Competitive exclusion may be affected by:
a. all of the above
b. disturbances to habitat
c. temperature changes
d. abundance of a resource
e. b and c only

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.

while the heads of the phospholipid structure attract water, the tails are hydrophobic. the model shows how the hydrophilic section folds around the fluid molecules to bring them into the cell so they don’t need to pass through the hydrophobic tails.