How many amino acids are essential?

Correct Answer: C

Rationale: The correct answer is C: 9. There are 9 essential amino acids that the body cannot synthesize and must be obtained through the diet. These 9 amino acids are histidine, isoleucine, leucine, lysine, methionine, phenylalanine, threonine, tryptophan, and valine. Choices A, B, and D are incorrect as they do not represent the correct number of essential amino acids.

Correct Answer: A

Rationale: Soluble fibers can indeed be fermented by gut bacteria in the large intestine, leading to the production of beneficial short-chain fatty acids. This fermentation process is important for gut health and provides various health benefits. Therefore, the statement is true. Choice B is incorrect as it contradicts the known scientific fact that soluble fibers can be broken down by gut bacteria through fermentation.

Correct Answer: A

Rationale: The correct answer is A: Iron. Iron is an essential nutrient needed by the body to make hemoglobin, the protein in red blood cells that carries oxygen. While other nutrients like vitamin B12, niacin, and folate are important for various bodily functions, they are not directly involved in the production of hemoglobin. Vitamin B12 is essential for nerve function and DNA synthesis, niacin is important for metabolism, and folate is crucial for cell division and DNA synthesis. Therefore, only iron is specifically required for hemoglobin production.

Correct Answer: C

Rationale: The correct answer is Vitamin B3, also known as Niacin. Niacin is essential for energy metabolism and can help improve cholesterol levels. Vitamin B1 is Thiamine, Vitamin B2 is Riboflavin, and Vitamin B12 is Cobalamin. These vitamins have different functions in the body and are not synonymous with Niacin.

Correct Answer: C

Rationale: The correct answer is C, leptin. Leptin is a hormone produced by fat cells that helps regulate energy balance by suppressing hunger, thus aiding in the regulation of body fat. Glucagon (choice A) is a hormone that raises blood glucose levels, ghrelin (choice B) stimulates appetite, and insulin (choice D) regulates blood sugar levels and promotes glucose uptake.