Ap Biology Chapter 32 Vocabulary

Front 1

Acoelomates

Back 1

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

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Anterior

Back 2

Referring to the head end of a bilaterally symmetrical animal.

Front 3

Archenteron

Back 3

The endoderm-lined cavity, formed during the gastrulation process that develops into the digestive tract of an animal.

Front 4

Bilateral symmetry

Back 4

Characterizing a body form with a central longitudinal plane that divides the body into two equal but opposite halves.

Front 5

Bilaterians

Back 5

Member of the clade Bilateria, animals with bilateral symmetry.

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Blastopore

Back 6

The opening of the archenteron in the gastrula that develops into the mouth in protostomes and the anus in deuterostomes.

Front 7

Blastula

Back 7

The hollow ball of cells marking the end stage of cleavage during early embryonic development.

Front 8

Body cavity

Back 8

A fluid-containing space between the digestive tract and the body wall.

Front 9

Body plan

Back 9

In animals, the set of morphological and developmental traits that define a grade (level of organizational complexity).

Front 10

Cambrian explosion

Back 10

A burst of evolutionary origins when most of the major body plans of animals appeared in a relatively brief time in geologic history; recorded in the fossil record about 542-525 million years ago.

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Cephalization

Back 11

An evolutionary trend toward the concentration of sensory equipment on the anterior end of the body.

Front 12

Cleavage

Back 12

The process of cytokinesis in animal cells, characterized by pinching of the plasma membrane. Also, the succession of rapid cell divisions without growth during early embryonic development that converts the zygote into a ball of cells.

Front 13

Coelom

Back 13

A body cavity completely lined with mesoderm.

Front 14

Coelomates

Back 14

Animal that possesses a true coelom (fluid-filled body cavity lined by tissue completely derived form mesoderm).

Front 15

Determinate cleavage

Back 15

A type of embryonic development in protostomes that rigidly casts the developmental fate of each embryonic cell very early.

Front 16

Deuterostome development

Back 16

In animals, a developmental mode distinguished by the development of the anus from the blastopore; often also characterized by enterocoelous development of the body cavity and by radial cleavage.

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Diploblastic

Back 17

Having two germ layers.

Front 18

Dorsal

Back 18

Pertaining to the back (top) of a bilaterally symmetrical animal.

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Ecdysozoans

Back 19

Member of a group of animal phyla with protostome development that some systematists hypothesize form a clade, including many molting animals.

Front 20

Ectoderm

Back 20

The outermost of the three primary germ layers in animal embryos; gives rise to the outer covering and, in some phyla, the nervous system, inner ear, and lens of the eye.

Front 21

Ediacaran fauna

Back 21

Earliest generally accepted animal fossils, dating from about 575 million years ago.

Front 22

Endoderm

Back 22

The innermost of the three primary germ layers in animal embryos; lines the archenteron and gives rise to the liver, pancreas, lungs, and the lining of the digestive tract.

Front 23

Enterocoelous

Back 23

Pattern of formation of the body cavity common in deuterostome development, in which the mesoderm buds from the wall of the archenteron and hollows, forming the body cavity.

Front 24

Eumetazoans

Back 24

Member of the clade Eumetazoa, animals with true tissues (all animals except sponges).

Front 25

Gastrula

Back 25

The three-layered, cup shaped embryonic stage.

Front 26

Gastrulation

Back 26

The formation of a gastrula from a blastrula.

Front 27

Germ layer

Back 27

Three main layers that form the various tissues and organs of an animal body.

Front 28

Grade

Back 28

Group of animal species that share the same level of organizational complexity.

Front 29

Indeterminate cleavage

Back 29

A type of embryonic development in deuterostomes, in which each cell produced by early cleavage divisions retains the capacity to develop into a complete embryo.

Front 30

Larva

Back 30

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

Front 31

Lophophore

Back 31

A horseshoe-shaped or circular fold of the body wall bearing ciliated tentacles that surrounds the mouth.

Front 32

Lophotrochozoans

Back 32

Member of a group of animal phyla with protostome development that some systematists hypothesize form a clade, characterized by lophophores or trochophore larvae.

Front 33

Mesoderm

Back 33

A middle primary germ layer of an early embryo that develops into the notochord, the lining of the coelom, muscles, skeleton, gonads, kidneys, and most of the circulatory system.

Front 34

Metamorphosis

Back 34

The resurgence of development in an animal larva that transforms it into a sexually mature adult.

Front 35

Parazoan

Back 35

Animal belonging to a grade of organization lacking true tissues (collections of specialized cells isolated from other tissues by membranes); a sponge (phylum Porifera).

Front 36

Posterior

Back 36

Pertaining to the rear, or tail end, of a bilaterally symmetrical animal.

Front 37

Protostome development

Back 37

In animals, a developmental mode distinguished by the development of the mouth from the blastopore; often also characterized by schizocoelous development of the body cavity and by spiral cleavage.

Front 38

Pseudocoelomates

Back 38

An animal whose body cavity is not completely lined by mesoderm.

Front 39

Radial cleavage

Back 39

A type of embryonic development in deuterostomes in which the planes of cell division that transform the zygote into a ball of cells are either parallel of perpendicular to the polar axis, thereby aligning tiers of cells one above the other.

Front 40

Radial symmetry

Back 40

Characterizing a body shaped like a pie or barrel, with many equal parts radiating outward like the spokes of a wheel; present in cnidarians and echinoderms; also can refer to flower structure.

Front 41

Schizocoelous

Back 41

Pattern of formation of the body cavity common in protostome development, in which initially solid masses of mesoderm split, forming the body cavity.

Front 42

Spiral cleavage

Back 42

A type of embryonic development in protostomes, in which the planes of cell division that transform the zygote into a ball of cells occur obliquely to the polar axis, resulting in cells of each tier sitting in the grooves between calls of adjacent tiers.

Front 43

Triplobastic

Back 43

Possessing three germ layers: the endoderm, mesoderm, and ectoderm. Most eumetazoans are triploblastic.

Front 44

Trochophore Larva

Back 44

Distinctive larval stage observed in certain invertebrates, including some annelids and molluscs.

Front 45

Ventral

Back 45

Pertaining to the underside, or bottom, of a bilaterally symmetrical animal.