How many amino acids are considered indispensable or essential?

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.

Correct Answer: B

Rationale: The correct answer is B, 'dispensable.' Dispensable amino acids are those that the body can synthesize in sufficient amounts, so they are not required to be obtained from the diet. Indispensable amino acids, on the other hand, are essential and must be obtained from the diet because the body cannot produce them in sufficient quantities. Choices C and D, 'simple' and 'complex,' are incorrect as they do not accurately describe amino acids in terms of synthesis by the body.

Correct Answer: A

Rationale: The correct answer is A: act as buffers. Amino acids can act as buffers by helping to maintain the pH balance in the body. Choice B is incorrect because amino acids do not primarily facilitate glucose storage. Choice C is incorrect as amino acids do not regulate the heartbeat. Choice D is also incorrect because amino acids do not control the level of blood cholesterol.

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: 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.