Chapter 32

Question 1

What is the definition of an animal? 4 points.

Answer 1

-Animals are heterotrophs that are multicellular eukaryotes.
-Usually have Hox genes.
-Do not have cell walls.
-Tissue and muscle are unique and defining characteristics.

Question 2

What is the cell structure and celuding cleavage, a blastula, blastocoel, gastrulation, and a gastrula?

Answer 2

Animals usually reproduce sexually meaning the diploid stage dominates the animal life cycle. After fertilization occurs, the zygote undergoes cell division known as cleavage. This cleavage leads to formation of multicellular and hollow blastrula. Theblastrula goes through gastrulation formina a gastrula with different layers of tissue.

Question 3

What are Hox genes and why are they relevant to animal evolution?

Answer 3

Most animals, and only animals, have Hox genes that regulate the development of body form.
The Hox family of genes has been highly conserved, but can produce a wide diversity of animal morphology.

Question 4

What is larva and metamorphosis?

Answer 4

A larva is sexually immature and morphologically different from the adult. It eventually undergoes metamorphosis to become a juvenile.

Question 5

What is a choanoflagellate? What was their role in the development of animals?

Answer 5

A group of protists, cited as the closest living relatives to animals. Not extinct, in marine habitats.

Question 6

What is the role of cadherin in cell to cell adhesion?

Answer 6

Cadherin regulates contact, formation, and stability meaning they’re key in tissue morphogenesis and homeostasis.

Question 7

What does the term Ediacaran biota refer to?

Answer 7

Early members of the animal fossil record, these dates back 560 Million years.

Question 8

What organisms are included in the Edicarian Biota?

Answer 8

2 examples are: Mawsonites spriggi and Spriggina floundersi.

Question 9

What is the age of the oldest anll specialization of animals?

Answer 9

The cambrian explosion is the mark of the earliest fossil appearance of many major groups of animals. Most of the fossils were bilaterans.

Question 10

What are the 3 germ layers?

Answer 10

Formed in earliest stages of embryonic development.
1. Endoderm (inner layer)
2. Ectoderm (outer layer)
3. Mesoderm (middle layer)

Question 11

Which germ layers give rise to the major organ systems?

Answer 11

The endoderm gives rise to internal organs.

Question 12

Describe animal development, incimal fossils?

Answer 12

Most animals reproduce sexually

Question 13

What is the Cambrian explosion?

Answer 13

The Cambrian explosion (535-525 Million years ago) marks the earliest fossil appearance of major groups of animals.

Question 14

When did mammals begin to replace dinosaurs as the main large herbivores & predators?

Answer 14

Cenozoic Era (65.5 Million Years Ago to the Present)

Question 15

What is a body plan?

Answer 15

A set of morphological and developmental traits. Animals can be categorized by presence and type of body plan.

Question 16

What is an example of a body plan?

Answer 16

Sea Jelly’s have a radially symmetrical body plan.
Crabs however have a Bilateral body plan.

Question 17

What are the 2 types of body symmetry?

Answer 17

Radial symmetry and Bilateral Symmetry

Question 18

What are the differences between the two types of body symmetry?

Answer 18

Bilaterally means into 2 sections. Radially means in wedges, or divided like a pie.

Question 19

What are tissues?

Answer 19

Groups of similar cells that act as functioning units.

Question 20

What are the 3 embryonic germ layers?

Answer 20

1. Ectoderm
2. Endoderm
3. Mesoderm

Question 21

What are some key differences between coelomates, pseudocoelomates and acoelomate?

Answer 21

Coelomates are organisms with a mesodermally lined body cavity, pseudocoelomates are organisms with patches of mesoderm on their body cavity, and acoelomates are organisms with no body cavity at all.

Question 22

What 5 features which are found in living animals reflect their shared phylogeny?

Answer 22

1. All animals share a common ancestor
2. Sponges are basal animals
3. Eumetazoa “true animals” is a clade of animals with true tissue
4. Most animla phyla belong to the clade Bilateria
5. There are 3 major clades of bilaterian animals, all of which are invertebrates, animals that lack a backbone, except Chordata, which are classified as vertebrates because they have a backbone.

Question 23

What are the 3 major clades of bilaterians?

Answer 23

1. Deuterostomina
2. Ecdysozoa
3. Lophotrochozoa

Question 24

What is an example of an Ecdysozoa?

Answer 24

A clade of intervertebrates that shed their exoskeletons through a process called ecdysis. An example os Arthopods, so insects and bees.

Question 25

What is an example of a Lophotrochozoa?

Answer 25

Another clade of Bilaterian Intervertabrates, some have feeding structures called lophophores and some go through a stage calles trochophore larva. An exmaple is Mullusca and Annelida.

Question 26

What is an example of a Deuterostomia?

Answer 26

Intervertabrates and Vertabrates also has echiderms. An example is Hemichordata and Enchinodermata.

Question 27

What is a lophophore?

Answer 27

A crown of ciliated tentacles that function in feeding.

Question 28

What is a juvenille?

Answer 28

Past larva stage and resembles physically the adult but not sexually the adult.

Question 29

How many animal species have been named to date?

Answer 29

1.3 Million species, and there's still millions more.

Question 30

When did the common ancestor of all animals exist?

Answer 30

700-770 Million years ago.

Question 31

What is cadherin?

Answer 31

A protein needed for cell adhesions and cell communication.

Question 32

What are bilaterians?

Answer 32

Symmetrically bilateral one way digestive system.

Question 33

What sorts of animals (and animal traits) are represented from Cambrian era fossils?

Answer 33

Most fossils from the Cambrian explosion are bilaterians. 1. Bilaterally symmetric body 2. Complete digestive tracht 3. One-way digestive system.

Question 34

What are some hypothesis for the cause of the Cambrian Explosion and decline of Ediacaran biota?

Answer 34

1. New predator prey realtionship 2. A rise in oxygen 3. Evolution of Hox gene complex.

Question 35

What is the Ectoderm?

Answer 35

Germ layer covering embryo's surface.

Question 36

What is the Endoderm?

Answer 36

Innermost germ layer that lines the developing digestive tube, called the archenteron.

Question 37

What is the Mesoderm?

Answer 37

The middle germ layer, found onlt in triploblastic animals.

Question 38

What are tripoblastic animals?

Answer 38

Animals with all 3 germ layers. Have mesoderm layers.

Question 39

What are Diploblastic animals?

Answer 39

Animals with only the ectoderm and endoderm.

Question 40

What is a true body cavity called?

Answer 40

A Coelomate.

Question 41

What lead to the Cambrian explosion and decline of the Ediacaran biota?

Answer 41

1. New predator Prey relationships 2. A rise in oxygen levels 3. Evolution of Hox gene.

Question 42

What is the cambrian explosion an example of?

Answer 42

Adaptive Radiation.

Question 43

What does cleavage lead to the formation of?

Answer 43

Blastula.