CHAPTER 12History of Life on Earth 251
Quick Review Looking Ahead
Answer the following without referring
to earlier sections of your book.
1.Comparethe structure of proteins, lipids, and
nucleic acids. (Chapter 2, Section 3)
2.Describethe role of enzymes in catalyzing
chemical reactions. (Chapter 2, Section 4)
3.Contrastprokaryotes and eukaryotes.
(Chapter 3, Section 2)
4.Identifythe structure and function of
chloroplasts and mitochondria. (Chapter 3,
Section 3)
5.Summarizethe role of DNA in heredity.
(Chapter 9, Section 1)
Did you have difficulty? For help, review the
sections indicated.Section 1
How Did Life Begin?
The Age of Earth
Formation of the Basic Chemicals of Life
Precursors of the First CellsSection 2
The Evolution of Cellular Life
The Evolution of Prokaryotes
The Evolution of Eukaryotes
Multicellularity
Mass ExtinctionsSection 3
Life Invaded the Land
The Ozone Layer
Plants and Fungi on Land
Arthropods
Vertebrateshttp://www.scilinks.org
National Science Teachers Association sciLINKS Internet
resources are located throughout this chapter.Reading Activity
Before you begin to read this chapter, write
down all of the key words for each section of
the chapter. Then, write a definition next to each
word that you have heard of. As you read the
chapter, write definitions next to the words that
you did not previously know, and modify as
needed your original definitions of words
familiar to you.Billions of years ago, the combination of simple
molecules and energy from sources such as lightning
may have given rise to the complex organic molecules
necessary for life.History of Life
on Earth
CHAPTER
12
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