Other Chapters' Lyrics:
Earth Science 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 -:- Life Science 1 - 2 - 3 - 3b - 4 - 4b - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 -:- Physical Science 3
Other Chapters' Notes:
Earth Science 1 - 2 - 3 - 4 - 5 - 6 - 7 - 8 - 9 - 10 - 11 -:- Life Science 1 - 2 - 3 - 3b - 4 - 4b - 5 - 6 - 7 - 8 - 9 - 10 - 11 - 12 -:- Physical Science 3
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Life Science Chapter 8 - Summary Notes
The development of life:
- Some scientists believe life began when a high energy reaction involving water, minerals, and gases formed complex molecules to support life.
- Eventually these molecules became the first true cells, and they were prokaryotes: cells without a nucleus.
- Cyanobacteria were the first prokaryotes to use sunlight, and through photosynthesis they introduced oxygen to Earth.
- Eventually eukaryotes, which have nuclei in their cells, came about. Humans are eukaryotes.
- The early eukaryotes eventually moved from water onto land. Some of them became dinosaurs.
Humans:
- Humans are a very recent addition to the geologic time scale. We are classified as primates, which also includes apes and monkeys.
- We are separate from those other primates and classified in a family called “hominid.”
The geologic record and Pangaea:
- Paleontologists use fossils to reconstruct the history of life from millions of years back.
- Relative dating examines cross sections of sedimentary rock. The oldest fossils are at the bottom and the newest at the top.
- Atoms gradually go from unstable to stable states. Absolute dating measures age by looking at how many atoms are unstable in a fossil.
- The geologic time scale is like a 4.6 billion year calendar that covers the entire duration of life on Earth.
- When a species dies out completely, it becomes extinct. There were times in Earth’s history when many species died at the same time. These periods are called mass extinctions.
- The earth’s crust is broken into huge moving pieces called tectonic plates.
- All of the land on earth was once united in one giant continent called Pangaea before they were separated by the movement of tectonic plates.