Final answer:
Chemical digestion transforms the carbohydrates in the saltine into smaller molecules like glucose through the enzyme amylase, with the solid cracker becoming a paste as a result.
Step-by-step explanation:
While Monica was chewing the saltine, a process called chemical digestion occurred. This process involves breaking down large molecules of food into smaller molecules that can be absorbed by the body. The saltine contains carbohydrates, which are one of the four major classes of biological macromolecules, alongside lipids, proteins, and nucleic acids.
Initiated in the mouth, the enzyme amylase begins the digestion of the starch in the saltine. Amylase catalyzes the breakdown of carbohydrates by hydrolysis, where a water molecule is added across the bonds linking monomers (in this case, glucose units) in the polymer (starch) to break them. This reaction cuts the long starch molecules into shorter sugar chains, and eventually into individual glucose molecules, which Monica perceives as a sweet taste. The initially solid cracker becomes a sticky paste as it is saturated with saliva and mechanically broken down by chewing, facilitating the action of amylase.
The presence of an easily digestible polysaccharide like starch in saltines explains why the cracker dissolves so quickly in the mouth. The process is an example of how hydrolysis reactions, assisted by enzymes, are essential for converting the energy stored in food into forms that the body can absorb and utilize.