Chemical digestion of carbohydrates begins in the

A. esophagus

B. stomach

C. duodenum

D. oral cavity

Answer Explanation:

D. oral cavity

- Correct: Chemical digestion of carbohydrates begins in the oral cavity. Salivary glands in the mouth secrete saliva, which contains an enzyme called amylase. Amylase breaks down complex carbohydrates (such as starch) into simpler sugars (such as maltose) through hydrolysis. This process initiates the digestion of carbohydrates before the food bolus reaches the stomach or small intestine.

A. esophagus

- Incorrect: The esophagus is primarily involved in the propulsion of food from the mouth to the stomach through peristaltic contractions. It does not play a significant role in the chemical digestion of carbohydrates.

B. stomach

- Incorrect: While the stomach plays a role in the digestion of proteins through the action of gastric juices containing pepsin and hydrochloric acid, it does not contribute significantly to the digestion of carbohydrates. In fact, the acidic environment of the stomach may temporarily inhibit the activity of salivary amylase.

C. duodenum

- Incorrect: The duodenum is the first part of the small intestine where the majority of chemical digestion occurs. While the duodenum receives pancreatic enzymes and bile that aid in the digestion of carbohydrates, proteins, and fats, the initial chemical digestion of carbohydrates primarily occurs in the oral cavity with the action of salivary amylase.

Therefore, the Correct Answer is D.

Q #1: Which is a function of the liver in human adults?

A. manufacturing red blood cells

B. producing chemical compounds known as auxins

C. storing the carbohydrate reserve glycogen

D. synthesizing the hormone insulin

Answer Explanation

C) storing the carbohydrate reserve glycogen

- Correct: One of the functions of the liver in human adults is storing the carbohydrate reserve glycogen. Glycogen is a polysaccharide that serves as a storage form of glucose in the body. When blood glucose levels are high, such as after a meal, the liver takes up excess glucose and converts it into glycogen for storage. When blood glucose levels drop, such as between meals or during fasting, the liver breaks down glycogen and releases glucose into the bloodstream to maintain blood sugar levels within a normal range.

A) manufacturing red blood cells

- Incorrect: The primary site of red blood cell production (erythropoiesis) in adults is the bone marrow, not the liver. While the liver is involved in the production of blood proteins and components, such as albumin, clotting factors, and plasma proteins, it is not responsible for manufacturing red blood cells.

B) producing chemical compounds known as auxins

- Incorrect: Auxins are a class of plant hormones involved in various physiological processes, such as cell elongation, apical dominance, and root development. They are not produced by the liver in human adults.

D) synthesizing the hormone insulin

- Incorrect: Insulin is a hormone produced by the pancreas, not the liver. Insulin plays a crucial role in regulating blood sugar levels by facilitating the uptake of glucose into cells for energy production or storage. While the liver responds to insulin by regulating glucose metabolism and storage, it does not synthesize insulin itself.
Q #2: Which of these cells secrete hormones?

A. parietal cells

B. mucous neck cells

C. enteroendocrine cells

D. chief cells

Answer Explanation

c) enteroendocrine cells

- Correct: Enteroendocrine cells are specialized cells located in the epithelium of the gastrointestinal tract that secrete hormones. These hormones play various roles in the regulation of digestion, nutrient absorption, and other physiological processes. Examples of hormones secreted by enteroendocrine cells include gastrin, secretin, cholecystokinin (CCK), and ghrelin.

a) parietal cells

- Incorrect: Parietal cells are found in the gastric glands of the stomach and secrete hydrochloric acid (HCl) and intrinsic factor, but they do not secrete hormones.

b) mucous neck cells

- Incorrect: Mucous neck cells are found in the gastric glands of the stomach and secrete mucus, which helps protect the stomach lining from the acidic environment, but they do not secrete hormones.

d) chief cells

- Incorrect: Chief cells are found in the gastric glands of the stomach and secrete pepsinogen, the precursor to the enzyme pepsin, which plays a role in protein digestion. Chief cells do not secrete hormones.
Q #3: Most of the nutrient absorption along the alimentary canal occurs in the

A. ascending colon

B. stomach

C. jejunum

D. ileum

Answer Explanation

C. jejunum

- Correct: Most of the nutrient absorption along the alimentary canal occurs in the jejunum, which is the middle segment of the small intestine. The jejunum has a highly folded inner surface covered with finger-like projections called villi and even smaller microvilli. These structures greatly increase the surface area available for absorption. The epithelial cells lining the villi contain numerous transport proteins and enzymes responsible for absorbing nutrients such as carbohydrates, proteins, fats, vitamins, and minerals into the bloodstream for distribution to the body's cells.

A. ascending colon

- Incorrect: The ascending colon is part of the large intestine (colon) where water and electrolytes are primarily absorbed, but it is not a major site of nutrient absorption.

B. stomach

- Incorrect: While some substances, such as water, electrolytes, alcohol, and certain drugs, can be absorbed in small amounts in the stomach, the stomach is not a major site of nutrient absorption. Its main function is to begin the digestion of proteins and store food temporarily.

D. ileum

- Incorrect: The ileum is the final segment of the small intestine, and while it does participate in nutrient absorption, the majority of nutrient absorption occurs in the jejunum, which precedes the ileum along the alimentary canal. The ileum primarily absorbs bile salts, vitamin B12, and some remaining nutrients not absorbed in the jejunum.

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Chemical digestion of carbohydrates begins in the

More Questions on TEAS 7 Science

Q #1: Which is a function of the liver in human adults?

Answer Explanation

Q #2: Which of these cells secrete hormones?

Answer Explanation

Q #3: Most of the nutrient absorption along the alimentary canal occurs in the

Answer Explanation

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