Are especially important because they are involved in a variety of processes, such as cell signaling, immune response, and enzyme activity.
a.
nucleic acids
b.
carbohydrates
c.
proteins
d.
lipids

How does oxygen move from the respiratory system to the circulatory system? a. by pumping through the heart b. by circulating in an artery c. by moving across a synapse d. by diffusion across a capillary wall

What are charcteristics of lithosphere?

According to the cell theory, which describes cells? a. all organisms are composed of multiple cells. b. all cells have the same structure and function. c. cells are found in everything on earth. d. living organisms are not created spontaneously