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Which of these nutrients is absorbed mainly in the duodenum?

A. glucose

B. iron

C. sodium

D. water

Answer Explanation:

b) iron

- Correct: Iron is mainly absorbed in the duodenum, particularly in its proximal portion. Iron absorption occurs through active transport mechanisms facilitated by specialized transport proteins in the duodenal epithelial cells. Once absorbed, iron can be transported into the bloodstream and utilized for various physiological functions, including the production of hemoglobin and other iron-containing proteins.

a) glucose

- Incorrect: Glucose is primarily absorbed in the small intestine, but its absorption occurs mainly in the jejunum and ileum rather than the duodenum. Glucose is absorbed through facilitated diffusion and active transport mechanisms in the epithelial cells lining the small intestine.

c) sodium

- Incorrect: Sodium is absorbed throughout the small intestine, including the duodenum, jejunum, and ileum. Its absorption occurs through active transport mechanisms in the epithelial cells lining the intestinal mucosa, primarily in conjunction with glucose and other nutrients.

d) water

- Incorrect: Absorption of water indeed takes place in the large intestine, particularly in the colon.

Therefore, the Correct Answer is B.

More Questions on TEAS 7 Science

  • Q #1: If no carbohydrate ingestion occurs in the body during a 24-hour period, liver activity provides for the body's needs by

    A. emulsification

    B. manufacturing more bile

    C. converting glycogen into glucose

    D. releasing iron

    Answer Explanation

    C) converting glycogen into glucose

    - Correct: When no carbohydrate ingestion occurs in the body during a 24-hour period, the liver can provide for the body's glucose needs by converting stored glycogen into glucose through a process known as glycogenolysis. Glycogen is a polysaccharide that serves as a storage form of glucose in the liver and muscles. When blood glucose levels decrease, such as during fasting or low carbohydrate intake, the liver breaks down glycogen into glucose molecules, which are then released into the bloodstream to maintain blood glucose levels and provide energy to cells throughout the body.

    A) emulsification

    - Incorrect: Emulsification is a process by which bile breaks down large fat globules into smaller droplets to aid in fat digestion in the small intestine. It is not related to the liver's role in glucose metabolism.

    B) manufacturing more bile

    - Incorrect: The liver produces bile continuously, regardless of carbohydrate ingestion. While the liver's production of bile is important for fat digestion and absorption, it is not directly related to glucose metabolism.

    D) releasing iron

    - Incorrect: The liver is involved in storing and regulating iron levels in the body, but releasing iron is not directly related to providing for the body's glucose needs in the absence of carbohydrate ingestion.

  • 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: Into which parts of the human digestive system are digestive enzymes secreted?

    A. mouth, esophagus, stomach

    B. stomach, small intestine, large intestine

    C. mouth, stomach, small intestine

    D. esophagus, stomach, large intestine

    Answer Explanation

    A) Mouth, Esophagus, Stomach: This option is incorrect because while saliva in the mouth does contain digestive enzymes (such as amylase for breaking down carbohydrates), the esophagus is not a site of enzyme secretion. The stomach secretes gastric juices which primarily contain hydrochloric acid and pepsinogen (which is converted to pepsin, a protein-digesting enzyme), but the esophagus itself does not secrete digestive enzymes.

    B) Stomach, Small Intestine, Large Intestine: This option is incorrect because while both the small intestine and the large intestine play crucial roles in digestion and absorption, enzyme secretion mainly occurs in the stomach and small intestine. The large intestine primarily absorbs water and salts and does not secrete digestive enzymes.

    C) Mouth, Stomach, Small Intestine: This option is correct. Enzymes are secreted in the mouth (amylase), stomach (pepsin for protein digestion), and small intestine (various enzymes including pancreatic enzymes like lipase, protease, and amylase, as well as enzymes produced by the intestinal lining).

    D) Esophagus, Stomach, Large Intestine: This option is incorrect because while the stomach does secrete digestive enzymes, the esophagus and large intestine do not. The large intestine primarily absorbs water and salts and does not secrete digestive enzymes.