Which cells in the islet of the pancreas are responsible for synthesizing insulin?

Correct Answer: B

Rationale: Beta cells in the islets of Langerhans in the pancreas are responsible for the production and secretion of insulin, which is crucial for regulating blood glucose levels. Alpha cells, on the other hand, produce glucagon, a hormone that raises blood glucose levels. Gamma cells and Delta cells do not exist in the islets of Langerhans; therefore, they are incorrect choices.

Correct Answer: B

Rationale: The correct answer is B. The classification of the 20 common amino acids is not based on the properties of their side chains, but rather on the structure of their amino and carboxyl groups. These groups are consistent among all amino acids, while the side chains, also known as R groups, are what vary and give each amino acid its unique properties. Choice A is correct because proteins are indeed composed of amino acids. Choice C is incorrect because while the side chains of amino acids can vary, the general structure of an amino acid - a central carbon atom bonded to an amino group, a carboxyl group, a hydrogen atom, and a side chain - is consistent. Choice D is correct because amino acids do polymerize to form long chains called polypeptides, which can then fold into complex shapes to form proteins.

Correct Answer: A

Rationale: The first statement is correct as bacterial plaque can indeed metabolize sucrose, lactose, and fructose. However, the second statement is inaccurate. Fructose, despite being found naturally in honey and known also as levulose, is not less cariogenic than either sucrose or lactose. This means that its consumption does not result in fewer cavities or tooth decay. Therefore, the correct answer is that bacterial plaque can metabolize these sugars, but fructose is not less cariogenic. Choices B, C, and D are incorrect because they either wrongly assert that bacterial plaque cannot metabolize these sugars or wrongly claim that fructose is less cariogenic.

Correct Answer: D

Rationale: Prevident is indicated for all the situations listed in the choices. It is recommended for patients with a high risk of caries to reduce the risk of tooth decay. It is also used in dental procedures like crown and bridge work to strengthen enamel and prevent cavities. Furthermore, it is utilized for orthodontic decalcification to aid in remineralizing the tooth structure and prevent further damage. Therefore, the correct answer is 'All of the above.' While choices A, B, and C are individually correct, selecting 'All of the above' is the most appropriate as it encompasses all the possible indications for Prevident.

Correct Answer: A

Rationale: The correct answer is 'A: Avoid giving the infant nighttime bottles' because prolonged exposure to sugars in milk during the night can lead to caries. Options 'B: Have the infant drink pasteurized skim milk' and 'D: Give the infant fruit juice to drink' are not recommended as they contain sugars that can cause cavities, especially in infants. Option 'C: Feed the infant iron-rich foods' is incorrect because while a balanced diet is important, iron-rich foods do not directly prevent caries development.