How is air like water in science ​

Water acts like air, according to Bernoulli's principle, because both are fluids. Bernoulli's principle can be applied to various types of fluid flow. Bernoulli's principle is valid for incompressible flows (e.g. most liquid flows like water) and compressible flows (e.g. gases like air) moving at low Mach numbers.
Plus they both help you with living.

It should be cryosphere and hydrosphere

Cell division is important to single celled organisms because it allows the cells to reproduce. through cell division, cells make exact copies of themselves. when single celled organisms go through cell division, they make exact copies of themselves which is how they reproduce.