Vitamins co-transported with Na^+ include all except:

Correct Answer: B

Rationale: Folate is absorbed via a proton-coupled transporter, not Na^+-dependent like thiamine, niacin, riboflavin, and pyridoxine.

Correct Answer: A

Rationale: The esophagus lacks BER, relying on peristalsis triggered by swallowing, unlike other GIT segments.

Correct Answer: C

Rationale: The actual structural unit that secretes insulin is the beta cell. Beta cells are found on the islets of Langerhans, which are in the pancreas.

Correct Answer: C

Rationale: The pancreas acts as an endocrine gland, secreting insulin directly into the bloodstream, and an exocrine gland, secreting digestive enzymes through ducts.

Correct Answer: B

Rationale: Synaptic signalling involves neurons releasing neurotransmitters at synapses to affect nearby neurons, which is a rapid and localized process.