The Extent to Which Mars Has Been Habitable Essentially Boils

question 101

Multiple Choice

The extent to which Mars has been habitable essentially boils down to the

• A) question of whether liquid water has ever been present on its surface
• B) question of whether oceans of liquid water have existed on its surface
• C) amount of water that has been present on its surface
• D) length of time liquid water has been present at or below its surface

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Definitions:

Gills

Respiratory organs found in many aquatic organisms, which extract oxygen from water and expel carbon dioxide.

Lungs

Organs of respiration in vertebrates where blood exchanges oxygen and carbon dioxide with the air breathed in.

Gas Exchange

The biological process through which organisms exchange oxygen and carbon dioxide with their surroundings, essential for respiration.

Buoyancy Of Water

The upward force exerted by water that opposes the weight of an object immersed in it, allowing it to float or seem lighter.