The source of the oxygen produced by photosynthesis has been identified through experiments using radioactive tracers. the oxygen comes from

Why are fossils not found in igneous rocks? igneous rocks are made from cooling of lava or magma. igneous rocks are found too deep underground. igneous rocks are too dark in color to contain fossils. igneous rocks are too dense to contain fossils.

2. which is the last step in the scientific method?

Which organs of the urinary system allow you to consciously control when urination will occur? a. kidneys and the urethra b. kidneys and the ureters c. bladder and the urethra d. bladder and the ureters