Which nutrient has a protein-sparing effect?
- A. Glycerol
- B. Carbohydrate
- C. Nitrogen
- D. Fatty acids
Correct Answer: B
Rationale: Carbohydrates have a protein-sparing effect, meaning that adequate carbohydrate intake can prevent the use of protein for energy. Glycerol, nitrogen, and fatty acids do not have a protein-sparing effect. Glycerol is a component of fats and oils, nitrogen is a component of proteins, and fatty acids are used primarily as an energy source.
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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.
Proteins from plant sources such as grains, nuts, and legumes are classified as:
- A. incomplete.
- B. complete.
- C. indispensable.
- D. dispensable.
Correct Answer: A
Rationale: The correct answer is A: 'incomplete.' Proteins from plant sources like grains, nuts, and legumes are considered incomplete because they often lack one or more essential amino acids required by the body. Choice B, 'complete,' is incorrect because complete proteins contain all essential amino acids in adequate amounts. Choice C, 'indispensable,' is incorrect as it refers to essential amino acids rather than the classification of plant proteins. Choice D, 'dispensable,' is also incorrect as it implies that these proteins are not necessary, which is not the case.
Which of the following enzymes is found in pancreatic secretions?
- A. Rennin
- B. Pepsin
- C. Chymotrypsin
- D. Casein
Correct Answer: C
Rationale: Chymotrypsin is an enzyme found in pancreatic secretions that plays a role in protein digestion. Rennin is primarily found in the stomach and is involved in milk digestion. Pepsin is also a stomach enzyme that aids in protein breakdown. Casein is a protein found in milk, not an enzyme involved in pancreatic secretions. Therefore, the correct answer is Chymotrypsin.
Proteins are absorbed primarily in the form of:
- A. fatty acids.
- B. disaccharides.
- C. amino acids.
- D. polypeptides.
Correct Answer: C
Rationale: The correct answer is C: amino acids. Proteins are broken down by digestive enzymes into amino acids before being absorbed in the small intestine. Amino acids are the building blocks of proteins and are the form in which they are primarily absorbed. Choice A (fatty acids) is incorrect as fatty acids are the end products of fat digestion, not protein digestion. Choice B (disaccharides) is incorrect because disaccharides are sugars that are broken down into monosaccharides, not proteins. Choice D (polypeptides) is incorrect as proteins are broken down into amino acids and not absorbed as polypeptides.
How many amino acids are considered indispensable or essential?
- A. 9
- B. 10
- C. 12
- D. 14
Correct Answer: A
Rationale: The correct answer is A: 9. Nine amino acids are considered essential or indispensable because they cannot be synthesized by the body and must be obtained through the diet. These amino acids include histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Choices B, C, and D are incorrect as the number of essential amino acids is specifically 9, as they are crucial for various bodily functions.