Proton pumps are used in various ways by members of every kingdom of organisms. What does this most probably mean?
A)
Proton pumps must have evolved before any living organisms were present on the earth.
B)
Proton pumps are fundamental to all cell types.
C)
The high concentration of protons in the ancient atmosphere must have necessitated a pump mechanism.
D)
Cells with proton pumps were maintained in each Kingdom by natural selection.
E)
Proton pumps are necessary to all cell membranes.
Answer: D