Biology STAAR Practice Test 2025 – Complete Exam Prep

The primary role of the digestive system is to break down food for nutrient absorption. This system is essential because it transforms the food we consume into smaller, digestible components, allowing the body to absorb nutrients such as carbohydrates, proteins, fats, vitamins, and minerals. These nutrients are vital for energy production, growth, and overall cellular function.

During the digestive process, food is mechanically and chemically processed in various organs, including the mouth, stomach, and intestines. Enzymes produced by the digestive organs play a key role in breaking food down into its simplest forms, which can then be absorbed into the bloodstream and delivered to the body's cells for use.

While the other choices outline important biological functions—delivering oxygen and nutrients through the circulatory system, transmitting signals via the nervous system, and producing hormones through the endocrine system—none are directly related to the primary role of digesting food and facilitating the absorption of nutrients.