Action potentials carried to the heart by means of fibers that secrete acetylcholine are

How is ribosomal rna useful as a molecular clock? a. a large portion of the dna ring is not vital to structure or function, allowing it to accumulate neutral mutations. b. its rate of mutation increases over time as organisms continue to evolve and differentiate from each other. c. a slow mutation rate makes it useful for determining evolutionary relationships between ancient species. d. it is only found in select organisms, making it easier to compare relationships between species that have it.

What is the difference between how ionic and covalent bonds form

An animal cell (left) and a plant cell (right) are shown.which organelle, labeled x in the diagram, is found in both plant and animal cells?