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In humans, chemical digestion is accomplished

A. by enzyme action that begins in the mouth and ends in the

B. esophagus

C. stomach

D. small intestine

Answer Explanation:

C) small intestine

- Correct: Chemical digestion in humans is a complex process involving various enzymes acting on different nutrients. While digestion does begin in the mouth with the action of enzymes like salivary amylase on carbohydrates, the majority of chemical digestion occurs in the small intestine. Enzymes secreted by the pancreas (such as pancreatic amylase, lipase, and proteases) and the small intestine itself (such as maltase, sucrase, lactase, and peptidases) break down carbohydrates, fats, and proteins into smaller molecules. Additionally, bile salts produced by the liver and stored in the gallbladder aid in the emulsification and digestion of fats in the small intestine. Therefore, chemical digestion largely concludes in the small intestine before nutrients are absorbed into the bloodstream.

A) esophagus

- Incorrect: The esophagus is primarily involved in the mechanical process of swallowing, which pushes food down into the stomach. While some minor enzymatic activity may occur due to saliva coating the food during swallowing, significant chemical digestion does not occur in the esophagus.

B) stomach

- Incorrect: While the stomach does play a role in chemical digestion, particularly in the breakdown of proteins by the enzyme pepsin and the denaturation of proteins by hydrochloric acid, the majority of chemical digestion occurs in the small intestine. The stomach mainly serves to mechanically churn food and begin the process of protein digestion.

D) gallbladder

- Incorrect: The gallbladder stores and releases bile produced by the liver, which aids in the emulsification and digestion of fats in the small intestine. However, the gallbladder itself is not directly involved in chemical digestion, and the majority of digestive enzymes are not secreted or stored in the gallbladder.

Therefore, the Correct Answer is C.

More Questions on TEAS 7 Science

  • Q #1: The pancreas is an organ connected to the digestive tract of humans by a duct (tube) through

    A. which digestive enzymes flow. These enzymes are important to the digestive system because

    B. they

    C. form proteins needed in the stomach

    D. form the acids that break down food

    Answer Explanation

    The enzymes secreted by the pancreas play a crucial role in the digestion process by breaking down various nutrients, such as carbohydrates, proteins, and fats, into smaller molecules.

    These smaller molecules are then absorbed through the walls of the small intestine into the bloodstream and subsequently transported to cells throughout the body for energy production, growth, and repair.

    Therefore, these enzymes are essential for converting complex food substances into molecules that can be utilized by the body's cells for various metabolic processes.

  • Q #2: Hardened deposits of cholesterol that accumulate in the structure that stores bile are known as

    A. gallstones

    B. ulcers

    C. goiters

    D. allergies

    Answer Explanation

    A) gallstones

    - Correct: Hardened deposits of cholesterol that accumulate in the structure that stores bile, which is the gallbladder, are known as gallstones. Gallstones can also contain other substances, such as bilirubin or calcium salts, in addition to cholesterol. These stones can vary in size and may cause symptoms such as abdominal pain, nausea, and jaundice. In severe cases, gallstones may require medical intervention, including surgery, to remove them.

    B) ulcers

    - Incorrect: Ulcers are sores or lesions that develop in the lining of the digestive tract, commonly in the stomach (gastric ulcers) or the upper part of the small intestine (duodenal ulcers). They are not related to hardened deposits of cholesterol in the gallbladder.

    C) goiters

    - Incorrect: Goiters are abnormal enlargements of the thyroid gland in the neck. They can be caused by iodine deficiency, thyroid disorders, or other factors, but they are not related to gallstones.

    D) allergies

    - Incorrect: Allergies are immune responses to specific substances (allergens) that the body perceives as harmful, leading to symptoms such as sneezing, itching, or anaphylaxis. They are not related to hardened deposits of cholesterol in the gallbladder.

  • Q #3: Which components of the human diet contain the greatest amounts of sugars and starches?

    A. meat and eggs

    B. fruits and vegetables

    C. minerals and milk

    D. water and vitamins

    Answer Explanation

    B) fruits and vegetables

    - Correct: Fruits and vegetables contain the greatest amounts of sugars and starches in the human diet. Both fruits and vegetables are rich sources of carbohydrates, including natural sugars, fiber, and starches. These carbohydrates provide a readily available source of energy for the body. Examples of fruits with natural sugars include apples, bananas, and grapes, while starch-containing vegetables include potatoes, corn, and peas.

    A) meat and eggs

    - Incorrect: Meat and eggs are primarily sources of proteins and fats, not sugars and starches. They contain minimal amounts of carbohydrates.

    C) minerals and milk

    - Incorrect: Minerals are inorganic compounds essential for various physiological functions, and milk is a source of proteins, fats, and carbohydrates (mainly lactose, a sugar). While milk contains some sugars, fruits and vegetables typically contribute more significant amounts of sugars and starches to the diet.

    D) water and vitamins

    - Incorrect: Water and vitamins are essential components of the diet, but they do not contain sugars and starches. Water is a vital component for hydration, and vitamins are organic compounds required for various biochemical processes in the body.