Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

Which main process can be described as the mechanical breakdown of food in the human body?

1. Absorption

2. Digestion

3. Ingestion

4. Elimination

The correct answer is: Digestion

Digestion is the main process that encompasses the mechanical breakdown of food within the human body. This process not only involves the physical breakdown of food into smaller pieces, which makes it easier for enzymes to act on them, but also involves a series of chemical reactions. During digestion, food is mixed and crushed in the mouth through chewing, and then in the stomach through churning actions, which prepares it for further breakdown and nutrient absorption in the intestines. This dual role of mechanical and chemical processing is essential for efficiently converting food into nutrients that the body can utilize. The other processes listed have different roles in the digestive system. While absorption refers to the process where nutrients are taken into the bloodstream from the digestive tract, ingestion is the act of taking food into the body. Elimination is the final stage, whereby waste products are expelled from the body after the nutrients have been absorbed. Thus, digestion specifically highlights the essential role of breaking down food for nutrient acquisition.