Question

Students in biology are studying the macromolecules of life. They used a calorimeter to determine the calories in various types of food. Once the lab was completed, the students ate the left over food samples. Monica commented that in just 6 or 7 "chews" of the saltine, it was gone; nothing but a sticky paste in her mouth. Elaborate on what happened chemically while chewing the saltine. Include the macromolecules present.

Answer 1

Three macromolecules are represented. The saltine is a carbohydrate. Nucleic acids direct digestion. Digestion took place in Monica's mouth thanks to enzymes or proteins.

Answer 2

As the epithelial cells in the digestive system can absorb only simpler particles, complex molecules such as proteins, lipids, etc must be broken down.

This process begins with the ingestion of food and takes place in the mouth. Through the combined effects of teeth, saliva and tongue, the food is mechanically broken down and the chemical digestion begins through the enzymes  in the saliva.

Carbohydrates are broken down into maltose and oligosaccharides through the enzyme amylase. The digestion for both proteins and lipids begins in the stomach.

Water soluble vitamins can be directly absorbed into the bloodstream, whereas fat soluble vitamins are absorbed in the same way as lipids.