All life forms currently have a basic cell membrane so we presume that the earliest forms of life had this "fence" isolating the internal organization from the external chaos. It is likely that the primordial environment was acidic. In order for a cell to function in this type of environment, the cell membrane would have to include A) a sodium (Na⁺) pump. B) a proton (H⁺) pump. C) mitochondria underneath in order to provide energy for active transport. D) an acid-proof cell wall. E) a totally nonpermeable membrane.

Question

Quizplus · Accepted Answer

In an acidic environment, the concentration of protons (H+) is high outside the cell. To maintain a stable internal environment, the cell membrane would need to actively transport protons out of the cell, which would require a proton pump. Therefore, (B) is the best choice. A sodium pump (A) would not be necessary in an acidic environment, and (C) and (D) are not relevant to the question. A totally nonpermeable membrane (E) would be detrimental, as the cell needs to allow certain molecules to pass through in order to function.

All Life Forms Currently Have a Basic Cell Membrane So