How is the enzyme trypsin activated?
- A. By zymogen.
- B. By bile.
- C. By gastrin.
- D. By enterokinase.
Correct Answer: D
Rationale: The correct answer is D: By enterokinase. Trypsin is activated by enterokinase, an enzyme secreted by the small intestine. Enterokinase plays a crucial role in converting trypsinogen into its active form, trypsin. Choices A, B, and C are incorrect because trypsin is specifically activated by enterokinase, not by zymogen, bile, or gastrin.
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Infections are common in people who have inadequate protein intake because of an insufficient quantity of:
- A. insulin.
- B. lipoprotein.
- C. antibodies.
- D. albumin.
Correct Answer: C
Rationale: Inadequate protein intake can lead to a decrease in antibody production, making individuals more susceptible to infections. Insulin (Choice A) is a hormone involved in regulating blood sugar levels, not related to protein intake. Lipoprotein (Choice B) is a type of lipid-protein complex involved in lipid transport, not directly related to antibody production. Albumin (Choice D) is a protein that helps maintain oncotic pressure and carries various substances in the blood, but it is not primarily responsible for fighting infections like antibodies.
What is the most prevalent dietary disaccharide?
- A. Lactose
- B. Fructose
- C. Sucrose
- D. Galactose
Correct Answer: C
Rationale: Sucrose is the correct answer as it is the most common disaccharide found in the diet, commonly known as table sugar. Lactose is a disaccharide found in dairy products, not as prevalent in the overall diet as sucrose. Fructose is a monosaccharide commonly found in fruits and honey, not a disaccharide. Galactose is a monosaccharide commonly found in dairy products and is not the most prevalent dietary disaccharide.
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.
In an analysis of the amino acid composition of foods, the amino acid occurring in the smallest amount is called:
- A. indispensable.
- B. dispensable.
- C. complementary.
- D. limiting.
Correct Answer: D
Rationale: The correct answer is D, 'limiting.' In the analysis of the amino acid composition of foods, the amino acid that occurs in the smallest amount is referred to as the limiting amino acid. This term is used because when one essential amino acid is deficient, it limits the synthesis of proteins, making it crucial in determining protein quality. Choices A, B, and C are incorrect. 'Indispensable' and 'dispensable' refer to the essentiality of amino acids, and 'complementary' does not describe the concept of the amino acid occurring in the smallest amount.
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.
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