The Average Age of the Surface of Venus Has Been

question 79

Multiple Choice

The average age of the surface of Venus has been determined primarily from

• A) the number of impact craters per unit area of surface.
• B) the amount of weathering of lava flows imaged by the Magellan radar mapper.
• C) soil analysis by Russian landers.
• D) radio-isotope analysis of rocks brought back from Venus by space probes.

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Definitions:

Plasma Membrane

The semipermeable membrane surrounding the cytoplasm of a cell, composed of a phospholipid bilayer with embedded proteins.

Concentration Differences

Variations in the amount of a particular substance within a given volume, leading to a gradient that can cause diffusion.

Sodium-Potassium Pump

A membrane-bound ATPase enzyme that pumps sodium out of cells while moving potassium into cells, crucial for maintaining cellular ion balance and membrane potential.

Plasma Membrane

A bi-layer of lipids and proteins that surrounds a cell, controlling the passage of substances in and out of the cell.