exam 3 ch 18

Question 1

Plant resins can harden into amber, preserving insects and other biological material

Answer 1

amber and freezing:

Question 2

extremely dry environments that cause the drying out of organisms

Answer 2

Desiccating environments:

Question 3

Ground that remains frozen for many years

Answer 3

Permafrost:

Question 4

Structures are buried in sediments and dissolved minerals either replace the
original mineral content, or precipitate in and around it

Answer 4

permineralization and replacement:

Question 5

Remains decay after being buried in sediment; Molds consist of unfilled spaces & casts form when new material infiltrates the space, fills it, and hardens into rock.

Answer 5

Natural molds and casts:

Question 6

Record behavior instead of direct anatomical form

Answer 6

trace fossils:

Question 7

(taphos = burial) The study of the fossilization process

Answer 7

Taphonomy:

Question 8

Factors that contribute to the difference between what was once alive and its representation in
the fossil record

Answer 8

Taphonomic bias:

Question 9

First confirmed life forms, the prokaryotes (no nucleus), evolve.
-Cyanobacteria (Stromatolites) create enough oxygen to accumulate in the atmosphere

Answer 9

Archean Eon 4.0Ga-2.5Ga:

Question 10

Period in which the Earth & moon were hit more frequently by a higher
number of large asteroids

Answer 10

4.1 to 3.8 billion years Late-Heavy Bombardment:

Question 11

The pull of the moon slows the Earth’s rotation

Answer 11

tidal Braking:

Question 12

Water vapor, carbon dioxide, nitrogen, methane, ammonia, but no free oxygen.
-Sun ~92% of current brightness

Answer 12

Eoarchean atmosphere:

Question 13

-The atmosphere & likely surface, had more intense ultraviolet radiation as ozone could not form
from an anoxic atmosphere

Answer 13

Eoarchean atmosphere:

Question 14

may have been the primary fuel production method in Eoarchean

Answer 14

Anoxygenic photosynthesis

Question 15

Photosynthesis that uses hydrogen sulfide as a reductant (instead
of water) to make sugars and gives elemental sulfur off as waste (instead of oxygen)

Answer 15

3.77 Ga Anoxygenic photosynthesis:

Question 16

First major continent, composed of cratons from Southern Africa and
Australia

Answer 16

3.6 Ga Vaalbara Supercontinent:

Question 17

A stable part of a continent that experiences minimal deformation over very long periods.

Answer 17

Craton:

Question 18

First Definitive fossils of archaea and
cyanobacteria

Answer 18

Paleoarchean (3.6–3.2 Ga)
~3.5 Ga:

Question 19

Layers of compacted sand and microorganisms created by photosynthetic
microorganisms such as cyanobacteria or sulfate-reducing bacteria

Answer 19

3.48 Ga Stromatolites:

Question 20

Oldest fossils of methane-producing archaean microbes

Answer 20

3.42 Ga fossil threads:

Question 21

Rocks have Sulfur- isotope ratios indicative of microbial sulfate reduction

Answer 21

3.48 Ga Sulfides:

Question 22

ATP production that uses sulfate as a terminal
electron acceptor, reducing it to hydrogen sulfide (H2S)

Answer 22

3.4 Ga Microbial sulfate reduction:

Question 23

Iron sulfide associated with biology because most is produced by bacteria that extract their oxygen from sulfate and produce hydrogen.

Answer 23

Pyrite (FeS₂):

Question 24

Reduces atmospheric N2 to organic NH4.

Answer 24

3.2 Ga (minimum) Biological Nitrogen fixation:

Question 25

The key enzyme for biological nitrogen fixation, the only mechanism capable of catalyzing the
reduction of atmospheric N2 into fixed nitrogen known to have evolved

Answer 25

3.2 Ga Nitrogenase evolved:

Question 26

Oldest fossils of methane-producing archaean microbes

Answer 26

3.42 Ga fossil threads:

Question 27

Cellular respiration in
which the terminal electron acceptor is carbon (CH4)

Answer 27

Methanogenesis:

Question 28

Anaerobic archaea that produce methane as a byproduct of their energy
metabolism

Answer 28

Methanogens:

Question 29

First evidence of photosynthetic production of O2

Answer 29

Mesoarchean (3.2–2.8 Ga):

Question 30

Carbon dioxide and nitrogen dominate, shrinking amounts of methane,
ammonia, with the beginnings of free oxyge

Answer 30

Mesoarchean atmosphere:

Question 31

Second supercontinent formed when multiple cratons fused with Vaalbara

Answer 31

3.0 – 2.8 Ga Ur Supercontinent:

Question 32

Isotopic composition of rocks confirms O2 was present

Answer 32

3.2-2.8Ga Photosynthetic production of O2:

Question 33

Group of bacteria that obtain energy via oxygenic photosynthesis

Answer 33

Cyanobacteria

Question 34

suggests oxygenic
photosynthesis may have begun as early as 3.4 Ga

Answer 34

Cyanobacteria Phlogenetic anaylysis

Question 35

First truly large supercontinent “Kenorland”, evidence of Eukaryotes.

Answer 35

Neoarchean (2.8–2.5 Ga):

Question 36

First truly large supercontinent that spanned from northern to
southern latitudes

Answer 36

2.7 – 2.4 Kenorland supercontinent:

Question 37

Ammonia (NH4)from nitrogen fixation is
aerobically (using oxygen) oxidized by nitrifying microbes to nitrite (NO2-) or nitrate (NO3-)

Answer 37

2.7 Ga Aerobic Nitrogen metabolism:

Question 38

Strongly negative 15N values in carbonate sediments indicate
the generation of biomass from assimilation of NH4, in mildly-oxygenated aquatic settings

Answer 38

2.7 Ga Aerobic Nitrogen metabolism:

Question 39

Large cells engulfed independent mitochondria and became reliant on their
processes

Answer 39

Endosymbiosis:

Question 40

DNA is packaged within the nucleus, however mitochondria have their
own circular DNA revealing bacterial ancestry

Answer 40

Mitochondrial DNA:

Question 41

Possibly the bacteria most closely related to mitochondria.

Answer 41

Iodidimonas:

Question 42

Most phylogenetic analysis puts it as the most closely related bacterium to mitochondria.

Answer 42

Rickettsiales bacterium: