Earth History 870:035
Fall, 2006
Exam 2
Name: _______________________
Part 1 (3 pts each)
Read each question carefully and then consult the list of possible answers on the following page. Fill in the
number associated with the correct answer.
Answers
Questions
_____
1. During photosynthesis, plants utilize a slightly larger proportion of 12C relative to 13C than the
proportion of 12C to 13C found in the atmosphere. The preferential use of one isotope over another
is known as ______.
2. What is the Precambrian portion of North America that is exposed at Earth’s surface?
3. What is the evolution of similar features in two or more unrelated (or distantly related) biological
groups or taxa?
4. What is an elongate or “podlike” body of rock, consisting of metamorphosed volcanic and
sedimentary materials, that is characteristic of Archean terranes?
5. Who was the first person to create amino acids and simple proteins in the lab from a mixture of
water vapor and carbon-, hydrogen- and nitrogen-bearing compounds?
6. What geologic time unit corresponds with the interval from Earth’s origin to about 2.5 billion
years ago?
7. What term is given to the stable interior region of a continent that has not undergone significant
orogenic activity since Precambrian time?
8. When water evaporates, H2O molecules containing 16O evaporate more readily than those
containing 18O, so that water vapor is slightly enriched in isotopically light oxygen. The
preferential evaporation of 16O is an example of what process?
9. What is an event or relatively brief interval of time in which approximately 40% or more of the
known genera become extinct?
10. What name is given to one of the earliest known skeletal fossils, a calcitic tube found in rocks
approximately 570 million years old?
11. What is a nucleic acid that can carry genetic information to sites where proteins are being
formed, and can carry amino acids for the constructions of proteins?
12. What term is given to the idea that eukaryotes may have originated when cytoskeletonbearing prokaryotes engulfed other prokaryotes, which then became internal symbionts?
13. What name is given to the supercontinent that assembled and then fragmented in late
Proterozoic time, approximately 1 billion to 0.8 billion years ago?
14. What is the earliest diverse assemblage of multicellular animals, preserved as impressions in
late Proterozoic rocks of Australia?
15. What is one of two or more varieties of an element that differ in the number of neutrons within
the atomic nucleus?
16. What is a group of eukaryotic planktonic algae that originated in Proterozoic time and became
very diverse in late Proterozoic time?
17. What theory states that most evolutionary change occurs in rapid speciation events, but that
once a species is established it remains relatively unchanged throughout its stratigraphic range?
18. What Proterozoic (~1.2 to 1.0 Ga) tectonic event resulted in continental accretion along the
eastern margin of Laurentia?
19. What is a mafic rock body of Proterozoic age that is associated with the midcontinent rift
(including the subsurface of Iowa)?
20. What term refers to the general tendency for increasing size through time within an evolving
lineage?
_____
_____
_____
_____
_____
_____
_____
_____
_____
_____
_____
_____
_____
_____
_____
_____
_____
_____
_____
1
List of possible answers for questions in Part 1
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
acritarchs
adaptive breakthrough
amino acid
Archean Eon
Baltica
banded iron formation
Canadian shield
chloroplasts
Cloudina
continental accretion
convergence
Cope's rule
craton
cyanobacteria
cytoskeleton
Darwin, Charles
DNA
Ediacara fauna
endosymbiont theory
eukaryote
evolutionary radiation
extinction
fractionation
Gondwanaland
greenstone belt
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
Grenville orogeny
Grenville province
isotope
iterative evolution
Keweenawan basalt
mass extinction
midcontinent rift
Miller, Stanley
mitochondria
partial melting
photosynthesis
phyletic gradualism
phylogeny
prokaryote
protein
Proterozoic Eon
protocontinent
punctuated equilibrium
respiration
RNA
Rodinia
stromatolite
trace fossils
trans-Hudson belt
Urey, Harold
21. Suppose you analyze oxygen isotopes from two samples of marine calcite, one Permian and the other
Pleistocene. You determine that the Permian calcite is much lighter isotopically than the Pleistocene calcite.
Explain how you would interpret this result. (8 pts)
2
22. (a) What is a stromatolite? (b) Explain how stromatolites are formed. (c) Discuss the geologic history of
stromatolites and relate their abundance through time to changes in Earth’s physical and biologic
environment. (12 pts)
23. (a) What is meant by the term “evolutionary radiation?” (b) Give an example of an evolutionary radiation
and discuss the factors that may have facilitated it. (10 pts)
3
24. Discuss the Proterozoic assembly of Laurentia. Include in your answer a description of the main events
that took place, and their approximate dates. (10 pts)
4