The enzyme pepsin is produced in the cells of the stomach but not in the cells of the small intestine. The small intestine produces a different enzyme, trypsin. The reason that the stomach and small intestine produce different enzymes is that the gene that codes for pepsin is

A. in the cells of the stomach, but not in the cells of the small intestine

B. expressed in the stomach but not expressed in the small intestine

C. mutated in the small intestine

D. digested by the trypsin in the small intestine

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.

Therefore, the Correct Answer is B.

Q #1: After food enters the small intestine, lipases, proteases, and amylases are secreted into the small intestine by the

A. liver

B. gallbladder

C. salivary glands

D. pancreas

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.
Q #2: Salmonella bacteria can cause humans to have stomach cramps, vomiting, diarrhea, and fever. The effect these bacteria have on humans indicates that Salmonella bacteria are

A. predators

B. pathogenic organisms

C. parasitic fungi

D. decomposers

Answer Explanation

B) pathogenic organisms

- Correct: Salmonella bacteria are pathogenic organisms, meaning they can cause disease in humans and other animals. When ingested, Salmonella bacteria can lead to symptoms such as stomach cramps, vomiting, diarrhea, and fever. Salmonella infection, known as salmonellosis, is a common cause of foodborne illness, often associated with the consumption of contaminated food, particularly undercooked poultry, eggs, and unpasteurized dairy products.

A) predators

- Incorrect: Predators are organisms that hunt, kill, and consume other organisms for food. Salmonella bacteria are not predators; they do not actively hunt and consume other organisms.

C) parasitic fungi

- Incorrect: Salmonella bacteria are not parasitic fungi. Parasitic fungi are fungi that derive nutrients from living organisms, often causing harm or disease. Salmonella bacteria are a distinct type of pathogenic bacteria, not fungi.

D) decomposers

- Incorrect: Decomposers are organisms that break down and feed on dead organic matter, aiding in the process of decomposition. Salmonella bacteria are not decomposers; they are pathogenic bacteria that can cause illness in humans and animals.
Q #3: The absorptive surface of the small intestine is greater than that of other human digestive organs because of its length and the presence of

A. alveoli

B. neurons

C. villi

D. nephrons

Answer Explanation

C) villi

- Correct: The absorptive surface of the small intestine is greatly increased due to the presence of villi. Villi are finger-like projections that line the inner surface of the small intestine. These structures greatly increase the surface area available for absorption. Each villus contains capillaries and lacteals (lymphatic vessels) that absorb nutrients from digested food. The large surface area provided by the villi allows for more efficient absorption of nutrients such as carbohydrates, proteins, fats, vitamins, and minerals.

A) alveoli

- Incorrect: Alveoli are tiny air sacs in the lungs where gas exchange occurs during respiration. They are not found in the digestive system and do not contribute to the absorptive surface of the small intestine.

B) neurons

- Incorrect: Neurons are nerve cells that transmit signals throughout the body, including the digestive system. While neurons play a role in regulating digestion and other digestive processes, they do not directly contribute to the absorptive surface of the small intestine.

D) nephrons

- Incorrect: Nephrons are the functional units of the kidneys responsible for filtering blood and producing urine. They are not part of the digestive system and do not contribute to the absorptive surface of the small intestine.

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The enzyme pepsin is produced in the cells of the stomach but not in the cells of the small intestine. The small intestine produces a different enzyme, trypsin. The reason that the stomach and small intestine produce different enzymes is that the gene that codes for pepsin is

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