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In which organ of the human body is urea produced as a result of the breakdown of amino acids?

A. liver

B. pancreas

C. stomach

D. small intestine

Answer Explanation:

A) liver

- Correct: Urea is produced in the liver as a result of the breakdown of amino acids. Amino acids are the building blocks of proteins, and when proteins are metabolized for energy or other purposes, their constituent amino acids are broken down in a process called deamination. During deamination, the amino groups (-NH2) are removed from the amino acids, forming ammonia (NH3). The liver converts ammonia into urea through a series of biochemical reactions known as the urea cycle. Urea is then excreted by the kidneys in the urine, helping to remove nitrogenous waste from the body.

B) pancreas

- Incorrect: The pancreas is an organ involved in the production of digestive enzymes and hormones such as insulin and glucagon. It is not primarily responsible for the production of urea from the breakdown of amino acids.

C) stomach

- Incorrect: The stomach is primarily involved in the mechanical and chemical digestion of food, particularly proteins. While protein digestion begins in the stomach with the action of gastric juices containing enzymes such as pepsin, urea production from the breakdown of amino acids occurs mainly in the liver.

D) small intestine

- Incorrect: The small intestine is primarily involved in the absorption of nutrients from digested food, rather than the production of urea from the breakdown of amino acids. While some amino acids may be absorbed in the small intestine, urea production primarily occurs in the liver.

Therefore, the Correct Answer is A.

More Questions on TEAS 7 Science

  • Q #1: Which of these organs is not considered an accessory digestive structure?

    A. mouth

    B. salivary glands

    C. pancreas

    D. liver

    Answer Explanation

    a) mouth

    - Correct: The mouth is not considered an accessory digestive structure; it is an integral part of the alimentary canal (digestive tract). The mouth is where the process of digestion begins, as food is ingested, chewed, and mixed with saliva. Saliva, produced by the salivary glands, contains enzymes (such as amylase) that initiate the breakdown of carbohydrates. Once food is sufficiently broken down in the mouth, it is formed into a bolus and swallowed, entering the esophagus and continuing its journey through the digestive system.

    b) salivary glands

    - Incorrect: Salivary glands are accessory digestive structures that secrete saliva into the mouth. Saliva contains enzymes and lubricants that aid in the mechanical and chemical digestion of food.

    c) pancreas

    - Incorrect: The pancreas is an accessory digestive structure that plays a crucial role in digestion by producing and secreting digestive enzymes into the small intestine. These enzymes aid in the breakdown of carbohydrates, proteins, and fats.

    d) liver

    - Incorrect: The liver is also an accessory digestive structure that contributes to digestion by producing bile, which is stored in the gallbladder and released into the small intestine to aid in the emulsification and digestion of fats. Additionally, the liver plays a role in processing nutrients absorbed from the small intestine and regulating glucose metabolism.

  • Q #2: Which of the following organs has 3 layers of smooth muscle in its muscularis externa?

    A. small intestine

    B. esophagus

    C. stomach

    D. large intestine

    Answer Explanation

    C. stomach

    - Correct: The stomach has three layers of smooth muscle in its muscularis externa, which is the muscular layer of the gastrointestinal tract responsible for peristalsis and mixing of food. These muscle layers are arranged in longitudinal, circular, and oblique orientations, allowing for the mechanical processing of ingested food and the propulsion of food through the digestive tract. This muscular arrangement contributes to the stomach's ability to churn and mix food with gastric juices during digestion.

    A. small intestine

    - Incorrect: While the small intestine does have smooth muscle in its muscularis externa, it typically has two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.

    B. esophagus

    - Incorrect: The esophagus also has smooth muscle in its muscularis externa, but it typically has two layers of smooth muscle: an inner circular layer and an outer longitudinal layer.

    D. large intestine

    - Incorrect: The large intestine, like the small intestine, typically has two layers of smooth muscle in its muscularis externa: an inner circular layer and an outer longitudinal layer.

  • Q #3: The digestive system breaks down food into:

    A. nutrients

    B. amylase

    C. saliva

    D. sphincters

    Answer Explanation

    a. nutrients

    - Correct: The digestive system breaks down food into nutrients. These nutrients include carbohydrates, proteins, fats, vitamins, minerals, and water, which are essential for various physiological functions in the body. Once broken down into nutrients through mechanical and chemical digestion, these substances are absorbed by the intestines and transported via the bloodstream to cells throughout the body for energy production, growth, repair, and other metabolic processes.

    b. amylase

    - Incorrect: Amylase is an enzyme involved in the digestion of carbohydrates. It is produced by salivary glands in the mouth and by the pancreas and helps break down complex carbohydrates into simpler sugars. While amylase is an important component of the digestive process, it is not the end product of digestion.

    c. saliva

    - Incorrect: Saliva is a fluid secreted by salivary glands in the mouth. It contains water, electrolytes, mucus, and enzymes such as amylase. Saliva helps moisten food, initiate the digestion of carbohydrates, and facilitate swallowing, but it is not the end product of digestion.

    d. sphincters

    - Incorrect: Sphincters are ring-like muscles that control the movement of materials through various parts of the digestive tract by opening and closing. While sphincters play a crucial role in regulating the flow of food and waste through the digestive system, they are not the end products of digestion.