The disease caused by the protozoan Entamoeba histolytica is: MCQ with Answer and Explanation

Explanation:
Vasoactive Intestinal Peptide (VIP) is a 28-amino acid neuropeptide that acts as a neurotransmitter and a hormone. In the gastrointestinal tract, its primary functions are stimulatory and relaxant: it stimulates the secretion of water and electrolytes into the intestinal lumen (acting as a secretagogue), relaxes the smooth muscle of the gut (including the lower esophageal sphincter, stomach, and gall bladder), and stimulates the pancreas to secrete a bicarbonate-rich juice. It also causes vasodilation in the gut. Excessive VIP secretion can lead to severe watery diarrhea (as in VIPoma).

Explanation:
Restriction enzymes recognize specific palindromic sequences and cleave the DNA backbone, producing sticky or blunt ends for cloning.

Explanation:
The liver converts toxic ammonia (from amino acid deamination) into less toxic urea via the urea cycle (ornithine cycle) in hepatocytes. Urea is then excreted by the kidneys. The kidneys filter urea but do not produce it. Pancreas produces enzymes/hormones, spleen filters blood.