Ch 32 Introduction to Animal Evolution Flashcards Preview

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Flashcards in Ch 32 Introduction to Animal Evolution Deck (49):
1

Characteristics of animals

1) Multicellular eukaryotes
2) Heterotrophs
3) Cells lack cell walls
4) Bodies held together by structural proteins (collagen)

2

Collagen comprises much of what?

The fibers in connective tissues

3

What is the most abundant protein in the bodies of animals?

Collagen

4

How do most animals reproduce?

Sexually

5

Cleavage

Rapid cell division of the zygote

6

What tissues are unique, defining characteristics of animals?

1) Muscle tissue
2) Nervous tissue

7

Tissue

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

8

How do animal body plans vary?

According to the organization of the animal's tissues

9

During development, what gives rise to the tissues and organs of the animal embryo?

Germ layers

10

Blastula

Formed by cell cleavage

11

Ectoderm

The germ layer covering the embryo's surface

12

Endoderm

The innermost germ layer

13

The endoderm lines what?

The archenteron

14

Archenteron

Developing digestive tube

15

Diploblastic animals

Possess an ectoderm and endoderm

16

Three diploblastic animals

1) Corals
2) Jellyfish
3) Comb jellies

17

Triploblastic animals

Posses an ectoderm, mesoderm, and endoderm

18

Bilaterian

Possess bilateral symmetry

19

Cephalization

Organization of senses and locomotion toward a head region

20

All multicellular animals posses what kind of symmetry?

Bilateral symmetry

21

Larva

Sexually immature and anatomically distinct from the adult

22

Juvenile

Resembles an adult, but is not sexually mature

23

Animal diversity arose from what?

A hypothesized ancestor

24

How long ago did the hypothesized ancestor of animals live?

Between 675 and 800 mya

25

The hypothesized ancestor of animals resemble what?

Modern choanoflagellates

26

Choanoflagellates

Protists that are the closest living relatives of animals

27

Cambrian explosion

Marks the earliest fossil appearance of many major groups (phyla) of living animals

28

How long ago was the Cambrian explosion?

535 to 525 mya

29

Three main hypotheses regarding the cause of the Cambrian explosion:

1) New predator-prey relationships
2) A rise in atmospheric oxygen
3) The evolution of the Hox gene complex

30

What organisms posses Hox genes?

Most animals, and only animals

31

Hog genes

Regulate many other genes and control the development of body form

32

Despite being highly conserved, the Hox family of genes produces what?

A wide variety of animal morphologies

33

Most species are what?

Arthropods

34

How many species of arthropods are there?

Over one million

35

How many of all known animals of arthropods?

About 3/4

36

Protosome cell proliferation

Cell proliferation following fertilization is by spiral cleavage

37

Deuterostome cell proliferation

Cell proliferation following fertilization is by radial cleavage

38

Protostome coelom development

Coelom forms within the middle tissue germ layer

39

Deuterostome coelom development

Coelom forms from outpocketing of the middle tissue germ layer

40

Protostome initial opening

Initial opening into the gut becomes the mouth

41

Deuterostom initial opening

Initial opening into the gut becomes the anus

42

What distinguishes protostomes and deuterostomes?

Embryonic development

43

Coelom

The body cavity surrounding the gut

44

What was previously the basis for major classification within the protostomes?

Coelom

45

Protostome groups previously based on coelom have been shown to be what?

Polyphyletic

46

Phylum Placozoa

Possibly the simplest animals with the smallest genome

47

How many genes are possessed within the genome of placozoans?

11,500 genes

48

How many cell types are possessed by placozoans?

Only four cell types

49

Phylum Placozoa lack what?

1) Symmetry
2) Organs
3) Muscles
4) Nervous system