U 3 L 1 Evolution of the Atmosphere

respiration

the process by which oxygen combines with food to release energy and carbon dioxide

What force keeps our atmosphere from floating out into space?

gravity

meteorite

mass of stone or metal that has passed through the atmosphere and struck the earth's surface

meteoroid

mass of stone or metal traveling through space

The earth has fewer meteorite impacts because_____.

of the earth's atmosphere

photosynthesis

process by which plants use chlorophyll and energy from sunlight to manufacture food from carbon dioxide

cyanobacteria

single-celled photosynthetic bacteria

The first major source of oxygen gas was _____.

cyanobacteria

What would be the result if Earth's unique atmosphere did not exist?

Life would no longer be possible.

The atmosphere has many roles, including:

+provides gases for respiration and photosynthesis +provides food for life +provides protection from UV radiation and meteorites Xprovides a surface to build and live on +stabilizes a habitable temperature

Which of the following factors caused the early atmosphere to become thicker?

+volcanic outgassing +meteorite and comet impacts Xcyanobacteria Xbanded iron formations

ozone

a molecule composed of three oxygen atoms; absorbs UV radiation

In the paleoatmosphere, the primary gases were _____.

carbon dioxide, nitrogen, and water vapor