Chapter 32 Vocabulary

Question 0

Cleavage

Answer 0

A succession of mitotic cell divisions without cell growth between the divisions

Question 1

Tissues

Answer 1

Groups of cells that have a common structure, function, or both

Question 2

Blastula

Answer 2

Multicellular stage formed after cleavage

Question 3

Gastrulation

Answer 3

Process during which the layers of embryonic tissues that will develop into actual body parts are produced

Question 4

Gastrula

Answer 4

The resulting developmental stage during which the layers of embryonic tissue develop into actual body parts

Question 5

Larva

Answer 5

A sexually immature form of an animal that is morphologically distinct from the adult, usually eats different food, and may even have a different habitat than an adult

Question 6

Metamorphosis

Answer 6

A developmental transformation that turns the animal into a juvenile that resembles an adult but is not yet sexually mature

Question 7

Homeoboxes

Answer 7

All animals have developmental genes that regulate the expression of other genes, and many of these regulatory genes contain sets of DNA sequences called homeoboxes

Question 8

Hox genes

Answer 8

Play important roles in the development of animal embryos, controlling the expression of dozens or even hundreds of other genes that influence animal morphology

Question 9

Ediacaran biota

Answer 9

An early group of soft-bodied multicellular eukaryotes

Question 10

Cambrian explosion

Answer 10

A way of animal diversification occurred 535-525 million years ago, during the Cambrian period of the Paleozoic era

Question 11

Body plan

Answer 11

A particular set of morphological and developmental traits, integrated into a functional whole - the living animal

Question 12

Plan

Answer 12

Body plans do provide a succinct way to compare and contrast key animal features

Question 13

Radial symmetry

Answer 13

The type of symmetry found in a flower pot

Question 14

Bilateral symmetry

Answer 14

A bilateral animal has two axes of orientation: front to back and top to bottom

Question 15

Dorsal

Answer 15

Top side

Question 16

Ventral

Answer 16

Bottom side

Question 17

Anterior

Answer 17

Front end

Question 18

Posterior

Answer 18

Back end

Question 19

Cephalization

Answer 19

An evolutionary trend: many animals with a bilaterally symmetrical body plan have sensory equipment concentrated at the anterior end, including a central nervous system (“brain”) in the head

Question 20

Germ layers

Answer 20

Layers that form the various tissues and organs of the body

Question 21

Ectoderm

Answer 21

The germ layer covering the surface of the embryo, gives rise to the outer covering of the animal and, in some phyla, to the central nervous system

Question 22

Endoderm

Answer 22

The innermost germ layer, lines the pouch that forms during gastrulation (the archenteron) and gives rise to the lining of the digestive tract (or cavity) and organs such as the liver and lungs of vertebrates

Question 23

Diploblastic

Answer 23

Animals that have only ectoderm and endoderm germ layers. Include animals called cnidarians as well as comb jellies, no mesoderm

Question 24

Mesoderm

Answer 24

A third germ layer which fills much of the space between the ectoderm and endoderm. In bilaterally symmetric animals

Question 25

Triploblastic

Answer 25

Having three germ layers

Question 26

Body cavity

Answer 26

A fluid – or air filled space located between the digestive tract and the outer body wall

Question 27

Coelem

Answer 27

Body cavity between the digestive tract and outer body wall

Question 28

Coelomates

Answer 28

Animals with a true coelom

Question 29

Pseudocoelomates

Answer 29

Some triploblastic animals have a body cavity that is formed from mesoderm and endoderm. Such a cavity is called a “pseudoderm” and the animals that have one are called pseudocoelomates

Question 30

Acoelomates

Answer 30

Triploblastic animals that lack a body cavity altogether

Question 31

Grade

Answer 31

A group whose members share key biological features

Question 32

Clade

Answer 32

A group that includes an ancestral species and all of its descendants

Question 33

Protostome development

Answer 33

In animals, a developmental mode mode distinguished by the development of the mouth from the blastopore: often also characterized by spiral cleavage and by the body cavity forming when solid masses of mesoderm split

Question 34

Deuterostome development

Answer 34

In animals, a developmental mode distinguished by the development of the anus from the blastopore; often also characterized by radial cleavage and by the body cavity forming as out pockets of mesodermal tissue

Question 35

Spiral cleavage

Answer 35

Many animals with protostome development undergo spiral cleavage, in which planes of cell division and diagonal to the vertical axis of the embryo; as seen in the eight-cell stage of the embryo, smaller cells are centered over the grooves between larger, underlying cells

Question 36

Determinate cleavage

Answer 36

Determined developmental fate of each embryonic cell very early

Question 37

Radial cleavage

Answer 37

Deuterostome development predominantly characterized by radial cleavage. The cleavage planes are either parallel or perpendicular to the vertical axis of the embryo; as seen at the eight-cell stage, the tiers of cells are aligned one directly above the other

Question 38

Indeterminate cleavage

Answer 38

Each cell produced by early cleavage divisions retains the capacity to develop into a complete embryo

Question 39

Archenteron

Answer 39

During gastrulation, an embryos developing digestive tube initially forms as a blind pouch, the archenteron, which becomes the gut

Question 40

Blastopore

Answer 40

The indentation that during gastrulation leads to the formation of the archenteron

Question 41

Protostome

Answer 41

First mouth

Question 42

Eumetazoans

Answer 42

“True animals”, a Clade that all animals except a few sponges and a few others belong to

Question 43

Bilaterians

Answer 43

Bilateral symmetry and the presence of three germ layers are shared derived characters that help define the Clade Bilateria. This Clade contains the majority of animal phyla, and its members are known as bilaterians

Question 44

Ecdysozoans

Answer 44

Ecdysozoa refers to a characteristic shared by nematodes, arthropods, and some of the other ecdysozoan phyla that are not included in our survey. Member of a group of animal phyla identified as a Clade by molecular evidence. Many are molting animals

Question 45

Lophotrochozoan

Answer 45

Member of a group of animal phyla identified as a clade by molecular evidence. Lophotrochozoans included organisms that have lophophores or trochophore larvae

Question 46

Lophophore

Answer 46

A crown of ciliated tentacles that function in feeding

Question 47

Trochophore larva

Answer 47

Distinctive larval stage observed in some lophotrochozoan animals, including some Annelida and molluscs

Question 48

Ecdysis

Answer 48

The process of shedding old exoskeleton