Please answer this scientific question quickly (reposted question)

Match the digestive enzymes to the macromolecules they to digest. break down fats into glycerol and fatty acids break down carbohydrates into simple sugars break down nucleic acids into nitrogenous bases and simple sugars break down proteins into amino acids

Where do the respiratory and circulatory systems meet? a. in the heart b. in the muscles c. in the lungs d. in the brain

Consider the following reaction: 2h2 + o2 —> 2h2o a) what are the reactants in this reaction? b) what are the products in this reaction? c) how many molecules of oxygen are used in this reaction?