Explain why arteries and veins are defined by the direction in which they carry blood rather than by the blood composition

not too sure but maybe in the hot springs.

answer: substrate concentration. enzymes work best when there is a high enough substrate concentration for the reaction they catalyse.

the "power" of a lens is its resolution power, or its ability to distinguish between to closely located points. with the low power lens, it is likely you will see the rough form of the hay and maybe some movement of dots around the hay. however, when observed with the high power lens, the detailed features of the hay become visible and the microbes being grown are more clearly visible.

i hope this you