chapter32

Question 1

What are the features of all animals?

Answer 1

Heterotrophy, multicellularity, no cell walls

Question 2

What are most animals capable of?

Answer 2

The ability to actively move, sexual reproduction, specialized tissues (muscle and nerve cells)

Question 3

What are the five key innovations in animal evolution?

Answer 3

Symmetry, tissues with specialized structures/functions, body cavity, patterns of embryonic development, segmentation (repeated body units)

Question 4

Are sponges symmetrical?

Answer 4

No, they are asymmetrical

Question 5

What is radial symmetry?

Answer 5

When many lines of symmetry all go through a central point

Question 6

What is bilateral symmetry?

Answer 6

Body divides equally along one plane

Question 7

What is the advantage of bilateral symmetry?

Answer 7

Move in a constant direction (head end leading), associated with brain sensory structures like eyes and ears (cephalization)

Question 8

What allowed for the specialized structures and functions?

Answer 8

The evolution of tissues

Question 9

What does it mean when a zygote is totipotent?

Answer 9

They are stem cells and can give rise to any and all cells of an animal’s body

Question 10

When do cells specialize?

Answer 10

During embryonic development

Question 11

Is specialization reversible?

Answer 11

It is irreversible in all animals except sponges

Question 12

What is cleavage?

Answer 12

Succession of mitotic cell divisions without cell growth between the divisions

Question 13

What is a blastula?

Answer 13

Hollow ball of cells produced by cleavage; cavity inside is the blastocoel

Question 14

What is the definition of gastrula?

Answer 14

Formed from the blastula when one end of the embryo folds inward, expands and fills blastocoel

Question 15

What is the definition of archenteron?

Answer 15

It’s the pouch inside the gastrula; opens to the outside by the blastopore

Question 16

What makes a body cavity possible?

Answer 16

The development of advanced organ systems

Question 17

What are the three germ layers?

Answer 17

Ectoderm, endoderm, mesoderm

Question 18

What is the ectoderm?

Answer 18

Gives rise to the outer covering of the body and nervous system

Question 19

What is the endoderm?

Answer 19

Gives rise to the digestive system which includes intestines and organs (liver, lungs)

Question 20

What is the mesoderm?

Answer 20

It is the middle layer that gives rise to the skeleton and muscles

Question 21

What are animals that have all three germ layers called?

Answer 21

They are triploblastic, members of the bilateria

Question 22

How many layers do cnidarians have?

Answer 22

They only have two (ectoderm and endoderm)

Question 23

What does it mean when cnidarians are diploblastic?

Answer 23

They have no organs

Question 24

What are the three body plans for bilaterally symmetrical animals?

Answer 24

Acoelomate, pseudocoelomate, and coelomate

Question 25

What does acoelomate mean and give an example?

Answer 25

The animal has no body cavity between the digestive tract and muscle layer (flatworms)

Question 26

What does pseudocoelomate mean and give an example?

Answer 26

The animal has a body cavity that develops between mesoderm and endoderm (roundworms)

Question 27

What does coelomate mean and give an example?

Answer 27

The animal's body cavity develops entirely within the mesoderm (annelids)

Question 28

What does the circulatory system do?

Answer 28

Functions to carry nutrients and oxygen to tissues, removes waste by diffusion

Question 29

What is an open circulatory system?

Answer 29

Blood passes from vessels into sinuses, mixes with body fluid, re-enters vessels in another location

Question 30

What is a closed circulatory system?

Answer 30

Blood is confined to vessels and is physically separated from other body fluids

Question 31

What are the two types of development that bilaterians have?

Answer 31

Protostome and deuterostome

Question 32

What does protostome mean?

Answer 32

The mouth develops from the blastopore, 'first mouth'

Question 33

What does deuterostome mean?

Answer 33

Anus develops from the blastopore

Question 34

What does archenteron mean?

Answer 34

Primitive gut

Question 35

What does blastopore mean?

Answer 35

Opening into the archenteron

Question 36

What is spiral cleavage?

Answer 36

The new layers of cells fall into the space between the older cells

Question 37

What is radial cleavage?

Answer 37

Pairs of new cells that position directly above older cells

Question 38

What is determinate development?

Answer 38

The type of tissue that each embryonic cell will form is determined early, protostomes

Question 39

What is indeterminate development?

Answer 39

Each cell remains totipotent and each cell is not determined for several cleavages, deuterostomes

Question 40

What are the advantages of segmentation?

Answer 40

Efficient and flexible movement, redundant organ systems

Question 41

What does metazoa mean?

Answer 41

Includes sponges that do not have embryonic germ layers

Question 42

What does eumetazoa mean?

Answer 42

Animals that do have embryonic germ layers

Question 43

What did molecular data help reveal?

Answer 43

Evolutionary relationships

Question 44

What is sponge morphology?

Answer 44

Monophyletic; shares common ancestor with other animals

Question 45

What is cnidarian morphology?

Answer 45

They evolved before bilaterally symmetrical animals

Question 46

What two animals were thought to be closely related?

Answer 46

Annelids and arthropods, this was based on segmentation but are grouped differently now