Biodiversity Test 4 Vocab Elon University - Kingston

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Stratification (seeds)

Exposure of seeds to a period of cold, moist conditions to break dormancy

Stratification mimics winter so seeds germinate at the right time. Scarification (seed coat damage) is different.This process is crucial for some plant species to ensure successful seed germination and establishment.

Stomata

Pores in the leaf epidermis for gas exchange, opened and closed by guard cells

Stomata allow CO2 in and water vapor/O2 out.They help regulate transpiration and photosynthesis.

Lignin

A rigid polymer in secondary cell walls that gives strength and waterproofing, especially in xylem

Lignin makes wood hard and was key to upright growth on land.

Phloem

Vascular tissue that transports sugars (sap) from sources to sinks

Phloem is made of living sieve tube members and companion cells.

Vascular bundle

A strand of xylem and phloem (often with cambium) running through stems, roots, and leaves

Scattered in monocot stems; arranged in a ring in eudicot stems.

Xylem

Vascular tissue conducting water and minerals from roots upward; dead at maturity, lignified

Contains tracheids and vessel elements.

Vessel elements

Wide, short xylem cells with perforated ends stacked into vessels; mainly in angiosperms

Vessels conduct water more efficiently than tracheids.

Tracheids

Long, tapered, lignified water-conducting xylem cells with pits; found in all vascular plants (the only type in most gymnosperms)

Water moves between tracheids through pits.

Pollen

The male gametophyte of seed plants, containing sperm cells, made in microsporangia

Pollen is carried by wind or animals to the stigma/ovule.

Megasporangium

Structure (within the ovule) that produces megaspores, which develop into the female gametophyte

Megaspore leads to the embryo sac (egg).

Microsporangium

Structure (in the anther) that produces microspores, which become pollen

Pollen sacs of the anther.

Stamen

Male flower part: anther + filament

Anther makes pollen; filament holds it up.

Carpel

Female flower part: stigma, style, and ovary containing ovules (a pistil is one or more fused carpels)

Carpel = megasporophyll.

Sieve tube member

Living phloem cell, lacking a nucleus at maturity, joined end to end through sieve plates to carry sugars

Supported metabolically by companion cells.

Companion cell

Nucleated cell adjacent to a sieve tube member that supports it metabolically and helps load/unload sugars

Connected by plasmodesmata.

Cotyledons

Seed leaves in the embryo that store or absorb food; one in monocots, two in eudicots

Eudicot cotyledons often store food; monocot cotyledon absorbs endosperm nutrients.

Ovules

Structures in the ovary containing the megasporangium and female gametophyte; become seeds after fertilization

The ovary becomes the fruit; ovules become seeds.

Endosperm

Nutritive tissue in angiosperm seeds, typically triploid (3n), from fusion of a sperm with two polar nuclei

Product of double fertilization.

Adventitious root

A root arising from a stem or leaf rather than from another root (e.g., prop roots, fibrous roots of monocots)

Common in monocots, ivy, and cuttings.

Cortex

Ground tissue between the epidermis and vascular tissue in roots and stems, mostly parenchyma

Pith is the ground tissue inside the vascular ring.

Guard cell

Paired epidermal cells that change turgor to open and close a stoma

Turgid = open; flaccid = closed.

Cork cambium

Lateral meristem that produces cork (outward) and phelloderm (inward); forms periderm

Replaces the epidermis in woody plants.

Vascular cambium

Lateral meristem producing secondary xylem inward and secondary phloem outward

Responsible for increase in girth (wood).

Sieve plate

Perforated end wall between sieve tube members allowing sap flow

Specific to phloem.

Sapwood

Outer, younger, functional secondary xylem that still conducts water

Heartwood

Inner, older secondary xylem no longer conducting water, clogged with resins/tannins; provides support and decay resistance

Usually darker than sapwood.

Pneumatophores

Roots growing upward out of waterlogged soil (e.g., mangroves, bald cypress) for gas exchange

'Knees' of bald cypress.

Prop roots

Adventitious roots growing from the stem down into the soil to support the plant (e.g., corn, mangrove)

Modified roots for support.

Sclerenchyma

Support tissue with thick, lignified secondary walls; cells often dead at maturity (fibers and sclereids)

Gives strength; e.g., nut shells, pear grit.

Parenchyma

Most common ground tissue: thin-walled living cells for photosynthesis, storage, and wound repair

Can divide and differentiate; found in cortex, pith, mesophyll.

Saprophyte

Organism that feeds on dead or decaying organic matter

Many slime molds and fungi are saprophytic decomposers.

Coenocytic

Having many nuclei in one cytoplasmic mass with no cell divisions (no cross walls)

True of the plasmodium of plasmodial slime molds.

Plasmodial slime mold

Amoebozoan whose feeding stage is a giant multinucleate, coenocytic plasmodium (e.g., Physarum)

Plasmodium creeps via cytoplasmic streaming and forms sporangia.

Zoospores

Motile (flagellated) spores

Swimming spores released in water.

Scarification

Abrasion, cutting, or digestion of the seed coat so water can enter and dormancy is broken

Natural examples: passing through an animal gut, fire, or abrasion

Sporangia

Structures that produce spores (in slime molds, fruiting bodies atop stalks)

Singular: sporangium.

Pseudopodia

Temporary extensions of the cell (cytoplasm) used for movement and engulfing food

'False feet'; characteristic of amoebozoans.

Phagocytosis

Engulfing food particles or cells by pseudopodia into a food vacuole

The vacuole then fuses with lysosomes for digestion.

Plasmodium (slime mold)

Multinucleate, coenocytic feeding mass of a plasmodial slime mold

Formed by repeated mitosis without cytokinesis.

Ovule (vs. ovary)

The ovule becomes the seed; the ovary becomes the fruit

Ovules sit inside the ovary at the base of the carpel.