Based on scientific research, which statement best describes mutations? a. mutations are rare occurrences. b. mutations are always harmful. c. mutations cannot be inherited. d. mutations cannot be acquired.

The circles, or orbits, for electrons are called energy levels. each level can hold only a certain number of electrons. add electrons to each level until you can't add any more. how many electrons can each level hold?

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.

Which event would lead to primary succession of a forest?