Multicellular Organisms: Plant and Animal Form and Function

Comprehensive vocabulary flashcards covering the introductory themes, cellular features, taxonomy, and form and function of multicellular plants, fungi, and animals.

Multicellular Organism Themes

The four overarching physiological themes shared by multicellular organisms: Form and Function (create and maintain structure), Nutrition (obtain and use nutrients and energy), Transport (balance water and solutes, transport fluids and gases), and Sense (sense and respond to internal and external environments).

Protists

A paraphyletic group containing all eukaryotes except for fungi, animals, and plants.

Plants

Eukaryotic, photosynthetic, multicellular autotrophs characterized by cellulose cell walls, plasmodesmata, a large central vacuole, vascular tissue, starch storage, and a sessile lifestyle.

Cuticle

A waxy exterior coating evolved by land plants as an adaptive response to desiccation (the removal of moisture).

Fungi

Eukaryotic, multicellular absorptive heterotrophs with chitin-containing cell walls that acquire nutrients through external digestion.

Opisthokonts

A clade sharing a common ancestor that comprises fungi, choanoflagellates, and animals.

Hyphae

Filamentous fungal structures that form mycelium, produce fruiting bodies, possess a large surface area to volume ratio, and carry out external digestion.

Animals

Eukaryotic, multicellular, ingestive heterotrophs that lack cell walls and possess an extracellular matrix, lysosomes, gap junctions, and internal digestion.

Extracellular Matrix (ECM)

A flexible or gel-like structure made from collagen, other fibers, and proteoglycans (glycoproteins) that allows animal cells to change shape and move.

Gap Junctions

Specialized intercellular junctions in animal cells that permit direct communication and electrical signaling.

Gymnosperm

A vascular seed plant lacking flowers and fruits that evolved approximately $380\text{--}350$ million years ago.

Angiosperm

A vascular seed plant with flowers and fruits that evolved approximately $140$ million years ago.

Eudicot

A monophyletic clade of angiosperms characterized by two embryonic seed leaves, taproots, branched leaf veins, vascular bundles arranged in a ring, and floral organs in multiples of $4$ or $5$.

Monocot

A monophyletic clade of angiosperms characterized by one embryonic seed leaf, fibrous root systems, parallel leaf veins, scattered vascular bundles, and floral organs in multiples of $3$.

Phenotypic Plasticity

Within-species variation in morphology (phenotype) resulting from variable environmental conditions, enabled in plant organs by indeterminate growth and totipotency.

Taproot

A root system characterized by one large, dominant primary root that grows deep into the soil.

Fibrous Root System

A root system consisting of many thin, equally sized roots that spread out near the surface of the soil.

Prop Roots

Specialized aerial roots that grow downward from horizontal branches or stems into the soil to provide extra mechanical support.

Stolon

A modified stem that grows horizontally aboveground along the soil surface, producing adventitious roots and leaves at each node.

Rhizome

A modified stem that grows horizontally belowground rather than vertically.

Tuber

A swollen, underground rhizome modified for storing carbohydrates.

Bulb

A modified leaf organ composed of thickened leaf bases that store nutrients.

Middle Lamella

A layer of gelatinous polysaccharides and pectin that adheres adjacent plant cell walls together.

Primary Cell Wall

The outer plant cell layer composed of cellulose microfibrils, hemicellulose (which binds microfibrils), and pectin (which imparts flexibility).

Secondary Cell Wall

A rigid inner cell wall layer found in specialized tissues where lignin replaces pectin, cellulose, and hemicellulose.

Parenchyma

The most abundant plant ground tissue cells, functioning in basic metabolism, storage, and structural support.

Collenchyma

Plant ground tissue cells that provide flexible mechanical support to growing organs.

Sclerenchyma

Plant cells containing lignified cell walls that are dead at maturity, existing as fibers or sclereids to provide rigid support.

Trichomes

Fine, hair-like epidermal outgrowths that reflect sunlight to keep leaves cool, reduce water loss, trap insects, and deter herbivores.

Xylem

A lignified vascular tissue, dead at maturity, that conducts water and dissolved nutrients unidirectionally from the roots to the shoot system.

Vessel Elements

Short, wide tracheary elements containing both pits and perforations that are found exclusively in angiosperms.

Phloem

Living vascular tissue comprised of sieve-tube elements and companion cells that transports photosynthates (sugars) throughout the plant.

Totipotency

The capacity of an undifferentiated cell to divide and give rise to all parts of the embryo and adult organism.

Vascular Cambium

A lateral meristem located between the xylem and phloem that produces secondary xylem (wood) toward the interior and secondary phloem (bark) toward the exterior.

Lenticels

Spongy regions located in cork tissue that permit gas exchange through the bark.

Cephalization

The concentration of sensory and information-gathering organs at the anterior end of a bilaterally symmetrical animal.

Coelom

An internal, fluid-filled body cavity completely enclosed by mesodermal tissues on both the inside and outside.

Pseudocoelom

An internal body cavity enclosed by mesodermal tissue on the outside only.

Acoelomate

An animal that lacks a fluid-filled body cavity, having its internal space between the gut and body wall filled with mesenchyme.

Peritoneum

The mesodermal muscle tissue layer that lines the organs inside coelomate body cavities.

Hydrostatic Skeleton

A support structure that uses a combination of fluid pressure within a body cavity and muscle contractions to facilitate movement and locomotion.

Homeostasis

The maintenance of stable equilibrium conditions within a narrow range in an animal's internal environment in contrast to the external environment.

Negative Feedback

A homeostatic regulatory process involving sensors, integrators, and effectors that counteracts deviations and returns a controlled variable to its genetically determined set point.