Which process involves the breakdown of large, insoluble food molecules into smaller, soluble ones?

The process that involves the breakdown of large, insoluble food molecules into smaller, soluble ones is digestion. During digestion, complex food substances, such as proteins, carbohydrates, and fats, are broken down by various enzymes into simpler, more absorbable forms. For example, proteins are split into amino acids, carbohydrates into simple sugars, and fats into fatty acids and glycerol. This breakdown is essential because the smaller, soluble molecules can then be easily absorbed into the bloodstream through the walls of the intestines, allowing the body to utilize the nutrients.

Other processes like absorption, metabolism, and fermentation play different roles. Absorption refers specifically to the process through which the smaller, soluble molecules created by digestion enter the bloodstream. Metabolism involves the chemical reactions that occur within the body to maintain life, including the conversion of digested nutrients into energy, but it does not specifically refer to the breakdown of food. Fermentation is a specific type of anaerobic respiration that occurs in some microorganisms and involves the conversion of sugars into acids, gases, or alcohol, which is not directly related to the breakdown of food molecules in the digestive system.