How many red blood cells does an adult male have, under normal circumstances

Which element provides strength to the exoskeleton of clams and oysters

The body is protected against harmful flu viruses by

What do all macromolecules have in common with each other? oa. they all are formed from the same elements. ob. they all have major roles in cell membranesoc. they all act as catalysts in the body. od. they all have peptide bonds between carbon atoms.