The study of animals' structures, behaviors, functions, and evolution is called one from the choices given: ethology. zoology. biology. physiology.

Zoology is the branch in which all these aspects been studied.

A liquid that can easily pass through cell membranes is water. That is what is used in determining the concentration of the solute inside a living cell. You can place the cells in different osmotic environments. Then you observe and determine the environment that causes no uptake of water.