Which disaccharide passes through the human digestive tract without being digested?

The correct response identifies cellulose as a disaccharide that passes through the human digestive tract without being digested. Cellulose is a form of plant fiber and is comprised of long chains of glucose molecules linked together. Humans lack the necessary enzymes, specifically cellulase, to break these bonds; hence, cellulose remains largely undigested as it travels through the gastrointestinal tract. This characteristic allows cellulose to contribute to dietary fiber, aiding in digestive health by promoting regular bowel movements and providing a sense of fullness.

In contrast, sucrose, lactose, and even fructose are breakdown products of carbohydrates that can be digested and absorbed by the human body, contributing to energy. Therefore, while they are important sources of energy in the diet, they do not share the same undigested characteristic as cellulose.