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Lecture 4

BIOL 1202 Lecture Notes - Lecture 4: Symbiogenesis, Cyanobacteria, Natural Selection


Department
Biological Sciences
Course Code
BIOL 1202
Professor
Pomarico
Lecture
4

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CHAPTER 25 MASTERING BIOLOGY
1. Why do some scientists believe that RNA, rather than DNA, was the first genetic
material?
a. RNA has both information storage and catalytic properties.
2. Earth probably formed _____ years ago, and the first life evolved as early as _____ years
ago.
a. 4.5 billion years ago, / 3.9 billion years ago
3. How were conditions on the early Earth of more than 3 billion years ago different from
those on today's Earth?
a. Only early earth was intensely bombarded by large space debris
4. Which of the following is the correct sequence of events in the origin of life?
I. formation of protobionts
II. synthesis of organic monomers
III. synthesis of organic polymers
IV. formation of DNA-based genetic systems
a. II, III, I, IV
5. Several scientific laboratories across the globe are involved in research concerning the
origin of life on Earth. Which of these questions is currently the most problematic and
would have the greatest impact on our understanding if we were able to answer it?
a. How did RNA sequences come to carry the code for amino acid sequences?
6. Which measurement(s) would help determine absolute dates by radiometric means?
a. Two of the above are correct
7. Approximately how far back in time does the fossil record extend?
a. 3.5 billion years
8. Which section of sea-floor crust should have the thickest layer of overlying sediment,
assuming a continuous rate of sediment deposition?
The figure represents a cross section of the sea floor through a mid-ocean rift valley, with
alternating patches of black and white indicating sea floor with reversed magnetic
polarities. At the arrow labeled "I" (the rift valley), the igneous rock of the sea floor is so
young that it can be accurately dated using carbon-14 dating. At the arrow labeled "III,"
however, the igneous rock is about 1 million years old, and potassium-40 dating is
typically used to date such rocks. Note: The horizontal arrows indicate the direction of
sea-floor spreading, away from the rift valley.
a.
b. E
9. The earliest organisms were most likely ___.
a. Prokaryotic
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