Natural populations fluctuate through time. One of the forces causing variation in population size is variation in the physical environment, which can have both direct and indirect effects on populations. Variation in population size linked to environmental factors (aside from those that occur daily or seasonally) is likely to:

A) be predictable and constant.
B) be density-dependent.
C) affect the biotic potential exponentially.
D) be irregular, perhaps even random.
E) track the logistic growth model.

what tree

explanation:

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.

la transducción de señal ocurre cuando una molécula de señalización de fluido extracelular activa un receptor de superficie de la célula.