This topic contains a solution. Click here to go to the answer

Author Question: During the Precambrian, the development of the ozone layer helped A) primitive organisms on ... (Read 35 times)

stephzh

  • Hero Member
  • *****
  • Posts: 556
During the Precambrian, the development of the ozone layer helped
 
  A) primitive organisms on Earth's surface to nucleate.
  B) shield Earth's surface from harmful ultraviolet radiation.
  C) promote the emergence of stromatolites.
  D) promote the development of anaerobic organisms.

Question 2

The oldest known fossils of single-celled organisms are
 
  A) 4.6 billion years old.
  B) 3.9 billion years old.
  C) 3.3-3.5 billion years old.
  D) 1.3-1.5 billion years old.



Related Topics

Need homework help now?

Ask unlimited questions for free

Ask a Question
Marked as best answer by a Subject Expert

blakcmamba

  • Sr. Member
  • ****
  • Posts: 335
Answer to Question 1

Answer: B

Answer to Question 2

Answer: D




stephzh

  • Member
  • Posts: 556
Reply 2 on: Jul 29, 2018
Great answer, keep it coming :)


connor417

  • Member
  • Posts: 329
Reply 3 on: Yesterday
Thanks for the timely response, appreciate it

 

Did you know?

The term pharmacology is derived from the Greek words pharmakon("claim, medicine, poison, or remedy") and logos ("study").

Did you know?

The use of salicylates dates back 2,500 years to Hippocrates’s recommendation of willow bark (from which a salicylate is derived) as an aid to the pains of childbirth. However, overdosage of salicylates can harm body fluids, electrolytes, the CNS, the GI tract, the ears, the lungs, the blood, the liver, and the kidneys and cause coma or death.

Did you know?

More than nineteen million Americans carry the factor V gene that causes blood clots, pulmonary embolism, and heart disease.

Did you know?

Fungal nail infections account for up to 30% of all skin infections. They affect 5% of the general population—mostly people over the age of 70.

Did you know?

Limit intake of red meat and dairy products made with whole milk. Choose skim milk, low-fat or fat-free dairy products. Limit fried food. Use healthy oils when cooking.

For a complete list of videos, visit our video library