edHelper.com
Life Science

The Beginning of Life on Earth

The Beginning of Life on Earth
Reading Level
     edHelper's suggested reading level:   high interest, readability grades 6 to 8
     Flesch-Kincaid grade level:   5.77

Vocabulary
     challenging words:    methane, amino, atmospheric, enzyme, prokaryotes, nucleus, magma, characteristic, ammonia, heated, billion, theory, environment, reproduce, primitive, life
     content words:    Monera Kingdom

Print The Beginning of Life on Earth
edHelper.com subscriber options:
     Print The Beginning of Life on Earth  (font options, pick words for additional puzzles, and more)
     Quickly print reading comprehension
     Print a proofreading activity

Feedback on The Beginning of Life on Earth
     Leave your feedback on The Beginning of Life on Earth  (use this link if you found an error in the story)

The Beginning of Life on Earth
By Patti Hutchison 		  
1     When did life begin on earth? We know it did not begin when the earth was formed 4.6 billion years ago. The earth was constantly being struck by meteorites at that time. Also, there was no oxygen in the air. The first fossils of life were formed about 3.5 billion years ago. This makes scientists believe the first life began between 3.9 and 3.5 billion years ago.
 
2     Scientists believe that a kind of atmospheric "soup" of hydrogen, ammonia, and methane reacted when lightning struck them. They formed the building blocks of life. These building blocks are called amino acids. They form proteins. Proteins are the basic substances of living things.
 
3     Proteins were the first step. Other substances needed are DNA and RNA. These substances allow living things to reproduce. This is a basic characteristic of living things.
 
4     DNA carries the instructions for cell function. RNA can act as an enzyme that also helps cells function.
 
5     Some scientists believe that life began deep under the sea near hydrothermal vents. Here, ocean water seeps through the cracks in the ocean floor. The water is heated by the magma. It rises through the ocean. All of the energy and nutrients needed for life are found near these hydrothermal vents.

Paragraphs 6 to 11:
For the complete story with questions: click here for printable
Copyright © 2008 edHelper