1. which of the following traits is not characteristic of animals?
multicellular body structure
composed of cells with cell walls
heterotrophic food-getting pattern
composed of eukaryotic cells
2. which of the following describes the most important difference between invertebrates and vertebrates?
vertebrates contain multiple tissues, while invertebrates do not.
invertebrates contain multiple tissues, while vertebrates do not.
vertebrates contain a backbone, while invertebrates do not.
invertebrates contain a backbone, while vertebrates do not.

did you fail the test? xd

the relative atomic mass of an element is the mass of one atom of that element, relative to 1/12th of the mass of a  1212c atom. to convert to an absolute mass in kg, it is necessary to multiply by  1.661×10−271.661×10−27.

the relative atomic mass is roughly equal to the number of neutrons, plus the number of protons, in the nucleus of the atom.

for elements with more than one stable isotope (different types of nucleus with different numbers of neutrons but the same number of protons), the quoted mass is usually the average mass, weighted by the relative abundance of the different isotopes.