In which individual does negative nitrogen balance occur?
- A. Adult who engages in a weight-training program.
- B. Woman who is pregnant or lactating.
- C. Child who is growing.
- D. Older adult with anorexia.
Correct Answer: D
Rationale: Negative nitrogen balance occurs when the body loses more nitrogen than it gains. This imbalance is often seen in conditions like anorexia in older adults, where insufficient protein intake leads to muscle breakdown and negative nitrogen balance. Choices A, B, and C do not typically lead to negative nitrogen balance as seen in anorexia in older adults.
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What can excessive intakes of dietary protein do?
- A. cause vitamin deficiencies.
- B. impair kidney function.
- C. increase weight loss.
- D. decrease production of indispensable amino acids.
Correct Answer: B
Rationale: Excessive intake of dietary protein can lead to impaired kidney function over time. Excessive protein consumption can put a strain on the kidneys as they work to eliminate the byproducts of protein metabolism. This can potentially lead to kidney damage. Choices A, C, and D are incorrect. Excessive protein intake is not directly linked to causing vitamin deficiencies, increasing weight loss, or decreasing the production of indispensable amino acids.
Which of the following is an example of a plasma protein?
- A. Collagen.
- B. Myosin.
- C. Albumin.
- D. Phospholipid.
Correct Answer: C
Rationale: The correct answer is C, albumin. Albumin is a plasma protein that plays a crucial role in maintaining fluid balance in the blood. Collagen (choice A) is a structural protein found in connective tissues, not a plasma protein. Myosin (choice B) is a protein involved in muscle contraction, not found in the blood plasma. Phospholipid (choice D) is a type of lipid molecule, not a protein present in plasma.
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.
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.
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.