Observations from plant breeding and animal husbandry over thousands of years has shown:
variations are limited to the confines of a particular taxon
step by step transitions between divisions or phyla have occurred
variation is the result of evolution from one species to another
observable changes from one basic kind into another have never been documented

when you breathe in, or inhale, your diaphragm contracts (tightens) and moves downward. this increases the space in your chest cavity, into which your lungs expand. the intercostal muscles between your ribs also enlarge the chest cavity. they contract to pull your rib cage both upward and outward when you inhale.

sex cells are usually half's then they find another half and make a fertilize egg

igneous rocks are formed by solidification of cooled magma (molten rock), with or without crystallization, either below the surface as intrusive (plutonic) rocks or on the surface as extrusive (volcanic) rocks.  

the composition depends on the source magma. there are almost a thousand types of composition found till now.  

hope this