Download 1. Relative dating is using comparison to date rocks or fossils. Law

Evolution Review Sheet Answer Key
4.5.2017
1. Relative dating is using comparison to date rocks or fossils. Law of superposition and
index fossils are both examples of relative dating. Relative dating provides an estimate
of age versus absolute dating that gives an exact age based on radioactive decay of
Carbon-14 or Uranium-235. Absolute dating is the most exact method for determining
age of geologic samples.
2. Trilobites and ammonites are both index fossils because they both lived on multiple
continents and existed for a short amount of time.
3. A half-life is the amount of time it takes for one-half of a radioactive isotope to decay or
break down. Carbon-14, Uranium-235, Plutonium-238
4. The question asks how much of a 96 g sample will be left after 8.1 days when the halflife is 2.7 days. 3 half-lives of gold go by in 8.1 days.
# of Halflives
0
1
2
3
Time
Amount
0-2.6
2.7
5.4
8.1
96g
48g
24g
12g
5. The theory of continental drift is Alfred Wegener’s theory that the Earth is made of
plates that move, or “drift” over time. The theory suggests the continents were all once
together as Pangea. The puzzle-like fit of continents, fossils of plants and animals found
at the boundaries of continents that are now apart, and the magnetic reversals on the
sea-floor at points of sea-floor spreading are all evidence for continental drift.
6. An ice core is a cylinder of ice drilled from the Antarctic or Greenland ice sheets. Ice
cores have dissolved gases trapped inside. Scientists are able to study the gases in the
ice cores to understand past climate (weather) conditions.
7. Genetic variation naturally occurs as genes combine or mutate, there is variation among
organisms. When variation or mutation gives an organism an advantage for survival,
then that organism is more “fit” for its environment. When an environment changes
and the more fit organisms survive, that is survival of the fittest.
8. Homologous structures are when organisms have anatomical features that have the
same structure even though they may have a different function. The wings of a bat, legs
of a cat, and human arms are all examples. Homologous structures indicate common
ancestry.
9. Genetic variation is when there is naturally occurring variation in a population due to
the way genes combine (dominant and recessive) or mutations. Examples of variation
are: eye color, hair color, freckles, face shape, stripes, dimples
10. The law of superposition says that youngest rocks or fossils are found in the top rock
layers, oldest at the bottom.
11. A, B, and C are all rock layers. D is a fault. E is an intrusion.
Evolution Review Sheet Answer Key
4.5.2017
B, A, C, E, D
12. An analogous structure is when organisms have features that serve the same purpose
but their structure or the way they are built is different.
Bird and butterfly wings; fins and flippers on fish or whales
13.
Time Period
Pre-Cambrian
Paleozoic
Mesozoic
Cenozoic Era
Biotic
First signs of bacteria/life
Abiotic
Pangea/supercontinent was all
one
Beginning of Earth
Earth largely aquatic habitat
Age of Invertebrates
(lots o’ fish!)
Trilobites & ammonites
Dinosaurs Roar!
Mammals appeared! Age of
Mammals!
Extinction believed to be due to
asteroid impact that blocked
sunlight.
Pangea splits
Ice Age
Current time!
14. There are THREE types of plate boundaries: divergent is where sea-floor spreading
occurs, convergent forms mountains and mountain ranges, transform faults cause
earthquakes.
15.
Example
Carbon-14
Ice cores
Index fossils
Type of Dating
Absolute
Relative
Relative
Uranium
Absolute
Rock layers
Relative
Description
Used for dating living things
Tells of past climate and atmosphere
Used for relative dating. Trilobites
and ammonites
Really long half-life; used to date
older materials
Youngest on the top; oldest on
bottom