International Board of Certified Lactation Consultant (IBCLC) Practice Exam

What two sugars compose lactose?

1. Glucose and fructose

2. Glucose and sucrose

3. Glucose and galactose

4. Galactose and mannose

The correct answer is: Glucose and galactose

Lactose is a disaccharide sugar composed of two monosaccharides: glucose and galactose. This sugar is primarily found in milk and dairy products and is significant in the diet of infants and young mammals, providing essential energy. Glucose is a simple sugar that serves as a primary energy source for the body's cells, while galactose is another monosaccharide that the body can convert into glucose. When lactose is digested, it is broken down by the enzyme lactase into these two component sugars, allowing for absorption in the intestines and utilization by the body. The other options do not represent the correct composition of lactose. Sucrose, for example, is composed of glucose and fructose, while mannose is a different type of sugar not involved in the composition of lactose at all. Understanding the correct sugars that form lactose is important for recognizing its role in nutrition and metabolism, particularly in contexts such as infant feeding and digestive health.