Because it repeats the same process over and over again.
So we can tell how many times a heart beats per second
The answer is a haemoccult test. This test involves laboratory testing of three consecutive stool samples for the presence of blood which is invisible to the eye (occult blood). Presence of blood in the stool, however, does not necessarily mean that a person has colorectal cancer.
A phylum has more biodiversity because class is what narrows the phyla down even more. ( The order of largest biodiversity to smallest biodiversity is domain, kingdom, phylum, class, order, genus, species)