Which of the following best describes mechanical digestion?

• A. The absorption of nutrients through the intestinal wall.
• B. The transport of digested food molecules into the bloodstream.
• C. The physical breakdown of food into smaller pieces without changing its chemical structure.
• D. The enzymatic conversion of macromolecules into their monomer components.

Answer: (C)

Verified step by step guidance

1. Understand the concept of mechanical digestion: Mechanical digestion refers to the physical breakdown of food into smaller pieces without altering its chemical structure. This process prepares food for further enzymatic digestion.
2. Identify examples of mechanical digestion: Common examples include chewing (mastication) in the mouth and the churning of food by the stomach muscles.
3. Differentiate mechanical digestion from chemical digestion: Chemical digestion involves enzymatic reactions that break down macromolecules (e.g., proteins, carbohydrates, lipids) into their monomer components, whereas mechanical digestion does not involve chemical changes.
4. Analyze the options provided: Eliminate choices that describe chemical digestion (e.g., enzymatic conversion of macromolecules) or absorption processes (e.g., transport of nutrients into the bloodstream). Focus on the option that describes physical breakdown.
5. Select the correct answer: Based on the definition and examples, the correct description of mechanical digestion is 'The physical breakdown of food into smaller pieces without changing its chemical structure.'