Which statement about water is correct?
a. the atoms within a molecule of water are held together by hydrogen bonds.
b. water has a low heat capacity allowing enzymatic reactions to happen at a wide range of temperatures.
c. water molecules are polar, therefore fatty acids do not dissolve.
d. ice has a higher density than liquid water, therefore some organisms can live under the ice.

both anaerobic and aerobic respiration use glucose (or other carbohydrates), proteins and lipids to produce atp and nadh. cell uses those energy molecules, obtained from food and   breaks them down during the chemical reactions of respiration. in anaerobic respiration, nadh is regenerated to nad+ by enzymes lactate dehydrogenase (lactate is produced, e.g. in muscle cells) or by alcohol dehydrogenase where ethanol is produced (alcohol fermentation), while in aerobic respiration, electrons from nadh are deposited in the mitochondria to regenerate nad+ (electron transport chain. anaerobic respiration produces 2 atp per molecule of glucose compared to aerobic respiration where about 38 atp molecules are produced.