Chapter 35, Problem 2STP

Summary Introduction

Introduction:

The digestive system breaks down the food so that nutrients can be absorbed by the body. There are three primary functions of the digestive system. The digestive system absorbs food, breaks it down so that nutrients can be absorbed and removes that cannot be digested.

Answer to Problem 2STP

Correct answer:

The correct answer is option (A) 1.

Explanation of Solution

Explanation/justification for the correct answer:

Option (A) 1. The number 1 refers to the mouth. Chemical and mechanical digestion happens first in the mouth. Mechanical digestion requires chewing food to break it down into smaller parts. Chemical digestion requires breaking down large molecules into small molecules that can then be consumed by cells. So, the correct answer is option (A).

Explanation for incorrect answer:

Option (B) 2. The number 2 refers to the esophagus. The esophagus is a muscle tube that binds the pharynx to the stomach. The swallowing reflex is triggered as the tongue moves the chewed food to the back of the mouth. The food is pushed into the upper part of the esophagus by the action of the tongue. So, this is an incorrect answer.

Option (C) The number 3 refers to the stomach. Stomach is the third organ of digestive system where chemical and mechanical digestion occurs. When food passes through the esophagus then it moves into the stomach. So, this is an incorrect answer.

Option (D) The number 4 refers to the small intestine. In the digestive system, small intestine is the longest structure. Mechanical digestion of food occurs in this organ. The smooth muscles in the wall of the small intestine begin the process of mechanical digestion and force the food further into the digestive tract by peristalsis. So, this is an incorrect option.