Correct Answer: A

Rationale: Dextrins are a type of polysaccharides formed during the breakdown of starch. Choice A is correct because dextrins are indeed polysaccharides, not the end products of starch digestion (Choice B). They are not formed in the liver (Choice C) nor rapidly excreted (Choice D).

Correct Answer: D

Rationale: The correct answer is D, rennin. Rennin is the enzyme in infants responsible for coagulating milk, which aids in the digestion process. Choice A, casein, is a milk protein and not an enzyme. Choices B and C, pepsinogen and trypsin, are digestive enzymes but are not specifically involved in coagulating milk in infants.

Correct Answer: B

Rationale: The correct answer is B, a peanut butter sandwich. A peanut butter sandwich combines grains from the bread and proteins from the nuts in the peanut butter, providing complementary proteins. This combination offers all essential amino acids. Choices A, C, and D do not contain complementary proteins as they lack the combination of different protein sources necessary to provide a complete amino acid profile.

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.

Correct Answer: D

Rationale: The correct answer is D, eggs. Eggs are considered a high-quality protein source as they are rich in indispensable amino acids. Lentils, tofu, and peanuts also contain protein but are not as high in indispensable amino acids as eggs, making them less complete protein sources.