Bio I Ch. 17 Questions
Short Answer
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1.
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Why is the fossil record an incomplete history of life?
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2.
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Why are the divisions of geologic time NOT standard lengths, such as 100 million
years?
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3.
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What was the pattern of mammalian evolution during the Cenozoic Era?
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4.
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How does a study of modern proteinoid microspheres help scientists investigate
the origin of cells?
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5.
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What was the source of the oxygen gas that began to accumulate in the atmosphere
over 2 billion years ago?
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6.
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What are two kinds of information that scientists attempt to infer from the
study of fossils?
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7.
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What information does relative dating provide?
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8.
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Why did oceans not exist on Earth 4 billion years ago?
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9.
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What do the membranes of microspheres and those of cells have in common?
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10.
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What happened to the dinosaurs at the end of the Cretaceous Period?
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Other
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USING SCIENCE SKILLS
Figure 17–1
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11.
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Using Tables and Graphs Use Figure 17-1 to determine the approximate
half-life of carbon-14.
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12.
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Using Tables and Graphs According to Figure 17-1, how many half-lives
have passed if a fossil has 1/8 of its original amount of carbon-14?
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13.
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Using Tables and Graphs A fossil bone was found to contain about 1/16 of
the amount of carbon-14 that was originally present. Use Figure 17-1 to determine the approximate age
of the bone.
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14.
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Inferring According to Figure 17-1, in which case would carbon-14 be more
useful for dating: wooden beams in Native American cave dwellings, which probably are less than 7000
years old, or the fossil of an early mammal that is probably almost 100,000 years old? Explain your
answer.
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15.
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Predicting As carbon-14 decays, it changes to nitrogen-14, which is
released as a gas. Refer to Figure 17-1 to predict how the amount of nitrogen gas produced would
change over the period of radioactive decay. Why does that change take place?
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USING SCIENCE SKILLS
Geologic Time
Scale | Era | Period | End Date
(in millions of
years ago) | | Cenozoic | Quaternary | present | | | Tertiary | 1.8 | | | Mesozoic | Cretaceous | 65 | | | Jurassic | 145 | | | Triassic | 208 | | | Paleozoic | Permian | 245 | | | Carboniferous | 290 | | | Devonian | 360 | | | Silurian | 410 | | | Ordovician | 440 | | | Cambrian | 505 | | | Precambrian Time | Vendian | 544 | | | | | | |
Figure 17–2
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16.
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Interpreting Graphics How many geologic periods are shown in Figure 17-2,
and which is the earliest?
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17.
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Applying Concepts The Paleozoic Era ended with the disappearance of many
land and aquatic species. What is that type of event called? Use Figure 17-2 to name the period in
which that event took place.
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18.
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Calculating Use Figure 17-2 to determine the length in years of the
Devonian Period.
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19.
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Interpreting Graphics The end of the Mesozoic Era marks the extinction of
dinosaurs. How long ago did the dinosaurs become extinct if it happened during the Jurasic
period?
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20.
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Interpreting Graphics The first marsupials, a group that includes the
modern kangaroo, evolved about 150 million years ago. According to Figure 17-2, during which geologic
period did marsupials evolve?
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