Final answer:
The most true statement is B), highlighting that hydroxyl groups on monosaccharides are reactive and can be chemically modified, facilitating the formation of disaccharides through dehydration synthesis and glycosidic bonds.
Step-by-step explanation:
The statement that is most true among those provided is B) The hydroxyl groups on monosaccharides are reaction hot spots and can be replaced by other functional groups to produce derivatives of the original sugar. Monosaccharides contain multiple hydroxyl (-OH) groups that can participate in chemical reactions, making them reactive. These reactions can include the formation of glycosidic bonds during dehydration synthesis, where two monosaccharides combine to form a disaccharide with the release of a water molecule.
An example of this is the formation of a glycosidic bond in disaccharides like sucrose, lactose, and maltose. The other options are incorrect: A) A disaccharide consists of two monosaccharides linked by a glycosidic bond, not a sugar linked to another molecule like an amino acid or nucleotide. C) The presence of double bonds in the hydrocarbon tail of a fatty acid greatly influences its structure, as it can alter the fatty acid's melting point and chemistry.