Complete the following statements by writing the appropriate word or phrase on the blank: The superficial region of the skin is the , composed of (3 words) tissue. The deeper region tissue is the , composed of connective tissue. The most numerous cell of the epidermis is the . The two primary layers of the dermis are the dermis, composed of areolar connective tissue, and the dermis, composed of dense irregular connective tissue.

epidermis, stratified squamous epithelium, dermis, keratinocyte

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.