Massachusetts Comprehensive Assessment System (MCAS) Biology Practice Test

What is the sequence of events that occurs in the digestive system from food intake to waste elimination?

1. Mechanical breakdown, transportation, chemical breakdown, absorption, elimination

2. Transportation, elimination, absorption, chemical breakdown, mechanical breakdown

3. Mechanical breakdown, chemical breakdown, absorption, transportation, elimination

4. Mechanical breakdown, transportation, chemical breakdown, absorption, elimination

The correct answer is: Mechanical breakdown, transportation, chemical breakdown, absorption, elimination

The sequence of events in the digestive system is best captured by the chosen answer, which accurately reflects the physiological processes involved in digestion. Initially, the mechanical breakdown of food occurs as it is chewed and mixed with saliva in the mouth, which begins the process of digestion. This action prepares the food for further processing and increases its surface area for enzymes to act upon. Following mechanical breakdown, the food is transported through the esophagus to the stomach, where it continues to undergo both mechanical and chemical breakdown. In the stomach, gastric juices further digest the food chemically, breaking it down into a semi-liquid state known as chyme. Next, absorption occurs primarily in the small intestine. Here, nutrients from the digested food pass through the intestinal walls into the bloodstream, providing the body with essential nutrients needed for energy, growth, and cell repair. Finally, any remaining undigested material and waste products are transported to the large intestine, where water is reabsorbed, and the waste is eventually eliminated from the body through the rectum and anus. This sequence – mechanical breakdown, transportation, chemical breakdown, absorption, and elimination – accurately depicts the flow of food through the digestive system, highlighting the critical processes involved in nutrient extraction and waste disposal. Understanding