Final answer:
Peristalsis is the process of muscle contractions that move food in a wave-like fashion down the digestive tract, which is crucial for proper digestion and nutrient absorption.
Step-by-step explanation:
A series of muscle contractions that transports food down the digestive tract in a wave-like fashion describes peristalsis. This involuntary process is essential for moving food through the gastrointestinal tract. Peristalsis is made up of alternating waves of muscle contraction and relaxation, which pushes the food ahead and mixes it with digestive juices. This process is critical as it ensures that food moves in the right direction and nutrients are properly absorbed.