exam 4 ch 18.2

Question 1

Metazoans (animals) evolve

Answer 1

Tonian & Cryogenian1.0Ga – 635Ma:

Question 2

Complexity of multicellular life expands; Eumetazoans to chordates.

Answer 2

Ediacaran 635-538.8Ma:

Question 3

The evolution and radiation of nitrogen-fixing photosynthetic cyanobacteria and resulting changes to the nitrogen cycle in the open oceans led to photosynthesis expanding dramatically also increasing Oxygen levels

Answer 3

850-540Ma NeoProterozoic Oxygenation event (Second Great Oxidation Event):

Question 4

Weakened planetary greenhouse effect resulting in much of the planet covered by ice

Answer 4

720 to 635Ma Cryogenian (Snowball Earth):

Question 5

Metazoans have multicellular bodies that form a blastula
during development

Answer 5

800-760Ma Animals (Metazoans) evolve:

Question 6

Animal embryo at the early stage of development when it is a hollow ball of cells

Answer 6

Blastula:

Question 7

First fossils of primitive sponges (Porifera)

Answer 7

760Ma Evidence of Metazoans (animals) evolving into sponges:

Question 8

share gene-chromosome combinations, while chromosomes of sponges and other
animals are arranged in a different manner

Answer 8

Comb jellies (ctenophores) and non-animals

Question 9

were the first lineage to branch off from the animal tree.

Answer 9

Comb jellies (ctenophores)

Question 10

Comb jellies (ctenophores) have a high diversity of
synapse

Answer 10

700Ma Phylogeny suggests Animals evolved into ctenophores (comb jellies):

Question 11

Sponges & Comb jellies (ctenophores) have two germ layers?

Answer 11

the endoderm and ectoderm and undergo gastrulation.

Question 12

Sponges are predicted to have lost their?

Answer 12

nervous-like cells

Question 13

Cells on the outside of an embryo migrate inward, reorganizing it into a multilayered structure

Answer 13

Gastrulation:

Question 14

The ozone layer forms, complexity of multicellular
life expands.

Answer 14

Ediacaran 635Ma – 538.8Ma:

Question 15

Oxygen reaches high enough levels to form a thin ozone layer capable of protecting life from
harmful wavelengths of UV radiation

Answer 15

600 Ma ozone layer forms:

Question 16

First likely fossil indicating Fungi colonized the land during the Ediacaran

Answer 16

635Ma Fungi:

Question 17

Fossils for possible oldest evidence of amoebae in terrestrial habitats
during the Neoproterozoic, coexisting with terrestrial Fungi.

Answer 17

20-635Ma Land colonized:

Question 18

Land plants (embryophytes) are considered to have
evolved from a branch of green algal ancestors that developed carotenoids, chlorophyll a and b, and ability to store carbohydrates like starch during this time

Answer 18

25 Ma Green algal (streptophytes) ancestor of land plants:

Question 19

Metazoans evolve a third germ layer

Answer 19

34–604 Ma Eumetazoans evolve:

Question 20

Organisms that undergo gastrulation and have embryonic tissues organized into 3 germ layers; a mesoderm,
ectoderm, and endoderm.

Answer 20

Eumetazoans:

Question 21

Outer cell layer.

Answer 21

Ectoderm:

Question 22

Inner cell layer.

Answer 22

Endoderm:

Question 23

Middle cell layer – formed from cells migrating inward from other 2 layers

Answer 23

Mesoderm:

Question 24

Bilaterians evolve from early Eumetazoans to have bilateral symmetry during embryonic development

Answer 24

fossils of Bilaterians:

Question 25

An extinct group of organisms that dominated the Earth During the Ediacara

Answer 25

Ediacaran biota (Flora & Fauna):

Question 26

Evolutionary radiation of prehistoric Ediacaran biota as well as an increase
in animal diversity

Answer 26

Avalon explosion, ~575Ma

Question 27

A rapid increase in the diversity of species in a clade

Answer 27

Evolutionary radiation:

Question 28

Process where floral and faunal groups are replaced over time

Answer 28

Biotic replacement:

Question 29

Organisms with mouth and anus openings in
which the anus forms before the mouth during embryonic development

Answer 29

Fossils for Bilaterians evolving into Deuterostomes:

Question 30

Mouth forms first

Answer 30

Split from Protostomes:

Question 31

Cells that work together to perform rudimentary spinal cord and vertebrae-like
functions

Answer 31

Notochord:

Question 32

ossils of bilaterians evolving into chordates: Organisms with a notochord.