The projection from the posterior edge of the soft palate elevates and helps close off the nasopharynx when swallowing. The projection is called the

Correct Answer: C

Rationale: The correct answer is C: uvula. The uvula is a teardrop-shaped projection from the posterior edge of the soft palate that elevates during swallowing to help close off the nasopharynx, preventing food or liquids from entering the nasal cavity. The uvula's contraction is essential for proper swallowing function. A: Buccal fat pad - located in the cheek area, not involved in swallowing or closing off the nasopharynx. B: Epiglottis - a flap of tissue that covers the trachea during swallowing to prevent food from entering the airway, not related to closing off the nasopharynx. D: Palatine tonsil - located on the sides of the throat, important for immune function but not directly involved in swallowing or closing off the nasopharynx.

Correct Answer: D

Rationale: The correct answer is D because the described sequence of events matches the process of swallowing. Raising the larynx and hyoid bone helps to protect the airway, closing the epiglottis prevents food from entering the trachea, closing the soft palate blocks the nasopharynx to prevent food from entering the nasal cavity, and the contraction of the diaphragm and abdominal muscles along with relaxation of the lower esophageal sphincter facilitate the movement of food into the esophagus. This series of actions is characteristic of the swallowing reflex. Choices A, B, and C are incorrect. Low blood glucose levels do not directly trigger the swallowing reflex. Irritation in the GI tract would not lead to the described sequence of events. Bolus entering the larynx or nasopharynx would not be part of the normal swallowing process and would typically trigger the gagging reflex instead.

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: The correct answer is D because glucose and galactose are taken into the epithelial cell by cotransport, where they are coupled with sodium ions. This process maintains a concentration gradient for glucose and galactose to move against. Once inside the cell, they are passed into the interstitial fluid by facilitated diffusion, where transport proteins assist their movement down their concentration gradient. Choices A and B are incorrect because they do not involve active transport, which is necessary to move molecules against their concentration gradient. Choice C is incorrect because active transport requires energy input, whereas facilitated diffusion does not.

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.