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.

Correct Answer: D

Rationale: The correct term for a vegetarian diet that includes both dairy foods and eggs is 'ovolactovegetarian.' This term specifically indicates the inclusion of eggs ('ovo') and dairy ('lacto') in the diet. Choice A, 'lactovegetarian,' is incorrect because it only includes dairy products without eggs. Choice B, 'vegan,' is incorrect as it excludes all animal products, including dairy and eggs. Choice C, 'semi-vegetarian,' is incorrect as it is a term used for individuals who occasionally eat meat, poultry, or fish but primarily follow a plant-based diet.

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.

Correct Answer: A

Rationale: Albumin is the correct answer. It is a plasma protein that helps maintain osmotic pressure, thereby playing a vital role in regulating fluid balance in the body. Fibrinogen is involved in blood clotting, not fluid balance. Hemoglobin is responsible for oxygen transport in red blood cells, not fluid balance. Collagen is a structural protein found in connective tissues, not directly involved in fluid balance.

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.