For About the Last ________ Years, Earth Has Had About

question 82

Multiple Choice

For about the last ________ years, Earth has had about the same balance of chemical components that now persists.

• A) 10,000
• B) 100,000
• C) 1 million
• D) 500 million
• E) 1 billion

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Definitions:

Alveoli

are the tiny air sacs in the lungs where the exchange of oxygen and carbon dioxide takes place.

Gas Exchange

The biological process by which gases (mainly oxygen and carbon dioxide) are transferred between the blood and the external environment during the act of breathing.

Vocal Folds

Muscular membranes in the larynx that produce sound when air is expelled through them, also known as vocal cords.

Glottis

Vocal apparatus; includes vocal folds and the cleft between them.