Which compound is necessary for emulsification of fat in the body?
- A. Bile salts
- B. Cholecystokinin
- C. Chyme
- D. Trypsin
Correct Answer: A
Rationale: Bile salts are essential for emulsifying fats in the body. They break down fats into smaller droplets, increasing the surface area for enzymes to work on during digestion. Cholecystokinin is a hormone that stimulates the release of bile and pancreatic enzymes, but it is not directly involved in emulsification. Chyme is the semi-fluid mass of partly digested food that moves from the stomach to the small intestine and does not play a role in emulsifying fats. Trypsin is an enzyme produced by the pancreas that acts on proteins, not fats.
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Pepsinogen secreted by the gastric cells is converted into pepsin by:
- A. enterokinase
- B. hydrochloric acid
- C. gastric lipase
- D. pancreatic lipase
Correct Answer: B
Rationale: Pepsinogen is converted into its active form, pepsin, by hydrochloric acid in the stomach. Hydrochloric acid helps in unfolding the pepsinogen molecule to transform it into pepsin, which is crucial for protein digestion. Therefore, the correct answer is hydrochloric acid (choice B). Enterokinase (choice A) is an enzyme produced in the small intestine that activates trypsinogen into trypsin, not pepsinogen. Gastric lipase (choice C) is an enzyme that digests fats, not involved in converting pepsinogen to pepsin. Pancreatic lipase (choice D) is an enzyme produced by the pancreas that aids in breaking down fats in the small intestine, not part of the process of pepsin activation.
How can cholesterol absorption be decreased?
- A. Vitamin K.
- B. Plant sterols.
- C. Trans fats.
- D. Phospholipids.
Correct Answer: B
Rationale: The correct answer is B: Plant sterols. Plant sterols can reduce cholesterol absorption by competing with cholesterol for absorption sites. Vitamin K, choice A, does not have a significant impact on cholesterol absorption. Trans fats, choice C, are known to increase cholesterol levels rather than decrease absorption. Phospholipids, choice D, play a role in cell structure and are not directly involved in reducing cholesterol absorption.
What group makes each amino acid unique?
- A. Radical group
- B. Amino group
- C. Carboxyl group
- D. Peptide bond
Correct Answer: A
Rationale: The correct answer is the radical group (R-group) because it is the unique side chain that differentiates each amino acid. The amino group (choice B) and carboxyl group (choice C) are functional groups common to all amino acids but do not make them unique. The peptide bond (choice D) is the bond formed between amino acids in a protein chain, not the group that makes each amino acid unique.
Two amino acids are chemically joined by a:
- A. double bond.
- B. hydrogen bond.
- C. carboxyl bond.
- D. peptide bond.
Correct Answer: D
Rationale: The correct answer is D, peptide bond. A peptide bond is formed through a dehydration synthesis reaction between the amine group of one amino acid and the carboxyl group of another amino acid. This bond is crucial in protein synthesis. Choices A, B, and C are incorrect. A double bond involves sharing two pairs of electrons, a hydrogen bond is a weak attraction between a hydrogen atom and an electronegative atom, and a carboxyl bond is not a common term in biochemistry.
Which type of carbohydrate helps maintain normal blood glucose levels during fasting periods?
- A. Glucose
- B. Galactose
- C. Dextrins
- D. Glycogen
Correct Answer: D
Rationale: The correct answer is glycogen. Glycogen is a type of carbohydrate stored in the body that is broken down into glucose to help maintain blood glucose levels during fasting periods. Glucose (choice A) is the simplest form of sugar and is a product of carbohydrate digestion, not the stored form like glycogen. Galactose (choice B) is a monosaccharide found in dairy products. Dextrins (choice C) are intermediate products of starch digestion and not directly involved in maintaining blood glucose levels during fasting.