Chapter 32

Question 1

Animal basic classifications (4)

Answer 1

• Multicellular
• Heterotrophic Eukaryotes
• Tissues develop from embryonic layers

Question 2

Key animal history (3)

Answer 2

• Spans more than 0.5 Billion years
• Characterized by “body plans”
• Animals related by common descent

Question 3

Animals heterotrophic characteristics

Answer 3

• They cannot construct their own organic molecules

- They obtain it from food; which is ingested and digested within their bodies

Question 4

Animal cell structure/specialization

Answer 4

• multicellular eukaryotes
• lack cell walls
• bodies held together by structural proteins such as collagen
• nervous and muscle tissue are unique, defining characteristic of animals

Question 5

Tissue

Answer 5

-Collections of specialized cells isolated from other tissues by membranous layers act as a functional unit

Question 6

Reproduction

Answer 6

(most) reproduce sexually; diploid stage usually dominating life cycle

Question 7

After a sperm fertilizes an egg…(steps)

Answer 7

1. zygote undergoes rapid cell division (cleavage)
2. Cleavage leads to formation of a multicellular, hollow (Blastula)
3. Blastula undergoes Gastrulation, forming a (Gastrula) with different layers of embryonic tissues.

Question 8

Gastrula layers (outermost to innermost)

Answer 8

1. Ectoderm
2. Blastocoel
3. Endoderm
4. Archenteron
5. Blastopore (opening)

Question 9

Most animals have at least one…

Answer 9

Larval stage

Question 10

Larva

Answer 10

• sexually immature
• morphologically distinct from the adult
• eventually undergoes (metamorphosis) to become juvenile.

Question 11

Metamorphosis

Answer 11

Larval stage to juvenile stage

Question 12

Hox genes

Answer 12

Most (and only) animals have them.

• subset of homeotic genes
• regulate development of body form
• Although they’re highly conserved, they can produce a wide diversity of animal morphology.

Question 13

Diversity of current and extinct animal kingdom

Answer 13

Great diversity of living species, even greater diversity of extinct ones.

Question 14

Common ancestor of all living animals tine frame

Answer 14

between 700 and 770 million years ago

Question 15

Morphological and molecular data suggest that common ancestor…

Answer 15

-resembled a modern choanoflagellate

Question 16

Choanoflagellate

Answer 16

protists that are the closest living relatives of animals

Question 17

Body plan

Answer 17

• a set of morphological and developmental traits

- some have been conserved, while others have changed multiple times over the course of evolution

Question 18

Molecular control of gastrulation has…

Answer 18

remained unchanged for more than 500million years

Question 19

Symmetry

Answer 19

Method of classification based on body symmetry/lack of

• Radial
• Lateral
• None

Question 20

Radial symmetry

Answer 20

no front, back, left or right

Question 21

Bilateral symmetry

Answer 21

Two sided symmetry. Has a…

• dorsal (top) and ventral (bottom) side
• left and right
• Anterior (front) and posterior (back)
• Many have Cephalization

Question 22

Cephalization

Answer 22

Many have sensory “equipment” concentrated at the anterior end (development of head).

Question 23

Animal body plans vary according to…

Answer 23

the organization of animal’s tissues

Question 24

Three germ layers give rise to…

Answer 24

tissues and organs of animal embryos

Question 25

Ectoderm

Answer 25

The germ layer covering the embryo’s surface

Question 26

Endoderm

Answer 26

is the innermost germ layer and lines the developing digestive tube (archenteron)

Question 27

Archenteron

Answer 27

The (developing) digestive tube

Question 28

Sponges

Answer 28

lack true tissues

Question 29

Diploblastic

Answer 29

animals that have ectoderm and endoderm

-cnidarians and a few others

Question 30

Triploblastic

Answer 30

animals that also have an intervening mesoderm

• All bilaterians
• flatworms
• arthropods
• vertebrates and a few others

Question 31

All bilaterians

Answer 31

have an intervening mesoderm layer

Question 32

Most triploblastic animals posess a

Answer 32

body cavity (coelom)

Question 33

Coelom

Answer 33

a true body cavity, derived from mesoderm

Question 34

Two classifications of development (cleavage stage)

Answer 34

1. Protostome development

2. Deuterostome development

Question 35

Protostome development (cleavage)

Answer 35

cleavage spirals and determinates

Question 36

Deuterostome development (cleavage)

Answer 36

cleavage is radial and indeterminate.

Question 37

unique aspect of indeterminate cleavage

Answer 37

each cell in the early stages of cleavage retains the capactiy to develop into a complete embryo

Question 38

By 500 million years ago…

Answer 38

most animal phyla with members alive today were established

Question 39

how many animal phyla

Answer 39

3 dozen

Question 40

Phylogenies

Answer 40

combine morphological, molecular and fossil data

Question 41

Animal Phylogeny (5 important points)

Answer 41

1. All animals share a common ancestor
2. Sponges are basal animals
3. Eumetazoa (true animals)
4. Most phyla belong to Bilateria (bilaterians)
5. 3 major clades of bilaterians

Question 42

Eumetazoa

Answer 42

clade of “true animals”–contain true tissues

Question 43

Bilaterian Animals

Answer 43

• all are invertebrates (animals that lack a backbone)

- except chordata (vertebrates–have a backbone

Question 44

Three clades of bilaterians

Answer 44

1. Deuterostomia
2. Ecdysozoa
3. Lophotrochozoa

Question 45

Deuterostomia

Answer 45

• both vertebrates and invertebrates* includes:
• hemichordates (acorn worms)
• echinoderms (sea stars and relatives)
• chordates

Question 46

Ecdysozoan

Answer 46

• invertebrates

- shed their exoskeletons (ecdysis)

Question 47

Ecdysis

Answer 47

-shedding of exoskeleton in ecdysozoan

Question 48

Lophotrochozoans

Answer 48

have either:

• lophophore (feeding structure)
• trochophore larva (distinct developmental stage)