; has anther and filament

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anther

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contains pollen-producing microsporangia

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pistil

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structure composed of one carpel or two or more fused carpels

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carpel

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organ that contains one or more ovules

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megasporangia

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the ovary

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style

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apical stalk of the pistil

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stigma

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terminal surface of the pistil that receives pollen grains

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petals

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inner leaves

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sepals

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outer leaves

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whorls

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from base to apex, the sepals, petals, stamens, and carpels are usually in circular arrangements called these

-attached to a stalk called the receptacle

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simple fruits

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develop from a single carpel or several united carpels

-cherries

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aggregate fruits

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develop from several separate carpels of a single flower

-raspberries

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multiple fruits

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formed from a cluster of flowers

-pineapples

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accessory fruits

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derived from the parts in addition to carpel and seeds

-pears

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cotyledon

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one (monocot) or two (dicot) seed leaves of an angio embryo

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endosperm

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nutrient rich tissue formed by the union of a sperm cell with two polar nuclei during double fertilization. provides nourishment to developing embryos

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radicle

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root of embryo: emerges from seed first.

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hypocotyl

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embryonic axis below the point at which cotyledons are atttached

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epicotyl

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embryonic axis above the point at which the cotyledons are attached

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coleptile

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sheath enclosing apical meristem and leaf primordia of the grass embryo, interpreted as the first leaf

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fibrous root system

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in monocots and some dicots; numerous thin roots equal in diameter, holds soil in place very effectively preventing erosion (ex grasses)

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taproot system

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in many dicots; a single large, deep-growing primary root with small lateral roots, food storage for flowers (ex carrots, beets)

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nodes

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where a stem bears leaves....points of leaf attachement

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internodes

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stem segments between nodes

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axillary buds

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potential to form a branch (dominant tissue)

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terminal bud

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primary growth of a shoot

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apical dominance

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terminal bud growth inhibits growth of the axillary buds ("pinching back" plants makes them bushy)

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blade

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flattened leaf

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petiole

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stalk which joins leaf to node of stem, holds leaf almost perpendicular to sun

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simple leaf

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single undivided blade

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compound leaf

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blade divided into several leaflets

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tissue

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an organization of cells that work together as a functional unit

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simple tissue

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only one cell type

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complex tissue

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composed of a number of different cell types (xylem and phloem)

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chalzal

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main seat for growth of the embryo; upper pole

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micropylar

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lower pole; produces stalk-like suspensor which anchors the embryo at the microphyle

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globular stage

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stage of embryo development that precedes cotyledon development

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heart shaped stage

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globular embryo in dicots forms two-lobed form, like a heart

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torpedo stage

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cotyledons and axis of embryo elongate, primary meristems also extend as the embryo enlarges, the cells of the suspensor are gradually crushed

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protoderm

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the future epidermis

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procambium

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primary meristemic tissue that gives rise to primary vascular tissue

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primary meristem

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protoderm, procambrium, and ground tissue

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apical meristems

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give rise to primary plant (entire body of many plants)

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lateral meristems

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give rise to secondary plant body

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shoot apical meristems

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supply the cells that extends stems and branches

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root apical meristems

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supply cells that extend roots

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vascular cambium

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cylindrical tissue, vertically eloongated cells that divide frequently

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cork cambium

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protective cells that protect outermost layers of stem from water loss and microorganisms

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periderm

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layer of growth of the cork cambium

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secondary growth

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growth in diameter of stems and roots by vascular and cork cambia

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wood

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secondary xylem

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bark

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everything external to the vascular cambium

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sieve-tube members

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cells that are alive but lack nucleus, ribosomes and vacuole

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companion cell

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non-conducting cell next to sieve-tube members, serves adjacent cells without nucleus, ribosomes, and distinct vacuole; regulates performance of sieve-tube members

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pith

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tissue internal to the vascular tissue

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cortex

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tissue external to the vascular tissue

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apical-basal pattern

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arrangement of cells along the main axis from root to shoot

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radial pattern

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concentric arrangement of tissue systems

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determinate growth

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in animals, body grows from embryonic stages but ceases to grow once adulthood is reached

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indeterminate growth

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in plants, the growth of roots and shoots is generated from specific regions of active cell division

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merstematic tissues

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analogous to stem cells in animals

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root cap

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protects delicate growing area of the rot as it pushes through the soil.

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three zones of root tissues

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cell division, cell elongation, and cell differentiation

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root hairs

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long, flattened epidermal cells that increase the root's surface area

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cortex

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directly internal to the root epidermis and often functions as food storage

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endodermis

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the next root structure internal to the cortex, contains suberin (water proof)

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stele

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vascular component of root which includes xylem and phloem and pericycle tissues

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pericycle

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consists of one or more layers of undifferentiated cells

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mesophyll

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two zones in leaf parenchyma that photosynthesize

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veins

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supply mesophyll cells with water and mineral, transport photosynthate

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epidermis

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outer most layer covered by waxy cuticle, prevents evaporation

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guard cells

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control gas exchange through pores in leaf (stomata)

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autotrophs

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not totally sufficient, must acquire organic molecules from CO2 and inorganic raw materials. Producers of the biosphere

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phototrophs

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organisms that use light energy to drive the synthesis of organic molecules from CO2 and water.

land plants, multicellular algae, unicellular protists, cyanobacteria, and purple sulfur bacteria

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heterotrophs

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organisms that are unable to produce their own food . obtain organic material by feeding on "producers".

Consumers of the biosphere. Humans are completely dependent on phototrophs for food and oxygen.

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thylakoids

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light capturing reacts occur here. contain chlorophyll and other pigments

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grana

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thylakoid stacks occur in disklike stacks here

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stroma

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area in which energy is used to synthesize carbohydrates

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starch

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a product of photosynthesis

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light reaction

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driver by light energy that is captured by chlorophyll pigments. produces ATP and the reduced electron carrier NADPH and H+

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Calvin-Benson cycle

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does not use light directly. Uses ATP, NADPH, H+ and CO2 to produce sugar

cycle requires the products of light reactions to run and it stops in the absence of light

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photophosphorylation

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pathway in which systems pass electrons from one molecule to another. some of this flow is coupled to synthesis of ATP. Both NADPH and H+ and ATP are produced by light reactions

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photons

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visible light is part of the electromagnetic radiation spectrum. It comes in discreet packets called photons

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brightness/intensity

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measure of photons striking an area per unit time.

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reflection

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photon bouncing off a molecule

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transmission

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photon passing through the molecule

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excitation

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photon absorbed by the molecule

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pigments

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molecules that absorb wavelengths in the visible range

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fluorescence

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emitting the absorbed light

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photophosphorylation

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passing of electron to chlorophyll to and electron acceptor begins the electron flow. the electrons flow through a series of carriers where redox reactions occur one after another and the energy of these redox reactions is used to pump protons

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noncyclic electron flow

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produces NAPDH+H+ and ATP and alos produces oxygen found in the atmosphere

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cyclic electron flow

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only produces only ATP

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series of redox reactions

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releasing energy that is used to transport protons across the membrane

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proton motive force

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difference in pH and electric charge across the membrane

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rubisco

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enzyme that catalyzes the fixation of carbon dioxide

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G3P

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end product of the Calvin cycle

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photorespiration

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uses ATP and NADPH produced in the light reaction to undo what the Calvin cycle accomplished

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C3 plants

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temperate zone plants; uses the Calvin cycle; wheat, rice, oats, and most trees

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C4 cycle

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extreme changes in climate; corn, sugarcane, tropical grasses

ultimately produces products that enter C3 cycle

separate fixation of four carbon compounds spatially from the reactions of Calvin cycle

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CAM cycle

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most extreme; reactions occur at night; ultimately produces products that enter C3 cycle; corn, cacti, ice plants, beets

separate the fixation of four carbon compounds temporally

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PEP carboxylase

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fixes CO2 to three carbon acceptor compound phosphenol pyruvate to form four carbon fixation product oxaloacetate.

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transpiration

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loss of water vapor by plant parts; most occurs through stomata

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water potential

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tendency of a solution to take up water from pure water across a membrane

low water potential means higher tendency to take up water from pure water

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wilting

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loss of pressure potential

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bulk flow

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movement of fluids in plants due to differences in pressure potential

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active transport

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opening fates to allow ions to get through biological membranes

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facilitated diffusion

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when concetration of ions is greater in the soil than in the plant, the plant can update ions this way

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proton pump

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ATP is used to move protons out of root cells, often against a proton gradient

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symport protein

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couples the diffusion of H+ back into the cell (along its electrochemical gradient) to the transport of Cl- into the cell (against its electrochemical gradient)

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membrane potential

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established with an increase in intracellular negativity

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apoplast

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cell walls and intracellular spaces

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symplast

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portion of plant body enclosed by membranes; the continuous cytoplasm of living cells

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plasmadesmata

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cells connected to each other via this method

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Casparian strips

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waxy, suberin-containing structures-create a belt that seals and prevents movement around cells of the endodermis into the stele

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root pressure

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due to higher solute concentration and more negative water potential in the xylem sap than the soil

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guttiation

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water is forced out through openings in the leaves (example of root pressure)

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transpiration

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water pulled up via this method in xylem transport

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cohesion

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hydrogen bonding between molecules

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proton gradient

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drives the acculumation of potassium in guard cells

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abscisic acid

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plant hormone that causes stomata to close then water supply is low

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xerophytes

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plants that are adapted to arid climates

many leaf modifications to reduce rate of transpiration

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trichomes

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hairs that help minimize transpiration by breaking up the flow of air, allowing the chamber of the crypt to have a higher humidity than the surrounding atmosphere.

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source

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photosynthesizing leaf or a starch-storing root

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sink

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root, flower, or other structure with inadequate sugar or amino acids

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Magnesium

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essential part of chlorophyll and is a cofactor in many enzymes

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phosphate

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involved in energy metabolism (ATP), is found in nucleic acids, and is involved in switching the activities of enzymes

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calcium

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affects the cytoskeleton and functions in the processing of hormonal an environmental cues

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chlorosis

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yellowing of older leaves

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humus

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plant litter such as dead leaves, break down to form this

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common ingredients in fertilizers

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Nitrogen, phosphorous, and potassium

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examples of macronutrients

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K, N, S, P

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cyanobacteria

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fix nitrogen; occurs in oceans and fresh water

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flavonoids

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pigment molecules

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nod factors

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influence root growth

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bacteroids

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intracellular bacteria surrounded by membranous vesicles

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leghemoglobin

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is produced by the plant cell. Makes the cells of the root look pink. Controls the level of free oxygen

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nitrogenase

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enzyme that catalyzes nitrogen fixation

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phytoremediation

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the ability for terrestrial plants to clean the soil contaminated with heavy metals

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bioremediation

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detoxify metal-contaminated soils by means of biological activity

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phytoextraction

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removal of toxins from soil

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phytostabilization

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complexation and immobilization of toxins within the soil

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phytodegradation

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degredation by micro-organisms in the soil

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carnivorous plants

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adapted to nitrogen poor environments by trapping and ingesting insects

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parasitic plants

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derive their mineral nutrients from the living bodies of other plants

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tropoism

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any growth response that results in the curvature of the whole plant towards or away from the stimuli

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phototropism

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growth in response to light

Positive: grow towards light
Negative: grow away from light

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expansins

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proteins activated by protons, modify hydrogen bonding between polysacc. in the plant wall

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auxins

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increase cell wall plasticity

produced at the tip.

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apical dominance

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tendency for lateral buds to remain dominant. cutting the growing tips stimulate later bud growth, unless auxin is applied to the location where the tip was removed.

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cytokinins

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aid germination, inhibit stem elongation, stimulate lateral bud growth, and delay leaf senescence.

mostly produced in roots and move to other part of the plant

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direct inhibition hypothesis

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auxin and cytokinin act antagonistically in regulating lateral bud growth

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gibberellins

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large family of closely related compounds that regulate from germination to fruit growth

cause wall loosening like auxin but does not do this by acidification

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abscisic acid

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stress hormone that induces the synthesis of proteins that help the embryo survive extreme dehydration

high levels of ABA inhibits seed germination

present in high concentrations in dormant buds

inhibits stem elongation

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ethylene

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gaseous hormone that promotes senescence.

compared to auxin that delays leaf abscission, ethylene promotes it strongly.

hastens the ripening of fruit

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photoreceptors

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proteins that regulate plant growth and other aspects of developement

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photomorphogenesis

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distinctly different light response of full de-etiolation because photosyn. can't be the driving force due to chlorophyll being absent in the day

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etiolated plant growth

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seedlings grow in teh dark have a pale, unusually tall and spindly appearance.

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blue light photoreceptors

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phototropin and cryptochromes

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red/far-red photoreceptors

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phytochromes

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phototropin

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photoreceptor for phototropism. upon absorbing blue light, phototropin initiates a signal transduction pathway leading to phototropic curvature.

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phototropism

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results in asymmetric growth

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heliotropism

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involves movements in pulvini at the bases of leaves and/or leaflets

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diaheliotropism

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keeps leaves perpendicular to sun al day to maximize photosynthesis

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paraheliotropism

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plants actively avoid direct sunlight. minimizes absorption of solar radiation rather than maximizing it. decreases the leaf temp and transpirational water loss and enhancing survival during drought periods.

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phytochromes

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mediate the effects of red and far-red light

controls seed germination, plant greening, flowering, detects and distinguishes light quality, and keeps track of light time

two identical proteins joined to form one phytochrome

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photoperiodism

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regulation of flowering by changing the length of day or night

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annuals

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complete lifecycle in less than a year

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biennials

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live almost two years

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perennials

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live for a few to many years

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sporophyte

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produces spores, dipoloid

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gametophyte

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haploid, multicellular phase of plants and algae that undergo alternation of generations, with each of its cells containing only a single set of chromosomes.

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tracheophyte

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plants that have lignified tissues for conducting water, minerals, and photosynthetic products through the plant.

ferns, clubmosses, flowering plants, conifers

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simple leaf

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has an undivided blade.

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sporangia

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plant, fungal, or algal structure producing and containing spores

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genetic self incompatibility

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a general name for several genetic mechanisms in angiosperms, which prevent self-fertilization and thus encourage outcrossing. In plants with SI, when a pollen grain produced in a plant reaches a stigma of the same plant or another plant with a similar genotype, the process of pollen germination, pollen tube growth, ovule fertilization, and embryo development is halted at one of its stages, and consequently no seeds are produced.

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parenchyma

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thin-walled cells of the ground tissue that make up the bulk of most nonwoody structures, yet sometimes their cell walls can be lignified. Parenchyma cells in between the epidermis and pericycle in a root or shoot constitute the cortex, and are used for storage of food.

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senescence

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biological aging