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Author Question: About 540 million years ago, a sudden increase in biological complexity occurred, known as the ... (Read 128 times)

aabwk4

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on: Jul 27, 2018
About 540 million years ago, a sudden increase in biological complexity occurred, known as the _______________.
 
  Fill in the blank(s) with correct word

Question 2

As Earth evolved with life, an oxygen abundance of only 0.1 percent would have created a(n) _______________, protecting organisms from the Sun's ultraviolet radiation.
 
  Fill in the blank(s) with correct word


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Mollythedog

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Reply #1 on: Jul 27, 2018
Answer to Question 1

Cambrian explosion

Answer to Question 2

ozone layer
ozone screen


aabwk4

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Reply 2 on: Jul 27, 2018
Gracias!

bigcheese9

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Reply 3 on: Yesterday
YES! Correct, THANKS for helping me on my review

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