Which of the following best describes the structure of DNA?
A. a molecule formed from twenty-three pairs of chromosomes
. B. an amino acid chain formed from a sequence of three nucleotides
C.
a polymer formed from linked subunits of four kinds of nitrogenous bases
D.
a protein formed from a chain of twenty possible amino acids

Abeaker of water was heated and then placed on a bench in the laboratory. the water cooled until it was the same temperature as the air in the laboratory. which of these explains the mechanism by which the water cooled? a. heat energy was transferred from the water to the air. b. water molecules from the water formed warm water currents. c. the water molecules absorbed energy from the molecules in the air. d. the water released radiation until it contained no heat energy.