The Survival of Pyrite Grains Transported in Streams Along with Other

question 26

Multiple Choice

The survival of pyrite grains transported in streams along with other Archean sediments shows us that bacteria-produced oxygen was

• A) very rapidly building in the early atmosphere.
• B) being taken out of the atmosphere by chemical sinks in early Earth.
• C) not yet forming and would require more time for evolution to change that fact.
• D) no match for the vast quantities of oxygen produced in other ways.

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Definitions:

Astrocytes

Star-shaped glial cells in the brain and spinal cord, involved in physical support and maintenance of the blood-brain barrier.

Blood-Brain Barrier

A selective barrier that prevents certain substances from entering the brain from the blood.

Autonomic Nervous System

The part of the nervous system that controls involuntary actions of the body, such as heart rate and digestion.

Motor Fibers

Nerve fibers that transmit impulses from the nervous system to muscles, causing them to contract.