In a multicellular organism, life begins as a single cell until occurs causing growth

Consider the model of the oxygen cycle on earth. the majority of earth's oxygen reservoirs are found in the a) atmosphere. b) biosphere. c) hydrosphere. d) lithosphere.

Predict the results of a two base insertion or deletion in a strand of dna that codes for a protien, how does this differ from a three base insertion or deletion?

Ecologist have observed a sharp increase of sulfur dioxide in the air . what might be a possible consequence of excessive sulfur dioxide in the air ? a. acid rain b. ozone layer depletion c.ozone layer hole d.increase in sea levels