Earth Is Approximately How Old

question 42

Multiple Choice

Earth is approximately how old?

• A)14 billion years
• B)4.54 billion years
• C)40 million years
• D)6,000 years

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Definitions:

Meninges

The three layers of protective tissue called the dura mater, arachnoid mater, and pia mater that encase the brain and spinal cord.

Myelin Sheaths

Protective coverings around nerve fibers that facilitate the rapid transmission of neural signals.

Synaptic Vesicles

Small sacs within a neuron that store neurotransmitters, which are chemicals released to communicate with adjoining neurons at a synapse.

Dopamine System

A neural system involved in reward, motivation, and the regulation of mood, whose key neurotransmitter is dopamine.