If a person was unable to break down food particles into molecules that could be absorbed by the body, you would predict

Answer Explanation

A) The stomach - This is an organ of the digestive system. It plays a crucial role in breaking down food through the secretion of gastric juices, which contain enzymes and acids to begin the process of digestion. Therefore, option A is correct.

B) The mouth - The mouth is also an organ of the digestive system. It is where the process of digestion begins, as it is responsible for chewing and breaking down food into smaller pieces. Additionally, saliva produced in the mouth contains enzymes that start the chemical breakdown of food. Therefore, option B is correct.

C) The intestines - Both the small intestine and the large intestine are essential organs of the digestive system. The small intestine is where most of the absorption of nutrients from food occurs, while the large intestine absorbs water and salts from the material that has not been digested. Therefore, option C is correct.

D) The heart - The heart is not an organ of the digestive system. Instead, it is a part of the circulatory system responsible for pumping blood throughout the body. While the circulatory system works in conjunction with the digestive system to transport nutrients absorbed from the intestines to various tissues and organs, the heart itself is not directly involved in digestion. Therefore, option D is incorrect.

Answer Explanation

D) pancreas

- Correct: After food enters the small intestine, lipases (for fat digestion), proteases (for protein digestion), and amylases (for carbohydrate digestion) are secreted into the small intestine by the pancreas. These digestive enzymes are produced by the pancreas and released into the duodenum, which is the first part of the small intestine. The pancreas plays a crucial role in providing these enzymes to aid in the breakdown of macronutrients (fats, proteins, and carbohydrates) into smaller molecules that can be absorbed by the intestinal lining.

A) liver

- Incorrect: The liver produces bile, which is stored in the gallbladder and released into the small intestine to aid in the emulsification of fats. While bile is important for fat digestion, it does not contain lipases, proteases, or amylases.

B) gallbladder

- Incorrect: The gallbladder stores and concentrates bile produced by the liver, but it does not secrete lipases, proteases, or amylases. Bile aids in the emulsification of fats but does not contain digestive enzymes.

C) salivary glands

- Incorrect: Salivary glands secrete saliva into the mouth, which contains amylase, an enzyme that begins the digestion of carbohydrates. However, after food enters the small intestine, digestive enzymes are primarily secreted by the pancreas, not the salivary glands.

Answer Explanation

Enzymes are proteins that catalyze specific biochemical reactions in living organisms.

The production of enzymes is regulated by gene expression, where specific genes are activated (expressed) to produce particular enzymes in different cells or tissues.

In this case, the gene responsible for coding the enzyme pepsin is expressed in the cells of the stomach, leading to the production of pepsin in the stomach.

Conversely, the gene for trypsin is expressed in the cells of the small intestine, resulting in the production of trypsin in the small intestine.

Therefore, the reason that the stomach and small intestine produce different enzymes is due to the differential gene expression in these respective tissues.