Correct Answer: D

Rationale: The correct answer is D, Maltose. A disaccharide is formed when two monosaccharides are joined together. Glucose, fructose, and galactose are all monosaccharides, not disaccharides. Therefore, they are not examples of disaccharides.

Correct Answer: A

Rationale: The correct answer is A: Low-density lipoprotein (LDL). LDL is often referred to as 'bad cholesterol' because it can lead to plaque buildup in arteries, increasing the risk of cardiovascular disease. High-density lipoprotein (HDL) is considered 'good cholesterol' as it helps remove LDL from the arteries, reducing the risk of cardiovascular issues. Very low-density lipoprotein (VLDL) and chylomicrons are also lipoproteins that transport fats in the bloodstream, but they are not as strongly associated with an increased risk of cardiovascular disease as LDL.

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.

Correct Answer: B

Rationale: Hemoglobin is a protein that carries oxygen in the blood, making it the correct answer. Choice A, Saline, is a salt solution and not a protein. Choice C, Cellulose, is a complex carbohydrate found in the cell walls of plants, not a protein. Choice D, Prostaglandins, are lipid compounds with hormone-like effects, not proteins.

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.