exam 4 ch 18.3

Question 1

6 Periods: of the Phanerozoic

Answer 1

Cambrian
Ordovician
Silurian
Devonian
Carboniferous
Permian

Question 2

Expansion and diversification of multicellular life and
the first representatives of all modern animal groups appear

Answer 2

The Cambrian Period:

Question 3

The super-ocean surrounding the Cambrian landmass

Answer 3

Panthalassic Ocean:

Question 4

Possible Supercontinent spanning across the south pole that broke up during the early Cambrian

Answer 4

Pannotia:

Question 5

Main Cambrian continent containing portions of modern South America, Africa, Antarctica, & Australia

Answer 5

Gondwanaland:

Question 6

The North American Craton present during the Cambrian.

Answer 6

Laurentia:

Question 7

Carbon Dioxide levels reach their highest of the Phanerozoic

Answer 7

Cambrian Atmosphere:

Question 8

Oxygen levels reached 14%

Answer 8

Cambrian Atmosphere:

Question 9

No ice at the poles, with surface temp’s reaching 100 degrees F at the equator

Answer 9

Ocean Surface Temperatures:

Question 10

Averaged 73–77 °F

Answer 10

Land surface temperatures:

Question 11

The rapid adaptive radiation of species within clades expanding to
encompass the major groups of life seen today

Answer 11

Cambrian Explosion:

Question 12

The process where a species or group of species rapidly diversifies into many new species

Answer 12

Adaptive radiation:

Question 13

A group of conserved transcription factors which regulate expression of genes related to body plan in the embryos of animals

Answer 13

Hox (Homeobox) genes:

Question 13

what caused the Cambrian Explosion?

Answer 13

1. Predators put selective pressure on mutations that provided protection.
2. Oxygen levels reached levels that made aerobic respiration more efficient, allowing for larger body sizes.
3. Worldwide spread of photosynthetic eukaryotic Algae increased food supply.
4. Evolution in Developmental Gene Regulatory Networks that control the construction of body plans

Question 14

Generation of different protein molecules from the same pre-mRNA by incorporation of a
different set and order of exons into the mRNA product.

Answer 14

Alternative splicing:

Question 15

became far more prominent.

Answer 15

Distal enhancers

Question 16

Sequences in the DNA far from the gene where transcription factor complexes bind and
can increase gene expression several-fold to over 100-fold.

Answer 16

Enhancers:

Question 17

provided a new level of transcriptional control.

Answer 17

CTCF sequences and TADs

Question 18

Architectural protein that organizes the genome structure in ways
that alter topological domain interactions and ultimately regulate gene expression.

Answer 18

CCCTC-binding factor (CTCF):

Question 19

DNA sequences organized into distinct regulatory territories
in the nucleus

Answer 19

topologically associating domain (TAD):

Question 20

Worms that burrowed and ate other animals

Answer 20

Archaeopriapulida:

Question 21

Different groups of fossils of likely ancestors of molluscs, brachiopods,
starfish, arthropods, Cephalopods (nautiloids)

Answer 21

Small shelly fossils (SSF):

Question 22

Bivalves with shells usually composed of the mineral calcite (calcium carbonate

Answer 22

Brachiopods:

Question 23

Filter feeders that dominated Cambrian oceans “sea lilies”.

Answer 23

Eocrinoids:

Question 24

Group of extinct marine arthropods

Answer 24

Trilobites:

Question 25

Any organism preserved in the rock record that is characteristic of a particular span of geologic time or environment

Answer 25

Index fossils:

Question 26

An extinct genus of an order that diverged from arthropods.

Answer 26

anomalocaris:

Question 27

An extinct group of sponges were the dominant reef builders in the
Cambrian

Answer 27

Cambrian archeocyathid reefs:

Question 28

Chordate that had tubes that were the precursors to
the heart and vertebrae.

Answer 28

Fossils of Pikaia (& Myllokunmingia):

Question 29

Haikouichthys: One of the first vertebrate fossils that also had a skull.

Answer 29

Haikouichthys:

Question 30

The Cambrian saw a diversification of photosynthetic eukaryotic Algae.

Answer 30

Cambrian plants:

Question 31

Pulses of anoxia in Cambrian oceans.

Answer 31

Cambrian–Ordovician extinction events: