Why Did the Oxygen Content of the Atmosphere Increase Dramatically

question 8

Multiple Choice

Why did the oxygen content of the atmosphere increase dramatically 2.5 billion years ago?

• A) The first life appeared on Earth.
• B) The sea and earth became saturated with oxygen.
• C) The Late Heavy Bombardment occurred.
• D) The Cambrian explosion led to diverse plant life.

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Definitions:

Extrinsic Eye Muscles

The skeletal muscles that move the eyeball.

Suspensory Ligaments

Fibrous tissues that support an organ or structure, such as the lens of the eye.

Eyeball

The spherical part of the eye that contains the optic nerve, retina, and lens, responsible for receiving and processing light for vision.

Orbicularis Oculi

The muscle in the eyelid responsible for blinking.