For water to travel across the cell membrane at a substantial rate, the water molecules travel through protein channels known as aquaporins.

Groups of organisms with low biotic potential, such as gray whales, that produce at most one offspring every other year a) are r-selected b) are k-selected c) are not subject to density-dependent limiting factors d) show the initial stages of the extinction process e) have escaped from the processes of natural selection and adaptation

According to the big bang theory, after the "bang," the universe remained dark until about  300,000 yearsone billion yearsthree minutesthree billion years  later, when neutral atoms began to form.

Heat from earths interior and pressure from overlying rock transform the remains of marine sediments into