The gallbladder contracts in response to

Correct Answer: B

Rationale: The gallbladder contracts in response to cholecystokinin and vagal stimulation. Cholecystokinin is released in response to the presence of fatty acids and amino acids in the duodenum, signaling the gallbladder to contract and release bile. Vagal stimulation also plays a role in gallbladder contraction by transmitting signals from the brain to the gallbladder. Secretin is primarily involved in stimulating pancreatic secretion, not gallbladder contraction. A low pH of chyme does not directly stimulate gallbladder contraction.

Correct Answer: D

Rationale: Correct Answer: D Rationale: Salivary amylase primarily digests carbohydrates in the oral cavity, breaking down starch into simpler sugars like maltose. It does not directly target the dextran film on tooth enamel formed from dietary sucrose. This film is typically broken down by dental plaque bacteria, not salivary amylase. Therefore, option D is incorrect. Summary of Incorrect Choices: A: This statement is correct. Chewing and swallowing do require energy expenditure. B: This statement is correct. Swallowing involves the coordinated action of multiple muscle groups. C: This statement is correct. The biofilm on tooth enamel contains enzymes from both saliva and bacteria, contributing to oral digestion.

Correct Answer: B

Rationale: The correct answer is B: Schwann cells and oligodendrocytes. Schwann cells produce myelin in the peripheral nervous system, while oligodendrocytes produce myelin in the central nervous system. Myelin insulates nerve axons, allowing for saltatory conduction, greatly increasing the speed of transmission. Nodes of Ranvier are gaps in the myelin sheath where action potentials are regenerated, not where myelin is produced. Neurons themselves do not produce myelin. Astrocytes and ependymal cells have supportive roles in the nervous system but do not produce myelin.

Correct Answer: D

Rationale: Step-by-step rationale: 1. FOXO1 activates genes related to greater longevity by regulating stress responses and promoting cell survival. 2. Caloric restriction activates FOXO1 to promote cellular stress resistance and increase lifespan. 3. Increased insulin signaling deactivates FOXO1, leading to decreased stress resistance and potentially shorter lifespan. 4. Therefore, all the statements (A, B, and C) are true regarding the protein FOXO1. It plays a crucial role in longevity through gene regulation, is activated by caloric restriction, and is deactivated by increased insulin signaling.

Correct Answer: B

Rationale: Failed to generate a rationale of 500+ characters after 5 retries.