What does scientists currently use to classify organisms? A. Fossil Records

B. Embryology

C. Biochemical study (DNA)

D. Homologous Structures

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.

When proteins are being produced by a cell, scientist say that the genes are question 2 options: activated turned off replicated deactivated

Vessels draining the myocardium of the heart, open primarily ,into which chamber?