APBIO Classification Vocabulary

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Protozoan

animal-like protist

Algae

A member of a diverse collection of photosynthetic protists that includes both unicellular and multicellular forms.

Cilia

short structure projecting from a cell and containing bundles of microtubules that move a cell through its surroundings

Flagella

long, thin whip-lies structures, with a core of microtubules, that enable some cells to move

Pseudopodia

temporary extension of a cell's cytoplasm and plasma membrane, used by certain protozoans for movement and feeding

Hyphae

a thread of cytoplasm, many of which mae up the body of a fungus

Mycelium

Interwoven mat of hyphae that functions as the feeding structure of a fungus

Absorptive nutrition

method by which fungi absorb small organic molecules from their surroundings

Spores

haploid single cell with a thick wall that functions in the dispersal stage in fungal reproduction

Sporangia

spore forming structure at the tip of a fungal hyphae

Lichen

mutualistic pairing of a fungus and an alga

Mycorrhizae

mutualistic pairing of a fungus and a plant

Fruiting body

above-ground reproductive structure of a fungus

Chitin

A structural polysaccharide, consisting of amino sugar monomers, found in many fungal cell walls and in the exoskeletons of all arthropods.

Dikaryotic

Referring to a fungal mycelium with two haploid nuclei per cell

Plasmogamy

In fungi, the fusion of the cytoplasm of cells from two individuals

Ascus

A saclike spore capsule located at the tip of a dikaryotic hypha of a sac fungus.

Basidium

A reproductive appendage that produces sexual spores on the gills of mushrooms (club fungi).

Cuticle

waxy coating on the leaves and other aboveground parts of plants that helps the plant retain water

Stomata

A microscopic pore surrounded by guard cells in the epidermis of leaves and stems that allows gas exchange between the environment and the interior of the plant.

Vascular tissue

Plant tissue consisting of cells joined into tubes that transport water and nutrients throughout the plant body.

Lignin

A strong polymer embedded in the cellulose matrix of the secondary cell walls of vascular plants that provides structural support in terrestrial species.

Pollen

In seed plants, a structure consisting of the male gametophyte enclosed within a pollen wall.

Gametophyte

In organisms (plants and some algae) that have alternation of generations, the multicellular haploid form that produces haploid gametes by mitosis. It produces haploid gametes by mitosis.

Sporophyte

In organisms (plants and some algae) that have alternation of generations, the multicellular diploid form that results from the union of gametes. It produces haploid spores by meiosis.

Alternation of generations

A life cycle in which there is both a multicellular diploid form, the sporophyte, and a multicellular haploid form, the gametophyte; characteristic of plants and some algae.

Seed

An adaptation of some terrestrial plants consisting of an embryo packaged along with a store of food within a protective coat.

Ovule

A structure that develops within the ovary of a seed plant and contains the female gametophyte.

Flower

In an angiosperm, a specialized shoot with up to four sets of modified leaves, bearing structures that function in sexual reproduction.

Stamen

The pollen-producing reproductive organ of a flower, consisting of an anther and a filament.

Carpel

The ovule-producing reproductive organ of a flower, consisting of the stigma, style, and ovary.

Endosperm

In angiosperms, a nutrient-rich tissue formed by the union of a sperm with two polar nuclei during double fertilization. It provides nourishment to the developing embryo in angiosperm seeds.

Fruit

A mature ovary of a flower. It protects dormant seeds and often functions in their dispersal.

Double fertilization

A mechanism of fertilization in angiosperms in which two sperm cells unite with two cells in the female gametophyte (embryo sac) to form the zygote and endosperm.

Blastula

A hollow ball of cells that marks the end of the cleavage stage during early embryonic development in animals.

Gastrula

An embryonic stage in animal development encompassing the formation of three layers: ectoderm, mesoderm, and endoderm.

Larva

A free-living, sexually immature form in some animal life cycles that may differ from the adult animal in morphology, nutrition, and habitat.

Sessile

anchored to a substrate

Radial symmetry

Symmetry in which the body is shaped like a pie or barrel (lacking a left side and a right side) and can be divided into mirror-imaged halves by any plane through its central axis.

Bilateral symmetry

Body symmetry in which a central longitudinal plane divides the body into two equal but opposite halves.

Gastrovascular cavity

A central cavity with a single opening in the body of certain animals that functions in both the digestion and distribution of nutrients.

Complete digestive tract

digestive tube with separate mouth and anus

Closed circulatory system

A circulatory system in which blood is confined to vessels and is kept separate from the interstitial fluid.

Open circulatory system

A circulatory system in which fluid bathes the tissues and organs directly and there is no distinction between the circulating fluid and the interstitial fluid

Acoelomates

A solid-bodied animal lacking a cavity between the gut and outer body wall.

Pseudocoelomate

An animal whose body cavity is lined by tissue derived from mesoderm and endoderm.

Coelom

A body cavity lined by tissue derived only from mesoderm.

Endoskeleton

A hard skeleton buried within the soft tissues of an animal.

Protostome

a multicellular organism whose mouth develops from a primary embryonic opening

Deuterostome

a multicellular organism whose anus develops from a primary embryonic opening

Exoskeleton

A hard encasement on the surface of an animal that provides protection and points of attachment for muscles.

Notochord

A longitudinal, flexible rod made of tightly packed mesodermal cells that runs along the anterior-posterior axis of a chordate in the dorsal part of the body.

Tetrapod

a group of animals with two sets of four limbs

Ectotherm

Referring to organisms for which external sources provide most of the heat for temperature regulation

Endotherm

Referring to organisms that are warmed by heat generated by their own metabolism.

Amniote

A member of a clade of tetrapods whose embryo develops in a fluid filled sac

Eutherian

Placental mammal; mammal whose young complete their embryonic development within the uterus, joined to the mother by the placenta.

Marsupial

A mammal whose young complete their embryonic development inside a maternal pouch.