Most animal cell membranes have proteins that pump ions out of the cell and potassium ions into the cell.

Scientists discovered fossils in several layers of the earth you see here. they found fossils of algae, snails, and clams in layer d. given that information, where do you think they found fossil evidence of simple land plants and amphibians?

Viruses such as hiv reproduce rapidly. what is the connection between reproduction rate and evolution?

What are the wavelike contractions of smooth muscle that move food down the esophagus called