Michigan Test for Teacher Certification (MTTC) Secondary Integrated Science Practice test

What function does the digestive system primarily serve?

1. Gas exchange

2. Food breakdown and absorption

3. Protection against pathogens

4. Hormonal regulation

The correct answer is: Food breakdown and absorption

The primary function of the digestive system is food breakdown and absorption. This intricate system is designed to process ingested food, breaking it down into smaller, absorbable units such as nutrients, vitamins, and minerals. These components are then transferred into the bloodstream to provide energy, support growth, and maintain overall bodily functions. The digestive process begins in the mouth, where enzymes in saliva start to break down carbohydrates. It continues in the stomach and small intestine, where further breakdown occurs, aided by various enzymes and digestive acids. The small intestine is particularly important for absorption, as it has a large surface area facilitated by villi and microvilli, allowing for maximum nutrient uptake into the bloodstream. In contrast, the other functions listed pertain to different systems: gas exchange is primarily the role of the respiratory system; protection against pathogens falls under the immune system; and hormonal regulation involves various endocrine glands. Each of these systems has distinct roles that do not involve the digestion or absorption of food, thus clarifying the primary function of the digestive system in contrast to these other bodily processes.