A theory by which prokaryotes gave rise to the first eukaryotic cells. Chloroplasts in plants and mitochondrion in other eukaryotes are believed to have once been prokaryotic organisms engulfed by larger prokaryotic cells.

oxygen is the first element in group 16 (via) of the periodic table. the periodic table is a chart that shows how chemical elements are related to each other. the elements in group 16 are said to belong to the chalcogen family. other elements in this group include  sulfur, selenium, tellurium,  and  polonium.  the name chalcogen comes from the greek word  chalkos,  meaning "ore." the first two members of the family, oxygen and sulfur, are found in most ores.

oxygen is by far the most abundant element in the earth's crust. nearly half of all the atoms in the earth are oxygen atoms. oxygen also makes up about one-fifth of the earth's atmosphere. nearly 90 percent of the weight of the oceans is due to oxygen. in addition, oxygen is thought to be the third most abundant element in the universe and in the solar system.

answer///africa and asia;

registered nurse (rn): the rn is responsible for carrying out both the medical plan of care prescribed by the physician as well as the nursing care plan developed by the nursing staff. the rn assesses each resident and modifies the nursing care as needed to meet the patient's needs.